Asymmetric C-C bond formation via the diastereoselective aza-Claisen rearrangement of N-allylketene N,O-acetals 4 is described. The starting materials, allylic alkylating agent 1 and optically pure oxazoline 2, are easily prepared and, in a one-pot procedure, generate rearranged oxazolines 5/7/9 in 97-98% enantiomeric excess and with 79-92% diastereoselectivity. The overall yields for this process (2 → 5/7/9) range from 73 to 87%. A combination of excellent N,O-acetal face selectivity, excellent (Z)-ketene N,O-acetal olefin selectivity, and moderate chair selectivity are shown to account for the observed diastereoselectivity.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Organic Chemistry|
|State||Published - 1986|
ASJC Scopus subject areas
- Organic Chemistry