Intramolecular Hydrogen Transfer Reactions of o-(Bromophenyl)dialkylsilyl Ethers. Preparation of Rapamycin-d1

Article abstract of DOI:10.1016/S0040-4039(00)74194-3

Radical translocations of o-(bromophenyl)dimethylsilyl ethers are efficient, but yields of α-silyloxy alkyl radicals formed by 1,5-hydrogen transfer are limited to 65-90 percent by competing 1,6- and 1,7-hydrogen transfers.Similarities in substituent effects on 1,5-hydrogen transfers and radical cyclizations are identified.