Catalytic synthesis and reactions of magnesiocycloalkanes. 2. Synthesis of substituted magnesiocyclopentanes in the presence of zirconium complexes

Catalytic cyclometalation reaction of unsaturated compounds in synthesis of magnesa- and aluminacarbocycles

“…The authors of the work [198] have shown that the reaction of styrene with R 2 Mg under the effect of Cp 2 ZrCl 2 catalyst led under mild conditions (20°C, Et 2 O/THF) to a 1:3 mixture of magnesacyclopentanes 153 and 154 in a total 80% yield [199]. Similar mixture of magnesacyclopentanes has been obtained as a result of catalytic cyclomagnesiation of o-, m-, p-methyl or mtert-butyl styrenes [200,201]. It should be noted that before discovery in 1989 of the above catalytic cyclomagnesiation reaction the authors of the present survey have succeeded in studying 1,2-carbomagnesiation of aolefins containing non-activated double bond assisted by RMgX or R 2 Mg [202,203].…”

Cyclomagnesation of Olefins with Ethylmagnesium Bromide in the Presence of Titanium Complexes

“…The yields and ratio of cyclo-and carbomagnesation products depends on the solvent nature, temperature, and initial reactant ratio [3,8]. As a rule, the reaction is catalyzed by zirconium complexes [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. We have found no published data on the use of coordination compounds derived from other transition metals to catalyze cyclomagnesation.…”

“…These studies were subsequently developed in [2][3][4][5][6][7][8][9]. According to the data of [3,6,8], depending on the conditions, the cyclomagnesation process can be accompanied by carbomagnesation [10][11][12][13][14] which involves formation of zirconacyclopentane intermediates.…”

10.1007/s11178-008-2004-9

“…In continuation of the investigation of this reaction, in order to extend it to cyclic allenes, and also aiming at the synthesis of new classes of unsaturated bicyclic organomagnesium compounds we studied a reaction of cyclonona-1,2-diene with EtMgR (R = Et, Hlg) in the presence of the catalyst Cp 2 ZrCl 2 exhibiting a high activity and selectivity in the cyclomagnesation of α-olefins [3][4][5], acetylenes [6], terminal 1,2-dienes [1,2], and compounds of norbornene series [2,7].…”

“…In reaction of cyclonona-1,2-diene with Et 2 Mg (Et 2 O) under the previously found optimal conditions for cyclomagnesation of α-olefins [3][4][5] and 1,2-dienes [1,2] (0°C, 8 h, cyclonona-1,2-diene: Et 2 Mg : Cp 2 ZrCl 2 = 10:20:0.05) organomagnesium compounds I and II formed in a ratio 91:9 in overall yield 79% (see the scheme). The yield of the reaction products was evaluated by the hydrolysis products III and IV.…”