Application of Chiral Mixed Phosphorus/Sulfur Ligands to Palladium-Catalyzed Allylic Substitutions

来自 ACS

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阅读量：

142

作者：

DA Evans，KR Campos，JS Tedrow，FE Michael，MR Gagné

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摘要：

A modular approach to the synthesis of a class of mixed phosphorus/sulfur ligands was designed to identify important ligand structural features for enantioselective palladium-catalyzed allylic subsitutions of acyclic and cyclic ayllic esters. After a systematic variation of the ligand substituents at sulfur, phosphorus, and the ligand backbone, ligand 11k was found to be optimal in the palladium-catalyzed allylic substitution of 1,3-diphenylpropenyl acetate with dimethyl malonate or benzylamine in high yield and excellent enantioselectivity (95-98% ee). A similar optimization of the mixed phosphorus/sulfur ligand for the palladium-catalyzed allylic substitution of cycloalkenyl acetates showed that 49g afforded the highest enantioselectivities (91-97% ee). Application of this methodology to heterocyclic substrates was developed as an efficient approach to the enantioselective synthesis of 3-substituted piperidines and dihydrothiopyrans. Models for asymmetric induction are discussed based on the absolute stereochemistry of the products, X-ray crystallographic data, and NMR spectroscopic data for relevant pi-allyl complexes.

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关键词：

tetrafluorophosphite mean amplitudes of vibration bond properties

DOI：

10.1021/ja992543i

被引量：

962

年份：

2000