Synlett 2007(7): 1085-1090  
DOI: 10.1055/s-2007-973898
LETTER
© Georg Thieme Verlag Stuttgart · New York

Three-Component Reactions of α- and β-Bromo Aldehydes with Amides and Dienophiles - An Easy Way to Versatile 1-Amido-2-Cyclohexenes

Sandra Hübnera, Helfried Neumanna, Dirk Michalika, Stefan Klausa, Dirk Strübinga, Anke Spannenberga, Axel Jacobi von Wangelinb, Matthias Beller*a
a Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Str. 29a, 18059 Rostock, Germany
Fax: +49(381)12815000; e-Mail: Matthias.Beller@catalysis.de;
b Institut für Organische Chemie, Universität Köln, Greinstraße 4, 50939 Köln, Germany
Further Information

Publication History

Received 2 February 2007
Publication Date:
13 April 2007 (online)

Abstract

The scope of the three-component reaction of aldehydes, amides, and dienophiles, the so-called AAD reaction, is extended to the formation of 2- and 3-bromo-substituted 1-amido-2-cyclohexene derivatives. The incorporation of the halogen substituent allows further elaboration of this interesting class of products.

8

The crystallographic data for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication CCDC 635328 (6).

10

rac - N -(5-Bromo-2-methyl-1,3-dioxo-2,3,3a,4,7,7a-hexahydro-1 H -isoindol-4-yl)-4-methoxybenzamide (5)
4-Methoxybenzamide (152 mg, 1.00 mmol) was filled in a CEM pressure tube (10 mL), then toluene (2 mL), α-bromo-crotonaldehyde (2.00 mmol, 298 mg), and N-methyl-maleimide (1.50 mmol, 167 mg) were added. The reaction vessel was sealed and the mixture was subject to microwave irradiation (max. 50 W, 2450 MHz) under stirring at 150 °C for 20 min. After cooling, compound 5 precipitated from the reaction mixture. It was obtained as a colorless solid (84% yield) after washing with CH2Cl2. Further purification was not necessary. The assignment of the NMR signals was carried out according to the numbering given in Table [2] .
Mp 257 °C. 1H NMR (500 MHz, DMSO-d 6): δ = 8.31 (d, 3 J 9,4 = 9.0 Hz, 1 H, H-9), 7.75 (m, 2 H, H-12), 7.05 (m, 2 H, H-13), 6.35 (ddd, 3 J 6,7 eq = 6.3 Hz, 3 J 6,7 ax = 4.0 Hz, 4 J 6,4 = 1.8 Hz, 1 H, H-6), 5.07 (m, 1 H, H-4), 3.82 (s, 3 H, H-15), 3.62 (dd, 3 J 3a,4 = 9.0 Hz, 3 J 3a,7a = 7.0 Hz, 1 H, H-3a), 3.32 (m, 1 H, H-7a), 2.82 (s, 3 H, H-8), 2.63 (ddd, 2 J 7 eq ,7 ax = 16.7 Hz, 3 J 7 eq ,6 = 6.3 Hz, 3 J 7 eq ,7a = 3.2 Hz, 1 H, H-7 eq ), 2.46 (m, 1 H, H-7 ax ) ppm. 13C{1H} NMR (125 MHz, DMSO-d 6): δ = 179.0 (CO), 177.8 (CO), 165.3 (CO), 161.9 (C-14), 129.7 (C-6), 128.9 (C-12), 126.0 (C-11), 122.7 (C-5), 113.8 (C-13), 55.4 (C-15), 47.7 (C-4), 43.6 (C-3a), 37.4 (C-7a), 25.1 (C-7), 24.6 (C-8) ppm. IR (mull): ν = 3403 (m), 1769 (m), 1695 (s), 1665 (s), 1617 (w), 1604 (m), 1575 (m), 1533 (m), 1498 (s), 1351 (w), 1323 (m), 1313 (m), 1284 (m), 1253 (m), 1223 (w), 1185 (m), 1135 (w), 1107 (m), 1044 (w), 1024 (m), 1009 (m), 954 (w), 929 (w), 882 (w), 850 (m), 818 (m), 782 (m), 767 (m), 723 (w), 699 (w), 654 (w), 611 (m), 595 (m), 580 (s) cm-1. MS (EI): m/z (%) = 394 (1) [M]+, 392 (1) [M]+, 313 (100) [M - Br]+, 259 (46) [M - C8H7O2]+, 257 (45) [M - C8H7O2]+, 202 (77), 135 (99), 112 (12), 107 (21), 92 (24), 77 (43), no further peaks >10%. HRMS (EI): m/z calcd for C17H17 79BrN2O4: 392.0366; found: 392.0355 [M]+.