Abstract We found that nitrogen-containing Lewis base mediated [4+ 2] annulation of but-3- yn-2-one with activated ketones could proceed efficiently to give the corresponding 2, 3- dihydropyran-4-ones in moderate to good yields under mild conditions. The substrate scope has been carefully examined. Moreover, a plausible reaction mechanism for the [4+ 2] annulation of but-3-yn-2-one with activated ketones mediated by DABCO has been ...
[Page, Philip C. Bulman; Williams, P. Howard; Collington, Eric W.; Finch, Harry Journal of the Chemical Society, Chemical Communications, 1987 , p. 756 - 757]