Diastereoselective synthesis of 1,1-disubstituted 4-phenyl-2,3,4,9-tetrahydrospiro-β-carbolines from β-phenyltryptamine and isatin derivatives

Diastereoselective synthesis of 1,1,4-trisubstituted-2,3,4,9-tetrahydrospiro-β-carbolines via glacial acetic acid catalyzed Pictet - Spengler reaction

“…To compare the reported 24 and the present results, base 32 was treated with sulfuric acid (conc.) in methanol to furnish the corresponding sulfate 33 in 95% yield (Scheme 4).…”

“…In this report, 24 the major diastereomer was shown to have R,R configuration using 2D NMR of the mixture without isolating the individual isomers.…”

“…22 Amongst the variously substituted THβCs very few reports are available typically for 1,4-disubstituted THβCs and also for 1,1,4-trisubstituted THβCs. [23][24][25] We now report a highly diastereoselective method o C to get a solid product in 97% yield. The structure was shown to be 8 by comparing with the reported 27d values.…”

Kojic acid aldol adduct with isatin as inhibitors of pyruvate dehydrogenase kinase

“…Isatin 1g was synthesized from isatin 1a and 1,3‐dichlorobut‐2‐ene according to a known method [72]. Isatin 1l was obtained from isatin 1a and bromine in acetic acid according to a known method [73]. Isatin 1m was synthesized from isatin 1l and methyl iodide according to a known method [74].…”

“…Isatin 1g was synthesized from isatin 1a and 1,3-dichlorobut-2-ene according to a known method [72]. Isatin 1l was obtained from isatin 1a and bromine in acetic acid according to a known method [73]. Isatin 1m was synthesized from isatin 1l and methyl iodide according to a known method [74] Isatin 1 (2 mmol), kojic acid (0.284 g, 2 mmol), and sodium acetate (0.016 g, 0.2 mmol) were refluxed in ethanol (4 ml) for 3 h. After the reaction was finished, the solid compound 2 was filtered out, twice rinsed with ice-cold ethanol (2 Â 2 ml), and dried under reduced pressure.…”