One-pot and regioselective synthesis of polysubstituted 3,4-dihydroquinazolines and 4,5-dihydro-3H-1,4-benzodiazepin-3-ones by sequential Ugi/Staudinger/aza-Wittig reaction

Synthesis of Imidazo[1,2-a]pyridine-Fused 1,3-Benzodiazepine Derivatives with Anticancer Activity via a One-Pot Cascade GBB-3CR/Pd(II)-Catalyzed Azide-Isocyanide Coupling/Cyclization Process

“…mp 272−274 °C; 1 H NMR (400 MHz, CDCl 3 ): δ (ppm) 8. 2H),7.61 (d,J = 8.8 Hz,1H),08 (m, 4H), 6.80 (t, J = 6.8 Hz, 1H), 4.73 (s, 1H), 2.82−2.74 (m, 1H), 2.12− 1.99 (m, 1H), 1.70 (d,J = 10.8 Hz,1H), 1.56−1.50 (m, 2H), 1.40 (s, 9H), 1.34−0.84 (m, 6H). 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ (ppm) 145.…”

“…Yellow solid (yield 0.454 g, 59%), purified by column chromatography with petroleum ether/EtOAc (8:1) as the eluent. mp 253−277 °C; 1 H NMR (400 MHz, CDCl 3 ): δ (ppm) 8.15 (d,J = 6.8 Hz,1H),8.07 (d,J = 7.6 Hz,1H),7.60 (d,J = 8.8 Hz,1H),3H), 7.09 (t, J = 7.6 Hz, 1H), 6.80 (t, J = 6.8 Hz, 1H), 4.61 (s, 1H), 1.93 (s, 3H), 1.71 (d, J = 12.0 Hz, 4H), 1.60−1.44 (m, 8H), 1.42 (s, 9H). 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ (ppm) 145.…”

Recent Advances in the Synthesis of Heterocycles by the Aza-Wittig Reaction

“…14 In 2019, Ding and co-workers devised an efficient one-pot method for the synthesis of novel 3,4-dihydroquinazolines 19 via sequential Ugi 4CC/Staudinger/aza-Wittig reactions (Scheme 4). 15 Ugi 4CC reaction between equivalent amounts of carboxylic acid 13, 2-azidobenzylamine 16, isocyanide 14, and aldehyde 15 gave azide 17; the starting material for the aza-Wittig procedure. While the aza-Wittig reaction is commonly performed using Ph 3 P (20), in this case the aza-Wittig formation of 3,4-dihydroquinazolines was performed using tributylphosphine (21).…”

“…30 In 2019, Ding and co-workers devised an efficient onepot method for the synthesis of 4,5-dihydro-3H-1,4-benzodiazepin-3-ones 90 (Scheme 20). 15 Ugi 4CC reaction between equivalent amounts of -keto acid 87, 2-azidobenzylamine 16, isocyanide 14, and aldehyde 15 gave azide 88 as the starting material for the aza-Wittig procedure. Subsequent Staudinger reaction of 88 using Ph 3 P (20) in toluene at reflux followed by intramolecular aza-Wittig reaction gave 4,5-dihydro-3H-1,4-benzodiazepin-3-ones 90 in good to excellent yields (70-90%).…”

A convenient method for the synthesis of 3,4-dihydroquinazolines from iminoester hydrochlorides via microwave irradiation

“…19 The majority of these methods are associated with the synthesis of quinazolinone derivatives. Besides these methods, there are certain methods of synthesis of 3,4-dihydroquinazolines in the literature: solid-phase synthesis; 20 reduction or oxidation of quinazolines, tetrahydroquinazolines, or quinazolinones; 21 synthesis from N-acylation and cesium carbonate-mediated N-alkylation reactions; 21 synthesis from o-iodoxybenzoic acid by mediated tandem reactions; 22 synthesis from sequential Ugi/Staudinger/aza-Wittig reactions; 23 and synthesis from paraand meta-substituted anilines. 24 In most of these methods, 2-aminobenzylamine or N-functionalization of the aliphatic amino group of 2-aminobenzylamine is used, which reacts with the aldehydes, carboxylic acids, amidines, and orthoformates, which require long-time reactions, harsher conditions, and the use of specific reactants and catalysts.…”