Aya Yoshimura

Organosulfide‐Catalyzed Diboration of Terminal Alkynes under Light

An efficient metal-free diboration of terminal alkynes is reported. In the presence of a catalytic amount of organosulfides under light, the addition of bis(pinacolato)diboron (B2pin2) to terminal alkynes takes place efficiently to produce the corresponding double borylation products in good yields. Mechanistic studies indicate that this metal-free sulfide-catalyzed diboration of alkynes likely occurs by generation of a boryl-centered radical with the aid of light and a sulfide, since such a radical was detected in the reaction mixture by electron spin resonance (ESR) spectroscopy. The present form of catalysis (sulfide/light) is thought to be unprecedented and provides a new means of preparation for organoboranes without heavy metal contamination in the products, which is highly desired in the preparation of drugs and electronic materials.

Air-induced double addition of P(O)–H bonds to alkynes: a clean and practical method for the preparation of 1,2-bisphosphorylethanes

An air-induced double addition of diphenyl phosphine oxide to various alkynes is reported. This reaction can proceed efficiently under metal- and solvent-free conditions, and is a clean and practically useful method for the preparation of the valuable 1,2-bisphosphorylethanes.

Rhodium-catalyzed hydrothiolation of alkynes with thiols for construction of sulfur-containing π-conjugated systems

AbstractTo synthesize sulfur-containing π-conjugated polymers, reaction conditions for rhodium-catalyzed hydrothiolation of terminal alkynes with arenethiols are optimized in detail. Under the optimized conditions, rhodium-catalyzed hydrothiolation of terminal alkynes proceeds regio- and stereoselectively to afford the corresponding vinyl sulfides via an anti-Markovnikov and syn-addition process. Then, the rhodium-catalyzed hydrothiolation is applied to polymerization of 2,5-diethynylthiophene with benzene-1,4-dithiol, which successfully provides sulfur-containing π-conjugated polymers with excellent regio- and stereoselectivities.

Novel reducing properties of a series of lanthanoid metals in the presence of SmI2

The reduction of dodecyl iodide, as model compound, with a series of lanthanoid (Ln) metals in the presence of catalytic amounts of samarium diiodide (SmI2) has been investigated in detail. The reducing activity of SmI2/Ln and the kinds of reduced products were found to be dependent on the individual Ln, but not on SmI2.