(Z)-1-alkenyl selenides in high yields. Alternatively, (E)-1-alkenyl selenides were prepared by the reaction of 1-alkenylaluminums with organic diselenides in a one-potprocedure starting from the corresponding 1-alkynes, which provides a versatile tool for the preparation of stereo-defined unsaturated organic derivatives of selenium. The Cp2ZrCl2-catalyzed methylalumination and сycloalumination of 1-alkynyl
β-disubstituted 1-alkenyl sulfones and 1-alkenyl sulfides in high yields. S-Methyl methanethiosulfonate is shown to be a convenient and efficient sulfanylating agent for 1-alkenylaluminum derivatives. The Cp2ZrCl2-catalyzed methylalumination of 1-alkynyl sulfones and 1-alkynyl sulfides with Me3Al, followed by deuterolysis or hydrolysis, affords the corresponding β,β-disubstituted 1-alkenyl sulfones and