Ionic liquid accelerated intramolecular hetero-Diels–Alder reactions: a protocol for the synthesis of octahydroacridines

2-Azadienes derived in situ from arylamines and (R)-(+)-citronellal/3-methylcitronellal undergo intramolecular [4+2] hetero-Diels–Alder reactions in the air and moisture stable ionic liquid [bmim]BF4 in the absence of any acid catalyst to afford 1,2,3,4,4a,9,9a,10-octahydroacridine derivatives in high to quantitative yields.