catalytic asymmetric halohydroxylation of α,β‐unsaturated ketones with water as the nucleophile has been realized by applying a chiral N,N′‐dioxide/Fe(OTf)2 complex as the catalyst. Bromo‐, chloro‐ and iodo‐hydroxylations were all suitable in this catalytic system. A variety of α‐halo‐β‐hydroxy ketones were obtained in often good yields with generally high dr and ee values. Besides, a Michael/α‐halogenation
Chiral aldehyde catalysis is uniquely suitable for the direct asymmetric α-functionalization of N-unprotected amino acids, because aldehydes can reversibly form imines. However, there have been few successful reports of these transformations. In fact, only chiral aldehyde catalyzed aldol reactions of amino acids and alkylation of 2-amino malonates have been reported with good chiral induction. Here
polycyclization of oxotriphenylhexanoates. The polycyclization is governed by electronic effects, and three major synthetic paths have been established leading to stereochemically complex tricyclic frameworks with up to five stereogenic centers. The method is compatible with an array of functional groups, allowing pharmacophoric elements to be introduced post cyclization.
approach for the synthesis of 2‐acylpyrroles is reported in this paper. Synthesis of the target molecule started from chalcones and was carried out in two steps. Initial step involved the conversion of chalcones to corresponding 4‐substituted‐3‐acylpyrroles by reaction with TosMIC. In the subsequent step, target molecules were obtained in modest to good yields by polyphosphoric acid‐mediated acyl rearrangement
Enantioselective Phosphine-Catalyzed Allylic Alkylations of <i>mix</i>-Indene with MBH Carbonates
作者:Junyou Zhang、Hai-Hong Wu、Junliang Zhang
DOI:10.1021/acs.orglett.7b02895
日期:2017.11.17
reported using a simple chiral sulfinamide phosphine-catalyzed asymmetric allylicalkylation of a mixture of indenes with Morita–Baylis–Hillman carbonates. The resulting derivatives can serve as a valuable synthetic building block for some drugs and natural products. Broad substrate scope and high regio- and enantioselectivity of this reaction were particularly remarkable.