Narrative in the chemistry of (aryl/hetaryl)thiopyran-4-one

Synthesis of Alkyl Thiochromano[2,3-c]pyrrole-9-carboxylate Derivatives Utilizing Benzo[b]thiofuran-2,3-dione, Maleimides, and Alkyl Alcohol/Water Mixtures

“…The same product 7a was obtained when the above experiment was repeated using α-Phe (instead of α-Ala); the yield of 7a was slightly lower in the presence of α-Ala (91%) or α-Phe (90%). In either case, the product lacked the CH(Me) or CH(Bn)-moieties, characteristic of the employed α-amino acid, as evidenced from 1 H-, and 13 C-NMR spectral data, indicating unequivocally that the latter acids did not partake in generation of 7a. Indeed, a two-component reaction of 5 and 3a in aqueous MeOH (in the absence of α-amino acid) produced slightly higher yield (92%) of the same product 7a (Scheme 2 / A).…”

“…11 The synthesis, reactions and biological activity of (aryl / hetaryl)thiopyran-4-ones were briefly outlined in 2001, 12 and have been recently reviewed. 13 Meanwhile, researching for new routes toward their synthesis remained popular. The related chromenes, Suitable crystals of 7a were measured with an STADIVARIdiffractometer with Mo-Kα radiation.…”

“…= 148-150 °C. General procedure for the preparation of (N-substituted)-1,3-dioxo-1, 2, 3, 3a, 9, 9a-hexahydro-thiochromeno[2,3-c]pyrrple-9-hydroxy-9-carboxylic acids (11)(12)(13)(14) To a solution of the appropriate methyl thiochromeno[2,3-c]pyrrole-9carboxylate 7a-10a (0.33 mmole) in EtOH (5 ml) was added aqueous NaOH solution (5%, 6 ml). The resulting mixture was heated at 45 °C for 4-5 h. Thereafter, the resulting alkaline reaction mixture was acidified…”

“…1 H NMR (500 MHz, CDCl 3 ):  = 1.19, 1.26 (2d, J = 6.4 Hz, 6 H, CO 2 CH(CH 3 ) 2 ), 4.35 (d, J = 9.5 Hz, 1 H, H-9a), 4.46 (d, J = 9.5 Hz, 1 H, H-3a), 5.02 (s, 1 H, OH), 5.12 (m, 1 H, CO 2 CHMe 2 ), 6.81, 6.83 (2d, J = 6.3, 2.4 Hz, 2 H, H-11 / H-15), 7.35 (m, 3 H, H-5 + H-6 + H-7), 7.37 (m, 1 H, H-13), 7.40 (m, 2 H, H-12 / H-14), 7.77, 7.75 (2d, J = 7.1, 2.5 Hz, 1 H, H-8). 13 C NMR (125 MHz CDCl…”

“…1 H-NMR (500 MHz, DMSO-d6) δ: 3.74 (s, 3H, CO2CH3), 4.21 (d, J = 9.5 Hz, 1H, H-9a), 4.40 (d, J = 9.5 Hz, 1H, H-3a), 4.50 (s, 2H, H-10), 5.17 (s, 1H, OH), 6.70 (d, J = 7.3 Hz, 2H, H-12 / H-16), 7.17 (ps t, 2H, H-13 / H-15), 7.24 (t, J = 7.5 Hz, 1H, H-14), 7.28-7.31 (m, 2H, H-5 + H-6), 7.38 (ps t, 1H, H-7), 7.85 (d, J = 7.8 Hz, 1H, H-8) ppm 13. C NMR (125 MHz DMSO-d6) δ: 41.9 (C-9a), 42.8 (C-10), 49.3 (C-3a), 53.7 (CO2CH3), 78.0 (C-9), 125.9 (C-8), 127.4 (C-12 / C-16), 127.8 (C-8a), 128.5 (C-5), 128.7 (C-13 / C-15 + C-14), 129.5 (C-7), 130.2 (C-6), 134.3 (C-11), 138.3 (C-4a), 169.6 (CO2Me), 175.2 (C-3), 177.5 (C-1) ppm.…”