Reactivities of mixed organozinc and mixed organocopper reagents: 9. Solvent dependence of group transfer selectivity in sp3C coupling and acylation of mixed diorganocuprates and diorganozincs

• Solvation effects do not change the group transfer ability in alkylation of n-BuPhCuMgBr.
• In the alkylation of catalytic mixed cuprates, group transfer can be controlled by solvents.
• Group transfer in allylation of n-BuPhZn is not solvent dependent.
• The solvent effect on the group transfer is dependent on R1 and R2 in benzoylation of R1R2CuZnI.
• Solvation are important in coupling of mixed diorganocuprate and diorganozinc reagents.

The selectivity and/or reactivity of organyl group transfer of mixed diorganocuprates in their alkyl coupling in THF depends on N- or O-donor solvents as cosolvents. Selective n-Bu group transfer is observed in room temperature alkylation of Grignard reagent derived stoichiometric n-BuPhCuMgBr reagent in THF:cosolvent and solvation effects do not change the group transfer ability. However, in the alkylation of catalytic mixed cuprates derived from CuI catalyzed n-BuPh2ZnMgBr and n-Bu2PhZnMgBr, group transfer ability depends on the solvation effect and it can be controlled by using N- or O-donor solvents. In alkylation of CuI catalyzed mixed zincate n-BuPh2ZnMgBr and also n-Bu2PhZnMgBr in THF at reflux temperature Ph group transfer takes place (n-Bu/Ph transfer ratio is 1:9 and 4:6, respectively) whereas n-Bu transfer increases in THF:NMP (1:1) resulting n-Bu/Ph transfer ratio of 4:6 and 8:2, respectively. Group transfer ability in allylation of n-BuPhZn seems not to be solvent dependent. The solvent effect on the group transfer ability has been found to be dependent also on the R1 and R2 partnership in room temperature benzoylation of catalytic mixed cuprates, R1R2CuZnI, derived from CuI catalyzed R1R2Zn. These results are briefly discussed in terms of solvation of mixed diorganocuprate and diorganozinc reagents and provide useful information in their atom-economic alkyl, allyl and acyl coupling reactions.

Organyl group transfer in the alkyl coupling of mixed and stoichiometric diorganocuprates, n-BuPhCuMgBr are solvent dependent. Group transfer in allylation of n-BuPhZn seems not to be solvent dependent. The solvent effect on the group transfer has been found to be dependent also on the R1 and R2 partnership in the acylation of catalytic cuprates, R1R2CuZnI.Figure optionsDownload as PowerPoint slide