Strychnovoline

Scaevoline (101) and racemigerine (102) were isolated from Scaevola racemigera, along with cantleyine, tetrahydrocantleyine, the new tetrahydropyridine monoterpene strychnovoline, and derivatives of the above alkaloids. Structures of 101 and 102 were established with MS, IR, h NMR, and synthesis of 102 from 95 [284]. 

Methyl-2,6-naphthyridine (104) Neozeylanicine (70) 7-O-Nicotinoyl-strychnovoline (66) 7-O-Nicotinoyl-tetrahydrocantleyine (67)... 

Among the six new monoterpene alkaloids isolated from the aerial parts of Scaevola racemigera (39) was 7-O-nicotinoyl-strychnovoline (66). The molecular ion was observed at m/z 330, with a major fragment ion at m/z... 

M+-C6H5NO), and the IR spectrum showed carbonyl bands at 1710 and 1680 cm-1 for unsaturated ester and lactam moieties. The H NMR spectrum showed the signals that corresponded to strychnovoline (64), except that the signal for H-6 was shifted downfield from 4.06 ppm to 5.46 ppm, suggesting that it was esterified, and this unit was identified from the XH NMR spectrum as a nicotinoyl moiety. The structure 66 for the isolate, and its absolute configuration, were confirmed through semisynthesis (see Section III.G) (39). 

An exactly analogous strategy was used for the synthesis of strychnovo-line (64) from loganin (1) (Scheme 29) (38). Thus, treatment of the unsaturated lactone 297 with ammonia-saturated methanol followed by gaseous HC1 gave 7-O-acetyl-strychnovoline (298), which on reaction with metha-nolic HC1 gave 64, identical with the natural product. 

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