Carbene‐Catalyzed Enantioselective Decarboxylative Annulations to Access Dihydrobenzoxazinones and Quinolones

A direct decarboxylative strategy for the generation of aza‐o‐quinone methides (aza‐o‐QMs) by N‐heterocyclic carbene (NHC) catalysis has been discovered and explored. This process requires no stoichiometric additives in contrast with current approaches. Aza‐o‐QMs react with trifluoromethyl ketones through a formal [4+2] manifold to access highly enantioenriched dihydrobenzoxazin‐4‐one products, which can be converted to dihydroquinolones through an interesting stereoretentive aza‐Petasis–Ferrier rearrangement sequence. Complementary dispersion‐corrected density functional theory (DFT) studies provided an accurate prediction of the reaction enantioselectivity and lend further insight to the origins of stereocontrol. Additionally, a computed potential energy surface around the major transition structure suggests a concerted asynchronous mechanism for the formal annulation. Eine direkte Decarboxylierungsstrategie zur Bildung von Aza‐o‐chinonmethiden (aza‐o‐QMs) durch NHC‐Katalyse wird vorgestellt. Aza‐o‐QMs reagieren mit Trifluormethylketonen durch [4+2]‐Addition und ermöglichen den Zugang zu enantiomerenangereicherten Dihydrobenzoxazin‐4‐onen. DFT‐Studien erläutern die Stereokontrolle und weisen auf einen konzertierten asynchronen Mechanismus für die formale Anellierung hin.