Structure Elucidation and Chemistry

Only five unelaborated benzylisoquinolines have been found in Guatteria. All have been isolated previously from botanical sources belonging to different plant families. Four of them (1-4) are biogenetically commonplace, whereas the fifth, juziphine (5), is one of the relatively rare 7,8-dioxygenated analogs of this gen- 

Chemically Investigated Guatteria Species and Their Contained Alkaloids 

Alkaloid type and name ture formula (MW) Species Reference(s)  

Bisbenzylisoquinoline (- )-Guattegaumerine (+)-Aromoline (+)-Daphnoline (+)-Daphnandrine (+)-Coclobine 

---

This contribution is an attempt to close this gap and therefore the organization of the chapter will be as follows. After a short outline of problems related to the nomenclature and delimitation of genera within the tribe Tabemaemontaneae, a summary of chemically investigated Tabernaemontana plants will be presented. Subsequently, the structure elucidation and chemistry of the most relevant alkaloids will be discussed. Finally, some noteworthly pharmacological activities will be outlined. 

The great number of different alkaloids found in Tabemaemontana precludes a discussion of the structure elucidation and chemistry of all of them. To keep the treatment concise, a major compromise was necessary. The alkaloids that have been reported in previous volumes of this treatise (as indicated in Table I) and their trivial modification will not be mentioned here. This compromise eliminates from the discussion well-established and long-known alkaloids that were isolated not only from Tabemaemontana but also from other genera. Moreover, the plumeran alkaloids isolated up to 1976 and ebuman-type and bisindole alkaloids isolated up to 1979 are covered in Volumes XVII and XX. The main efforts of this chapter will be focused on more recently isolated compounds, some of which are structurally and biogenetically relevant and have been found only in plants of the genus Tabemaemontana. 

The isolation of polyporic acid (11) [Stahlschmidt, 1877 (597, 592)], atromentin (13) [Thorner, 1878 (653)] and thelephoric acid (16) [ZOPF, 1889 (730)] marked the start of the chemical investigation of fungal pigments. The structure elucidation and chemistry of these compounds has been amply covered in Thomson s book (655) and does not need to be repeated here. In recent years several papers dealing with ultraviolet (311), infrared (208) and mass spectra (304, 465) and with the chromatography (267) and detection (274) of simple terphenyl-quinones have been published. Details of their known distribution in fungi are given in Table 3 and their physical properties are summarised in Table 4. 

Nowadays, analytical chemistry has a large variety of methods, techniques and apparatus at its disposal and is able to play its instruments with high virtuosity. Therefore, the wide range of performance which analytical chemistry can achieve is extremely varied and extends from simple binary decisions (qualitative analysis) to quantitative analysis at the ultratrace level, from structure elucidation and species identification to studies of the dynamics and the topology of multispecies systems by means of temporally and spatially high-resolving techniques. 

Hippe Z (1991) Artificial intelligence in chemistry. Structure elucidation and simulation of organic reactions. Elsevier, Amsterdam... 

Lochnit, G., Dennis, R.D., Ulmer, A.J. and Geyer, R. (1998a) Structural elucidation and monkine-inducing activity of two biologically active zwitterionic glycosphingolipids derived from the porcine parasitic nematode Ascaris suum. Journal of Biological Chemistry 273, 466-474. 

The unique molecular skeleton of the C-nor-D-homosteroids represents significant challenges for organic chemists. The structure elucidation and the total synthesis of cyclopamine (3, also known as 11-deoxojervine), jervine (ll-oxo-3), and veratramine (4) are important milestones in steroid chemistry. Many synthetic strategies were developed in the 1960s-1970s for these targets. Notably, Masamune... 

HPTLC is a very fast and convenient assay to separate samples components and is often used in Organic Chemistry and in Synthetic approach. Unknown substances, after different display assay, were generally scraped off from the TLC/HPTLC plate, diluted into a tube and transferred into the MS system for structural elucidation and characterization. Now, a TLC-MS interface was developed by CAMAG, which can semi-automatically extract zones of interest and on-line direct them into any brand of a HPLC-MS system. The TLC-MS interface is connected by two fittings to any HPLC instrument coupled with mass spectrometer, without other system configuration adjustments or mass spectrometer modifications. By this way, the unknown substances can be directly extracted from a TLC/HPTLC plate, eluted and resolved by HPLC system and sensitive and selective mass spectrometric signals are obtained within a minute per substance zone [33],... 

Enzell. Tobacco chemistry. Structure elucidation and synthesis of 3,3-dim- NT489... 

NT479 Behr, D., I. Wahlberg, T. Nishida, and C. R. Enzell. Tobacco chemistry. Structure elucidation and synthesis of 5(13),7E-megastigmadien-6,9-diol, a NT491 new constituent of Greek tobacco. Acta Chem Scand Ser B 1977 31 609. 

Nuclear magnetic resonance (NMR) spectroscopy is the most widely used spectroscopic technique in synthetic chemistry [1], One main reason for the dominance of NMR is its versatility—by variation of only a few experimental parameters, a vast number of different NMR experiments can easily be performed, giving access to very different sets of information on the substance or the reaction under investigation. Today, NMR is dominant in structure elucidation, and in situ NMR spectroscopy can conveniently give insight into chemical reactions under real turnover conditions (in contrast to, e.g., x-ray crystallography, which can only provide a solid-state snapshot of a molecular conformation). 

Kitajima s structural elucidation and characterization of 5 have completely turned around our thinking about Cu202 structure and chemistry, because along with other information, the definite demonstration of the viability of a p-r 2 r 2-peroxo coordination in copper chemistry strongly suggests that this moiety is present in proteins such as oxy-Hc and oxy-Tyr. 

Since the late 1950s PMR spectroscopy has contributed immensely to many areas of the chemistry of alkaloids (7). With the advent of Fourier transform spectrometers CMR has rapidly approached the level of PMR in its application to problems of structural elucidation and stereochemistry. In the case of the alkaloids many classes of the isoquinoline family have been studied. These alkaloids are of particular interest not only because of their widespread occurrence in nature but also because of their pharmacological activity (2-5). Wenkert et al. (6) were the first to review progress in this area. More recently, Shamma and Hindenlang (7) have made an extensive compilation of chemical shift data on amines and alkaloids that includes many... 

Zdzislaw Hippe, Artificial Intelligence in Chemistry Structure Elucidation and Simulation of Organic Reactions, Elsevier, Amsterdam, Neth., 1991. 

The next step, which is the analysis of the model library, serves two goals in the case of OBOC libraries development of methods for structure elucidation and validation of chemistry used for library synthesis. Synthesis... 

A useful volume on the chemistry of terpenoids and steroids has appeared.1 Nineteen topics in monoterpenoid chemistry are reviewed with a literature coverage to early 1973 the topics are particularly suitable for use in advanced lecture courses and cover biosynthesis, structural elucidation, and synthesis. Monoterpenoid alkaloid chemistry has been reviewed.2... 

Streptomyces distallicus the structure elucidation and synthesis have also been made by them.165 A wide variety of porphyrins which are derivatives of porphin (125 R = H) occur in nature and exert three biological functions (a) oxygen storage and transport, as in hemoglobin, (b) cellular respiration as in the cytochromes, and (c) photosynthesis, as in the chlorophylls for detailed discussion of structures and synthesis of naturally occurring porphyrins, see references.166 Recent developments in the chemistry of polypyrrolic compounds have been reviewed.167 Several naturally occurring indole alkaloids have dimeric structures of type B,168 an example of which is c-toxiferine-I, a calabash curare alkaloid found in South American species of Strychnos.169... 

---