Stereochemistry of two new polyfunctionalized gem-dihalocyclopropanes.

The two new gem-dihalogenocyclopropanes (1'S,3R)-3-(2',2'-dichloro-1'-methylcyclopropyl)-6-oxoheptanoic acid, C(11)H(16)Cl(2)O(3), (2), and (1'S,3R)-3-(2',2'-dibromo-1'-methylcyclopropyl)-6-oxoheptanoic acid, C(11)H(16)Br(2)O(3), (3), are isostructural. Both present two stereogenic centers at C1' and C3. The absolute configuration was determined by X-ray methods. The cyclopropyl rings are unsymmetrical, the shortest bond being distal with respect to the alkyl-substituted C atom.