A Simple and Practical Synthesis of (+)-2-Bromobicyclo[2.2.1]hept-5-ene-2-carboxaldehyde via Chiral Lewis Acid Catalyzed [4+2] Cycloaddition

Abstract A chiral titanium complex derived from BINOL and Ti(O-i-Pr)4 catalyzes the Diels-Alder reaction of 2-bromoacrolein and cyclopentadiene with 97:3 enantioselectivity. Lower enantioselectivity was observed using other dienes or with methacrolein as dienophile.