Engaging yne-allenones in tunable catalytic silane-mediated conjugate transfer reductions.

New tunable catalytic [2+2] cycloaddition/silane-mediated conjugate transfer reductions of yne-allenones have been developed, by which substituent-diverse cyclobutarenes with generally good yields were selectively synthesized by adjusting Fe-H and Cu-H catalytic systems. Use of the Fe-H system triggers 1,6-conjugate reduction to dihydrocyclobuta[a]naphthalen-4-ols whereas the Cu-H complex enables 1,4-conjugate reduction to cyclobuta[a]naphthalen-4(2H)-ones.