Enantioselective Synthesis of Phospholenes<i>via</i>Asymmetric Organocatalytic Alkene Isomerization
作者:Lukas Hintermann、Marco Schmitz
DOI:10.1002/adsc.200800226
日期:2008.7.7
An asymmetric synthesis of the 2,5-diphenylphosphol-2-ene fragment (≥95% ee) has been realized via enantioselective Cinchona-alkaloid catalyzed double bond isomerization of a meso-2,5-diphenylphosphol-3-ene amide to a 2,5-diphenylphosphol-2-ene amide (up to 83% ee), followed by enantiomeric enrichment to ≥95% ee by crystallization. The 2,5-diphenylphosphol-2-ene amide (a cyclic phosphinic acid amide)
total synthesis of Fiaud’s acid, which is a building block for chiral phospholane synthesis, has been realized in five steps from thiophene, using nickel-catalyzed Wenkert arylation, McCormack cycloaddition, asymmetric dihydro-1H-phosphole isomerization, hydrolysis, and diastereoselective hydrogenation. The potential for an organocatalytic asymmetric stereoisomerization or alkeneisomerization as atom-economic