The synthesis, structure, and some reactions of sterically hindred α-silylisoxazoles

4-(4,5-Dihydro-4,4-dimethyl-2-isoxazolyl)-3-phenyl-5-silylmethylisozazole and 3-phenyl-5-silylmethyl-4-isoxazole-t-carboxamide derivatives were synthesized in synthetically useful yields from the corresponding oxazolyl-isoxazole or t-carboxamide by metalation of the isoxazole systems at the C(5) alkyl group followed by electrophilic quenching with either t-butylchlorodiphenylsilane or t-butylchlorodimethylsilane. The silylisoxazole systems were metalated at the C(5) position, producing the corresponding α-silyl carbanion, which upon quenching with MeOD produced C(5) deuterium incorporation. The reaction of silyloxazolylisoxazoles with titanium tetrachloride caused the oxazoline ring to open forming chloro-substituted carboxamide. The X-ray structure of a silyloxazolylisoxazole was obtained and indicates an "s-trans" ring juncture with respect to the heterocyclic rings.