A erythroidine

Erythrina isoquinolines (Phe C5N C4N C6 ) Erysonine, erysotrine, erythratidine, a-erythroidine and P-erythroidine (Erythrina species (Fabaceae) curare-like neuromuscular blockers). 

The primary evidence for the structure of a-erythroidine had come from Hofmann degradation of the reduction product XV. With one... 

These syntheses of Hofmann degradation products established the structure of XV but left two possibilities for a-erythroidine itself, II or XIX. The correctness of II was demonstrated by showing that a- and j8-erythroidines could be interconverted by warming in aqueous alkali. 

All of the aromatic alkaloids (except for erythratine) and -erythroi-dine possess two asymmetric carbon atoms—the spiro carbon (C-5) and the carbon substituted by methoxyl (C-3). a-Erythroidine has an additional center of asymmetry at C-12. Chemical, spectroscopic, and crystallographic methods have been used to assign relative and absolute configurations at the asymmetric centers. 

H2O), pK st(3) 7.4 Recrystallise a-erythroidine from pentane. It is best prepared freshly from the more stable hydrochloride. The hydrochloride (1.3g) in H2O (20mL) is basified with NaHC03 to pH 8 and extracted with C6H6 (6 X lOmL). The combined extracts are evaporated to a small volume and refrigerated. The free base separates as white hygroscopic crystals m 52-55°, which are recrystallised from pentane. Although stable in solution, the crystals turn brown on exposure to air. 

An interesting conversion of an erythrinan (9) into a -erythroidine derivative (12) has been reported (Scheme 1). Birch reduction of (9) followed by hydrolysis gave a good yield of the conjugated enone (10), which upon successive treatment with benzaldehyde, ozone, hydrogen peroxide, and diazomethane provided the... 

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