Synthesis of Cyclopentenols and Cyclopentenones via Nickel-Catalyzed Reductive Cycloaddition
作者:Aireal D. Jenkins、Ananda Herath、Minsoo Song、John Montgomery
DOI:10.1021/ja206722t
日期:2011.9.14
Strategies for the reductive cycloaddition of enals or enoates with alkynes have been developed. The enal-alkyne cycloaddition directly affords cyclopentenols, whereas the enoate-alkyne cycloaddition affords the analogous cyclopentenones. The mechanism of these processes likely involves formation and protonation of a metallacyclic intermediate. The general strategy provides a straightforward entry
Asymmetric conjugate hydrocyanation of α,β-unsaturated carboxylic acid derivatives catalyzed by a Ru[(S)-phgly]2[(S)-binap]–CH3OLi system was examined. The N-acylpyrrole gave the best result in terms of reactivity and enantioselectivity. A series of substrates with alkyl or heterosubstituted alkyl groups at the β-position reacted with a substrate-to-catalyst molar ratio of 200–2000 to afford the β-cyano
Structural Study-Guided Development of Versatile Phase-Transfer Catalysts for Asymmetric Conjugate Additions of Cyanide
作者:Brian A. Provencher、Keith J. Bartelson、Yan Liu、Bruce M. Foxman、Li Deng
DOI:10.1002/anie.201105536
日期:2011.11.4
Unprecedented phase‐transfercatalysts for the first example of an organocatalytic asymmetric conjugate addition of cyanide with acetone cyanohydrin are reported (see scheme). Utilizing an accessible cupreidinium salt and a cyanation reagent suitable for industrial scale, this reaction holds significant promise for practical asymmetric synthesis. The catalysts were developed as a result of key structural
报道了用于氰化物与丙酮氰醇的有机催化不对称共轭加成的第一个例子的前所未有的相转移催化剂(参见方案)。利用易于获得的铜盐和适用于工业规模的氰化试剂,该反应对实际不对称合成具有重要意义。这些催化剂是根据 X 射线分析获得的关键结构见解而开发的。
Enantioselective Conjugate Hydrocyanation of α,β-Unsaturated <i>N</i>-Acylpyrroles Catalyzed by Chiral Lithium(I) Phosphoryl Phenoxide
Enantioselective conjugate hydrocyanation of α,β-unsaturated N-acylpyrroles with the combined use of Me3SiCN, LiCN, and HCN has been developed in the presence of a chiral lithium(I) phosphoryl phenoxide catalyst. This reaction is useful for a variety of N-acylpyrroles, including previously unreported substrates, such as heteroaryl and halogen-substituted N-cinnamoylpyrroles. A gram-scale reaction and
interactions of phosphonium salts. Amino acid derived phosphonium salts and dipeptide derived phosphonium salts exhibited different properties for controlling the transition state, which could efficiently promote the Michael addition reaction to give opposite configurations of products with high yields and enantioselectivities. Preliminary investigations on the mechanism of the reaction and applications of