New electronically enriched boronobutadienes for the synthesis of hydroxylated cyclohexenes via tandem [4+2]/allylboration

This communication describes the preparation and behavior of ether-substituted 1-boronobutadienes 1 and 2 in the Vaultier tandem [4+2]/allylboration three-component reaction involving electron-poor dienophiles and aldehydes. Whereas diene 1 failed to undergo the second, allylboration step of this process, diene 2 reacted with maleimides to give products 12, and even reacted with moderately activated dienophiles such as acrylates and acrylamide derivative 14 to provide a new stereoselective approach to the synthesis of hydroxyalkylated cyclohexene derivatives.