Dithiolactones synthesis

An interesting variation on the Paal thiophene synthesis is observed when applied to an a,p-unsaturated 7-dialdehyde. Thus, treatment of o-phthaldehyde with Lawesson s reagent produced the dithiolactone 36. When 2,3-napthalenedicarboxaldehyde reacted under similar conditions, dithio-2,3-naphthalide 37 was produced in excellent yield. ... 

The aldol reaction of dithioester enethiolates has been used for the synthesis of dithiolactones [123], chiral substrates for the Claisen rearrangement [124, 125], and oxathianes [126]. Thioamide enethiolates may be employed in this reaction as well as shown with /Tthiolactams [26], or with a precursor of the antitumour agent vinblastine [127]. 

An attempted synthesis of thiete by thermolysis (300°) of a Diels-Alder adduct with anthracene was unsuccessful, no doubt because of the thermal instability of thiete.Thiete derivative 215 was obtained by other methods, and structure 217 was suggested as an intermediate in the desulfurization of 216. The unusual dithiolactone 218b is formally derived from a cycloaddition of carbon disulfide with acetylene 218a. " A 2-substituted-3,4-diphenyl-2H-thiete is obtained by treatment of the ylide, 8-methyl-1,3-diphenyldibenzo [e, h]-8-thiazulene, with diphenylcyclo-propenethione. 2-Methoxy-3,4-diphenyl-2H-thiete is one of several products obtained on photolysis of diphenylcyclopropenethione in methanol. ... 

The synthesis of the five-membered cyclic dithioate 65 is shown in Scheme 16 [52,53]. The parent y-dithiolactone (3,4,5-trihydrothiophene-2-thione) (146) is prepared by thionation of the corresponding thiolactone 147, as shown in Eq. 32 [74]. Preparations for the l,3-dithiolane-4-thione derivatives 148 have been reported [75,76] (Scheme 32). It was proposed that the adamantanespiro compound 148a was formed by a reaction of the thiocarbonyl ylide, generated from 149 by extrusion of N2, with carbon disulfide [75]. 

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