C–C-bond formation in reactions of [(η5-C5H4SiMe3)2Ti(CCR1)2]CuR with acyl chlorides and anhydrides

The chemical behaviour of selected {[Ti](CCR1)2}CuR complexes (1a: R1=SiMe3, R=CH3; 1b: R1=tBu, R=CH3; 1c: R1=tBu, R=CCSiMe3) towards a number of different acyl chlorides and anhydrides is described. The reaction of 1a or 1b with R2C(O)Cl (2a: R2=CH3, 2b: R2=C6H5) produces the ketones R2C(O)R (4a: R=R2=CH3; 4b: R=CH3, R2=C6H5; 4c: R=CCSiMe3, R2=CH3, 4d: R=CCSiMe3, R2=C6H5) along with {[Ti](CCR1)2}CuCl (3a: R1=SiMe3, 3b: R1=tBu). However, on treatment of 1b or 1c with [CH3C(O)]2O (5a) the ketones 4a or 4c are formed along with the copper(I) acetate complex {[Ti](CCtBu)2}CuOC(O)CH3 (6), while the reaction of 1b or 1c with CH3CO2H (5b) yields methane and 6. In addition, when 1b or 1c are reacted with maleic (7), phthalic (9a) or tetrachlorophthalic anhydride (9b) the copper(I) carboxylates {[Ti](CCtBu)2}CuOC(O)-cis-CHCH–C(O)R (8a: R=CH3, 8b: R=CCSiMe3) and {[Ti](CCtBu)2}CuOC(O)–C6H4−nCln-2-C(O)R (10a: n=0, R=CH3; 10b: n=0, R=CCSiMe3; 10c: n=4, R=CCSiMe3) are produced, which upon addition of, e.g. HBr afford via cleavage of the copper–oxygen σ-bond {[Ti](CCtBu)2}CuBr (3c) and the corresponding carboxylic acids cis-HO2C–CHCHC(O)CH3 (11a) or HO2C–C6H4-2-C(O)CH3 (11b), respectively.