4,7-Diethylbenzo[1,2,3]trithioles (1a-1c), 4,8-diethylbenzo[1,2-d:4,5-d']bis[1,2,3]trithiole (1d), and 6, 10-diethyl[1,2,3]trithiolo[h]benzopentathiepin (1d') were treated with sodium borohydride and 0.5 equiv. of p-xylylene dibromide to produce bridged molecules 2a-2d with two thiol groups. On oxidation of 2a with iodine in the presence of triethylamine, 28-membered macrocycle 3a, linked with two disulfide bonds, was obtained via a dimeric cyclization reaction, instead of a monomeric 14-membered macrocycle. Compounds 2b-2d were similarly treated with iodine and triethylamine to give 28-membered macrocycles 3b-3d. In the case of the reaction of 2c, a trimeric reaction occurred to produce 42-membered macrocycle 4 together with 3c. The structures of the cyclic molecules were determined by NMR and mass spectrometry, which was further supported by X-ray crystallographic analysis.
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