Dendrobium pierardii

The diacid (172) ( C-labelling indicated by ) was fed to the orchid Dendrobium pierardii and a very efficient incorporation into shihunine was recorded. A very much lower incorporation (a factor of 10" ) was found for pierardine (174) and this may indicate that this alkaloid was not being synthesized at the time of the experiment. 

Dendrobium pierardii Roxb. (D. aphyllum Roxb.) (Orchidaceae) (Vol. 1, p. 459) Pierardine (71) has now been synthesized and shown to possess the (S) configuration. Condensation of the lithium salt of phthalaldehydic acid with 3-dimethylaminopropylmagnesium chloride followed by lactonization with acid gave ( )-pierardine, which was resolved by recrystallization of its di-0-benzoyl-L-tartrate. The (— )-enantiomer was shown to be identical with an authentic sample of the alkaloid. The absolute configuration of pierardine as (3S)-(3-dimethylaminopropyl)phthalide (71) was determined by comparison of... 

Shihunine (57), previously isolated from Dendrobium lohohense Tang and Wang (99, 100) andD. pierardii Roxb. (Orchidaceae) (101), has been found as a racemate in Banisteriopsis caapi Morton (102). This plant species also contained the optically active dihydroshihunine 58, a compound only known before as a racemic synthetic material. Both 57 and 58 were identified by direct comparison with authentic samples. The absolute configuration of (+)-(58) was determined as 25 by comparison of the CD spectra of 58 and of the a-phenylethylamines (102). 

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