The nickel-catalyzed cycloaddition of unsaturated hydrocarbons and carbonyls is reported. Diynes and enynes were used as coupling partners. Carbonyl substrates include both aldehdyes and ketones. Reactions of diynes and aldehydes afforded the [3, 3] electrocyclic ring-opened tautomers, rather than pyrans, in high yields. The cycloaddition reaction of enynes and aldehydes afforded two distinct products. A new carbon-carbon bond is ...
