Dramatic effects of boryl substituents on thermal ring-closing reaction of vinylallenes.
The unidirectional thermal ring-closing reaction of cis-4-phenyl-5-borylpenta-1,2,4-triene giving 4-boryl-3-methylene-1-phenylcyclobutene proceeded significantly faster than that of the trans-isomer. The large rate difference between the cis- and trans-stereoisomers is ascribed to electronic participation of the vacant boron p orbital in the transition state SHOMO.
Murakami
Masahiro
M
Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan.
Ashida
Shinji
S
Matsuda
Takanori
T