(S,S)-N,N-Bis(alpha-methylbenzyl)formamide in combination with HMPA catalyzes the allenylation of aliphatic aldehydes with propargyltrichlorosilane with good enantioselectivity (up to 95% e.e.). (C) 1998 Elsevier Science Ltd. All rights reserved.
Synthesis of new derivatives from a Tröger base via exchange of the methano bridge with carbonyl compounds
method has been developed for the preparation of new Tröger base derivatives by an exchange reaction with the methano bridge of rac-Tröger base derivatives with carbonylcompounds in the presence of TiCl4 or POCl3. The use of chiral (S,S)-N,N-bis(α-methylbenzyl)formamide as a carbonylcompound gave the corresponding methano Tröger base derivatives with the diastereomeric ratios of up to 77:23.
The successful example of chiral formamides that function as asymmetriccatalysts is described. (S,S)-N,N-Bis(α-methylbenzyl)formamide mediates the enantioselective addition of allyl- and crotyltrichlorosilanes to aliphatic aldehydes with the assistance of hexamethylphosphoramide (HMPA) to afford the corresponding homoallylic alcohols in up to 98% enantiomeric excess.