| Summary: | For the first time, the Ti(O-<i>i</i>Pr)<sub>4</sub>-EtMgBr carbozincation of dialkyl-substituted alkynes with Et<sub>2</sub>Zn was carried out. It was found that the reaction of 1,2-disubstituted alkynes (5-decyne, 4-octyne, 3-hexyne) with Et<sub>2</sub>Zn is accompanied by the regioselective formation of stereoisomeric tetra-alkyl-substituted hexa-1,3-diene derivatives in high yield. It was also found that the 2-zincoethylzincation of dialkyl-substituted alkynes in the presence of catalytic amounts of Ti(O-<i>i</i>Pr)<sub>4</sub> 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 solvent on the carbozincation of the dilkyl-substituted alkynes under the conditions of titanium-magnesium catalysis was studied.
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