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Pure Appl. Chem., 2010, Vol. 82, No. 3, pp. 565-575

Published online 2010-02-18

Transition-metal-catalyzed cleavage of carbon–selenium bond and addition to alkynes and allenes

Shin-ichi Fujiwara1, Masashi Toyofuku2, Hitoshi Kuniyasu2 and Nobuaki Kambe2*

1 Department of Chemistry, Osaka Dental University, Kuzuha-hanazonocho 8-1, Hirakata Osaka 573-1121, Japan
2 Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan

Abstract: This account summarizes our recent results on transition-metal-catalyzed cleavage of C–Se bond and addition to unsaturated hydrocarbons such as alkynes and allenes. Pd(0)‑catalyzed intramolecular carbamoselenation of alkynes forms four- to eight-membered α-alkylidenelactams. Interestingly, four-membered ring formation is faster than five- and six-membered ring formation. Intramolecular vinylselenation of suitably structured alkynes offers pathways to conjugated δ-lactam frameworks. Electron-withdrawing groups on the vinyl moiety are essential to promote this reaction. Intermolecular 1,2-addition of selenol esters onto allenes proceeds with excellent regioselectivity and high stereoselectivity in the presence of a Pd(0) catalyst, producing functionalized allyl selenides. In addition, Pd(0)‑catalyzed intramolecular selenocarbamoylation of allenes gives α,β-unsaturated γ- and δ-lactams with perfect regioselectivity. The scope and limitations, as well as reaction pathways, are discussed.