Three-Component Coupling Strategy for Expeditious Synthesis of 4-Aminobenzoxazinones on Mineral Support

Abstract

Novel montmorillonite K-10 clay supported three-­component reactions of substituted salicylaldehydes, N-substituted ureas/carbamates and ammonium acetate or an amine expeditiously yield 3,4-dihydro-4-amino-2H-benz[e]-1,3-oxazin-2-ones via ­cycloisomerization of intermediate aldimines under solvent-free microwave irradiation in a one-pot procedure.

Key words

multi-component reactions - mineral support - microwaves - solvent-free - 4-aminobenzoxazinones

References

• 1 Patel M. Ko SS. McHugh RJ. Markwalder JA. Srivastava AS. Cordova BC. Klabe RM. Erickson-Viitanen S. Trainor GL. Seitz SP. Bioorg. Med. Chem. Lett.  1999,  9:  2805 
• 2 Patel M. McHugh RJ. Cordova BC. Klabe RM. Erickson-Viitanen S. Trainor GL. Koo SS. Bioorg. Med. Chem. Lett.  1999,  9:  3221 
• 3 Waxman L. Darke PL. Antiviral Chem. Chemother.  2000,  11:  1 
• 4 Klasek A. Koristek K. Polis J. Kosmrij J. Tetrahedron  2000,  56:  1551 
• 5 Girgis AS. Pharmazie  2000,  426 
• 6 Mindl J. Hrabik O. Sterba V. Kavalek J. Collect. Czech. Chem. Commun.  2000,  65:  1262 
• 7 Ugi I. Domling A. Endeavour  1994,  18:  115 
• 8 Heck S. Domling A. Synlett  2000,  424 
• 9 Kraus GA. Nagy JO. Tetrahedron  1985,  41:  3537 
• 10 Posner GH. Chem. Rev.  1986,  86:  831 
• 11 Ugi I. J. Prakt. Chem.  1997,  339:  499 
• 12 Bienayme H. Bourzid K. Tetrahedron Lett.  1988,  39:  2735 
• 13 Ziegler T. Kaiser HJ. Schlomer R. Koch C. Tetrahedron  1999,  55:  8397 
• 14 Caddick S. Tetrahedron  1995,  51:  10403 
• 15 Loupy A. Petit A. Hamelin J. Texier-Bouller F. Jacquault P. Mathe D. Synthesis  1998,  1213 
• 16 Varma RS. Green Chem.  1999,  1:  43 
• 17 Lidstrom P. Tierney J. Wathey B. Westman J. Tetrahedron  2001,  57:  9225 
• 18 Perreux L. Loupy A. Tetrahedron  2001,  57:  9199 
• 19 Balogh M. Laszlo P. Organic Chemistry Using Clays   Springer; Berlin: 1993. 
• 20 Chisem J. Chisem IC. Rafelt JS. Macquarrie DJ. Clark JH. Chem. Commun.  1997,  2203 
• 21 Meshram HM. Shekhar KC. Ganesh YSS. Yadav JS. Synlett  2000,  1273 
• 22 Yadav LDS. Singh A. Tetrahedron Lett.  2003,  44:  5637 
• 23 Yadav LDS. Dubey S. Yadav BS. Tetrahedron  2003,  59:  5411 
• 24 Yadav LDS. Kapoor R. Tetrahedron Lett.  2003,  44:  8951 
• 25 Yadav LDS. Singh S. Synthesis  2003,  63 
• 26 O’Callaghan CN. McMurry TBM. J. Chem. Res., Synop.  1997,  78 ; J. Chem. Res. Miniprint 1997, 643
• 27 Bagnell L. Cablewski T. Strauss CR. Trainor RW. J. Org. Chem.  1996,  61:  7355 
• 28 Varma RS. Kumar D. Liesen PJ. J. Chem. Soc., Perkin Trans. 1  1998,  4093 
• 29 Bandgar BP. Uppalla LS. Kurule DS. Green Chem.  1999,  1:  243 
• 30 Varma RS. Dahiya R. J. Org. Chem.  1998,  63:  8038 
• 31 Yadav LDS. Saigal S. Pal DR. J. Chem. Res., Synop.  1998,  307 

32

A CEM Discover Focused Microwave Synthesis System operating at 2450 MHz was used at an output of 560 W for all the experiments. The temperature (85 ± 5 °C) was monitored by a built-in infrared sensor and the irradiation time was set at 2 min.

33

General Procedure for the Synthesis of 3,4-Dihydro-4-amino-3-aryl-2 H -benz[ e ]-1,3-oxazin-2-ones 8a-u. To a solution of salicylaldehyde 1 (5 mmol) and substituted aryl/alkylurea 2 (5 mmol) in a small amount of CH₂Cl₂ (10 mL) was added ammonium acetate or aniline (5 mmol) and montmorillonite K-10 clay (0.50 g) mixed thoroughly and dried under reduced pressure. The contents were taken in a 100 mL conical flask and subjected to MW irradiation at 560 W for 2 min. The reaction mixture was then thoroughly mixed outside the MW oven for 2 min and again irradiated for another 2 min. This intermittent irradiation mixing cycle was repeated for a total irradiation time (Table [2] ). After completion of the reaction as indicated by TLC (hexane-EtOAc, 8:2, v/v), the product was extracted with CH₂Cl₂ (3 × 80 mL), the extract was filtered and the filtrate was evaporated under reduced pressure to leave the crude product which was recrystallized from EtOH to give an analytically pure sample of 8 as yellowish needles.

34

Characterization Data for Representative Compounds.
Compound 8a: yellowish needles; mp 125-126 °C. IR (KBr): ν = 3360, 3000, 1715, 1592, 1570, 1449 cm^-1. ¹H NMR (400 MHz, DMSO-d ₆ ): δ = 3.06 (br s, 2 H, exchanges with D₂O), 6.75 (t, 1 H, J = 8.0 Hz), 7.19-7.87 (m, 9 H). ¹³C NMR (100 MHz, DMSO-d ₆ ): δ = 78.0, 113.1, 114.2, 118.6, 120.3, 122.6, 129.0, 129.4, 130.2, 150.0, 166.4, 177.0. MS (EI): m/z = 240 [M⁺]. Anal. Calcd for C₁₄H₁₂N₂O₂: C, 69.99; H, 5.03; N, 11.66. Found: C, 69.89; H, 5.23; N, 11.46.
Compound 8h: yellowish needles; mp 116-117 °C. IR (KBr): ν = 3364, 3012, 1700, 1592, 1571, 1450 cm^-1. ¹H NMR (400 MHz, DMSO-d ₆ ): δ = 2.31 (s, 3 H), 3.05 (br s, 2 H, exchanges with D₂O), 6.75 (t, 1 H, J = 7.9 Hz), 7.14-7.84 (m, 8 H). ¹³C NMR (100 MHz DMSO-d ₆ ): δ = 21.2, 78.2, 113.0, 114.0, 118.2, 120.5, 122.5, 128.7, 129.5, 130.4 150.1, 166.0, 177.0. MS (EI): m/z = 254 [M⁺]. Anal. Calcd for C₁₅H₁₄N₂O₂: C, 70.85; H, 5.55; N, 11.02. Found: C, 70.55; H, 5.85; N, 10.82.
Compound 8r: yellowish needles; mp 210-211 °C. IR (KBr): ν = 3370, 3016, 1720, 1598, 1577, 1454 cm^-1. ¹H NMR (400 MHz, DMSO-d ₆ ): δ = 1.09 (t, 3 H, J = 6.8 Hz), 2.57 (q, 2 H, J = 6.8 Hz), 3.09 (br s, 2 H, exchanges with D₂O), 6.79 (t, 1 H, J = 8.0 Hz), 7.86 (d, 1 H, J = 2.5 Hz), 8.23 (d, 1 H, J = 2.5, 2.5 Hz). ¹³C NMR (100 MHz, DMSO-d ₆ ): δ = 13.9, 58.5, 78.9, 118.6, 122.4, 129.5, 130.7, 150.6, 166.3, 177.3. MS (EI): m/z = 350 [M⁺]. Anal. Calcd for C₁₀H₁₀N₂O₂Br₂: C, 34.32; H, 2.88; N, 8.00. Found: C, 34.42; H, 3.18; N, 8.10.,