PHOTOCHEMICAL CYCLOADDITION OF α,β-ACETYLENIC KETONES WITH SIMPLE OLEFINS

Article abstract of DOI:10.1016/S0040-4020(01)92377-4

Irradiation of 3-pentyn-2-one (1) in the presence of tetramethylethylene, isobutylene, and cis- and trans-2-butene leads to vinyldihydrofurans 3, 5, 6, 8, and 9 (Table 1) in a novel <3+2> photochemical cycloaddition reaction.A related adduct 13 is formed between tetramethylethylene and 5,5-dimethyl-3-hexyn-2-one (2).A mechanism incorporating an initial biradical that closes to a carbene (eqn 3) is proposed to account for these reactions.