Photoinduced chlorine atom-transfer cyclization/photohydrolysis of 3-acyl-2-chloro-N-(ω-phenylalkynyl)pyrroles: a one-pot synthesis of benzoyl-substituted fused pyrroles.

A one-pot synthesis of benzoyl-substituted fused pyrroles or indoles in moderate to high yields has been achieved by the photocyclization/photohydrolysis reactions of N-(ω-phenylalkynyl)-2-chloropyrrole-3-carbaldehydes or 3-acyl-N-(ω-phenylbutynyl)-2-haloindoles in wet acetone. The formation of all these products could be inferred by a two-step reactions, namely, photoinduced chlorine atom-transfer cyclization and subsequent photohydrolysis.

One-pot synthesis of benzo[f]quinolin-3-ones and benzo[a]phenanthridein-5-ones by the photoanuulation of 6-chloropyridin-2-ones and 3-chloroisoquinolin-1-ones to phenylacetylene.

The one-pot synthesis of benzo[f]quinolin-3-ones and benzo[a]phenanthridein-5-ones was achieved by the inter- and intramolecular photoannulation of 6-chloropyridin-2-ones and 3-chloroisoquinolin-1-ones with phenylacetylene or tethered phenylacetylene. The reactions were proceeded by photoaddition of 6-chloropyridin-2-ones and 3-chloroisoquinolin-1-ones to phenylacetylene to give the chlorine-substituted stilbenoids, and then 6π electrocyclization of the stilbenoids and oxidation aromatization to afford the polycyclic products.

Photoinduced Intramolecular addition of 3-acyl-2-haloindoles to alkenes.

1,2-Fused indoles and pyrroles were prepared via an efficient intramolecular photoaddition reaction of 1-(omega-alkenyl)-2-haloindole-3-carbaldehydes and 1-(omega-alkenyl)-2-chloropyrrole-3-carbaldehydes. The presence of an acyl group was necessary for the photocyclization reactions. The halogen-atom-retained exo- and endo-cyclization products were generally produced with results similar to those of an atom-transfer cyclization reaction. In contrast, unsaturated cyclization products were obtained in the photoreaction of substrates having methyl groups on the vinyl group.