Sequential alkoxy radical fragmentation-cyclopropylcarbinyl rearrangement. Synthesis of highly functionalized eleven-membered rings

4 pages, 1 table, 2 schemes.The steroidal 5α-alcohol (3) with (diacetoxyiodo)-benzene and iodine under irradiation with visible light undergoes a tandem alkoxy radical β-fragmentation-cyclopropylcarbinyl rearrangement reaction to give the eleven-membered cyclic ketone (4). Under oxygen pressure peroxidation of the C-radical intermediate takes place to afford the highly functionalized eleven-membered cyclic ketone (6) in moderate yield.This work was supported by the Investigation Progmmme nr PB90-0083 of the Dirección General de Investigación Científica y Técnica. A.B. thanks the Ministerio de Educación y Ciencia, Spain, for a fellowship