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Regio‐ and Diastereoselective Dimerization of Diazo Carbonyls: A Cooperative Catalytic Approach to Complex Scaffolds with Four Contiguous Stereocenters
Author(s) -
Petzold Martin,
Günther Andre,
Jones Peter G.,
Werz Daniel B.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001548
Subject(s) - stereocenter , chemistry , diazo , catalysis , cycloaddition , stereochemistry , combinatorial chemistry , lactone , lewis acids and bases , brønsted–lowry acid–base theory , enantioselective synthesis , organic chemistry
Abstract Starting from readily available o ‐diazoacyl‐substituted arene carboxylates, scaffolds with the 5,9‐epoxycyclohepta[b]pyran‐2(3 H )‐one core were obtained by cooperative Rh II , Lewis and Brønsted acid catalysis. Four new bonds, three functional groups (lactone, ketal, and alcohol) and four contiguous stereocenters are formed during this regio‐ and diastereoselective process in a single synthetic step. Intensive optimization and mechanistic studies, including the trapping, isolation, and elucidation of reaction intermediates, led to a plausible mechanistic scenario. The reaction is proposed to involve carbonyl ylides but also transient species of the ketocarbene equilibrium that undergo a cascade of cycloaddition and skeletal rearrangements.