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Vol. 81
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Fig. 1-
-Lcurosine; ~lviiicaleukoblastine;---equimolar
solution of eatliarmthiiie ~ u vindolinc d
Recently we have reported the characterization2 H5(2), 20.70; (N)-CH3(l),1.69. Found: COCH,, and partial structures of catharanthine and vindo- 4.62; OCH3, OCzH6, 21.99; (S)-CHa, 1.28. Karrer, Schniid and co-workers have postulated line, two new alkaloids from b’inca rosea Linn. Catharanthine was shown to be a C ~ I H Z ~ O Z Xthe Z , formation of dimeric curare alkaloids from either pentacyclic ester indole alkaloid (I) and vindoline two strychnine type or two @-carbolinetype alkaa CZ5Ha2O6X2 pentacyclic dihydroindole compound loids bonded through CI7 and indole nitrogen in (11). Similarities in the infrared spectra of these the case of B-carboline c o n i p ~ u n d s . ~ Our results clearly indicate that another variation, namely, an indole and dihydroindole coinbined in a manner which leaves the indole S H free (vide supra) is also possible. While essential two compounds and leurosine and vincaleuko- structural features of vindoline and catharanthine blastine prompted us to use the infrared summa- are clearly present in the molecules of leurosine and tion technique which proved successful in the de- vincaleukoblastine, the mode of attachment remains duction of structural features of reserpine3 and t o be elucidated. The question whether vindoline other Rauwoljia alkaloid^.^ and catharanthine are precursors of these new diConiparison of the infrared spectra of an equi- meric compounds or artifacts formed during the molar solution of vindoline and catharanthine with processing of the plant material is also under that of leurosine (or vincaleukoblastine) showed study. an excellent agreement of wave lengths and intenThe authors are grateful to Sliss ,inn I’m Call111 sities of bands in the portion of the spectra be- and Dr. I
