Rearrangement of Homoallylic Alcohols with Thallium(III): Diastereoselective Synthesis of Indans Bearing a β-Hydroxy Ketone Moiety

Abstract

Several aspects of the synthesis of indans through a thallium(III)-mediated ring contraction reaction of 1,2-dihydronaphthalene derivatives bearing suitably positioned primary and secondary hydroxyl groups are disclosed. The relative configuration of 3-(2,3-dihydro-1H-inden-3-yl)-2-methyl-3-oxopropyl 4-bromobenzoate was assigned by X-ray crystal structure analysis, allowing additional insights into the mechanism of the thallium(III)-promoted oxidative rearrangement of homoallylic alcohols. The reaction of primary homoallylic alcohols bearing the electron-withdrawing group bromine gave indans in 52-55% yield using an excess of thallium trinitrate (TTN). Furthermore, the thallium(III)-mediated oxidative rearrangement of the secondary homoallylic alcohols gave, in a dia­stereoselective fashion, indans bearing up to three stereocenters.