Catalytic asymmetric formal γ-allylation of deconjugated butenolides
作者:Amit K. Simlandy、Santanu Mukherjee
DOI:10.1039/c5ob02362a
日期:——
A formal γ-allylation of deconjugatedbutenolides is reported based on a two-step sequence consisting of a catalytic diastereo- and enantioselective vinylogous nucleophilic addition to vinyl sulfones and Julia–Kocienski olefination. This highly modular approach delivers densely functionalized butenolides containing a quaternarystereogenic centre in excellent yield with high enantioselectivity.
γ-substituted deconjugated butenolides is described. While Lewis base catalyst quinidine leveraged O-selective nitrosocarbonyl aldol reaction exclusively at the γ-position of deconjugated butenolides to produce γ-aminoxylation products, Lewis acid catalyst Cu(OTf)2 steered the competitive N-selective nitrosocarbonyl aldol reaction at the β-position, resulting in heterodifunctionalized butenolides. Both processes
deconjugated butenolides that allows access to hybrid molecular frameworks composed of unsaturated butyrolactone and butyrolactam motifs is reported. The reaction is catalyzed by inexpensive quinidine, and products are isolated in high yields as a single diastereomer. The γ-selective monofunctionalization was also accomplished through substrate modification.