Studies on the reactions of 3-sulfolenes and their application to the Synthesis of ph-siologically active compounds.

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1. Reactions of 3-sulfolenes and their application to the synthesis of natural products. (1) Synthesis and reactions of 2-tributylstannyl-3-sulfolene(a). Compound a was synthesized for the first time and coupled with vinyl halides in the presence of Pd(PPh3)_4 to give 2-vinyl-3-sulfolenes which underwent desulfonylation to afford conjugate trienes highly stereoselectively. (2) Synthesis and reaction of 4-methylene-2-sulfolene and its application to the synthesis of (<plus-minus>)-Ipsenol, the aggregation pheromone of bark beetles. (3) Efficient synthesis of a indolizidine alkaloid, Elaeokanine A and B. 3-Hydroxymethyl-3-sulfolene was alkylated regioselectively at the 2-position and resulting 3-sulfolene derivative was manupulated to give N-(acetyloxymethyl)-3- (t-butyldiphenylsiloxymethyl)-3-sulfolene-2-propamide, which was suniected to hetero- Diels-Alder reaction to provide indolizidine ring having desired functionality for the Elaeokanine A and B. (4) Convergent synthesis of active- … More type vitamin D using 3-sulfolene reaction as a key step. 1,3,4,7-Tetrahydro-benzo[c]thiophene 2,2-dioxide was synthesized and subjected to Aldol condensation with cyclohexanecarbaldehyde followed by successive desulfonylation and dehydroxylation to give the conjugated triene such as that in vitamin D. This provides basically a novel convergent synthetic method for vitamin D.2. Synthesis and reactions of 4,6-dihydrothieno[3,4-c]furan 5,5-dioxide (b) and their application to the synthesis of natural products. (1) Diels-Alder reactions of b with typical dienophiles (3 equivs) under a variety of conditions. Compound b reacted with dimethyl acetylenedicarboxylate, dimethyl fumarate, dimethyl maleate, maleic anhydride, N-phenylmaleimide, and 1,4-naphthoquinone under various conditions to furnish four kinds of cycloadduct; type A (cycloadduct to furan having bismethylene), type B(biscycloadduct), type C(monocycloadduct to sulfolene), and type D(cycloadduct to furan). The type of reaction depends on the kind of dienophile and reaction conditions(solvent, temperature, time, and pressure). These reactions demonstrate that b is a useful building block for synthesizing bioactive compounds such as anthracycline antibiotics. (2) Construction of the ring A of active-type vitamin D including conjugated triene. Compound b was hydroxyalkylated with cyclohexanecarbaldehyde to gibe Aldol product, which undrewent Diels-Alder cycloaddition with methyl vinyl ketone to afford type A compound in 2-(1). Less