5662-93-1Relevant articles and documents
Practical Stereoselective Synthesis of (2E)- and (2Z)-4-Cycloalkylidenebut-2-enoic Acids
Karagiozov, Stoyan K.,Abbott, Frank S.
, p. 871 - 888 (2004)
Stereoselective synthesis of α,β-unsaturated esters 7 and 8 was achieved through Horner-Wadsworth-Emmons reaction of β,β -disubstituted α,β-unsaturated aldehydes. Thus, aldehydes 6 undergo olefination with phosphonate carbanion generated from triethyl phosphonoacetate 3 and lithium hydroxide or butyl lithium/DMPU to give (E)-α,β -unsaturated esters 7 with excellent selectivity. The treatment of 6 with the new Horner-Emmons reagents, ethyl(diphenylphosphono)acetate 4a and ethyl (di-o-tolyl-phosphono) acetate 4b in the presence of benzyltrimethyl ammonium hydroxide (Triton B) afforded (Z)-α,β-unsaturated esters 8 with 73-89% selectivity. The esters 7 and 8 were converted to (2E)- and (2Z)-4-cycloalkylidenebut-2-enoic acids 9 and 10, respectively.
