New synthetic approach to substituted isoindolo[2,1-a]quinoline carboxylic acids via intramolecular Diels–Alder reaction of 4-(N-furyl-2)-4-arylaminobutenes-1 with maleic anhydride

Intramolecular [4+2] cycloaddition of furfurylsubstituted homoallylamines to allylhalides, acryloyl chloride and maleic anhydride

“…As we have shown earlier [3], cycloaddition of maleic anhydride to 4-furyl-4-aminobutenes 5 was preceded by the preliminary N-acylation leading to the formation of the intermediate maleinamide 13b (R=CO 2 H,Scheme 2). Obviously the interaction between acrylic anhydride and amine 10f proceeded in the analogous manner through the formation of the intermediate N-acryloyl derivative 13a (R=H).…”

“…Yield (17) (10), 94 (45), 91 (23), 82 (7), 81 (100), 77 (21), 65 (9), 53 (22) NO 6 : C,63.50;H,5.84;N,3.89. Found: ,63.68;,6.03;N,3.94.…”

“…It was interesting to compare the data received for the 28A/28B isomeric pairs with those for the pairs of their carboxylic analogues 9 synthesized earlier [3] (Scheme 1). The measurements were obtained for all the isomers 28A/28B, and the data described below are given only for the methoxyphenyl substituted pairs of compounds 28cA/28cB and 9A/9B ( Figure 3).…”

“…Recently we have proposed several effective synthetic approaches to the potential biologically active compounds such as hydrogenated hydroxyisoquinolines 1 [1,2], isoindolo [2,1-a]quinoline-2 [3][4][5] and isoindolo [2,1-b]benzazepinecarboxylic acids 3 [6,7] (Scheme 1) using furylsubstituted homoallylamines 4, 5 as starting materials. Amines 4 and 5 were obtained from easily available imines 6 and 7 correspondingly.…”

“…It is worth noting that the homoallylamines 10a,f [2], 11a c [3], and 12a c [6,7] were obtained and characterized by our group earlier, and the aryl-10b, hetaryl substituted amines 10c e were first synthesized. Amines 10 12 ( Fig.…”