Enol ethers, trimethylsilyl trichlorotitanium enolates

Trichlorotitanium enolates are formed in variable yield from trimethylsilyl enol ethers and an equivalent of TiCU in dichloromethane at 20-35 C. These highly Lewis acidic preformed enolates then undergo aldol reactions at -70 C to give moderate levels of syn selectivity, as in equation (13). Trichlorotitanium enolates have also been used by Reetz et al. in their studies on diastereofacially selective aldol additions to a-alkoxy aldehydes.Trichlorotitanium enolates are formed in situ in the aldol reaction of aromatic ketones and aldehydes using TiCU and EtsN. ... 

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