Proline-Promoted Efficient Synthesis of 4-Aryl-3,4-dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-diones in Aqueous Media

Abstract

The reaction of 4-hydroxycoumarin with Meldrum’s acid and benzaldehydes in aqueous media in the presence of proline (10 mol%) led to 4-aryl-3,4-dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-diones in good yields.

chromene - proline - aqueous media - Meldrum’s acid - 4-hydroxycoumarin - benzaldehydes

References and Notes

1 Miao H. Yang Z. Org. Lett.  2000,  2:  1765 

2 Kumar P. Bodas MS. Org. Lett.  2000,  2:  3821 

3 Chauder BA. Lopes CC. Lopes RSC. Dasilva AJM. Snieckus V. Synthesis  1998,  279 

4 Parker AK. Mindt TL. Org. Lett.  2001,  3:  3875 

5 Yu N. Aramini JM. Germann MW. Huang Z. Tetrahedron Lett.  2000,  41:  6993 

6 Hepworth JD. Gabbutt CD. Heron BM. Comprehensive Heterocyclic Chemistry   Vol. 5:  Katritzky AR. Rees CW. Scriven EFV. Pergamon; Oxford: 1996.  p.351-468  

7 Yavari I. Ramazani A. J. Chem. Res., Synop.  1996,  382 

8 Yavari I. Adib M. Sayahi MH. Tetrahedron Lett.  2002,  43:  2927 

9 Yavari I. Sabbaghan M. Hossaini Z. Synlett  2006,  2501 

10 Yavari I. Hossaini Z. Sabbaghan M. Tetrahedron Lett.  2006,  47:  6037 

11 Yavari I. Moradi L. Tetrahedron Lett.  2006,  47:  1627 

12

4-Phenyl-3,4-dihydro-2 H ,5 H -pyrano[3,2- c ]chromene-2,5-dione (4a) To a stirred solution of benzaldehyde (0.21 g, 2 mmol) and Meldrum’s acid (0.29 g, 2 mmol) in 50% aq EtOH (10 mL) were added 4-hydroxycoumarin (0.32 g, 2 mmol) and proline (11.5 mg, 10 mol%). The reaction mixture was stirred at reflux for 40 min. After completion of the reaction (monitored by TLC), the precipitate was collected by filtration and washed by cold 50% aq EtOH (5 mL) to afford 4a, yield 0.55 g (94%); white powder; mp 169-171 °C. IR (KBr): 1788 (C=O), 1707 (C=O), 1630, 1104 cm^-1. ¹H NMR (500.1 MHz, CDCl₃): δ = 3.15 (dd, ² J = 16.2 Hz, ³ J = 1.7 Hz, 1 H, CH), 3.21 (dd, ² J = 16.2 Hz, ³ J = 7.6 Hz, 1 H, CH), 4.54 (dd, ³ J = 7.6 Hz, ³ J = 1.7 Hz, 1 H, CH), 7.26-7.29 (m, 3 H, 3 CH), 7.31 (d, ³ J = 6.8 Hz, 1 H, CH), 7.32 (d, ³ J = 6.9 Hz, 1 H, CH), 7.36-7.39 (m, 2 H, 2 CH), 7.62 (t, ³ J = 7.3 Hz, 1 H, CH), 7.92 (dd, ³ J = 8.2 Hz, ⁴ J = 1.6 Hz, 1 H, CH). ¹³C NMR (125.7 MHz, CDCl₃): δ = 36.3 (CH₂), 36.4 (CH), 106.8 (C), 113.9 (C), 117.3 (CH), 123.2 (CH), 125.1 (CH), 127.1 (2 CH), 128.5 (CH), 129.7 (2 CH), 133.4 (CH), 139.8 (C), 153.6 (C), 157.7 (C), 161.2 (C=O), 164.7 (C=O). MS (EI): m/z (%) = 292 (8) [M⁺], 264 (5), 249 (5), 111 (18), 95 (18), 85 (30), 71 (58), 57 (100), 43 (94). Anal. Calcd (%) for C₁₈H₁₂O₄ (292.29): C, 73.97; H, 4.14. Found: C, 73.70; H, 4.31. All other compounds isolated possessed spectroscopic and analytical data in agreement with their proposed structures.