engleski

Synthesis and photochemistry of styryl substituted annelated furan derivatives. IV. Concentration directed intra- and/or intermolecular [2+2] cycloaddition

New cyclobutane derivatives are synthesized by intermolecular photochemical [2+2] ethene-ethene "head-to-head" (9a, b) and "head-to-tail" (10a, b-11a, b) as well as [2+2] ethene-furan (12a, b) cycloaddition from the 2-[2-(2-vinylphenyl)ethenyl]benzo[b]furan (2a) and 2-[2-(2-methylphenyl)ethenyl]benzo[b]furan (2b), respectively. All compounds are isolated and characterised by spectroscopic methods. At the benzene solution irradiation of 5×10-1 M concentration and higher the 2-[2-(2-vinylphenyl)ethenyl]benzo[b]furan (2a) gives only dimeric products (9a-12a). At the 1×10-1 M concentration a mixture of dimers (9a-12a) and 7, 12-dihydro-7, 12-methano-6H-benzo[4, 5]cyclohepta[1, 2-b]benzofuran (5) is formed in a ratio 2:1.

synthesis ; photochemistry ; furan ; cyclobutane ; benzo[b]furan ; cycloaddition

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