Orantine

Proteobacteria, Myxobacteria Chondromyces crocatus (chondramides A—D) [90]. F Basidiomycota Cortinarius violaceusa [5]. P Acanthaceae Aphelandra spp. (aphel-andrine, orantine [102]) Veronicaceae Chaenorhinum sp. [(S)-/ -Tyr chaenorhine, chaenorpine] [103]. 

Treatment of aphelandrine (179) with base (e.g., NaOCH3/CH3OH, 110°C, 1 hr, sealed tube) gave the isomerization product orantine (189). 

Under these reaction conditions 179 and 189 are in equilibrium (see Scheme 35). Using similar reaction conditions, several aphelandrine derivatives have been isomerized to the corresponding orantine derivatives (128). 

Orantine (ephedradine A) was isolated as a natural alkaloid from the crude drug mao, which itself is prepared from the aerial part of Ephedra plants (129). The structure, including the absolute configuration, was deduced by X-ray crystallography after preliminary chemical and spectroscopic work. The natural product and the isomerization product of aphelandrine (179) are also identical in their chiroptical properties (128). 

Rh2(5-DOSP)4 as catalyst and the presence of a chiral auxiliary bound to the diazoacetate derivatives, trans-2,3-dihydrobenzofurans have been prepared in good yields and high diastereoselectivities. This efficient method has been applied to the total syntheses of the complex macrocyclic spermine alkaloid (—)-ephedradine A (orantine) 32, an ypo-tensive component of the crude Chinese drug mao-kon prepared from the roots of Ephedra plants and the penta-cyclic indole alkaloid (—)-serotobenine 33 extracted from Rhaphidophara decursiva ... 

---