Stereochemistry and mechanism of the wittig reaction

Autor:	L. D. Bergel'son, V. A. Vaver, L. I. Barsukov, M. M. Shemyakin
Rok vydání:	1963
Předmět:	chemistry.chemical_classification Steric effects chemistry.chemical_compound Relative yield Chemistry Stereochemistry Wittig reaction Substituent Molecule Stereoselectivity General Chemistry Lewis acids and bases Aldehyde
Zdroj:	Bulletin of the Academy of Sciences, USSR Division of Chemical Science. 12:957-966
ISSN:	1573-9171 0568-5230
DOI:	10.1007/bf00845473
Popis:	1. Steric control of the Wittig reaction can be effected by changing the reaction conditions and the structures of the starting compounds. 2. Stereoselective synthesis of cis olefins from alkylideneor benzylidene-triphenylphosphoranes and aldehydes can be effected in presence of Lewis bases. The maximum relative yield of cis olefins is attained by carrying out the reaction in N,N-dimethylformamide in presence of Br− and I−, which form complexes with phosphoranes. 3. The stereoselective synthesis of trans olefins was effected when the phosphorylid molecule contained an electron-accepting substituent on the ylid C atom. Thus, irrespective of the external conditions, the reaction ofα-(triphenylphosphoranylidene)alkanoic esters with aldehydes gives only the corresponding trans olefins.
Databáze:	OpenAIRE
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