STEREOCHEMISTRY OF THE THERMAL ISOMERIZATIONS OF (1S,2R)-1-(E-STYRYL)-2-PHENYLCYCLOPROPANE TO 3,4-DIPHENYLCYCLOPENTENES

被引:19
作者
ASUNCION, LA [1 ]
BALDWIN, JE [1 ]
机构
[1] SYRACUSE UNIV,DEPT CHEM,SYRACUSE,NY 13244
关键词
D O I
10.1021/ja00148a009
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
One stereoisomer of 1-(E-styryl)-2-phenylcyclopropane undergoes reversible thermal stereomutations to equilibrate with three other stereoisomers and gives more slowly the four isomers of 3,4-diphenylcyclopentene. Appropriate kinetic data and analyses have provided rate constants for the four stereochemically distinct paths leading from one enantiomer of trans-1-(E-styryl) -2-phenylcyclopropane to 3,4-diphenylcyclopentenes: at 160 OC the relative significances of the four distinct paths followed in these vinylcyclopropane to cyclopentene rearrangements are (67 +/- 3)% si, (12 +/- 3)% ar, (17 +/- 1)% sr, and (4 +/- 1)% ai. The orbital symmetry ''allowed'' si and ar paths are phenylcyclopropane isomerizes to 3,4-diphenylcyclopropanes at comparable rates, with the ''forbidden'' paths favored over the ''allowed'' routes, 91:9. The rearrangements may be considered to be processes mediated by kinetically competitive diradical transition structures rather than controlled by orbital symmetry considerations.
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收藏
页码:10672 / 10677
页数:6
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