Chiral NHC-catalyzed oxodiene Diels-Alder reactions with α-chloroaldehyde bisulfite salts

alpha-Chloroaldehyde bisulfite adducts were successfully employed in chiral NHC-catalyzed hetero-Diels-Alder reactions with various oxodienes under biphasic reaction conditions with high levels of enantioselectivity. This new protocol makes possible entantioselective additions from commercially available chloroacetaldehyde sodium bisulfite and demonstrates that this unique class of catalysts readily tolerates aqueous conditions.