Aromatization of 1,6,7,7a-tetrahydro-2H-indol-2-ones by a novel process. Preparation of key-intermediate methyl 1-benzyl-5-methoxy-1H-indole-3-acetate and the syntheses of serotonin, melatonin, and bufotenin.
Imine 7 of 1,4-cyclohexanedione mono-ethylene ketal 6 was reacted with maleic anhydride, affording the cyclized adduct 8. Methyl esterification of 8, accompanied by transacetalization, led to the dihydrooxindole derivative 10. Aromatization of 10 was then accomplished with POCl(3), leading directly to the key-intermediate title compound 11 in 74% yield from ketone 6. Serotonin, melatonin, and bufotenin were then obtained by standard reactions.
Revial
Gilbert
G
Laboratoire de Chimie Organique, CNRS (ESA 7084), ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05, France.
Jabin
Ivan
I
Lim
Sethy
S
Pfau
Michel
M
D002027:Bufotenin / Q000138:chemical synthesis*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods; D002855:Chromatography, Thin Layer; D003500:Cyclization; D007097:Imines / Q000737:chemistry; D007210:Indoleacetic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008550:Melatonin / Q000138:chemical synthesis*; D015394:Molecular Structure; D010851:Picrates / Q000737:chemistry; D012701:Serotonin / Q000138:chemical synthesis*
D007097:Imines; D007210:Indoleacetic Acids; D007211:Indoles; D010851:Picrates; C459659:methyl-1-benzyl-5-methoxy-1H-indole-3-acetate; D002027:Bufotenin; D012701:Serotonin; D008550:Melatonin