The reaction of 4,5‐diphenylimidazol‐2‐thione (1) with aromatic ketones 2a‐i using the acidified acetic acid method afforded the 4,5‐diphenyl(2‐imidazolylthio)acetophenones 3a‐h in good yields. While, the cyclized product 4i was obtained directly upon reaction of 1 with α‐acetyl naphthalene. Compounds 3a‐h were cyclized directly to the corresponding 3‐aryl‐5,6‐diphenylimidazo[2,1‐b]thiazoles (4a‐c) and (4e‐h). In the same manner the reaction of 1 with aliphatic and/or alicyclic ketones gave the 3‐(4,5‐diphenyl‐2‐imidazolylthio)acetone derivatives 5a‐d, 2‐(4,5‐diphenylimidazolylthio)cycloalkanones 8a,d and the tricyclic compounds 9b‐c respectively. The cyclized compounds 6a‐d and 9a,d were obtained by cyclization of 5a‐d and 8a,b respectively. Oxidation of 1 gives the corresponding bis(4,5‐diphenyl‐2‐imidazolyl)‐disulfide (10) in 90% yield. Some of the synthesized compounds were tested for antifungal and antibacterial activity.
4‐Hydrazino‐2‐methylpyrimidino[4′,5′:4,5]thiazolo[3,2‐a]benzimidazole (4) was obtained from hydrazinolysis of the 4‐chloro derivative 3 with hydrazine hydrate. The hydrazino derivative 4 was further cyclized to the corresponding pyrazole 5, pyrazolone 6 and 5‐methyl‐1,2,4‐triazolo[1″,5″:3′,4′]pyrimidino[5′,6′:5,4]‐thiazolo[3,2‐a]benzimidazole (9) and 5‐methy‐1,2,4‐triazolo[4″,3″:3′,4′]pyrimidino[5′,6′:5,4]thiazolo‐[3,2‐a]benzimidazole (10), respectively. The triazolo derivative 10 was isomerized to the triazolo derivative 9 under a variety of reaction conditions.
Sonication of a zinc/copper couple, N,O‐bis(trimethylsilyl)‐acetamide (BSA) and α,α'‐oligobromo ketones in benzene gives rise to oxyallyl intermediates which cycloadd to anthracene. Starting from 1,1,3,3‐tetrabromoacetone (2a) and anthracene (1a), we obtained 11,11,13‐tribrominated adduct 4 as the major product (42%). The expected 11,13‐dibrominated adduct trans‐3 was formed as a minor product (5%), but it became the main product when the known oxyallyl methodology was applied. Dibenzohomobarrelenes 9 and 17 were prepared by short routes.
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