Toward the development of a general chiral auxiliary. Enantioselective alkylation and a new catalytic asymmetric addition of silyloxyfurans: application to a total synthesis of (-)-rasfonin.
An enantioselective total synthesis of the apoptosis-inducing natural product, (-)-rasfonin, is described. Camphor lactam-mediated asymmetric alkylation reactions enabled the installation of three stereogenic centers with >95:5 diastereoselectivity. A modified Corey-Peterson olefination was employed in the construction of the (E,E)-diene system. A highly diastereoselective, asymmetric vinylogous Mukaiyama aldol addition was conducted using a chiral cationic oxazaborolidine catalyst. The pyranone core of the natural product was prepared via a DBU-promoted rearrangement of a furanol to its corresponding pyranol with concomitant [1,4]-silyl transfer.
Boeckman
Robert K
RK
Department of Chemistry, University of Rochester, P.O. Box 270216, Hutchison Hall, Rochester, New York 14627-0216, USA. rkb@rkbmac.chem.rochester.edu
Pero
Joseph E
JE
Boehmler
Debra J
DJ
D000478:Alkylation; D002384:Catalysis; D005231:Fatty Acids, Unsaturated / Q000138:chemical synthesis* / Q000737:chemistry; D005663:Furans / Q000737:chemistry*; D011753:Pyrones / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D005231:Fatty Acids, Unsaturated; D005663:Furans; D011753:Pyrones; C416827:rasfonin