title: Organosulfide-Catalyzed Diboration of Terminal Alkynes under Light.
abstract: 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.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531 (Japan).|National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki, 305-8565 (Japan).
authors.forename: Aya
authors.initials: A
authors.lastname: Yoshimura
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531 (Japan).
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takamachi
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki, 305-8565 (Japan).
authors.forename: Li-Biao
authors.initials: LB
authors.lastname: Han
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531 (Japan). ogawa@chem.osakafu-u.ac.jp.
authors.forename: Akiya
authors.initials: A
authors.lastname: Ogawa
keywords: alkynes; borylation; organocatalysis; photochemistry; sulfides