Application of Hydroxy(tosyloxy)iodobenzene in the Wittig-Ring Expansion Sequence for the Synthesis of β‑Benzocyclo-alkenones from α-Benzocycloalkenones

摘要

The conversion of α-benzocycloalkenones to homologous β-benzocyclo-alkenones containing six, seven and eight-membered rings is reported. This was accomplished via a Wittig olefination-oxidative rearrangement sequence using [hydroxy(tosyloxy)iodo]-benzene (HTIB) is the oxidant, that enables the synthesis of regioisomeric pairs of methyl-substituted β-benzocycloalkenones. The incorporation of carbon-13 at C-1 of the β-tetralone nucleus was also demonstrated. The Wittig-HTIB approach is a useful alternative to analogous sequences in which Tl(NO3)3·3H2O or the Prevost combination (AgNO3/I2) are employed in the oxidation step.