psycosmo (Hive Bee)
09-25-02 04:12
No 360191
      Avoid Pictet-Spengler cyclization?  Bookmark   

OK, I know this issue has been practically beat to death, but when I UTSFE I didnt find anything about a formic acid/DMF reaction on a primary amine.
Here in front of me I have a reference that describes making nn-dimethylphenethylamines from phenethylamines using formic/DMF in 45-85% yields, apparantly without much (or any) cyclization to isoquinolines. Makes me wonder.................
anywayz heres the ref
George G Cherayil
"N-Dimethylation of b-phenethylamine derivitives"
Journal of Pharmacutical Sciences 62(12) Dec, 1973
Abstract: Direct N-methylation of 3,4 dimethoxyphenethylamine, tyramine and 3-methoxytyramine, by refluxing each compound with a mixture of formaldehyde and formic acid in the presence of dimethylformamide, to the corresponding N-dimethyl derivitives in 45-86% yield is reported......................"(continues) Might cyclization still be a problem for certain other amines?
Hope that makes up for that dumb yeast post I made w/o UTSFE
(Chief Bee)
09-25-02 04:56
No 360212
      Tryptamine is very sensitive to pictet-spengler ...  Bookmark   

Tryptamine is very sensitive to pictet-spengler cyclization, as the 2-position is so activated. You cannot have formic acid in the mixture and still avoid cyclization.