Stereoselective synthesis via sequential crotylboration/aldol reaction-oxonia-cope rearrangement
Abstract
Reported herein is the synthesis and applications of a series of novel functionalized achiral and chiral allylboronates via the nucleophilic addition of borylcopper on allylic acetates derived from vinylalumination or Baylis-Hillman reaction of aldehydes. The applications include allylboration of aromatic and aliphatic aldehydes, in the presence of Lewis or Bronsted acid catalysts. While the aromatic aldehydes furnish cis- or trans-β,γ-disubstituted-α-methylene-γ-butyrolactones diastereoselectively, the aliphatic aldehydes provide either β,γ-disubstituted-α-methylene-γ-butyrolactones, or γ-substituted-α-alkylidene-γ-butyrolactones. The formation of different lactones has been investigated and a catalytic cycle involving an oxonia-Cope rearrangement has been proposed. Extension of this methodology for a boron-mediated vinylogous aldol reaction also has been described.
Degree
Ph.D.
Advisors
Ramachandran, Purdue University.
Subject Area
Organic chemistry
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