Methyl 6-methoxycarbazole-3-carboxylate

One year later, we extended the aforementioned palladium(II)-catalyzed approach to a series of 6-oxygenated carbazole alkaloids, glycozoline (86), glycozolinine (glycozolinol) (91), glycomaurrol (92), micromeline (100), and methyl 6-methoxycarbazole-3-carboxylate (104) (547). The palladium(0)-catalyzed coupling of 4-bromoanisole (670) and p-toluidine (1028), followed by palladium(II)-catalyzed oxidative cyclization, afforded directly glycozoline (86). 

Oxidation of 3-formyl-6-methoxycarbazole (97) with manganese dioxide and potassium cyanide in methanol afforded methyl 6-methoxycarbazole-3-carboxylate (104). Regioselective bromination of 97 afforded the 5-bromocarbazole 1031. Cleavage of the methyl ether to 1032, followed by nickel-mediated prenylation, provided micromeline (100) (547) (Scheme 5.154). 

Our palladium-catalyzed approach for the construction of the carbazole framework led to the 6-oxygenated tricyclic carbazole alkaloids glycozoline (128), methyl 6-methoxycarbazole-3-carboxylate (133), glycomaurrol (135) and micromeline (130), as well as to the furo[2,3-c]carbazole alkaloid eustifoline-D (132) (Scheme 29) [149]. Palladium-catalyzed coupling of p-bromoanisole (125) and p-toluidine (126) as the first step led almost quantitatively to the diarylamine 127. Oxidative cyclization of intermediate 127 using 0.1 equiv. of palladium(ll) acetate in the presence of an excess of copper(ll) acetate provided glycozoline... 

Xon-tryptamines.—Mukonine (1), from the stem bark of Murraya koenigii Spreng., is simply " the methyl ester of mukoeic acid (l-methoxycarbazole-3-carboxylic acid), isolated earlier from the same source. A pyranocarbazole... 

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