A. Cuthbertson et B. Indrevoll, A method for the one-pot regioselective formation of the two disulfide bonds of alpha-conotoxin SI, TETRAHEDR L, 41(19), 2000, pp. 3661-3663
A one-pot method for the regioselective formation of the disulfide bridges
of rx-conotoxin SI employing temperature-controlled orthogonal protecting g
roups is reported. The pairing of t-butyl and 4-methylbenzyl sidechain prot
ecting groups was chosen for the four cysteine residues. Cleavage of the pe
ptide from a solid support afforded a fully S-protected crude product. The
first disulfide bridge was formed directly from the crude material by simul
taneous cleavage and oxidation of the t-butyl groups in TFA:DMSO:anisole (9
7.9:2:0.1) at room temperature. The subsequent heating of this solution res
ulted in the cleavage of the 4-methylbenzyl groups with simultaneous oxidat
ion yielding the desired bicyclic product. (C) 2000 Elsevier Science Ltd. A
ll rights reserved.