1 260 0 mac 0 Me Me may ' Cl TMSOT' _' M 25 27 "SnMes 25 \“°“ l 0 Me 0 Me Me _. / CI Me 23 29 Scheme 6. secondary tin compound 25, a tertiary tin compound 30 gave 32 as major product when treated with TiCl4 (Scheme 7). Although the reaction type seems quite different from that of 25, we believe that a similar re— action pattern involving the Type B reaction proceeds to afford 31, which subsequently undergoes a 1,2-acyl migration to give the final product. We have ...