This paper reports the regio-, diastereo- and highly enantioselective vinylogous aldol reaction of 2-trimethylsilyloxyfuran (TMSOF) promoted by the SiCl4/Lewis base catalytic system. Several electron-pair donors proved to be effective as SiCl4 activators versus the TMSOF gamma-selective addition to aldehydes giving rise to different diastereoisomeric ratios, while Denmark's chiral bis-phosphoramide (R,R)-7 gave the highest enantioselectivity for both the anti- and syn-diastereoisomers. Furthermore, by using ambident electrophiles such as alpha,beta-unsaturated aldehydes, the SiCl4/Lewis base-promoted process leads exclusively to the 1,2-addition products.
Highly enantioselective vinylogous addition of 2-trimethylsilyloxyfuran to aldehydes promoted by the SiCl4/chiral Lewis base system
Rosaria Villano;
2006
Abstract
This paper reports the regio-, diastereo- and highly enantioselective vinylogous aldol reaction of 2-trimethylsilyloxyfuran (TMSOF) promoted by the SiCl4/Lewis base catalytic system. Several electron-pair donors proved to be effective as SiCl4 activators versus the TMSOF gamma-selective addition to aldehydes giving rise to different diastereoisomeric ratios, while Denmark's chiral bis-phosphoramide (R,R)-7 gave the highest enantioselectivity for both the anti- and syn-diastereoisomers. Furthermore, by using ambident electrophiles such as alpha,beta-unsaturated aldehydes, the SiCl4/Lewis base-promoted process leads exclusively to the 1,2-addition products.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
