title: Titanium reagents for the synthesis of 2-substituted benzo[b]thiophenes on the solid phase.
abstract: Titanium(IV) benzylidenes (Schrock carbenes) bearing a masked sulfur nucleophile in the ortho position were generated from thioacetals with use of low-valent titanocene complex Cp(2)Ti[P(OEt)(3)](2) and alkylidenated Merrifield resin-bound esters to give enol ethers. Treatment of the resin-bound enol ethers with a 5:5:90 mixture of TFA, TFAA, and dichloromethane led to cleavage from resin, removal of the tert-butyldimethylsilyl (TBDMS) protecting group, and concomitant cyclization to complete the traceless solid-phase synthesis (SPS) of benzothiophenes. Switching the nature of the linker from acid-stable to acid-sensitive ensured good purity.
authors.affiliation: Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Christine F
authors.initials: CF
authors.lastname: Roberts
authors.forename: Richard C
authors.initials: RC
authors.lastname: Hartley