“…Compounds 3,5,7,9, were obtained exclusively when two equivalents of furfuryl amines were reacted separately with 1a -1d. Compounds 11, and 12 were similarly prepared from maleimides 1f and 1 g. (2) ,4,4a,5,8,8a,9, 4,4,4a,5,8,8a,9, ,4,4a,5,8,8a,9, General method of preparation of compounds (13)(14)(15)(16)(17)(18)(19)(20)(21)(22) …”