ChemInform Abstract: Synthesis of Phytyl- and Chroman-Derivatized Photoaffinity Labels Based on α-Tocopherol.

Abstract

Photoaffinity analogues of α-tocopherol have been prepared by substituting photosensitive functional groups at either the terminus of an alkyl chain of varying length mimicking the phytyl tail or on C-3 of the chroman portion of tocopherol. The alkyl chain-modified compounds 2a−d contain a hexyl to nonyl alkyl chain extending from C-2 of the chroman, terminating in a tetrafluoroazidobenzyloxy group. These compounds were prepared starting from the commercially available Trolox acid 4, followed by esterification, protection, and reduction to the silyl-protected Trolox aldehyde 7, which was coupled using Wittig chemistry to different ω-hydroxyphosphonium bromides. Reduction of the alkene product, coupling with p-azidotetrafluorobenzyl bromide, and deprotection of the phenolic silyl group gave compounds 2a−d in excellent yields. Chroman-functionalized photoaffinity labels were synthesized starting from the protected tocopherol chromene 16b which was a key intermediate for preparation of a 3-hydroxy derivative...