Tandem conjugate addition. Aldol reactions employing 9-(phenylseleno)-9-borabicyclononane: a novel method for effecting formal aldol condensations at the .alpha.-carbon of .alpha.,.beta.-unsaturated ketones
Stereoselective Synthesis of Medium-Sized Cyclic Compounds by Means of Tandem Reactions of a Cyclic Oxosulfonium Ylide with Acetates of Baylis−Hillman Adducts
five-membered cyclic oxosulfonium ylide 3 with β-acetoxy-α-methylene ketones in the presence of two equimolar amounts of base afforded the cycloheptene oxide derivatives 7a−i as single stereoisomers in 19−77% yields. The products were considered to form through a Michael-type addition of the ylide, followed by elimination of the acetoxy group and an intramolecular Corey−Chaykovsky reaction. On the
Synthesis of (±)-Tetrabenazine by Visible Light Photoredox Catalysis
作者:Lindsey R. Orgren、Emily E. Maverick、Christopher C. Marvin
DOI:10.1021/acs.joc.5b02199
日期:2015.12.18
(±)-Tetrabenazine was synthesized in six steps from commercially available compounds. The key cyclization substrate was assembled rapidly via Baylis–Hillman and aza-Michael reactions. Annulation of the final ring was achieved throughvisiblelightphotocatalysis, wherein carbon–carbon bondformation was driven by the oxidation of a tertiary amine. Solvent played a critical role in the photoredox cyclization
[GRAPHICS]The reaction of the five-membered cyclic oxosulfonium ylide 2 with alpha-methylene-beta-acetoxy ketones in the presence of two equimolar amounts of base afforded the cycloheptene oxide derivatives with stereoselectivity in 19-74% yield via a Michael-type addition of the ylide followed by elimination of the acetoxy group and an intramolecular Corey-Chaykovsky reaction.
LEONARD, W. R.;LIVINHOUSE, T., J. ORG. CHEM., 1985, 50, N 5, 730-732