Mukoeic acid

Murrayafoline A Koenoline Murrayanine Mukoeic acid Mukonine... 

The reaction of the complex salt 6a with the arylamine 12 affords by regio-selective electrophilic substitution the iron complex 13 [88] (Scheme 11). The oxidative cyclization of complex 13 with very active manganese dioxide provides directly mukonine 14, which by ester cleavage was converted to mukoeic acid 15 [89]. Further applications of the iron-mediated construction of the carbazole framework to the synthesis of 1-oxygenated carbazole alkaloids include murrayanine, koenoline, and murrayafoline A [89]. 

In 1996, Wu et al. reported the isolation of clausine E (25) from the stem bark of C. excavata (46). One year later, Ito et al. reported the isolation of the same alkaloid from the same source and named it clauszoline-I (25) (47). This alkaloid showed inhibition of rabbit platelet aggregation and caused vasocontraction. The UV, IR, and H-NMR spectra were similar to those of mukoeic acid (10) with respect to the position of substituents. The presence of a carbomethoxy group at C-3 was indicated by an IR band at 1703 cm . Moreover, two significant mass fragments at m/z 210 (M —OMe) and 182 (M —COOMe) confirmed the presence of a carbomethoxy group. On the basis of these spectral data, structure 25 was assigned to clausine E (clauszoline-I) (Scheme 2.6). 

Clausine R (34) was isolated from the acetone extract of the root bark of C. excavata (43). The UV spectrum (2max 241, 282, and 320 nm) resembled that of mukoeic acid (10) (see Scheme 2.4), which indicated a 1-oxygenated 3-carboxycarba-zole framework. The H-NMR spectrum is similar to that of clausine Q (19) (see Scheme 2.5), except for the presence of a carbomethoxy signal at 5 3.86 instead of the aldehyde proton at 10.01 as in clausine Q. The presence of a carbomethoxy group... 

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... 

Carbazole alkaloids have been isolated from a few Rutaceae species, especially Murraya koenigii, the leaves of which have been used in southern India as a flavoring in food. Murrayanine, mukoeic acid, girinimbine, and mahanimbine have been isolated from the leaves. Carbazole alkaloids occur in all parts of this plant. 

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