Synthesis of Unsymmetrical Diolate, Oxametallacyclopentene, Amido-Alkoxide and Thiolato-Alkoxide Complexes Using Dialkyl and Diaryl Titanium Aminotroponiminate Complexes:  A Route to Unsymmetrical Vicinal Diols

The reactivity of [TiR 2 (Me 2 ATI) 2 ] complexes, where Me 2 ATI = N,N ‘ -dimethylaminotroponiminate, or L, with CO or RNC in the presence of various organic electrophiles has been investigated. The compounds TiMe 2 L 2 and TiPh 2 L 2 react with CO and aldehydes or ketones to afford unsymmetrical diolate complexes that convert to the corresponding vicinal diols after hydrolysis. Phenyl acetylene also reacts to form the oxametallacyclopentene complex [Ti(OCMe 2 CH CPh)(Me 2 ATI) 2 ]. Treatment of TiMe 2 L 2 with RNC yields the free imine and a source of low-valent titanium. Trapping this intermediate with 2 equiv of benzaldehyde or benzil affords the titanium diolate or enediolate complex, respectively. When 1 equiv each of benzophenone and either N -tosylbenzaldimine or acetone were added to the intermediate, [Ti(Ph 2 COCN(SO 2 tol)HPh)(Me 2 ATI) 2 ] and [Ti(Ph 2 COCOMe 2 )(Me 2 ATI) 2 ], respectively, were obtained. The titanium thiolato-alkoxide complex [Ti(Ph 2 CSCOMe 2 )(Me 2 ATI) 2 ] was prepared by use of thiobenzophenone and acetone. This chemistry allows for the preparation of unsymmetrical diols and oxametallacyclopentene complexes from Ti(IV) dialkyls, CO, and either carbonyl compounds or alkynes. Amido-alkoxide and thiolato-alkoxide complexes can be prepared by the reaction of Ti(IV) dialkyl complex, 2 equiv of benzophenone, and either an imine or thioketone.