E. Pascual-alfonso et al., Improvements in the hetero Diels-Alder reactions of 1-dimethylamino-1-azadienes in the presence of an electrophilic scavenger resin, SYNLETT, (2), 2000, pp. 205-208
Reactions between 1-dimethylamino-1-azadienes and several quinones in the p
resence of a chloroformyl polystyrene resin proceeded with up to 2.5-fold i
ncrease in the isolated yields of the hetero Diels-Alder products, owing to
efficient scavenging of dimethylamine liberated from the primary cycloaddu
cts.