Studies On The Photoinduced Cyclization O-Haloheteroaromatic Compounds

This thesis deals with the studies on synthetically useful photocyclization reactions. Besides a concise review on the new progress made in this field in recent years, it mainly describes the photoinduced cyclization of o-haloheteroaromatic compounds reactions which are outlined as follows:(1) 1,2-fused indoles and pyrroles were prepared via an efficient intramolecular photoaddition reaction of 1-(ω-alkenyl)-2-haloindole-3-carbaldehydes and 1-(ω-alkenyl)-2-chloropyrrole-3-carbaldehydes. This method provides halogen-atom-transfer compounds in moderate to good yields without no reduction products found.(2) A one-pot synthesis of fused benzo[c]carbazoles in excellent yields was achieved by the photocyclization reactions of 2-halogen-1-(co-phenylalkynyl)indole-3-carbaldehydes in acetone.(3) A one-pot synthesis of benzoyl-substituted fused pyrroles or indoles in moderate to high yields was achieved by the photocyclization/photohydrolysis reactions of N-(ω-phenylalkynyl)-2-chloropyrrole-3-carbaldehydes or 3-acyl-N-(ω-phenylbutynyl)-2-haloindole-3-carbaldehydes in wet acetone. The formation of all these products could be inferred by a two-step reactions, namely, photoinduced chlorine atom-transfer cyclization of N-(ω-phenylalkynyl)-2-chloropyrrole-5-carbaldehydes or 3-acyl-N-(co-phenylbutynyl)-2-chloroindoles and subsequent photohydrolysis.(4) An convenient synthesis of indolo[2,1-a]isoquinoline was achieved by the photocyclization of N-substituted-2-chloroindole-3-carbaldehydes in acetone. This method provids good yields and avoids affording reductive byproducts.