A novel reaction of titanacyclopentenes and aldehydes with or without Lewis acids

Oxatitanacyclopentenes were prepared in high yields from the reaction of aldehydes with titanacyclopenetens via substitution of ethylene. No insertion product was obtained in this reaction. The combination of alkynes and aldehydes played an important role in the successive formation of oxatitanacyclopentenes. Some oxatitanacyclopentenes are very stable and can be purified using column chromatography. The cooperation between Ti and LA led to very different results from that between Zr and LA.