^Ti(O-iPr)₄^{-EtMgBr-catalyzed reaction of dialkyl-substituted alkynes with Et}₂^Zn

For the first time, Ti(O-iPr)₄-EtMgBr carbozincation of dialkyl-substituted alkynes with Et₂Zn was carried out. It was found that the reaction of 1,2-disubstituted alkynes (5-decyne, 4-octyne, 3-hexyne) with Et₂Zn is accompanied by the regioselective formation of stereoisomeric tetraalkyl-substituted hexa-1,3-diene derivatives in high yield. It was found that 2-zincoethylzincation of dialkyl-substituted alkynes in the presence of catalytic amounts of Ti(O-iPr)₄ and EtMgBr does not stop at the stage of ethylzincation of the triple bond, but is accompanied by the involvement of a second alkyne molecule with the formation of two stereoisomeric hexa-1,3-diene derivatives. The effect of the nature of the solvent on the carbozincation of dilkyl-substituted acetylenes under the conditions of titanium-magnesium catalysis was studied.