Synthesis of functionalized long-chain thiols and thiophenols for the formation of self-assembled monolayers on gold

Article abstract of DOI:10.1055/s-1999-3498

The terminally 2-thienyl- and phenyl-substituted eicosane derivatives 4 and 5 were prepared by reacting 1-[(20-bromoeicosyl)oxy]-4-methoxybenzene (3) with 2-lithiothiophene and lithium diphenylcuprate, respectively. Reaction of 4 and 5 with BBr₃ leads to the corresponding bromides 6, 7 which afforded the aryl-substituted eicosanethiols 8 and 9 by nucleophilic substitution with thiourea. 4-Eicosylthiophenol (13) was prepared from eicosylbenzene (11) by chlorosulfonation and subsequent reduction of the sulfonyl chloride. Synthesis of the thiol 22 with phenylenedioxy groups incorporated in the alkyl chain involves formation of 19 from allyloxy(bromobutoxy)benzene (18) and (4-(2-thienyl)butoxy)phenol (17). Hydroboration of 19 yields the corresponding alcohol 20, which under Mitsunobu conditions and subsequent reduction with LiAlH₄ can be transformed to 22.