ETUDE DES PETITS CYCLES-XLIII. REACTIONS D'ADDITION SUR LES α-CYCLOPROPYLIDENE-CETONES ET SUR LES α-CYCLOPROPYLIDENE-ALDEHYDES

Article abstract of DOI:10.1016/S0040-4020(01)91581-9

α-Cyclopropylidene ketones and aldehydes show high reactivity towards 1,4-addition of methanol in acidic or basic medium, water and hydrochloric acid giving α-(1-methoxy cyclopropyl) ketones and aldehydes, α-(1-hydroxy cyclopropyl) ketones and α-(1-chloro cyclopropyl) ketones and aldehydes respectively.The reaction of α-cyclopropylidene-ketones with Grignard reagents gives mainly α-cyclopropyl ketones (the 1,4-addition product) besides α-cyclopropylidene carbinols (the 1,2-addition product).Addition of methyl-lithium and lithium dimethylcuprate lead to the expected 1,2- and 1,4-addition products,respectively.The comparison of the se results and those corresponding to α-isopropylidene-ketones confirms the higher tendency of α-cyclopropylidene-ketones to give 1,4-addition products; the measurement of polarographic reduction potentials confirms, in some cases, this difference.The reaction of HOBr (NBS, DMSO, H2O) with α-cyclopropylidene ketones produces α-hydroxy β-bromo ketones whereas the corresponding α-isopropylidene ketones give β-hydroxy α-bromo ketones.