Reactivity of 1,2‐Diaza‐1,3‐dienes with Azomethine Ylides: [3+4] versus [3+2] Cycloadditions

Abstract

Abstract:The multicomponent 1,3-dipolar cycloaddition of different 1,2-diaza-1,3-dienes with in situ-generated azomethine ylides produces 1,2,4-triazepines or pyrrolidines by means of [3+4] or [3+2] cycloadditions, respectively. The regioselectivity is controlled by the electron-withdrawing group bound to the azo-moiety of the 1,2-diaza-1,3-diene which promotes exclusively the [3+4] cycloaddition. When the electron-withdrawing group is replaced with a phenyl group only a [3+2] cycloaddition occurs.

Metal and Oxidant-Free Brønsted Acid-Mediated Cascade Reaction to Substituted Benzofurans

“…White solid; mp 130−132 °C; 1 H NMR (400 MHz, CDCl 3 , 25 °C): δ 1.14 (t, 3H, J = 6.8 Hz), 2.59 (s, 3H), 2.64 (s, 3H), 4.39 (q, 2H, J = 7.2 Hz), 5.73 (br s, 1H), 6.61 (dd, 1H, J = 2.0 Hz, J = 0.4 Hz), 6.76 (d, 1H, J = 2.0 Hz); 13 C NMR (100 MHz, CDCl 3 , 25 °C): δ 14. 3, 14.6, 21.5, 60.7, 95.4, 110.3, 114.7, 118.1, 132.8, 153.3, 154.8, 161.0, 165.0 13 C NMR (100 MHz, CDCl 3 , 25 °C) δ: 14.7 (q), 21.5 (q), 65.4 (t), 95.4 (d), 110.0 (s), 114.7 (d), 118.1 (s), 118.8 (t), 132.1 (d), 132.9 (s) 3,51.5,98.0,108.7,112.6,119.5,121.9,153.6,154.4,162.9,165.2;IR (nujol) H,7.30. Found: C,69.68,H,7.28.…”

“…3, 14.6, 21.5, 60.7, 95.4, 110.3, 114.7, 118.1, 132.8, 153.3, 154.8, 161.0, 165.0 13 C NMR (100 MHz, CDCl 3 , 25 °C) δ: 14.7 (q), 21.5 (q), 65.4 (t), 95.4 (d), 110.0 (s), 114.7 (d), 118.1 (s), 118.8 (t), 132.1 (d), 132.9 (s) 3,51.5,98.0,108.7,112.6,119.5,121.9,153.6,154.4,162.9,165.2;IR (nujol) H,7.30. Found: C,69.68,H,7.28.…”

“…NMR (400 MHz, CDCl 3 , 25 °C): δ 2.59 (s, 3H, CH 3 ), 2.64 (s, 3H, CH 3 ), 3.91 (s, 3H, OCH 3 ), 5.27 (br s, 1H, OH), 6.61 (dd, 1H, J = 2.0 Hz, J = 0.8 Hz, Ph), 6.76 (dd, 1H, J = 2.0 Hz, J = 0.4 Hz, Ph); NMR (100 MHz, CDCl 3 , 25 °C): δ 14.6 (q), 21.4 (q), 51.4 (q), 95.4 (d), 110.0 (s), 114.7 (d), 118.2 (s), 132.9 (s), 153.1 (s), 154.8 (s), 161.1 (s), 165.2 (s); IR (nujol) ν max : 3328, 1678 cm −1 ; MS m/z (ESI): 221 (M + H + ); Anal. Calcd for C 12 H 12 O 4 (220.22): C, 65.45;H, 5.49. Found: C, 65.57;H, 5.44.…”

Synthesis of pyrrolizidines and indolizidines by multicomponent 1,3-dipolar cycloaddition of azomethine ylides

“…The multicomponent 1,3-DC of 1,2-diaza-1,3-diene 128 with formaldehyde and ethyl pipecolate gave regioselectively indolizidine derivatives 129 in moderate yield (Scheme 26) [68]. Coldham and co-workers have described the three-component 1,3-DC of the γ-chloro aldehyde 95 for the synthesis of pyrrolizidines (Scheme 17) [63].…”

Current Trends towards the Synthesis of Bioactive Heterocycles and Natural Products Using 1,3-Dipolar Cycloadditions (1,3-DC) with Azomethine Ylides

“…) 78. AgOAc-catalyzed [3+2] cycloaddition of the azomethine ylides derived from imino esters 107 and alkenes 178 was successfully achieved to give pyrrolidines 179 in good yields…”