Kirt (Junior Member)
12-22-99 15:48
No 115853
      Difference between Ephedrine and Psudoephedrine?     


I am a beginner to the chemistry field and could someone tell me the difference between Ephedrine and Psudoephedrine? Can a person extract the E needed out of ephedrine as well as he/she can from psudoephedrine? What ingrediants need I look for that I do not want?? Someone, Please? Also, here is a dumb one, what is H2O2?

------------------

I'm out! The Captain

 
 
 
 
    hypo
(Member)
12-22-99 18:59
No 115854
      Re: Difference between Ephedrine and Psudoephedrine?     

E differs from P by configuration on the carbon bearing the OH-group. Since OH group is probably what you want to remove, P is as good as E.

H2O2 is hydrogen peroxide. I suggest that you do not proceed to the experimentation level until you get some chemistry intro.

 
 
 
 
    Kirt
(Junior Member)
12-22-99 22:18
No 115855
      Re: Difference between Ephedrine and Psudoephedrine?     

Hey Hypo, I know my questions sound dumb but I already had a dream and it was a beautiful one! The yeild could use a little improving but the dream was sweet! I just ain't to hip on all the chemcal terms! WHich would be very helpful if I were! So one can extract good e from ephedrine just as well as psudoephidrine? I was told awhile back that the ephedrine pills were not what I wanted! It was the psudo only!
Anyone help me understand Y this would be true?

------------------

I'm out! The Captain

 
 
 
 
    Android
(Member)
12-23-99 13:47
No 115856
      Re: Difference between Ephedrine and Psudoephedrine?     

The only difference that's important to me between the two, is psuedo's readily available where I live. That, and I don't care for the high the Ephedrine reduced meth gives me. Leans more towards the adrenaline and not enough euphoria.
Chemically, they're mirror images of each other. Kinda like a newbee and a gnat.

------------------
"ARROGANT & CYNICAL"
(Ticklish,too!)

 
 
 
 
    mrr pyrex
(Member)
12-23-99 14:32
No 115857
      Re: Difference between Ephedrine and Psudoephedrine?     

Good one Android!!  Gnat and Newbee....Rollin on the floor, pissin uncontrollably :-) Pyrex out of piss
 
 
 
 
    hypo
(Member)
12-24-99 17:02
No 115858
      Re: Difference between Ephedrine and Psudoephedrine?     

E and P are NOT mirror images, damnit! They are epimers, it means they differ in only one stereocenter.
 
 
 
 
    Xtract
(Member)
12-24-99 17:26
No 115859
      Re: Difference between Ephedrine and Psudoephedrine?     

Droid I respect youre opinion are you saying there is a differance in highs? Ive thought for a long time they maybeee way differant. You noticed they took Ephedrine off the market? Why???? Psudo is Psudo i.e. not th....  same not mirror images, Phuck I hate when I cant seee what Ive typed. Do any of you know what they really look like?


Xmenot

 
 
 
 
    Android
(Member)
12-25-99 00:32
No 115860
      Re: Difference between Ephedrine and Psudoephedrine?     

I see no argument with the newbee/gnat theory, wypo. Not certain of you facts, maybe?
Xgnat. Brown nosing will only attract flies. What I'm saying is of no importance. Ask anyone!

------------------
"ARROGANT & CYNICAL"
(Ticklish,too!)

 
 
 
 
    dextram
(Member)
12-25-99 00:50
No 115861
      Re: Difference between Ephedrine and Psudoephedrine?     

That sounds like pretty reputable talk the real question would of course be though will in fact due to the difference in the chirality of the epicentrical OH group will this in fact cause slightly different reactions such that possibly during workup maybe pseudo goes through transition upon the c2 spot and that ephedrine would go through trabsition in the c5 spot irregardless of these activities how many might agree that this in fact is a cyclization event in the benzene ring???

I have some reliable pictures of pseudo and the structure problem is the citation is not so specific in the dfination of the diagrams it appears pseudo forms a bit of a different ester, that the ster is in fact not a benzene ring strugture I dont know enough about different esters to really explain presently but these esters concerned might possibly be esters from that umm stuff a while back umm something explosive it is um found in asprin apparently can be got from asprin, used to make colored crystals to check for MDMA apparently is a process for eluting chemical physical charesterics um posed within the last month I belive, I think polymerization is a real posibility with and strange products whith these methods including many possible amphetamine like substances not all of course should be defined as meth.

 
 
 
 
    anhydrous
(Junior Member)
01-12-00 06:41
No 115862
      Re: Difference between Ephedrine and Psudoephedrine?     

refluxing your psudo will give you 50/50 and old trick of mine
 
 
 
 
    Sky
(Member)
01-12-00 07:22
No 115863
      Re: Difference between Ephedrine and Psudoephedrine?     

I've got DL psudoephadrine from DR. that made much better meth than the OTC shit you can get I know its been Discussed in here I think there are different Isomers in both psudo and Ephadrine. and the shit you get OTC is not going too be the good stuff.
 
 
 
 
    Methamphibian man
(Member)
01-12-00 12:04
No 115864
      Re: Difference between Ephedrine and Psudoephedrine?     

Just an observation: sudafed 12 hour is a pill that has ONLY psudeoephedrine in it with a thin outside coating that is easily scraped and peeled or washed off. it is the cheapest price too!
 
 
 
 
    Yman
(Member)
01-12-00 12:50
No 115865
      Re: Difference between Ephedrine and Psudoephedrine?     

Hey wow,...Android did not really flame us ! and in his own way really did answer our questions. Thanks Wo.... An. Did you see the way Worlock trashed that guy the other day? POor NewBee> Seeyaa.
 
 
 
 
    Xaja
(Member)
01-12-00 12:50
No 115866
      Re: Difference between Ephedrine and Psudoephedrine?     

Yeah but it's got binder shit in it that can make life very difficult. Although you can dissolve it in cold water, filter real quick with a buckner, then heat it. Whole lotta jelly shit comes out. But now the bitch: it won't filter anymore. Jelly shit clogs filters. But for small quantities, heat it in an enamel dish and the jelly shit seems to stick to the enamel. But it really is a bitch. Avoid them if you can.
 
 
 
 
    Snotbrain
(Member)
01-12-00 23:49
No 115867
      Re: Difference between Ephedrine and Psudoephedrine?     

Anhydrous, please explain further your reflux routine. ??  You reflux what, how, to get what??

H2O2 is what it takes to make you blonder, kirt!  

 
 
 
 
    Snotbrain
(Member)
01-13-00 00:44
No 115868
      Re: Difference between Ephedrine and Psudoephedrine?     

I wonder if the reflux accomplishes the same thing as the heating and pressurization referred to in the dwarfer "nickel" thread? (By readyeddie)

do you use acid also: or just water??

snodder

 
 
 
 
    Acme
(Member)
01-13-00 08:51
No 115869
      Re: Difference between Ephedrine and Psudoephedrine?     

This came up in the general forum 3 monthes ago

  posted 10-12-1999 09:03 AM          
--------------------------------------------------------------------------------
This will seem pathetic, but is the d- or l- isomer the desired one, and how exactly is pseudoephedrine different from ephedrine (just stereochemistry or r they consitutionally different)
Also are any of these compounds at all stimulating on there own, or dangerous? (i know of an OTC medicine which is DXM and pseudo, any problems there?)


Acme
Member   posted 10-12-1999 01:58 PM          
--------------------------------------------------------------------------------
Hoping you can deciper this shorthand
They both have the formula
C6H5CH[CH(NHCH3)CH3]OH
they differ in stereochemistry
eph (-) 1R,2S
eph (+) 1S,2R
psu (-) 1R,2R
psu (+) 1S,2S
Not sure which is called d- or l- . It would be a wild guess to say (+) is d im just not sure.
Hopefully some wiser bee can clue us in on which is d or l and which one would be best (for your cold, of course)


CHEM GUY
Member   posted 10-12-1999 02:00 PM          
--------------------------------------------------------------------------------
Slappy, where did you get that info? I'm not questioning you but I just want the reference-
 
CHEM GUY
Member   posted 10-12-1999 09:15 PM          
--------------------------------------------------------------------------------
From Fornsic science international, 48 (1990), 123-34
"...(-) ephedrine or (+) pseudoephedrine yeilds (+) methamphetamine."

From the journal of Forensic science, page 956

"...(-) ephedrine and (+) pseudoephedrine yeild d-methamphetamine"

Therefore (+) methamphetamine is d-methamphetamine.
 

 
 
 
 
    Archaic~Sage
(Member)
01-14-00 11:14
No 115870
      Re: Difference between Ephedrine and Psudoephedrine?     

" Can a person extract the E needed out of
                    ephedrine as well as he/she can from psudoephedrine? "

First off, one cant extract E from ephedrine because E is ephedrine. What you want is the ephedrine or psuedoephedrine that is in common cold pills.

the alkilne ephedrine is the precurser that you use to produce(dreams).
It dosent really matter which you use because they will both work...psuedo is also my fave. because it produces nicer dreams for me...

becareful some pills have crap in them called  a binder that turns into a plastic or rubber shit when you try to extract them...
ruins it and is hard to clean up...

SAGE

 
 
 
 
    Mo Diddly
(Member)
01-16-00 06:12
No 115871
      Re: Difference between Ephedrine and Psudoephedrine?     

Helvetica Chemical Acta 1929 pg 365+ is the best reference that I've ever seen on the subject.  If a library isn't nearby get a plane ticket and go there or have someone get the reference for you.
 
 
 
 
    Blanka
(Member)
01-16-00 07:15
No 115872
      Re: Difference between Ephedrine and Psudoephedrine?     

they took off ephedrine off the market because it raises blood pressure... pseudo lowers it... pseudo is therefore more desirable as a nasal decongestion. What would pills contain that the Ephedra plant wouldn't have to make the resulting meth less potent or what does the plant contain? I BELIEVE the pseudo in pills has the synthetic form that converts to inactive meth making the meth made from pills "cut". what a good way to piss meth cooks off. But either way the plant shit is better... never tried reducing pure ephedrine from pills though.. hard to find... it's usually in the energy pills rather than in the nasal decongestions. Any suggestions to what I can do with the nor-ephedrine that I pulled outta the plantS?
 
 
 
 
    readyeddie
(Member)
01-16-00 07:21
No 115873
      Re: Difference between Ephedrine and Psudoephedrine?     

Snotbrain that is what i think he is talking about.First of all it must be the good pseudo used in this racimazation.The good pseudo is in the sudafed red hots for sure.The cheaper brands seem to be bullshit or fake.Second 25-30% HCL is used.Third you only have to heat not boil it's about the same way you do when you form a ester for the electro but for alot longer of time.Fourth it needs to be in a closed bottle or something to keep steam out and to keep the HCl from evaporating away.A reflux also is suppose to work fine as long as you keep it to a simmer and not a boil.At about 20 hours you will get around a 30 70 mix at 30 hours you will get like a 50 50 mix.It's real simple but takes alot of time.    
 
 
 
 
    Blanka
(Member)
01-16-00 07:32
No 115874
      Re: Difference between Ephedrine and Psudoephedrine?     

can you find the references on that readyeddie? it's the first time I heard it
 
 
 
 
    Blanka
(Member)
01-16-00 07:43
No 115875
      Re: Difference between Ephedrine and Psudoephedrine?     

ephedrine meth vs. psuedo meth (if there is a difference) i don't see that there could be a significant difference that would make experimenting worth the time but you can separate the eph from sudo from the plant by using chloroform which the
 
 
 
 
    Zion
(Member)
01-16-00 07:44
No 115877
      Re: Difference between Ephedrine and Psudoephedrine?     

Agreed the red hots have the best in them, but also some myserious bad stuff that fucks the reaction of your reduction, or eXtraction. The non-name brands dont have as much of the good stuff in em. Like Wor said a few weeks ago. Name brand Sudafed has more of the necassary precursors in it but I think more of the B.S. also. But are we really sure what the differance tween E and Psudo is????? sorry about dis'n you earlier this millenium noteph.
 
 
 
 
    Blanka
(Member)
01-16-00 07:44
No 115876
      Re: Difference between Ephedrine and Psudoephedrine?     

can you find the references on that readyeddie? it's the first time I heard it
 
 
 
 
    Huffalump
( )
01-16-00 08:55
No 115878
      Re: Difference between Ephedrine and Psudoephedrine?     

Android,

Did you use pfed or ephidrine in the electro you posted a while back?  I've got quite a bit of purified pfed right now, and have been working towards an electro.  If there's no hope, I'll just shoot for rp. 

Huffalump

 
 
 
 
    readyeddie
(Member)
01-16-00 08:59
No 115879
      Re: Difference between Ephedrine and Psudoephedrine?     

It all depends on what kind of reduction you do some reductions retain others change.Lets take a look at the lithium in ammonia reduction this method retains.So it does not matter if pseudo or ephedrine is used it will give the same product which is d-meth.The same goes for the ester formula and most hydrogenation methods.Now for the red/p and iodine method this one changes but does so in a good way racimazation occures during reflux the boiling acid changes it to a mix of ld meth.So now on to the reductions that change and racimazation doesn't occure their are a few and their not hard to figure out these you will have to do what?Blanka as i told dwarfer i had to get rid of all my photo copies and books the references or out their.Fester if you should happen to read this would you look it up and post it hear for these bees thanks.
 
 
 
 
    Blanka
(Member)
01-16-00 10:18
No 115881
      Re: Difference between Ephedrine and Psudoephedrine?     

damn.. I hate when I lose my connection during a post... I especially hate when part of the post dissappears or when posts appear 3 times.. anyways... eph and pseudo have two chiral centers. they are both at the first 2 carbon sites of the propane cchain. so what the hell does that mean? it means when you make meth, and one of these chiral centers is removed, you will have one of two possiblilities for the meth (-) or (+) meth... so pseudo and eph can yeild both the good meth and useless meth depending on which "kind" of pseudo or ephedrine you use (+ or -) Ok? you still there.. so when I say I don't think there is gonna be a significant difference, i actually mean that if you try to start with OTC shit that contains eph (plants and some pills) or pseudo (pills) there is gonna be a small difference in what you get at the end because what you are starting with to get the meth is not pure... now which do people prefer?? I think the shit from plants is better. And if we are talking about starting with pure products turning into pure meth, it depends on which pseudo and which eph you are talking about (+ or -). If you compare   -(-) ephedrine and +(-) pseudo, there is no difference in the meth you get, they will both be as good... pure (+) meth. I forgot who posted that since the chiral center is removed you will get the same shit no matter what.. or something to that effect... this is totally incorrect as there as 2 not one chiral centers, on of which is removed when the molecule is reduced to meth.
 
 
 
 
    Blanka
(Member)
01-16-00 10:33
No 115882
      Re: Difference between Ephedrine and Psudoephedrine?     

besides the chirality of the tw molecles, I don't think there is a difference... you can find out for sure if there would be any difference by getting a source of l-eph, d-eph, l-pseudo, and d-pseudo and the recemic eph and pseudo to mess around with but you gotta know for sure what you are starting with.. i can't say for sure because I have never made l-meth but it is stated in many books that the d isomer is more potent. this is a waste of time though cuz i'm pretty sure all the people aren't wrong about l-meth (that it is crap).. after reading what eddy put though, i'm wondering if there is a majik method of racemizing l meth like pseudo was easily racemized... not like it would be of any use since they don't use l-meth in vicks... all these bees up in here and we can't find that stupid ref about heating the eph to 100' to recemize it? anyone know what book eddy is talking about? I don't doubt you though mister ed.. talking horse
 
 
 
 
    Sploofer
( )
01-16-00 11:19
No 115883
      Re: Difference between Ephedrine and Psudoephedrine?     

Whats it mater man agin why be concerned where the oh group might be had at is it looking like this in all of the concerned shit??? COH and the good shit looking like this???ch and semi good shit like this-chh\

So i yes I fuel such arguments these are all know configereations and end results to known methods metamphetamine the l kind is the reult of what aint now known is know to be not l meth at least mosy of the people uptodate do in fact know the vicks is different then orriginally transcribed the shit is hydrated the entire ring is hydrated however mouthwash even if titled simmiliarly could in fact be a different stuff althgether.................................

the vicks shit real vicks is l - meth do you belive this or do ya think it cost maintains about three to five times the price of the other stuff??

The other stuff its the hydrated stuff mainly proaly the entire central ring is hydrated this is not meth eph or pseudo this is mostly a different thing alltogether hummm>?>>

So we will find that a cyclixzzzation process is relivant to all these concerned w/ isomerization certain cyclizations can be had crystaline like at a given stage in process these are very cutting edge typ crystalizations to be shure  DESCRIPTIVE

Anyways thes CRYSATALS THE PROTECTED FORM WOULD GO INTO metabolized as the rotational varity is seemingly likely who knows??

The cyclating benzeene varity of concerning meth in paticuliar is \potent>>>>>>>>>>>>.................

However the amphetamine is less potent and the sulp less potent still more less impoteniated is finding ephedrine adn pseudo ephedrine this is the grand therum to the rationals are eluted that they are discoved lacking man do ya unc=derstand they dint make s seence???

the pseudo if in fat its methylate dlike ephedrine is the same???

Unless in pseudo we got the oh not attacthed to the side carbon but maybe shit attaches and screws up the ring itself this is pseudo shit????????//  Alhough I think some brands are quite real and they have what is not methylated ephedrine this is also pseudo see non wesern society and laws are not foundation to you r therums I cite the japaneezium rationals in the lit at large it is also finding big differences w/ these western fables pseudo is a bunch of varuios shit not paticullarly usefull shit I say a mixture of shit it is to be shure 600 hundred milligrams produced a metabolic and psycholiogical simmily to twently percent that ammount in the lab rats and humas thus tested why even conside r it was anty more to be eluted see it like ephedrine but its gut shit!

 
 
 
 
    Blanka
(Member)
01-16-00 15:02
No 115885
      Re: Difference between Ephedrine and Psudoephedrine?     

the strange thing about l-meth is that when you have the racemate, even though the levo meth is supposed to be crap, the product is more potent than if it were just dextro meth.. it juss doesn't make sense.. it escapes logical reasoning.. any geniuses wanna help me here cuz I'm not anywhere close to being a expert on this stuff
 
 
 
 
    dwarfer
(Member)
01-18-00 05:10
No 115891
      Re: Difference between Ephedrine and Psudoephedrine?     

Well, all in all the one thing I can agree with with certitude is that plants do the best when they make their blend, as far as future processing goes......-MA, +MA, -AMP, +Amp all designed to make molecules which nestle nicely in my synapse: standing on each other's shoulders they can reach the high cupboards where the cookies are stored.

:< )

 
 
 
 
    PolytheneSam
(Master Searcher)
01-25-03 15:55
No 401378
      The article here mentions the RP process with...     

The article here mentions the RP process with ephedrine and gives references to it.  Post 115871 (Mo Diddly: "Re: Difference between Ephedrine and Psudoephedrine?", Stimulants)
It also shows the absolute configurations of each of the four isomers.

http://www.geocities.com/dritte123/PSPF.html
The hardest thing to explain is the obvious
 
 
 
 
    Worlock
(Tweaker God)
01-25-03 18:41
No 401404
      Ephedrine vs Pseudo
(Rated as: good read)
    

Ephedrine from Ma Huang: (-)-ephedrine
 m.p. 35 - 40 °C
 [a]D = -41°
 moderate water solubility

Pseudoephedrine from Ma Huang:(+)-pseudoephedrine
 m.p. 119 °C
 [a]D = +52°
 relatively insoluble in water





http://www.cem.msu.edu/~reusch/VirtualText/sterism3.htm


Worlockium
 
 
 
 
    Rhodium
(Chief Bee)
01-25-03 20:03
No 401416
      Hermann Emde's Ephedrine Chemistry Treatise
(Rated as: excellent)
    

Ephedrine/Pseudoephedrine Stereochemistry, Physical Properties and Reduction to Methamphetamine
Hermann Emde
Helvetica Chimica Acta, Vol. 12, pp 365-376 (1929) (../rhodium/djvu /ephedrine-emde-1.djvu)
____ ___ __ _

(Pseudo)Ephedrine Resolution, Racemisation & Interconversion
Hermann Emde
Helvetica Chimica Acta, Vol. 12, pp 377-384 (1929) (../rhodium/djvu /ephedrine-emde-2.djvu)
____ ___ __ _

(Pseudo)Ephedrine Halogenation to the Corresponding Bromo- and Chloroephedrines by reaction with PX5, SOCl2 or conc. aqueous HX, as well as their hydrolysis back to aminoalcohols.
Hermann Emde
Helvetica Chimica Acta, Vol. 12, pp 384-399 (1929) (../rhodium/djvu /ephedrine-emde-3.djvu)
____ ___ __ _

Reaction of (Pseudo)Ephedrine with sulfuric acid to form a cyclic sulfonamide/sulfuric acid ester (Ephedrine betaine), as well as a discussion of common byproducts
Hermann Emde
Helvetica Chimica Acta, Vol. 12, pp 399-405 (1929) (../rhodium/djvu /ephedrine-emde-4.djvu)
____ ___ __ _

Crystal Symmetry and Diastereomeric Properties of (pseudo)Ephedrines, their Hydriodide salts and Betaines latest addition (06-12-04):
Hermann Emde & Fritz Spaenhauer
Helvetica Chimica Acta, Vol. 13, pp 3-9 (1930) (../rhodium/djvu /ephedrine-emde-5.hca_1930_13_3.djvu)



Note: You need a plugin from http://www.lizardtech.com/download/ to be able to read *.djvu documents.
 
 
 
 
    Rhodium
(Chief Bee)
06-29-03 01:15
No 443176
      More articles about Ephedrine/Pseudoephedrine
(Rated as: excellent)
    

Über die Synthese der isomeren Ephedrine und ihrer Homologen
Wilhelm Nagajosi Nagai - Seïzo Kanao
Liebigs Ann. Chem. 470, 157-182 (1929) (../rhodium/pdf /ephedrine.isomers.nagai-kanao.pdf)

A landmark article about the synthesis of Ephedrine, Pseudoephedrine and all their respective Nor- and N-methyl homologs as well as both the racemic mixtures and the separate optical isomers of each substance, in total 18 1-Phenyl-2-Amino-1-Propanol homolog isomers. In addition to this, the physical properties for all substances (melting points, boiling points, density, refractive index, specific rotation, solubilities, crystal shapes, elemental analysis, and even the mp for 3-7 different salts/derivatives of each isomer is presented (where applicable).

The only error in the article is the assumption that the pseudo-compounds were 1-Phenyl-1-Amino-2-Propanols  [Formula II, p 157] (as they knew that the ordinary ephedrines were 1-Phenyl-2-Amino-1-Propanols  [Formula I, p 157] ).  75 years ago the concept of stereochemistry was not as developed as it is today, and they had no other analytical tools than to observe melting points and crystal shapes, therefore they could not imagine that ephedrine/pseudoephedrine were diastereomers, and thus all four isomers (d-eph, l-eph, d-pseudo, l-psdeudo) had the exactly same structural formula, just with different 3D-orientation (stereochemistry).


Über eine neue Synthese des -Ephedrine
E. Späth - G. Koller
Chem. Ber. 58, 1268-1271 (1925) (../rhodium/pdf /pseudoephedrine.spath-koller.pdf)

A synthesis of pseudoephedrine using the odd route Benzaldehyde  1-Phenyl-1-propanol Propenylbenzene 1-Phenyl-1,2-dibromopropane 1-Phenyl-1-methoxy-2-bromopropane 1-Phenyl-1-methoxy-2-(methylamino)propane   Pseudoephedrine
 
 
 
 
    Rhodium
(Chief Bee)
12-09-03 18:19
No 475656
      Chou: Properties of (pseudo)Ephedrine
(Rated as: good read)
    

Isolation and Properties of Ephedrine and its Salts
T.-Q. Chou
J. Biol. Chem. 70, 109-115 (1926) (../rhodium/chemistry /ephedrine.chou-jbc.html)
____ ___ __ _

Comparison of Ephedrine and Pseudo-Ephedrine From Ma-Huang (Ephedra vulgaris, var. helvetica)
T.-Q. Chou & B. E. Read
Proc. Soc. Exp. Biol. Med. 618-620 (1926) (../rhodium/chemistry /comparison.ephedrines.html)
 
 
 
 
    Rhodium
(Chief Bee)
01-16-04 13:01
No 482808
      Synthesis of all pseudo/ephedrine isomers
(Rated as: excellent)
    

Die Synthesen des Ephedrins, des Pseudoephedrins, ihrer optischen Antipoden und Razemkörper
Ernst Späth und Rudolf Göhring
Monatsh. 41, 319-338 (1920) (../rhodium/pdf /ephedrins.spath.pdf)
____ ___ __ _

Die Konfiguration des Ephedrins
Karl Freudenberg & Fritz Nikolai
Ann. Chem. 510, 223-230 (1934) (../rhodium/pdf /ephedrine.absolute.configuration.pdf)

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Rhodium
(Chief Bee)
07-02-04 18:17
No 516974
      Synthesis of (1S,2S)-pseudoephedrine
(Rated as: excellent)
    

An enantioselective synthesis of (1S,2S)-pseudoephedrine
G. Vidyasagar Reddy, G. Venkat Rao, V. Sreevani and D. S. Iyengar
Tetrahedron Letters 41(6), 953-954 (2000) (../rhodium/chemistry /pseudoephedrine.oxazolidinone.html)

Abstract
Synthesis of (1S,2S)-pseudoephedrine is described via reduction of an alanine-derived oxazolidinone followed by treating with phenyl magnesium bromide and chemoselective N-methylation in an efficient and practical manner.


In recent years there has been considerable interest in the synthesis of optically pure amino alcohols because of their wide occurrence in several biologically active molecules and also their application as chiral building blocks, auxiliaries and ligands in asymmetric synthesis1-2. Among this class, ephedrine and pseudoephedrine have found wide application for a variety of purposes in organic synthesis. Pseudoephedrine, especially, has been used extensively in asymmetric alkylations of corresponding carboxamides3-4. Recently, we have reported chemoselective reduction of N-protected oxazolidinones to the corresponding lactol derivatives and their application in the synthesis of vicinal amino alcohols5. In this paper, we wish to report a new approach for the synthesis of (1S,2S)-pseudoephedrine by using the synthetic potential of our methodology. The key steps involved in the present synthesis are: (i) reduction of the N-Cbz oxazolidinone derived from alanine (2 to 3); (ii) Grignard addition to the lactol to give the amino alcohol (3 to 4); and (iii) chemoselective N-methylation (4 to 8) as shown in Scheme 1.

The oxazolidinone (2)6, readily obtained from N-Cbz-L-alanine (1) by reacting with paraformaldehyde in the presence of catalytic PTSA, was treated with 1 equiv. of sodium borohydride to give the lactol 3 in excellent yield (95%) as a colourless syrup [α]D -2° (c 1, MeOH). Treatment of lactol (3) with phenyl magnesium bromide afforded an inseparable diastereomeric mixture (4 and 5) in 92% combined yield, ratio 95:5 from 1H NMR. The newly created stereocentre in the major isomer 4 was initially assumed to be S by analogy with our earlier related work5, and was confirmed by conversion into the known title compound. To circumvent the separation problem, the diastereomeric mixture was reacted with paraformaldehyde in the presence of cat. PTSA to furnish oxazolines 6 and 7 in a combined yield of 96%. Oxazoline 6 was easily separated from 7 by using column chromatography in 94% yield (based on crude 6 and 7) as a colourless syrup, [α]D -21.5° (c 1, MeOH). Treatment of oxazoline 6 with NaCNBH3/TMSCl smoothly afforded the N-methyl amino alcohol 8 in 93% yield. Acidic hydrolysis of 8 afforded (1S,2S)-pseudoephedrine hydrochloride as white crystalline solid in 92% yield. M.p. 184–186°C, [α]D +59.8° (c 2, H2O) lit7 m.p. 185–188, [α]D +61° (c 1, H2O), thereby confirming the structure assignment and configurations.

In summary, we have demonstrated an efficient new synthesis of pseudoephedrine in excellent yield. This synthesis will be amenable to the syntheses of analogous compounds with ease. Further work is in progress and will be reported in due course.




Scheme 1.
Reagents and conditions:
(i) (CH2O)n, PTSA, benzene, reflux, 1 h; (ii) 1 equiv. NaBH4, MeOH, 2 h; (iii) PhMgBr, THF, 0°C–rt, 3 h;
(iv) (CH2O)n, PTSA, benzene, reflux, 1 h; (v) NaCNBH3/TMSCl, CH3CN, rt, 30 min; (vi) conc. HCl, reflux, 2 h



References

1. Bycoroft, B.W. Dictionary of Antibiotics and Related Substance; Chapman and Hall: London, 1988.
2. Reetz, M. T.; Rrewes, M. W.; Schmitz, A. Angew. Chem., Int. Ed. Engl. 26, 1141 (1987)
3. Myers, A. G.; Gleason, J. L.; Yoon, T. J. Am. Chem. Soc. 117, 8488 (1995)
4. Myers, A. G.; Yang, B. H.; Chen, H.; Gleason, J. L. J. Am. Chem. Soc. 116, 9361 (1994)
5. Reddy, G. V. S.; Rao, G. V.; Iyengar, D. S. Tetrahedron Lett. 40, 2653 (1999)
6. Ishai, D. B. J. Am. Chem. Soc. 79, 5736 (1957)
7. Aldrich Fine Chemical Catalog, 1998–1999, p. 1441.



Ref #6:
Reaction of Acylamino Acids with Paraformaldehyde
Dov Ben-Ishai
J. Am. Chem. Soc. 79, 5736-5738 (1957) (../rhodium/pdf /aminoacid.oxazolidinone.pdf)

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    nightshade
07-18-04 22:45
      is the psuedoephedrine that one extracts from...
(Rated as: UTFSE!)
    
 
 
 
    Rhodium
(Chief Bee)
09-29-04 16:40
No 533749
      Synthesis of Ephedrine & Pseudoephedrine
(Rated as: excellent)
    

Zur Synthese des Pseudo-Ephedrins
Ernst Späth
Chem. Ber. 58, 197-199 (1925) (../rhodium/pdf /pseudoephedrine.spath-1925.pdf)



____ ___ __ _

Synthesis of Ephedrine from Propionic Acid
I. Kh. Fel'dman, N. N. Bel'tsova, and A. A. Ginesina
J. Appl. Chem. USSR (Engl.Transl.) 35, 1309-1311 (1962) (../rhodium/chemistry /propionic2ephedrone2ephedrine.html)


____ ___ __ _

Synthesis of Ephedrine and Similar Compounds. I. A New Synthesis of Ephedrine
Richard H. V. Manske & Treat B. Johnson
J. Am. Chem. Soc. 51, 580-582 (1929) (../rhodium/chemistry /ephedrine.manske.html)



The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Rhodium
(Chief Bee)
10-13-04 01:18
No 535588
      Early descriptions of (pseudo)ephedrine chemistry
(Rated as: good read)
    

Ueber das 'Pseudo-Ephedrin'
A. Ladenburg & C. Oelschlägel
Ber. 22, 1823-1827 (1889) (../rhodium/pdf /pseudoephedrine-1889.pdf)
____ ___ __ _

Ueber das Ephedrin und das Pseudoephedrin
P. Rabe
Ber. 44, 824-827 (1911) (../rhodium/pdf /ephedrine.rabe-1911.pdf)

The Hive - Clandestine Chemists Without Borders