10103. allo-Yohimbine

Nomenclature

CAS number: 522-94-1
17-Hydroxyyohimban-16-carboxylic acid methyl ester; alloyohimbine; dihydroyohimbine.
C21H26N2O3; mol wt 354.44.
C 71.16%, H 7.39%, N 7.90%, O 13.54%.

Description and references

From bark of Corynanthe johimbe K. Schum., Rubiaceae: Warnat, Ber. 59, 2388 (1926); Hahn, Brandenberg, ibid. 60, 699 (1927). Identity with dihydroyohimbine: Heinemann, ibid. 67, 15 (1934). Structure and stereochemistry: LeHir et al., Bull. Soc. Chim. Fr. 1953, 1027; Janot et al., ibid. 1961, 637. Revised structure and total synthesis: Tke et al., J. Org. Chem. 38, 2496 (1973). Total synthesis: E. Wenkert et al., J. Am. Chem. Soc. 101, 5370 (1979). Review: A. Chatterjee et al., “Rauwolfia Alkaloids” in Zechmeister, Progress in the Chemistry of Organic Natural Products vol. XIII (Springer Verlag, Vienna, 1956) pp 354-356.

Chemical structure

Properties

Trihydrate, needles from 50% alcohol, mp 98-99°. After drying at 100° and 0.01 mm Hg for 24 hrs, the anhydrous form melts at 135-140°. [α]D19 +84° (c = 0.40 in pyridine). uv max (methanol): 225, 280, 290 nm (log ε 4.52, 3.91, 3.74). Sol in ethanol, methanol, pyridine, dil acids; slightly sol in benzene. Practically insol in water.