Chen P, Tan SZ, Zhu L, Ouyang Q, Jia ZJ, Du W, Chen YC. Palladium-Catalyzed Inverse and Normal Dehydrogenative Aza-Morita-Baylis-Hillman Reactions with γ,δ-Unsaturated Compounds.
Angew Chem Int Ed Engl 2023;
62:e202301519. [PMID:
37009831 DOI:
10.1002/anie.202301519]
[Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/30/2023] [Accepted: 04/03/2023] [Indexed: 04/04/2023]
Abstract
σ-Lewis base-catalyzed regio- and enantioselective aza-Morita-Baylis-Hillman (MBH) reaction of α,β,γ,δ-unsaturated systems remains a challenge due to the intrinsic covalent activation mode. Here we demonstrate that a Pd0 complex can mediate the dehydrogenative reaction of γ,δ-unsaturated compounds to give corresponding electron-poor dienes, which further undergo δ-regioselective umpolung Friedel-Crafts-type addition to imines via auto-tandem Pd0-π-Lewis base catalysis. After β-H elimination of in situ formed PdII-complexes, unprecedented and chemically inverse aza-MBH-type adducts are finally furnished with fair to outstanding enantioselectivity, and a diversity of functional groups and both ketimine and aldimine acceptors can be well tolerated. Moreover, switchable α-regioselective normal aza-MBH-type reaction also can be realized by tuning catalytic conditions, whereas moderate to good enantioselectivity with low to excellent Z/E-selectivity is attained.
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