TMSBr/InBr3-promoted Prins cyclization/homobromination of dienyl alcohol with aldehyde to construct cis-THP containing an exocyclic E-alkene

A TMSBr/InBr3-promoted Prins cyclization/homobromination reaction of dienyl alcohol with aldehyde has been developed to construct a unique cis-E THP shown as the A ring in (−)-exiguolide and the B ring in bryostatins.