Cyclomagnesation of olefins with ethylmagnesium bromide in the presence of titanium complexes

Cyclomagnesation of terminal and cyclic olefins and 1,2-dienes with RMgHlg and R2Mg in the presence of dichloro(dicyclopentadienyi)titanium(IV) gives non-Grignard cyclic and acyclic organornaanesium compounds. The reaction direction depends on the structure of unsaturated initial compound. The most probable reaction mechanism is discussed.