Complete Kinetic Analysis of the Thermal Stereomutations of (+)-(1S,2S,3R)-r-1-Cyano-t-2-methyl-1,2,t-3-trideuteriocyclopropane

Article abstract of DOI:10.1021/ja00369a036

(+)-(1S,2S,3R)-r-1-Cyano-t-2-methyl-1,2,t-3-trideuteriocyclopropane has been synthesized in optically pure form.The kinetic of thermal stereomutations which interconvert this and seven other isomeric cyclopropanes have been followed: at 335.4 deg C in the gas phase, the title compound undergoes stereomutations with rate constants (x10⁵ s) k₁ = 0.55, k₂ = 0.61, k₃ = 0.10, k₁₂ = 0.88, k₁₃ = 0.083, and k₂₃ = 0; the cis-1-cyano-2-methyl-1,2,3-trideuteriocyclopropanes exhibit stereomutation rate constants (x10⁵ s) k'₁ = 0.62, k'₂ = 0.69, k'₃ = 0.15, k'₁₂ = 1.31, k'₁₃ = 0.09, and k'₂₃ = 0.While cyclopropanes 1,2-disubstituted with potent radical-stabilizing groups such as phenyl, cyano, and vinyl give stereomutation products by way of C(1)-C(2) bond cleavage only, the deuterium-labeled 1-cyano-2-methylcyclopropanes experience thermal stereomutations consistent with the intermediacy of two distinct trimethylene diradicals, one formed through cleavage of the C(1)-C(2) bond, the other by breaking C(1)-C(3).