26487-92-3Relevant articles and documents
Extended stereocontrol in silyl group-transfer cyclizations: Control of four contiguous chiral centers
Klimko,Singleton
, p. 979 - 982 (1994)
The potential for extended stereocontrol in silyl group-transfer cyclizations was explored in model studies which formed four contiguous chiral centers. The diastereofacial selectivity for the reaction of cyclized intermediates was outstanding for both fluoride and SnCl2-trityl chloride mediated reactions. Good simple diastereo-selectivity was observed in reactions initiated by prochiral silyl enolates.
Intramolecular Diels-Alder Cycloaddition Approach toward the cis-Fused Δ5,6-Hexahydroisoindol-1-one Core of Cytochalasins
Xu, Jingjing,Lin, Benguo,Jiang, Xiuqing,Jia, Zejun,Wu, Jinlong,Dai, Wei-Min
, p. 830 - 834 (2019/01/26)
Synthesis of the cis-fused Δ5,6-hexahydroisoindol-1-one core of cytochalasins B2-B5, K, Z8, Z9, Z12-Z15, and Z17 has been established starting from an intramolecular D
Stereoselective olefination of N-sulfonyl imines with stabilized phosphonium ylides for the synthesis of electron-deficient alkenes
Fang, Fan,Li, Yuan,Tian, Shi-Kai
supporting information; experimental part, p. 1084 - 1091 (2011/04/15)
An unprecedented protocol has been developed for thestereoselective synthesis of structurally diverse electron-deficient alkenes in moderate to excellent yields from readily accessible N-sulfonyl imines and stabilized phosphonium ylides. Significantly, the olefination reaction of N-sulfonylimines with nitrile-stabilized phosphonium ylides affords an array of α,β-unsaturated nitriles with high Z selectivity, and the reactions with ester-, amide-, and ketone-stabilized phosphonium ylides afford α,β-unsaturated esters, amides, and ketones with high E selectivity, respectively. Spectroscopic analysis of the reaction mixtures and trapping of the intermediates allow plausible mechanisms to be proposed. Initialimine/ylide addition leads to the formation of betaines that cyclize to form 1,2-azaphosphetanes that subsequently eliminate iminophosphoranes to yield alkenes. For the synthesis of electron-deficient 1,2-disubstituted alkenes, the presence of an electron-withdrawing group in the betaine allows rapid interconversion between its two diastereomers through proton transfer. The Z/E selectivity for alkene synthesis is determined by the different rates at which the two betaine diastereomers form the corresponding 1,2-azaphosphetane diastereomers. In contrast, the Z/E selectivity for the synthesis of electron-deficient trisubstituted alkenes originates from the diastereoselective addition of stabilized phosphonium ylides to N-sulfonyl imines.
