Intermolecular Cross-Double-Michael Addition between Nitro and Carbonyl Activated Olefins as a New Approach in C−C Bond Formation (original) (raw)
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Chemistry (Weinheim an der Bergstrasse, Germany), 2018
The catalyst-controlled enantioselective direct addition reaction of enolizable esters and related carboxylic acid derivatives to π electrophiles remains a difficult synthetic transformation. In this study, the suitability of α-hydroxy ketones as ester equivalents capable of being activated by bifunctional Brønsted base catalysts in the context of conjugate addition reactions to nitroolefins is demonstrated. The scope of the reaction, which affords the corresponding Michael adducts with very high stereoselectivity (diastereomeric ratio (d.r.) ≥95:5, up to 99 % enantiomeric excess (ee)), and its limitations are explored, as is the aftermath elaboration of adducts into densely functionalized enantioenriched products.
Acyl transfer-enabled catalytic asymmetric Michael addition of α-hydroxy-1-indanones to nitroolefins
OAE Publishing Inc., 2023
We report herein an enantioselective acyl transfer protocol via electrophile activation. The reaction cascade sequence encompasses dinuclear zinc-catalyzed asymmetric Michael addition, intramolecular cyclization, and retro-Claisen reaction, which leads to a step-and atom-economic approach to a variety of protected cyclic tertiary α-hydroxyketones in good yields with excellent enantioselectivities (24 examples, 56%-82% yield, 1.5-13 dr and 79%-96% ee). Besides, the large-scale synthesis and further transformation of the products demonstrate the effectiveness of this method for organic synthesis.