Synlett 2005(11): 1695-1698  
DOI: 10.1055/s-2005-869879
LETTER
© Georg Thieme Verlag Stuttgart · New York

First Total Synthesis of N-Oxido-3-aza-1,3,5(10)-trieno Steroids

Khalid Oumzil, Malika Ibrahim-Ouali*, Maurice Santelli*
UMR 6180 CNRS and Université d’Aix Marseille III, ‘Chirotechnologies: catalyse et biocatalyse’ Laboratoire de Synthèse Organique associé au CNRS, Faculté des Sciences de Saint Jérôme, 13397 Marseille Cedex 20, France
e-Mail: m.santelli@univ.u-3mrs.fr; e-Mail: m.ibrahim@univ.u-3mrs.fr;
Further Information

Publication History

Received 18 April 2005
Publication Date:
09 June 2005 (online)

Abstract

An efficient synthesis of 3-aza-steroids bearing a pyridine as an A ring was achieved via intramolecular cycloaddition of orthoquinodimethanes, which were generated from a 3-azabicy­clo[4.2.0]octa-1,3,5-trien-7-one ketal.

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The crystallographic data (CCDC 272301) can be obtained free of charge from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, CB2 1EZ, UK; e-mail: deposit@ccdc.cam.ac.uk.

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All compounds showed satisfactory spectroscopic data as well as microanalytical data. Diastereomeric ratios were established from the 1H NMR spectrum of the crude product.
Experimental procedure for the preparation of 11: A solution of 10 (0.75 g, 2.53 mmol) in 1,2,4-trichlorobenzene (50 mL) was stirred under argon at 200 °C for 24 h. After cooling, the solvent was removed under reduced pressure (0.2 Torr). The resulting oil was purified by flash chromatography on silica gel (EtOAc-Et2O, 2:8 to 5:5) to afford compounds 11a (0.336 g; 41%), 11b (0.232 g; 29%), and 11c (0.12 g; 15%) in 85% overall yield.
11a: White solid; mp 146-147 °C. IR (film): 3083, 2932, 1773, 1610 cm-1. 1H NMR (500 MHz, CDCl3): δ = 1.30 (d, J = 11.9 Hz, 1 H), 1.52 (m, 3 H), 1.92 (m, 3 H), 2.14 (m, 3 H), 2.73 (d, J = 3.8 Hz, 1 H), 2.76 (m, 1 H), 2.84 (dt, J = 8.5 Hz, J = 12.4 Hz, 1 H), 3.23 (m, 1 H), 3.34 (m, 1 H), 4.98 (m, 2 H), 5.42 (m, 1 H), 7.06 (d, J = 5.3 Hz, 1 H), 8.35 (m, 2 H). 13C NMR (250 MHz, CDCl3): δ = 21.6, 23.8, 27.5; 28.9, 34.2, 35.1, 37.0, 43.2, 44.8, 49.1, 96.7, 116.6, 121.3, 132.7, 137.2, 144.1, 147.5, 151.0, 177.2. Anal. Calcd for C19H21NO2: C, 77.26; H, 7.17. Found: C, 77.48; H, 7.26.
11b: Oil. IR (film): 2930, 2880, 1762, 1550 cm-1. 1H NMR (500 MHz, CDCl3) : δ = 1.49 (m, 1 H), 1.62 (m, 1 H), 1.64 (m, 1 H), 1.69 (m, 1 H), 1.71 (m, 1 H), 1.80 (d, J = 11.8 Hz, 1 H), 2.03 (m, 1 H), 2.12 (m, 1 H), 2.26 (m, 1 H), 2.52 (dd, J = 5.4, 11.8 Hz, 1 H), 2.65 (d, J = 10.5 Hz, 1 H), 2.89 (m, 1 H), 3.44 (d, J = 5.4 Hz, 1 H), 5.11 (d, J = 9.5 Hz, 1 H), 5.14 (d, J = 17.0 Hz, 1 H), 5.64 (dt, J = 9.9, 17.2 Hz, 1 H), 7.32 (d, J = 5.0 Hz, 1 H), 8.34 (s, 1 H), 8.39 (d, J = 5.0 Hz, 1 H). 13C NMR (250 MHz, CDCl3): δ = 25.8, 27.0, 27.1, 29.5, 38.9, 40.4, 41.7, 43.8, 49.1, 49.4, 96.3, 116.7, 119.8, 132.0, 137.2, 144.4, 147.1, 150.4, 175.5. HRMS (EI): m/z calcd for C19H21NO2 [M+]: 295.1572; found: 295.1571.
11c: Oil. IR (film): 2928, 1771, 1609 cm-1. 1H NMR (500 MHz, CDCl3): δ = 1.09 (qd, J = 5.7, 12.2 Hz, 1 H), 1.49 (qd, J = 2.7, 11.1 Hz, 1 H), 1.59 (m, 1 H), 1.91 (m, 2 H), 2.01 (d, J = 12.2 Hz, 1 H), 2.07 (dd, J = 4.2, 12.2 Hz, 1 H), 2.08 (m, 1 H), 2.12 (qd, J = 5.4, 11.9 Hz, 1 H), 2.12 (m, 1 H), 2.45 (td, J = 7.6, 11.3 Hz, 1 H), 2.90 (m, 1 H), 5.09 (m, 1 H), 5.88 (m, 1 H), 7.18 (d, J = 5.1 Hz, 1 H), 8.32 (s, 1 H), 8.37 (d, J = 5.1 Hz, 1 H). 13C NMR (250 MHz, CDCl3): δ = 25.7, 26.7, 29.8, 31.6, 32.9, 39.5, 39.8, 41.0, 51.4, 51.9, 94.3, 116.7, 119.0, 132.4, 135.4, 147.2, 147.5, 150.3, 179.7. HRMS (EI): m/z calcd for C19H21NO2 [M+]: 295.1572; found: 295.1569.