Tandem radical [2+1] cycloaddition. Remarkable silyl substituent effect on the chemoselectivity of the radical cyclization reactions
摘要:
Tandem radical cyclization of bromides 1 with Bu3SnH is extremely sensitive to the nature of the substituent on the diene moiety. Bicyclo[3.1.0] skeleton 3 is obtained in the presence of the silyl substituent. The tert-butyl substituent gives exclusively six-membered ring products 15. Tributyltin radical addition to the double bond becomes predominant when the substituent is phenyl.