1998•Journal of Chemical Research SynopsesRequires access
Selective Ring-expansion of Oxirane into Tetrahydropyran and Tetrahydrofuran by Reagent-controlled Conditions
Munetaka Tokumasu, Asami Sasaoka, Yoshikazu Hiraga, Katsuo Ohkata
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Abstract
Ring-expansion of methyl 2-bromomethyl-5-oxiranylpent-2-enoate (7) with various acids was studied; treatment with Lewis acids (TiBr4, MgBr2 and ZnBr2) afforded the tetrahydrofuran derivative 4-Br as a major product, while reaction with silver salt (AgNO3/KPF6), which is known to have a high halide affinity, gave preferentially the tetrahydropyran 3-ONO2 derivatives as the major products.