Ring opening of gem-dihalocyclopropanes: novel types of 1,4-elimination reactions
On treatment with Bu4N+ F-, cyclopropanecarboxylates I (R = Cl; R1 = Cl, F; R2 = OCMe3) undergo Cl-F exchange via cyclopropene intermediates. As a byproduct, H2C:CMeC.tplbond.CCO2CMe3 (II) is formed. I (R = R1 = Cl, R2 = CO2CMe3), II, and Me2CClC.tplbond.CCO2CMe3 are obtained when Me2C:CHCO2CMe3 is allowed to react with CHCl3 in strongly alk. medium. I (R = R1 = F, R2 = H) can be generated by oxidn. of the alc. In the presence of any base, however, instantaneous ring opening and dehydrofluorination occurs to give H2C:CMeCF:CHCHO. The solvolysis of 2,2-difluoro-3,3-dimethylcyclopropylmethyl p-toluenesulfonate in boiling aq. dioxane affords two ring opened products, 3,3-difluoro-2-methyl-1,4-pentadiene and 3,3-difluoro-2-methyl-4-penten-2-ol, besides 2,2-difluoro-3,3-dimethyl-1-cyclopropylmethanol. [on SciFinder (R)]
1990
46
15
5230
5236
CAN 114:42087
24-2
Alicyclic Compounds
Inst. Chim. Org.,Univ. Lausanne,Lausanne,Switz.
Journal
written in English.
78-80-8 Role: RCT (Reactant), RACT (Reactant or reagent) (condensation of, with di-Bu carbonate, pentenynoate from); 34619-03-9 (Di-tert-butyl carbonate) Role: RCT (Reactant), RACT (Reactant or reagent) (condensation of, with methylbutenyne, pentenynoate from); 131283-53-9 Role: RCT (Reactant), RACT (Reactant or reagent) (oxidn. of); 131262-17-4P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. and esterification of); 131262-12-9P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. and oxidn. of); 131262-13-0P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. and ring opening-dehydrofluorination of); 73557-47-8P; 131262-09-4P; 131262-10-7P; 131262-11-8P; 131262-14-1P; 131262-16-3P; 131262-18-5P; 131262-19-6P; 131262-20-9P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of); 39872-18-9P; 131262-08-3P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn., halogen exchange, and ring opening of); 131262-15-2 Role: RCT (Reactant), RACT (Reactant or reagent) (ring opening-dehydrofluorination and solvolysis of)
REVIEWED
EPFL