Highly selective introduction of heteroatom groups to isocyanides and its application to electrocyclic reactions

Ogawa, Akiya; Tamai, Taichi; Mitamura, Takenori; Nomoto, Akihiro

doi:10.1351/PAC-CON-12-07-01

Pure Appl. Chem., 2013, Vol. 85, No. 4, pp. 785-799

http://dx.doi.org/10.1351/PAC-CON-12-07-01

Published online 2012-12-07

Highly selective introduction of heteroatom groups to isocyanides and its application to electrocyclic reactions

Akiya Ogawa*, Taichi Tamai, Takenori Mitamura and Akihiro Nomoto

Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan

Abstract: Photoinduced cyclization of o-alkenylaryl isocyanides with (PhS)₂ in the presence of (PhTe)₂ affords the corresponding bisthiolated indene derivatives in good yields via radical cyclization process by thio radical. The procedure can be applied to the construction of tetracyclic systems by using bis(o-aminophenyl) disulfides in place of (PhS)₂. In sharp contrast, when o-alkynylaryl isocyanides are employed as the substrates, novel electrocyclic reactions take place upon photoirradiation or heating at 40~80 °C to generate quinoline 2,4‑biradical species, which are trapped with organic diselenides, ditellurides, and molecular iodine to give the corresponding 2,4-diseleno-, ditelluro-, and diiodo-quinoline derivatives, respectively, in good yields. The obtained quinoline derivatives are useful synthetic intermediates; for example, cross-coupling reactions using 2,4-diiodoquinolines lead to the preparation of functionalized quinoline derivatives.