Organic Reactions at High Pressure: Cycloaddition Reactions of 11-Methylene-1,6-methano[10]annulene
✍ Scribed by Prof. Dr. Frank-Gerrit Klärner; Dr. Barbara M. J. Dogan; Richard Weider; Prof. Dr. David Ginsburg; Prof. Dr. Emanuel Vogel
- Publisher
- John Wiley and Sons
- Year
- 1986
- Tongue
- English
- Weight
- 393 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0044-8249
No coin nor oath required. For personal study only.
✦ Synopsis
The (R,S)-aminal 3 , prepared from glycine methyl ester hydrochloride, methylamine, and pivalaldehyde,l'"l was treated with 14 chiral carboxylic or sulfonic acids. In two cases one of the two possible diastereomeric salts crystallized selectively: the salt from ( -)-2,3 :4,6-di-O-isopropylidene-2-ketogulonic acid [( -)-diacetone-2-ketogulonic acid] and ( S ) -3 , and that from (S)-( -)-mandelic acid and ( R ) -3 . For preparative resolution a single crystallization with mandelic acid gave enough enrichment so that N-benzoylation and recrystallization of 2 produced the two enantiomers with greater than 98% ee. Mandelic acid is recovered in 95% yield without detectable racemization.