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 [TiR2(Me2ATI)2] complexes, where Me2ATI = N,N‘-dimethylaminotroponiminate,
or L, with CO or RNC in the presence of various organic electrophiles has been investigated. The compounds
TiMe2L2 and TiPh2L2 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(OCMe2CHCPh)(Me2ATI)2]. Treatment of TiMe2L2 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(Ph2COCN(SO2tol)HPh)(Me2ATI)2] and [Ti(Ph2COCOMe2)(Me2ATI)2], respectively, were obtained. The titanium thiolato-alkoxide complex
[Ti(Ph2CSCOMe2)(Me2ATI)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.