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Light‐Driven Enantioselective Organocatalytic β‐Benzylation of Enals
Author(s) -
Dell'Amico Luca,
FernándezAlvarez Victor M.,
Maseras Feliu,
Melchiorre Paolo
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201612159
Subject(s) - enantioselective synthesis , iminium , chemistry , cycloaddition , organocatalysis , pyran , amine gas treating , catalysis , keto–enol tautomerism , organic chemistry
Abstract A photochemical organocatalytic strategy for the direct enantioselective β‐benzylation of α,β‐unsaturated aldehydes is reported. The chemistry capitalizes upon the light‐triggered enolization of 2‐alkyl‐benzophenones to afford hydroxy‐ o ‐quinodinomethanes. These fleeting intermediates are stereoselectively intercepted by chiral iminium ions, transiently formed upon condensation of a secondary amine catalyst with enals. Density functional theory (DFT) studies provided an explanation for why the reaction proceeds through an unconventional Michael‐type addition manifold, instead of a classical cycloaddition mechanism and subsequent ring‐opening.