Synthesis of the first [1,3]benzoxazino[3,2-b][1,2]benzoxazine and its tandem retro-Diels-Alder - Diels-Alder rearrangement to a novel [1,3]benzoxazino[2,3-b][1,3]benzoxazine

Domino retro Diels–Alder/Diels–Alder reaction: an efficient protocol for the synthesis of highly functionalized bicyclo[2.2.2]octenones and bicyclo[2.2.2]octadienones

“…At this stage, we decided to apply this strategy to the dienophiles cyclopentene (10) and 2,4-cyclohexadiene (11) which failed to undergo DA reaction with MOB 2a in previous methods. 17 Although a greater number of equivalents of dienophile 10 had to be used, DA adduct 24a was achieved in considerable yield (35%, entry 10 of Table 2).…”

“…m max (film)/cm −1 3067, 2978, 2944, 2837, 1779, 1741, 1714, 1598, 1498 and 1456; d , 2946, 2837, 1779, 1738, 1713, 1498, 1384, 1189 and 1138; d H (400 MHz, CDCl 3 ) 1.85 (3 H, s, CH 3 ), 3.34 (3 H, s, OCH 3 ), 3.34 (1 H, m, CH-CH), 3.39 (3 H, s, OCH 3 ), 3.40 (1 H, d, J 3.2 Hz, CH-CH), 3.60 (1 H, m, CH-C(OMe) 2 ), 3.68 (1 H, dd, J 1.6, 6.8 Hz, CH-CO), 6.00 (1 H, m, CH=CCH 3 ), 7.12-7.47 , 2824, 1765, 1742, 1713, 1062 and 754; d H (400 MHz, CDCl 3 ) 1.92 (3 H, d, J 1.6, CH 3 ), 3.60 (6 H, s, 2 × OCH 3 ), 3.36 (1 H, dd, J 3.6 and 8.6, CH-CH), 3.52 (1 H, dd, J 3.4 and 8.6, CH-CH), 3.61 (1 H, dd, J 1.8 and 3.6, CH-C(OMe) 2 ), 3.63 (1 H, dd, J 3.4 and 6.0 Hz, CH-CO), 5.82 (1 H, ddq, J 1.6, 6.0 and 1. (10), 119 (21), 91 (20), 59 ( 9) Methyl (1R*,2R*,6R*,7S*)-10,10-dimethoxy-3,5,11-trioxo-4phenyl-4-azatricyclo[5.2.2.0 2,6 ]undec-8-ene-8-carboxylate (23e). m max (film)/cm −1 1716 and 1748; d H (400 MHz, CDCl 3 ) 3.33 (3 H, s, OCH 3 ), 3.42 (3 H, s, OCH 3 ), 3.47 (1 H, dd, J 3.2 and 8.0, CH-CH), 3.58 (1 H, dd, J 3.2 and 8.0, CH-CH), 3.76 (3 H, s, CO 2 CH 3 ), 3.98 (1 H, dd, J 3.2 and 8.0, CH-C(OMe) 2 ), 4.33 (1 H, dd, J 2.0 and 1.6, CH-CO), 7.07 (1 H, dd, J 1.6 and 8.0, CH=CCO 2 CH 3 ), 7.30-7.44 (5 H, m (1R*,2R*,6S*,7R*)-9,9-Dimethoxytricyclo[5.2.2.0 2,6 ]undeca-10en-8-one (24a).…”

“…9 A novel [1,3]benzoxazino [2,3-b][1,3]benzoxazine was also prepared by a domino cascade of tandem rDA/DA transformation. 10 are extensively studied. 11 MOBs are highly reactive and are known for their facile dimerization.…”

Hydroxy-1-aminoindans and Derivatives: Preparation, Stability, and Reactivity

“…Because ortho -QMs behave as heterodienes, another possible trapping course is the Diels−Alder reaction . A QM, being an “inverse electron demand diene” in Diels−Alder reactions, requires electron-rich dienophiles, such as EVE . Heating a neat mixture of 26 and EVE in a pressure tube at 140 °C led to the Diels−Alder adduct 30 , while at 100 °C, it gave a mixture of 30 as a minor product together with the tertiary amine 31 as a major component that was not isolated, but the structure of which was established by 1 H NMR (Scheme ).…”

Cope Rearrangement versus a Novel Tandem Retro-Diels−Alder−Diels−Alder Reaction with Role Reversal

“…A mere Diels−Alder (DA) reaction of 6 and cyclopentadiene ( 5 ) leads to 8 . To our knowledge, the consecutive sequence 4 → 5 + 6 → 8 represents a novel tandem rDA−DA reaction with role reversal . An alternative possible pathway to 8 consists of a stereoselective Cope rearrangement in 4 .…”