Substrate-Controlled Generation of 3-Sulfonylated 1-Indenones and 3-Arylated ( Z)-Indenes via Cu-Catalyzed Radical Cyclization Cascades of o-Alkynylbenzonitriles.

Substrate-controlled generation of 3-sulfonylated 1-indenones and 3-arylated ( Z)-indenes through radical cyclization cascades of o-alkynylbenzonitriles with sulfonyl hydrazides was established by combining copper(II) with tert-butyl hydroperoxide (TBHP) as a catalytic oxidative system. With the installation of the aryl group (R1) into the alkynyl unit, sulfonyl radicals triggered addition-cyclization cascades to access 3-sulfonylated 1-indenones with good yields by using a Cu/TBHP system, whereas a series of new functionalized 3-arylated ( Z)-indenes were obtained in good yields when o-alkynylbenzonitriles bearing the alkyl group in the alkynyl unit were subjected with arylsulfonyl hydrazides with an electron-rich nature under the above conditions.