bottleneck
(Hive Bee)
01-17-03 05:48
No 399030
      Common work on lysergic acid from L-trp?
(Rated as: excellent)
 Bookmark   

Why don't people start working on trying to discover a new route to lysergic acid by way of tryptophan? Tryptophan is clearly one of the most economical and clandestinely appropriate precursors imaginable, and not that many atoms apart from lysergic acid, and if one desires an economic route, this is the precursor to shoot for.

If one person tries to work on this, he might fail, but if more people started working on it on the Hive, and shared information on their failures, other people could try out other things instead of working on what had already failed, and work might progress quicker.

This is the Hive. We like chemistry, not fungi. For the forseeable future, Claviceps paspali will be yielding about 2 grams max per liter, even under optimal conditions in huge, expensive biotech plants. To supply an annual demand of 200 million, 100 microgram doses, 20 kg of LSD tartrate is required. Using the POCl3 synthesis like Shulgin does, getting 52% like him, about 23 kg of lysergic acid monohydrate is required. Assuming as much as 2 grams yield of lysergic acid monohydrate per liter of culture broth extracted, about 12000 liters of broth are required. That's 12 cubic meters, or about 12 full-height refrigerators filled with culture broth. Claviceps grows slowly (about 20 days from preculture to extraction), which requires very high standards of sterility (i.e., this isn't exactly like brewing beer). This may be possible on a 1-5 liter scale, where you can put each container full of medium in an autoclave, and properly sterilize everything, but it's quite another thing to put a 100 liter "jug" into a pressure cooker, or even 20 five-liter jugs. And someone'd have to do that, oh, just 120 times per year to meet world demand.

In the future, with sexually bred Claviceps and maybe genetic engineering, it is likely there will be 10 g/L yielding strains, or even 20-30 g/L (or indeed 5000 g/L, why not?), and it is clear that no synthesis, even a miraculous 99% yielding one, using chemical reactions will ever be able to compete with that economy. However, in the present, even a 15% yielding synthesis from tryptophan, using relatively simple and inexpensive reagents, would begin to be competitive with current fermentation technique.

The most economical synthesis of lysergic acid thus far, as far as I can tell, is the one by Rebek from 1984 using L-tryptophan. The d-isomer is the sole product, but yield is still only about 4% to d-lysergic acid. The syntesis is elegant, but some reagents are expensive (though some cheaper could probably be found with a little effort), and a major loss of yield comes from the decision, as in all the
other reported syntheses of lysergic acid I have come across, to protect the indole structure in the form of an indoline, giving two low-yielding reactions at the beginning and the end.

The decision to use such protective measures is usually never defended to any greater extent than to cite some older article in which the same measure is used, but in which, funnily enough, there is also not provided any evidence except for references. And when you finally come to the "original" reference, you typically find it says no such thing.

To skip the indoline reduction/oxidation could potentially mean a sizeable gain in yield. There are many good indications that a tryptophan derivative could be intramolecularly cyclized predominantly the 4-position instead of the 2- by proper adjustment of experimental reagents and conditions, either as the acid chloride or an azlactone.

The only Friedel-Crafts catalyst reported for cyclization in these types of cases is aluminum chloride, a cheap but extremely reactive reagent, but this appears to be again due to the effect of reference-aping. I think there is at least a possibilty that something milder like ferric chloride could be used instead, or why not even some of the modern pillared clay-catalysts?

In any event, maybe without or maybe with N-protective agents, it should be possible to achieve the tricycle 4-amino-5-oxo-1,3,4,5-tetrahydrobenz[cd]indole, in presumably around 50% yield. This is just two or three steps from tryptophan. I.e., N-acylation, dehydration and condensation in the case of the azlactone method or chlorination and condensation in the case of the acid chloride method.

In a variation on Uhle in JACS 73, 2403-3 (1951), barring dialkylation, alkylation with an alpha-(halomethyl)succinic acid ester and subsequent intramolecular Knoevenagel condensation should afford 9-carboxynorlysergic acid. Decarboxylation might afford either norlysergic acid, ergolene, ergoline or 9-carboxyergolene, or even lead to the dreaded benz[cd]indoline-isomerization, with the former being the desirable outcome of course. Of course, given norlysergic acid, simple alkylation with alkyl halide will afford the active 6-alkyl analogues.

In any event, a succesful ergolene test after the Knoevenagel, even without successful decarboxylation, should prove the basic soundness of using the tricyclic aminoketone as a promising point for further synthetic operations.
 
 
 
 
    bottleneck
(Hive Bee)
01-21-03 06:07
No 400179
      Even though people don't appear too interested
(Rated as: excellent)
 Bookmark   

Even though people don't appear too interested in debating these things, I will expand a little on the possibilities as I see them.

To the point of the practicality of cyclizing tryptophan at the 4-position, in 1964, Szmuszkovicz (JOC 29, 843-9) described the 4-position cyclization in 68% yield of 3-indolesuccinic acid. The succinic acid is converted to the anhydride by dehydration with p-toluenesulfonic acid, and the anhydride is then used for intramolecular Friedel-Crafts acylation by means of aluminum chloride. The indole N is only protected by an acetamide group.

For reasons unknown, Rebek adopts a similar tactic, even though his strategy is to proceed through the indoline which can only condense at the 4-position as the 2- is no longer aromatic. In this case, the precursor is not an anhydride but an azlactone, formed by the acylation of the side-chain amino of tryptophan and subsequent dehydration of this "carboxylic acid amide" to form the azlactone. Rebek uses acetic anhydride for the dehydration, but presumably one could use other dehydrating agents, perhaps using alkyl chloroformate. He gets a combined yield of 57% for the dehydration+condensation steps.

In the first total synthesis of lysergic acid, Kornfeld et al (JACS 78, 3087-3114 Post 1956 (not existing)), benzamide-protected 3-(2,3-dihydro)indolepropionic acid is converted to the acid chloride and cyclized by means of aluminum chloride. Combined yield for the chlorination+condensation steps is 77%. H2SO4 and HF were also tried as Friedel-Crafts catalysts, but were "unsuccessful", and polyphosphoric acid gave only "very small conversion".

In 1994, Teranishi et al (Tetr. Lett. 35, 8173-8176) reported the predominant condensation at the 4-position by use of the acid chloride of trimethylacetamide-protected 3-indolepropionic acid, and aluminum chloride in combination with chloroacetyl chloride or propionyl chloride as Friedel-Crafts catalyst. Normal acetamide-protected 3-indolepropionyl chloride gives 0% of the 4-cyclized target when catalyzed by aluminum chloride, but the authors found 21% yield when propionyl chloride is added to the aluminum chloride in molar equivalence. Trimethylacetamide-protected 3-indolepropionyl chloride gives 35% yield of target when catalyzed by aluminum chloride, but 70% when propionyl chloride is added to the AlCl3, and 78% when chloroacetyl chloride is used instead of propionyl chloride.

All of these instances seem point to the possibility of using tryptophan directly to produce "Uhle aminoketone" without first hydrogenating to form the indoline derivative.

There appears to be a problem with using trimethylacetyl chloride, perhaps with regard to the hydroxyl group of the tryptophan, and indeed the standard procedure appears to be to conduct the N-acylation at -80 degrees C, probably a bit beyond the capability of most hobby labs.

If trimethylacetylation is not feasible, the most appealing route seems to be to form the azlactone by means of an N,'N-diacyltryptophan, probably N,N'-dibenzoyltryptophan which will have a very similar configuration to the indole anhydride successfully condensed by Szmuszkovicz.

 
 
 
 
    ChemisTris
(Hive Bee)
01-21-03 10:37
No 400225
      Claviceps paspali yield  Bookmark   

Nice posts, but re For the forseeable future, Claviceps paspali will be yielding about 2 grams max per liter, even under optimal conditions in huge, expensive biotech plants.
I don't know if this has been posted before/etc., but:

Effect of antifoams on the biosynthesis of ergot alkaloids by high-productive strain of Claviceps paspali F-2057.
Matosic, Srecko; Mehak, Milena; Suskovic, Jagoda; Golob, Zoran.
Faculty Food Technology and Biotechnology,  University Zagreb,  Croatia.
Acta Bot. Croat.  (1994),  53  39-47. (CA 124:173498)

Abstract
The effect of several surfactants, i. e., com. antifoams, on biosynthesis of ergot alkaloids was studied.  Addn. of some surfactants of polyglycol structure and Tweens to submerged cultures of a highly productive strain of C. paspali caused a change in alkaloid synthesis intensity.  Pluronik (polyetoxypolypropoxy polymer) added in the range of 0.25 to 0.75% markedly stimulated the prodn. of ergot alkaloids.  The Pluronik-supplemented culture reached maximal alkaloid yields one or two days earlier than the control.  Prodn. of alkaloids increased twice.  The maximal yield achieved was 5.35 gL-1 with the process productivity amounting to 17.2 mgL-1h-1.

smile

Got democracy?http://www.dhushara.com/book/multinet/democ/wed.htm
 
 
 
 
    sean1234
(Stranger)
01-21-03 16:11
No 400292
      1234  Bookmark   

along the same lines there are other things that can increase alkaloid production (in one of theses ergot threads around here, ill dig it up later).
Also, as far as the time frame to maturity of claviceps, im not sure that i understand your issue...as far as fungus goes thats pretty fast, and i sincerely doubt that an lsd cook would have any trouble waiting for that period of time. Also, the amounts of micrograms youre talking about is way more than i think most of us had in mind....i think even the Gambino family would have problems distributing that much acid.
but kudos on the tryptophan ideas...there is absolutely no reason why we shouldnt explore all possibilities thoroghly.

EDIT: here ya go.
Post 246873 (bujinkan: "Re: ergot and agar", Tryptamine Chemistry)

The yeild of lysergic acid and its derivs. is enhanced by using Claviceps Paspali NRRL 3027 mutants as the fermenting organism. Such mutants are obtained by subjecting the microorganism to x-rays and or UV radiations and or ethyleneimine treatment.


 
 
 
 
    bottleneck
(Hive Bee)
01-24-03 06:52
No 401116
      Replies  Bookmark   

ChemisTris:

 > "...markedly stimulated the prodn. of ergot alkaloids."


That is pretty cool. Maybe there's hope for these little buggers yet. The only thing I know concerning this stuff and ergot is the slightly confusing report given by Kelleher in Adv. Appl. Microbio. 11, 211-244 (1969):

"The observation that high alkaloid-producing cultures often showed an increased tendency to foam when samples were filtered with suction, suggested that these cultures might produce a surface active agent which, in turn, would affect alkaloid production (Kim, Lloydia 31, 422-, 1968). This prompted a study of the effects of a large number of surfactants representing the anionic, cationic, and non-ionic types. Among the surfactants found to have the greatest stimulatory effct on alkaloid production were some hydrophilic nonionic types. Table V presents the results obtanined with some Tween-type surfactants (polyoxyethylene sorbitan esters of fatty acids) as well as with blends of Tween and Arlacel 80 (a sorbitan monooleate).

These experiments also showed that certain lipophilic surfactants (e.g., Arlacel 80 and oleic acid) virtually eliminated alkaloid production while causing only moderate decreases in mycelial growth when added to the culture medium as low as 10 microliters per 100 milliliters. This observation emphasizes the necessity of removing traces of soaps and other cleansing agents from the experimental glassware and it offers a possible explanation for much of the variation that has been encountered with this and with similar alkaloid-producing fermentations.

Gröger and Tyler (Lloydia 26, 174-191, 1963) obtained nearly a threefold increase in alkaloid production upon adding 1,2-propanediol to their medium at a concentration of 3%.


Table V:
Enhancement of alkaloid production by surfactants

Surfactant              HLB*     Peak alk. conc. (mcg/ml)
None                       -     263
Tween 80 + Arlacel 80      7     604
Tween 80 + Arlacel 80      9     657
Tween 80 + Arlacel 80     11     919
Tween 80 + Arlacel 80     13     831
Tween 80                  15     744
Tween 81                  10     461
Tween 61                 9.6     464

* = Hydrophile-lipophile balance"




Sean1234:

 > "along the same lines there are other things that can increase alkaloid production (in one of theses ergot threads around here, ill dig it up later)."

I just wonder if all that is additive; "Tween 80 increases alkaloid production by 100%, something else increases it by 50%, so put them together they increase production by 200%"? I doubt it.

 > "Also, as far as the time frame to maturity of claviceps, im not sure that i understand your issue...as far as fungus goes thats pretty fast,"

Well, I don't know about that, not having much experience with practical ascomycology, I just know what I read, for example in Rehacek, Trends in Biotechnology 2, 166-172, 1984:

"In the course of optimization and scale-up of the process to production levels, several biological and technological difficulties remain. [...] The long cultivation period (2-3 weeks) requires very high standards of sterility in operation and equipment. The sensitivity of Claviceps cultures to mechanical stress and the necessity of high oxygen tension requires a well-balanced system of aereation and stirring. The fermentation mixture reacts very strongly to small alterations in the media composition. Most antifoams cause a considerable loss in alkaloid yield."

> and i sincerely doubt that an lsd cook would have any trouble waiting for that period of time.

Me too. But as said, human patience was not the main concern of my remarks.

 > Also, the amounts of micrograms youre talking about is way more than i think most of us had in mind.... i think even the Gambino family would have problems distributing that much acid.

That's true. My concern is that there should either be a method by which one small group of people can easily make a huge quantity of acid, or a method by which a huge number of people can make small quantities of acid.

Given the fact that most mushroom-guys probably don't know tartaric acid from steak tartar, and most chemistry-guys don't know a basidiocarp from Larry King (admitted, that is pretty close), the thought of a huge Claviceps-growing community springing up, similar to the Psilocybe-growing one, does seem a bit far-fetched.

For argument's sake, let's say some enterprising young soul manages to get a hold of an industrial variety of Claviceps paspali yielding about 5 grams of alkaloids per liter using tween-tricks and all. Let's say he wants to spread this variety to a number of people to ensure more people can make acid...

5 grams of alkaloids per liter means an annual requirement of 4600 liters of culture broth to supply 200 million 100 mcg doses.

When one has received his tube of Claviceps culture, he must, under sterile conditions of course, inoculate sterilzed agar dishes with the contents of the tube. When an good number of uncontaminated plates have been found, their contents are added to a 500 mL flask of liquid medium low in sugars. After 10 days, about 5 of these flasks (and those which haven't been contaminated) are added to each of the main (5 liter) flasks containing high-sugar medium, and the main fermentation is then left for the final 10 days. All of these variations in culture media are done to "trick" the fungus into beginning its production of alkaloids.

All this has taken about 30 days, if one is a skilled, well-equipped microbiologist, and maybe months of failures if one is not.

If one is lucky, one now has 10 liters of culture broth containing about 50 grams of lysergic and isolysergic acid amides. That's a lot of potential acid, I'd agree.

Then you basify and extract your 10 liters of culture broth with 10 liters of chloroform, extracting the chloroform with aqueous tartaric acid and evaporating under vacuum and low temperature the water to leave a powder of lysergic and isolysergic acid amides, which are then hydrolyzed to lysergic and isolysergic acid by treatment with aqueous alkanolic hydroxide. Now you have your, now slightly less than, 50 grams of lysergic and isolysergic acids monohydrates.

Then you go to the hardware store to pick up handy little bottles of diethylamine and phosphoryl chloride, and follow directions in TiHKAL. Bingo! About 43 grams of LSD tartrate.

Any sucker could do that. That was easy. Let's do it again, right? Wrong! Because next time your little fermentation maybe won't yield 50 grams of alkaloids, but 40 grams, or 30 grams. And third time will be even lower. This is known as "strain degeneration." Because Claviceps can't be reproduced by spores in the lab, the same organism is transferred from plate to plate, and this tends in the end to result in lower and lower yields of alkaloids, unless one only inoculates using high yielding isolates, which can only be done by tedious combined biological/chemical steps of culturing and testing for indoles.

So for this to be feasible, you probably have to have some guy sitting around all the time doing nothing but culturing, testing, isolating and plating high yielding strains of Claviceps, just to be able to supply hundreds of people with fresh cultures for free or at low cost. Maybe that also seems a bit far-fetched.

And those 50 grams you slaved so hard over would only be 1/460th of what is necessary to supply those theoretical 100 million doses. Just need another 460 guys with the same patience and diligence as you to supply a country like America with acid! Kind of makes you wonder who they buy all that ergotamine from. Must be about a hundred kilos or more to supply the world market annually, the annual production being around 4000 kilos for all peptide ergot alkaloids (Floss, Tetrahedron 32, 873-912, 1976). If only ergotamine was used to make LSD, that could mean as much as 5% of all ergotamine produced in the world was used for this purpose!

 > but kudos on the tryptophan ideas...there is absolutely no reason why we shouldnt explore all possibilities thoroghly.

Thanks!
 
 
 
 
    bottleneck
(Hive Bee)
01-24-03 06:59
No 401117
      On the notion of using an azlactone of an...  Bookmark   

On the notion of using an azlactone of an N-acyltryptophan, say the N-benzoyl, to acylate predominantly at the 4-position, I mention the article by Szmuszkovicz, but it occurs to me that the indolesuccinic anhydride differs from the tryptophan azlactone in that the heterocycle formed is cyclized at the alpha-position of the sidechain in the case of the anhydride while it is at the beta carbon in the case of the azlactone, giving a structure which almost can't reach the 2-position. In the case of the Friedel-Crafts reaction with aluminum chloride, the ether of the anhydride or azlactone is cleaved and in this case the structure opens up giving room to reach the 2-position. In this case, it should not make much difference on the site of attack whether the azlactone or an anhydride is used, but I really don't know enough about these things to theorize. I think there is a good chance, but obviously a safer-appearing bet would be to go through the N-trimethylacetyl already shown to undergo preferential 4-cyclization in the case of 3-indolepropionyl chloride.


"anhydride of N-acetyl-3-indolesuccinic acid" C(C)(=O)n2c1c(cccc1)c(c2)C3CC(=O)OC3=O

"azlactone of N,N'-dibenzoyltryptophan" C=5(c1ccccc1)OC(C(Cc3c2ccccc2n(c3)C(c4ccccc4)=O)N=5)=O

"N-trimethylacetyl-3-indolepropionyl chloride" C(C(C)(C)C)(=O)n2c1c(cccc1)c(c2)CCC(=O)Cl



Books on amino acids and peptide synthesis might be a good place to look for things like this, but so far it appears to be that, as opposed to benzoyl chloride, trimethylacetyl chloride will likely O-acylate tryptophan, giving N,N',O-tri(trimethylacetyl)tryptophan. The O-acylation results in a mixed anhydride of course, and as is well know, anhydrides can be used for Friedel-Crafts acylation. In principle therefore, I guess it should be possible to _directly_ cyclicize the anhydride to the aminoketone, 1-trimethylacetyl-4-(trimethylacetylamino-3,4-dihydrobenzo[cd]indol-5(1H)-one (yes, I had software-help naming this!), i.e. the trimethylacetyl-protected version of the "Uhle's aminoketone" target I mentioned as being the goal. This would be almost ideal, but unfortunately there are two ways the reaction could go. The Friedel-Crafts catalyst could acylate the benzene-ring with the tryptophan sidechain as intended, or it could either acylate or alkylate the benzene with the trimethylacetyl part of the anhydride. It is well known that different Friedel-Crafts catalysts tend to have very different yields of different isomers when several are possible. Given the facility of condensiting the O-acylated tryptophan (the anhydride) at all, I think it is likely a useful Friedel-Crafts catalyst can quickly be found by trying out three or four pretty different types.

Given the failure of this, one could instead attempt the hydrolysis of the anhydride, which should hydrolyze much more readily than the two amide functions. The should (?) produce N,N'-di(trimethylacetyl)tryptophan, which should be readily condensable to "Uhle's aminoketone" via the acid chloride or the azlactone. Happy end.

If this is not feasible, one might produce the di-trimethylacetylated tryptophan by protecting the -OH by esterification of tryptophan to the methyl ester (SOCl2/MeOH, 100% yield), reaction with trimethylacetyl chloride, and finally very careful, mild hydrolysis of the ester. But I am not sure if the trimethylacetamide functions won't hydrolyze under the same conditions required for the deesterification.


N,N',O-tri(trimethylacetyl)tryptophan C(C(C)(C)C)(=O)NC(Cc2c1ccccc1n(c2)C(C(C)(C)C)=O)C(=O)OC(C(C)(C)C)=O

1-trimethylacetyl-4-(trimethylacetylamino-3,4-dihydrobenzo[cd]indol-5(1H)-one C(C(C)(C)C)(=O)n3c1c2c(ccc1)C(C(Cc2c3)NC(C(C)(C)C)=O)=O

N,N'-di(trimethylacetyl)tryptophan C(C(C)(C)C)(=O)NC(Cc2c1ccccc1n(c2)C(C(C)(C)C)=O)C(=O)O

"azlactone of N,N'-di(trimethylacetyl)tryptophan" C=3(C(C)(C)C)OC(C(Cc2c1ccccc1n(c2)C(C(C)(C)C)=O)N=3)=O

"acid chloride of N,N'-di(trimethylacetyl)tryptophan" C(C(C)(C)C)(=O)NC(Cc2c1ccccc1n(c2)C(C(C)(C)C)=O)C(=O)Cl





I have been thinking more about how one might further elaborate the N,N'-protected Uhle's aminoketone.

In the Kornfeld article, the indoline version of "Uhle's bromoketone" is supplied with an methylaminoacetone moiety with the object of subsequent intramolecular condensation, ultimately resulting in the indoline version of 6-methyl-8-oxoergolene. N-alkylating "Uhle's aminoketone" with haloacetone should have the same result (except there will be no 6-methyl group of course).

Thus, the N-alkylation of N,N'-di(trimethylacetyl)-protected Uhle's aminoketone with bromoacetone should thus yield the N-acetonylated analogue, N-(1-trimethylacetyl-5-oxo-1,3,4,5-tetrahydrobenzo[cd]indol-4-yl)-N-(2-oxopropyl)trimethylacetamide.

Given that trimethylacetamides are labile to alkoxide, an alkoxide treatment to condense the N-acetonylated product above should conveniently also cleave the trimethylacetamide groups, resulting in 8-oxoergolene. Methyliodide will afford 6-methyl-8-oxoergolene. Darzens reaction might afford lysergaldehyde, though I don't know much about the limitations of a Darzens reaction. Given lysergaldehyde, reaction with manganese dioxide and diethylamine should afford LSD (analoguously to the synthesis of lysergamides from elymoclavine, Choong, Tetr. Lett. 19. 1627-8, 1977).

But there are probably many other likely routes from Uhle's aminoketone to LSD.


N-(1-trimethylacetyl-5-oxo-1,3,4,5-tetrahydrobenzo[cd]indol-4-yl)-N-(2-oxopropyl)trimethylacetamide C(=O)(CN(C3Cc2c1c(cccc1n(c2)C(C(C)(C)C)=O)C3=O)C(C(C)(C)C)=O)C

"indoline version of 6-methyl-8-oxoergolene" C\4(=O)CN(C\3CC2c1c(cccc1NC2)C/3=C/4)C

8-oxoergolene C\4(=O)CNC\3Cc2c1c(cccc1nc2)C/3=C/4

6-methyl-8-oxoergolene C\4(=O)CN(C\3Cc2c1c(cccc1nc2)C/3=C/4)C

lysergaldehyde C\4(C=O)CN(C\3Cc2c1c(cccc1nc2)C/3=C/4)C
 
 
 
 
    bottleneck
(Hive Bee)
01-25-03 05:12
No 401374
      This is very interesting.  Bookmark   

This is very interesting. "D-Lysergyl peptide synthase"... that does sound rather productive. I always knew I should have gotten into biochemistry instead. It sounds a bit like infant nanotechnology. I didn't know they had advanced to far in genetic engineering and stuff like that, and maybe I am a silly oaf and we will soon have seeds of ergine-producing dandelions floating on the air. See them drift upon the breeze!
 
 
 
 
    bottleneck
(Hive Bee)
02-08-03 06:20
No 405606
      Just an additional reference.  Bookmark   

I was checking out some old articles I hadn't looked at recently (because they are in German). Kind of a gem, at least as regards the topic of this thread: Stoll, Rutschmann & Petrzilka, Helvetica Chimica Acta 33, 2257-2261 (1950), "Über Derivate des 1,3,4,5-Tetrahydro-benz(cd)indols."

Here we have "Uhle's aminoketone", in hydrochloride and acetamide form, a year before Uhle ever published making a derivative of it, so I will swiftly make a mental note to adopt the name "Stoll's aminoketone" if writing further on these subjects.

Okay, so it's unstable as hell in freebase form, but stable in hydrochloride and N-acylated form, i.e., no different from the indoline analogue prepared by Kornfeld (Woodward) et al. ( ../rhodium/pdf /lysergic.acid.woodward.pdf page 3090). I still think it's worth a look-see. Also answers almost all worries whether the structure could survive conditions of intramolecular Knoevenagel (Stobbe) condensation and similar active methylene reactions. The "6,7-imine"-analogue sure does using potassium butoxide, giving a nice Keller-reaction afterwards.
 
 
 
 
    Rhodium
(Chief Bee)
02-08-03 18:30
No 405771
      Elymoclavine  Bookmark   

The article mentioned in Post 401117 (bottleneck: "On the notion of using an azlactone of an...", Tryptamine Chemistry) can be read at ../rhodium/chemistry /elymoclavine.html
 
 
 
 
    bottleneck
(Hive Bee)
02-10-03 06:05
No 406194
      Yes, it's very good, thanks for the reference...  Bookmark   

Yes, it's very good, thanks for the reference on your site about that article.

I stumbled across another article which describes a method which might also be applicable: Wuts & Bergh, Tetr. Lett. 27, 3995-3998 (1986) "The Oxidation of Aldehyde Bisulfite Adducts to Carboxylic Acids And Their Derivatives with Dimethylsulfoxide and Acetic Anhydride".

The yields are quite good, seemingly on par with the MnO2/cyanide technique used by Corey et al in the article referenced by Choong.