Preparation of 5-Hydroxy-1-alkenyboronates from 1-Alkynylboronates, Cp<sub>2</sub>ZrCl<sub>2</sub>/2EtMgBr, and Aldehydes

2004-11-11T00:00:00Z (GMT) by Abed Al Aziz Quntar Morris Srebnik
1-Alkynylboronates form five-membered zirconacycles with Cp<sub>2</sub>ZrCl<sub>2</sub>/2-EtMgBr as indicated by deuterium labeling. The zirconacycles add aldehydes to form seven-membered zirconacycles. Hydrolysis of the latter provides 5-hydroxy-1-alkenylboronates in fair to good isolated yields. Both aliphatic and aromatic aldehydes undergo insertion.