5-Yohimbic acid

When yohimbine is heated with potash solution it is eonverted into potassium yohimbate, from which yohimbic acid (the forms yohimboie and yohimboaic are also used and noryohimbine), C20H24O3N2. H2O, is liberated by acetie acid it crystallises from water in lustrous prisms, m.p. 269° or 299° (dry, dec.), [ajo 138-8° (pyridine), and, on esterification with methyl alcohol and its homologues, reproduces yohimbine and its homologues, analysis of which by Field confirmed the view that yohimbine is methyl yohimbate, and has the formula assigned to it by Fourneau and Page. ... 

Other contributions to this discussion have been made by Harvey, Miller and Robson, and by Dewar and King, and important additional experimental evidence for the location of the. CHOH group at has been provided by Witkop, who explains the improvement in the yield of yohimbone, which occurs when the decarboxylation of yohimbic acid takes place under oxidising conditions, as due to the primary formation of a j8-ketocarboxylic acid, which is readily decarboxylated. This may be represented, using part of the yohimbine formula fXIV), as follows MeO. OC. CH. 1 CHOH. ->HO. OC. CH. CHOH. ... 

Y-Legierung,/., Y-Metall, n. Y alloy, Y metal. Yohimboasaure, /, yohimboaic acid (yohimbic acid). 

In a specific case it has been possible to achieve isomerization at the C-15 to C-20 junction. Dehydration of yohimbic acid gives apoyohimbic acid (XVIb) which on subjection to the Schmidt reaction yields the ketone, ( +)-16-yohimbone (XVII) (10,11). When the same series of reactions is applied to 3-epi-a-yohimbine (XVIII), there is first generated the ketone XIX which spontaneously epimerized to XX which is ( — )-16-yohimbone (12). 

B. Beaclion of Yohimbic Acid unth Etfi l C hicroformaie... 

When yohimbic acid is treated a ith excess of ethyl chloroformate in pyridine solution at room temperature, a j9-laetone is formed (yifild, 37%). This reaction ia interpreted as confirmation for the ci position asaiguod to the oarboxymethyl and hydroxyl groups of yohimbine ... 

Other -lactones. The lactones of yohimbic acid and malic acidi give the expected reactione, but the lactone of 3-hydroxy-3-methylbutyrio add, which is somewhat less stable in water, only gives addition products with the alkali halides in low yield. The addition of sodium chloride, bromide and iodide to the lactone of 2,2-diphenylhydtaoryhe acid docs not give the corresponding add but rather diphenylethylene in a yield of 6,54, and 86%, respectively ... 

Venenatic and rauwolscinic acids, but not yohimbic or -yohimbic acids, are converted," albeit in very small yields, into lactams in which N-4 is bonded to C-22, C-3 carries an acetoxy-group, and the C-3—N-4 bond is cleaved, by heating with acetic anhydride-sodium acetate. A further study" of the cyanogen bromide-ethanol cleavage of the C-3—N-4 bond in yohimbine has shown that... 

According to Varchi et al. °, reserpine usually occurs at about 0.10-0.16% of natural extracts and deserpine in only 0.04%. Furthermore, five new indole alkaloids (Nb-methylajmaline, Nb-methylisoajmaline, 3-hydroxysarpagine, yohimbic acid, and isorauhimbic acid) were isolated from the dried roots... 

Barger and Field showed that when the sulphuric acid ester of yohimbine is hydrolysed with alkali it yields (a) yohimbic acid sulphuric esUr, O-SHjO, m.p. 289° dec.) of which the hydrochloride... 

Yam, mexican yellow phenophthalein yohimbic acid yttrla... 

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