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Copper‐Catalyzed Asymmetric Annulation Reactions of Carbenes with 2‐Iminyl‐ or 2‐Acyl‐Substituted Phenols: Convenient Access to Enantioenriched 2,3‐Dihydrobenzofurans
Ist Teil von
Angewandte Chemie International Edition, 2019-09, Vol.58 (39), p.13885-13889
Auflage
International ed. in English
Ort / Verlag
Germany: Wiley Subscription Services, Inc
Erscheinungsjahr
2019
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
We have developed a method for the highly diastereo‐ and enantioselective construction of 2,3‐dihydrobenzofurans bearing tetrasubstituted carbon stereocenters by means of annulation reactions between carbenes and 2‐iminyl‐ or 2‐acyl‐substituted phenols through catalysis by readily accessible copper(I)/bisoxazoline catalysts under mild conditions. These reactions feature a unique mechanism in which the copper catalyst serves a dual function: first it reacts with the diazo compound to generate a metal carbene, and second, upon formation of an oxonium ylide, it acts as a Lewis acid to activate the imine or ketone for diastereo‐ and enantioselective cyclization.
Full circle: A Cu‐catalyzed enantioselective annulation of aryldiazoacetates with 2‐iminyl‐ or 2‐acyl‐substituted phenols has been developed to prepare enantioenriched 2,3‐dihydrobenzofurans. In this reaction, the Cu catalyst first induces carbene formation, and then functions as a Lewis acid to activate the electrophile and control the diastereo‐ and enantioselectivity.