Wiley-VCH Verlag, ChemInform, 46(38), 2007
Elsevier, Tetrahedron, 32(63), p. 7717-7726
DOI: 10.1016/j.tet.2007.04.104
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The synthesis of 2,2-dibromocyclopropane-1,1-dicarboxylic acids is described. Reaction of substituted 1,1-dibromo-2-acyloxymethylcyclopropanes with methyl lithium at low temperature leads to a bromine–lithium exchange and then either formal protonation to give the corresponding monobromocyclopropanes or intramolecular cyclisation to give a substituted 3-oxabicyclo[3.1.0]hexane. Oxidative ring opening of these compounds leads stereoselectively to 1,1,2,2-tetrasubstituted cyclopropanes with four functionalities on the ring.