a
Laboratoire de Synthèse Organique, UMR 7652, Ecole Polytechnique, ENSTA Paris, CNRS, IP Paris, 91128 Palaiseau, France
› Author AffiliationsThis work was supported by the Agence Nationale de la Recherche (JCJC grant CycloSyn, ANR-18-CE07-0008). X.L. thanks the Agence Nationale de la Recherche for a M2 grant. A.S. thanks Labex CHARMMMAT (ANR-11-LABX-0039) for a M2 grant and the Agence Nationale de la Recherche for a PhD fellowship.
A Pd-catalyzed oxa-(4+4)-cycloaddition between 1-azadienes and (2-hydroxymethyl)allyl carbonates is described. Aurone-derived azadienes furnished polycyclic 1,5-oxazocines in good yields. Interestingly, linear azadienes have also been involved and yielded monocyclic heterocycles with complete regioselectivity. DFT calculations were carried out to gain insight on this observation.
2c
Dandapani S,
Germain AR,
Jewett I,
Le Quement S,
Marie J.-C,
Muncipinto G,
Duvall JR,
Carmody LC,
Perez JR,
Engel JC,
Gut J,
Kellar D,
Siqueira-Neto JL,
McKerrow JH,
Kaiser M,
Rodriguez A,
Palmer MA,
Foley M,
Schreiber SL,
Munoz B.
ACS Med. Chem. Lett. 2014; 5: 149
21 CCDC 2040269 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures
22 CCDC 2040268 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures
23 See the Supporting Information.
24Typical Procedure for the Pd-Catalyzed (4+4) Cycloadditions of 2a with 1a (Benzene, rt)
In a screw-cap SVL tube filled with argon, Pd2(dba)3 (13.7 mg, 0.015 mmol, 0.05 equiv) and dppe (12.0 mg, 0.03 mmol, 0.1 equiv) were added in benzene (3 mL, 0.1 M) and stirred for 15 min at rt. Carbonate 2a (84.7 mg, 0.45 mmol, 1.5 equiv) and azadiene 1a (113 mg, 0.30 mmol) were then added, the reaction mixture was stirred at rt for 16 h, filtered over silica, and concentrated under reduced pressure to afford the crude product. The residue was purified by flash column chromatography on silica gel (petroleum ether/EtOAc = 85:15) to afford 3a (109 mg, 81%) as a yellow solid; mp 46 °C.
IR (neat): 2922, 1597, 1494, 1452, 1384, 1346, 1180, 1157, 1095, 1069, 747 cm–1. 1H NMR (400 MHz, CDCl3, –20 °C): δ = 7.86 (d, J = 8.2 Hz, 2 H), 7.61–7.58 (m, 1 H), 7.41–7.12 (m, 10 H), 5.45 (s, 1 H), 5.24 (s, 1 H), 5.02 (s, 1 H), 4.91 (d, J = 13.5 Hz, 1 H), 4.58 (d, J = 12.6 Hz, 1 H), 4.24 (d, J = 12.6 Hz, 1 H), 4.10 (d, J = 13.5 Hz, 1 H), 2.44 (s, 3 H). 13C NMR (101 MHz, CDCl3, –20 °C): δ = 154.4, 153.0, 143.5, 139.3, 138.1, 136.4, 129.3 (2 C), 128.5, 128.4 (2 C), 127.8 (2 C), 127.6 (2 C), 126.6, 124.6, 123.1, 122.7, 120.0, 116.0, 111.3, 79.0, 75.9, 54.7, 21.6. HRMS (ESI+): m/z [M + H]+ calcd for C26H24NO4S+: 446.1421; found: 446.1410.
