An Aza Cyclopropylcarbinyl-Homoallyl Radical Rearrangement–Radical Cyclization Cascade. Synthesis of Dibenzoimidazoazepine and Oxazepine Derivatives

Abstract

The cycloaddition of the dibenzoxazepinium W-ylides, generated by heating of trans-1-aryl-7,11b-dihydro-1H-azirino[1,2-a]dibenzo[c,f]azepines, to the C═N double bond of 3-aryl-2H-azirines proceeds endo-stereoselectively giving regioisomeric cycloadducts in ca. 1:1 ratio, in good overall yields. In contrast to the dibenzoxazepinium ylides, the cycloaddition of the dibenzazepinium W-ylide proceeds regioselectively but without exo-endo-stereoselectivity. The reasons for this selectivity of the cycloaddition theoretically were studied at the DFT B3LYP/6-31G(d) level. Heating adducts, (2aRS,13SR,13aRS)-13,13a-diaryl-13,13a-dihydro-1H,2aH-azireno[1',2':3,4]imidazo[1,2-d]dibenzo[b,f][1,4]oxazepines and (2aRS,13SR,13aRS)-13,13a- diphenyl-2a,7,13,13a-tetrahydro-1H-azireno[1',2':3,4]imidazo[1,2-a]dibenzo[c,f]azepine, with an excess of AIBN in toluene gave new polyheterocyclic systems via a novel aza cyclopropylcarbinyl-homoallyl radical rearrangement-radical cyclization cascade. The energy profile of the cascade was studied at the DFT UB3LYP/6-31G(d) level. The transient imidazolinylmethyl radical was trapped by the use of other radical initiators as the corresponding peroxide or alcohol.

Fused aziridines as sources of azomethine ylides

“…It is possible to reduce the reaction time substantially by carring out the reaction without a solvent in a melt of the starting compounds. Increase of the temperature to 140°C does not affect the regioselectivity of the reaction but leads to a slight decrease in the yields of the cyclic adducts [22]. The azepine analog 26b (Ar = Ph) reacts with phenylazirine 42 regioselectively, but nonstereoselectively with formation of the cyclic adducts 52 and 53 [22].…”

2H-Azirinek új típusú reakciói

“…1 H NMR (500 MHz, DMSO-d6) δ 8,87 (s, 1H), 8,73 (d, J = 3,7 Hz, 1H), 8,07 (d, J = 7,9 Hz, 1H), 7,51 (dd, J = 7,6, 4,9 Hz, 1H), 7,32 (s, 1H), 4,27 -4,13 (m, 2H), 3,54 (s, 1H), 1,72 (s, 3H), 1,29 -1,17 (m, 3H), 0,97 (s, 9H); 13 Hz, 1H), 1,35 (d, J = 14,7 Hz, 1H), 1,22 (t, J = 7,0 Hz, 3H), 1,06 (s, 3H), 0,99 (s, 3H), 0,80 (s, 9H); 13 13 C NMR (126 MHz, CDCl3) δ 177,9,166,8,165,6,136,8,133,5,129,5,128,5,128,1,127,5,127,5,126,6,61,6,47,0,43,9,43,8,43,5,13,7,11,6; HRMS (ESI) 381,1814 [M+H] + (kalkulált: 381,1814). (±)-281{24}) 1 H NMR (500 MHz, CDCl3) δ 7,96 (s, 1H), 6,81 (s, 2H), 4,27 (q, J = 7,4 Hz, 2H), 3,83 (s, 6H), 3,80 (s, 3H), 3,45 (s, 1H), 2,18 (s, 3H), 1,75 (s, 3H), 1,31 (t, J = 6,7 Hz, 3H); 13…”

“…) 1 H NMR (500 MHz, DMSO-d6) δ 9,66 (s, 1H), 6,91 (s, 2H), 6,83 (s, 2H), 3,71 (s, 6H), 3,61 (s, 3H), 3,57 (s, 1H), 2,31 (s, 6H), 2,18 (s, 3H), 1,67 (s, 3H), 1,40 (s, 9H); 13 C NMR (126 MHz, DMSO-d6) δ 175,9, 165,2, 164,3, 152,5, 138,9, 135,9, 134,4, 133,9, 132,1, 128,8, 99,2, 82,5, 60,1, 55,8, 48,7, 43,5, 27,6, 20,6, 20, ), 3,99 (q, J = 7,1 Hz, 2H), 3,92 (qt, J = 6,7, 3,3 Hz, 2H), 3,77 (s, 3H), 3,75 (s, 3H), 1,58 (s, 3H), 1,53 (s, 3H), 1,42 (s, 3H), 1,37 (s, 3H); 13 C NMR (126 MHz, DMSO-d6) δ diasztereomer keverék : 172,4, 172,3, 168,1, 167,3, 167,3, 167,2, 159,2, 159,1, 139,2, 139,2, 136,2, 135,1, 129,8, 129,7, 128,3, 128,2, 127,6, 127,5, 126,9, 126,8, 120,6, 120,0, 119,2, 118,0, 113,0, 112,5, 61,8, 61,3, 55,3, 55,3, 50,6, 49,7, 42,5, 42,5, 15,7, 14,1, 13,8, 13 1H), 1,49 (s, 3H), 1,30 (s, 9H), 0,95 (t, J = 6,9 Hz, 3H); 13 C NMR (126 MHz, DMSO-d6) δ 172,1,166,6,166,3,136,8,134,5,131,9,129,5,128,3,128,1,127,9,126,7,61,5,52,5,52,4,51,2,35,2,28,4,…”

“…1 H NMR (500 MHz, Kloroform-d) δ 7,47 (d, J = 7,2 Hz, 2H), 7,24 (d, J = 8,7 Hz, 2H), 7,18 (t, J = 7,6 Hz, 2H), 7,09 (t, J = 7,3 Hz, 1H), 6,96 (d, J = 8,7 Hz, 2H), 3,86 (s, 3H), 3,37 (s, 3H), 3,08 (p, J = 6,9 Hz, 1H), 1,43 (d, J = 6,9 Hz, 6H), 13 C NMR (126 MHz, Kloroform-d) δ 159,6,152,5,136,0,135,2,132,2,128,3,128,0,126,8,125,8,123,7,114,4,55,3,30,6,26,7,21,4; HRMS (ESI) 307,1806 [M+H] + (kalkulált: 307,1805).…”

“…1 H NMR (500 MHz, Kloroform-d) δ 7,48 -7,36 (m, 5H), 7,35 -7,29 (m, 2H), 7,17 (t, J = 7,6 Hz, 2H), 7,09 (t, J = 7,3 Hz, 1H), 3,39 (s, 3H), 2,71 (tt, J = 11,7, 3,5 Hz, 1H), 2,04 -1,97 (m, 2H), 1,95 -1,87 (m, 2H), 1,87 -1,73 (m, 3H), 1,47 -1,33 (m, 3H), 13 C NMR (126 MHz, Kloroform-d) δ 152,2,136,4,135,2,131,6,130,9,128,9,128,4,128,2,128,0,126,9,125,9,77,3,36,6,31,6,30,7,26,5,25,9; HRMS (ESI) 317,2014 [M+H] + (kalkulált: 317,2013).…”