Studies on the Syntheses of Heterocyclic Compounds. CLXXVII : Syntheses of Sendaverine Derivatives and Investigation of their IR and NMR Spectra

Iodine(III)-Mediated Generation of Nitrogen-Tethered Orthoquinol Acetates for the Construction of Oxygenated Indole, Quinoline, and Phenanthridine Alkaloid Motifs

“…The synthesis of two variants 37a and 37b was achieved as depicted in Scheme 11. The known secondary amine 38 was prepared in 63% yield by reductive amination of the benzylated vanillin 13 and the primary amine 15 in methanol in the presence of sodium borohydride . As previously observed with the model compounds (vide supra), direct PIDA-mediated oxidative acetoxylation of the nonprotected amino diphenol 37 (P = H) gave intractable mixtures.…”

“…N -(4-Benzyloxy-3-methoxybenzyl)-4-benzyloxy-3-methoxyphenylethylamine (38). A solution of benzylated vanillin 13 (3.00 g, 12.4 mmol) and primary amine 15 (3.19 g, 12.4 mmol) in dry MeOH (40 mL) was refluxed for 3 h in the presence of 4 Å molecular sieves. Filtration, followed by evaporation, furnished the expected imine as an orange oil (5.77 g, 97% crude yield).…”

“…After stirring overnight, evaporation of the solution gave a solid residue, which was redissolved in CH 2 Cl 2 (80 mL), washed with H 2 O (3 × 20 mL), and dried over MgSO 4 . Evaporation of the solvent afforded an off-white solid, which was purified by column chromatography, eluting with pure EtOAc in order to remove impurities, and then with EtOAc/EtOH (1:1) to obtain 38 as an off-white solid (3.77 g, 65%): mp 94−95 °C (lit . mp 106.5−107.5 °C); IR (KBr) 3366 cm -1 ; 1 H NMR (CDCl 3 ) δ 1.25 (bs, 1H), 2.72−2.76 (m, 2H), 2.82−2.87 (m, 2H), 3.70 (s, 2H), 3.83 (s, 3H), 3.84 (s, 3H), 5.10 (s, 2H), 5.11 (s, 2H), 6.63−6.85 (m, 6H), 7.22−7.43 (m, 10H); 13 C NMR (CDCl 3 ) δ 149.5, 149.4, 146.9, 146.4, 137.2, 137.1, 133.2, 133.0, 128.3, 127.6, 127.1, 120.4, 120.0, 113.9, 113.7, 112.3, 111.6, 70.9, 70.8, 55.8, 53.4, 50.3, 35.6; EIMS m / z (rel intensity) 483 (M + , 2), 227 (57), 91 (100).…”