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Stereoselective Michael Additions of Phosphorylated Allyl Carbanions − Synthesis of Functionalized Cyclopentylphosphonates and Phosphane Oxides
Author(s) -
Ruan Wen Juan,
Hassner Alfred
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200104)2001:7<1259::aid-ejoc1259>3.0.co;2-d
Subject(s) - chemistry , stereoselectivity , phosphonate , stereocenter , diastereomer , carbanion , regioselectivity , stereochemistry , cyclopentane , adduct , michael reaction , medicinal chemistry , ketone , organic chemistry , enantioselective synthesis , catalysis
Dimethyl (2‐chloromethyl‐2‐propenyl)phosphonate ( 3b ) and ( tert ‐butyl)[2‐(chloromethyl)‐2‐propenyl](phenyl)phosphane oxide ( 3d ) were prepared and their reactions with α,β‐unsaturated esters 5a − c and ketone 5d , acting as phosphorylated trimethylenemethane equivalents by a [3+2] strategy, were investigated. With the use of LDA in the presence of DMPU, the Michael addition proceeded with high stereoselectivity and regioselectivity to afford methylenecyclopentyl‐substituted dimethyl phosphonate or ( tert ‐butyl)(phenyl)phosphane oxide derivatives 6a − d and 14( S P ) . Compound 3d reacted with 5a − b and 5d to give phosphorous diastereomers 10( R P ) and 11( S P ) , 12( R P ) and 13( S P ) , and 16( R P ) and 17( S P ) , with complete stereoselectivity at the three stereogenic centers of the 5‐methylenecyclopentanes, all possessing 1,2‐ trans and 2,3‐ trans stereochemistry. Formation of open‐chain syn adduct 15 and of a 2,3‐ cis ‐disubstituted cyclopentane compound 18( S P ) could also be achieved. The stereochemical features of all the products were ascertained by 1D and 2D NMR spectra.