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The application possibilities of the in situ reactions of trichloroacetyl isocyanate (TAI method) to structural assignment of alcohols by means of 1H NMR spectroscopy are critically evaluated. The possibilities of TAI acylations in various solvents are demonstrated and the reactivity of various functional groups, potentially complicating or extending the applications of TAI, is discussed. In addition to their use in structural analysis such reactions also can serve as model experiments for preparative purposes.

Dedicated to Professor Holger Erdtman on the occasion 0/ his 80th birthday.From the endemic Cuban species Rauuol/ia salicl/olia GRISEB nine alkaloids were isolated of which the following seven had been already described: ( + )-ajmalidine (I), ( -)-reserpiline (11), ( -)-iso-The structure of ( -)-raucubaine (VI11) had been previously determined by X-ray diffraction and the structure of the alkaloid (-)-raucubainine (IX) was suggested on the basis of its conversion to ( -)-raucubaine (V Ill). The absol ute configuration of ( -)-raucubaine and (-)-raucubainine was elucidated by CD spectroscopy.Rau volfia salicifolia GRISEB represents one of the three endemic Cuban species of the Rauvolfia genus. This species was phytochemically studied in 1957 by Korzun and coworkers! who proved the presence of deserpidine, reserpiline, rescinamine and reserpine in the extract. The alkaloids were characterized only by paper chromatographic comparison with the authentic compounds.In this study we describe the isolation of nine alkaloids: From the root bark we isolated (+ )-ajmalidine (I), (-)-reserpiline (II), (-)-isoreserpiline (III) and ( -)-isocarapanaubine (IV). The principal alkaloid present in the plant is reserpiline. Isocarapanaubine was isolated from the Rauvolfia genus for the second time, the first isolation being from Rauvolfia vo mitoria 2 • From the tree bark we obtained ( -)-reserpiline (II), ( -)-ajmalicine (V), ( + )-vellosimine (VI) and ( + )-yohimbine (VII). The leaves afforded ( -)-reserpiline (II), ( -)-ajmalicine (V) and the new alkaloids (-)-raucubaine (VIII) and (-)-raucubainine (IX).The structure of raucubaine (VIII) was determined already by X-ray analysis 3 ,4.Its IH-NMR spectrum displays signals of four arom atic protons whose mutual interactions indicate an ortho-disubstituted benzene nucleu s, a singlet at (5 2·71 due Part XLVI in the series Plant Substances; Part XLV: This Journal 47, 644 (1982). This work represents part of the Thesis of P. Sierra

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