Use of Thiazyl Chlorides, Alkyl Carbamates, and Thionyl Chloride To Fuse 1,2,5-Thiadiazoles to Quinones and To Oxidize, Chlorinate, and Aminate Them
作者:Shuhao Shi、Thomas J. Katz、Bingwei V. Yang、Longbin Liu
DOI:10.1021/jo00110a036
日期:1995.3
Thiazyl chlorides in a simple one-step procedure fuse 1,2,5-thiadiazole rings to quinones. So do alkyl carbamates mixed with excess thionyl chloride and pyridine. Evidence is put forward to support the hypothesis that NSCl or a related thiazyl derivative is the reactive species that brings about the transformations. Selenoyl chloride mixed with an alkyl carbamate, pyridine, and quinones similarly gives 1,2,5-selenodiazoloquinones. Thionyl chloride in pyridine chlorinates quinones and oxidizes hydroquinones. 2,3-Dichloro-1,4-quinones with S4N4 or. with alkyl N-sulfinylcarbamates give 1,2,5-thiadiazoloquinones. Quinones and their 2 3-dichloro derivatives with TsNSO in pyridine give betaine derivatives of 2,3-diaminoquinones, which pyrrolidine converts into 2-amino-3(tosylamino)quinones. A unified set of mechanisms is presented that accounts for these transformations.
Methoxycarbonyl shifts in Diels–Alder adducts of methoxycarbonyl-1,4-benzoquinones
作者:Mabel U. Akpuaka、Roy L. Beddoes、J. Malcolm Bruce、Steven Fitzjohn、Owen S. Mills
DOI:10.1039/c39820000686
日期:——
Treatment of 4a,5,8,8a-tetrahydro-4a-methoxycarbonyl-1,4-naphthaquinone with acetic anhydride gives the Δ8a,1 enol acetate, which in the presence of sodium acetate yields 1,4-diacetoxy-5,8-dihydro-6-methoxy-carbonylnaphthalene; the 2- and the 5-methyl, and the 2,5-dimethyl homologues behave analogously.