Reactions of Schiff bases. III. Formation of ethylenediamine derivatives from benzylidenealkylamines and magnesium-magnesium iodide mixtures

Abstract

cf. C.A. 51, 14580g. Mg powder (2.4 g.) and 12.7 g. iodine shaken with 20 ml. anhyd. Et2O and 30 ml. anhyd. C6H6 to disappearance of the iodine color, the mixt. treated with 0.1 mole Schiff base in 30 ml. anhyd. C6H6 while introducing N, the mixt. shaken until all the Mg had dissolved, hydrolyzed with ice H2O, the pptd. Mg(OH)2 brought into soln. with AcOH (usually 16 g. 30% AcOH soln.), the org. phase sepd., the aq. phase extd. 2-3 times with C6H6, the combined org. phases dried, 30 ml. Et2O added, the soln. satd. with HCl, the solvents distd., the residue boiled a short time with Me2CO or dioxane, the ext. kept overnight in the refrigerator, the ppt. filtered off, and crystd. from MeOH-Et2O gave the ethylenediamine derivs. Products with cyclic substituents on the N atom were worked up directly by distg. the solvents and crystg. the residue with MeOH. The following results were obtained on reduction with Mg-MgI2 mixts. [Schiff base used, yield (g.) on working up with Me2CO, yield (g.) on working up with dioxane, product obtained, m.p., m.p. of base, nD/t given]: PhCH:NMe (I), 8.3, 6.8, (MeNHCHPh)2.2HCl, 304 Deg, 135 Deg, 1.5101/144-7 Deg and 1.5203/126-8 Deg; PhCH:NEt, 3.8, 2.1, (EtNHCHPh)2.2HCl, 261 Deg, 86-7 Deg, 1.5101/101-3 Deg and 1.5203/78-9 Deg; PhCH:NPr (II), 6.5, 3.7, (PrNHCHPh)2 (III).2HCl, 205 Deg, 83 Deg, 1.5000/101-2 Deg and 1.5101/81-3 Deg; PhCH:NCHMe2 (IV), 2.2, 2.8, (Me2CHNHCHPh)2 (V).2HCl, 250-5 Deg, 119 Deg, 1.4683/153-6 Deg and 1.4840/118-20 Deg; PhCH:NBu, -, 4.2 [direct distn. of the Et2O-C6H6 residue yielded 7.8 g. (BuNHCHPh)2 (VI), b1 160-70 Deg], VI.2HCl, 185-220 Deg, oil, 1.5000/86-7 Deg and 1.5101/76-8 Deg; PhCH:NCH2Ph (VII), 11.9, 12.6, (PhCH2NHCHPh)2 (VIII).2HCl, 235-6 Deg, 151 Deg, 1.5400/168-70 Deg, and 1.5502/145-7 Deg (distn. of the Et2O-C6H6 residue gave VIII directly); PhCH:NCH2CH2Ph (IX), 13.5, 13.0, (PhCH2CH2NHCHPh)2 (X).2HCl, 239-40 Deg, 123 Deg, 1.5400/142-4 Deg and 1.5502/115-17 Deg (distn. of the Et2O-C6H6 residue gave 11.0 g. X directly); PhCH:NR (R = cyclohexyl) (XI), 3.6, 10.5, (RNHCHPh)2 (XII).2HCl, 261-3 Deg, 128 Deg, 1.5000/147-9 Deg and 1.5101/126-7 Deg (distn. of the Et2O-C6H6 residue gave 1.2 g. XII directly). For identification of the above compds., comparative substances were prepd. by treatment of Schiff bases with activated Al according to previously described methods (loc. cit.). Analogous to previous findings, benzylalkylamines were also formed in addn. to the ethylenediamines. The following results were obtained by Al reduction [Schiff base used (0.1 mole), g. substituted ethylenediamine formed, m.p., g. benzylalkylamine formed, b.p./mm., m.p. of HCl salt of benzylalkylamine given]: II, 6.2 III, 83 Deg, 2.7 PhCH2NHPr, 102-8 Deg/12, 184 Deg; IV, 4.8 V, 119 Deg, PhCH2NHCHMe2, 110-12 Deg/12, 192 Deg; VII, 7.7 VIII, 151 Deg, 6.9 (PhCH2)2NH, 180 Deg/12, 256-8 Deg; IX, 6.1 X, 123 Deg, PhCH2CH2NHCH2Ph, 177-9 Deg/12, 261 Deg; XI, 13.2 XII, 128 Deg, PhCH2NHR, 134-7 Deg/12, 282 Deg. Mg powder (5.4 g.) and 50 g. iodine in 90 ml. Et2O and 90 ml. C6H6 shaken to disappearance of the iodine color, excess Mg filtered off, the filtrate treated portionwise with 48 g. I in 60 ml. C6H6, the mixt. kept overnight in the refrigerator, the ppt. filtered off, washed with Et2O, and dried in a vacuum desiccator gave 84.8 g. (PhCH:NMe)2.MgI2, decompd. by H2O into I and MgI2.