Chlorophyll a, the major green pigment of the plant world, is certainly the most widespread and conspicuous of organic natural products. Few can be unaware of its decorative function, and all are beneficiaries of its central role in transforming sunlight into substance and sustenance. Yet the fruitful chemical study of this green badge of life did not commence until fairly recent times. For chlorophyll a is a very reactive, sensitive, and complicated substance. Only when, early in this century, the genius of Willstatter applied itself to the problem, were the first sure steps taken. That great investigator isolated the pigment-and its closely related frequent minor concomitant chlorophyll b as well-in the pure state, established correctly the empirical formula of the substance, and laid down a sound and extensive preliminary basis of transformation and degradation. These achievements can be measured against the fact that the isolation of chlorophyll in a state of purity is even now, after more than fifty years, no mean feat, and, further, that the empirical formula defined by Willstatter, repeatedly called into question by subsequent investigators, has stood the test of time. For some period after this solid foundation had been laid by Willstatter there was little activity until three new groups took the field late in the 1920s. Stoll, who had played a prominent role in the early studies as a collaborator of Willstatter, took up the work anew, and made important contributions, as did Conant in the United States. But by far the greatest contribution was made by Hans Fischer and his collaborators at Munich. Fresh from his dramatic conquest of the blood pigment, Fischer hurled his legions into the attack on chlorophyll, and during a period of approximately fifteen years, built a monumental corpus of fact. As this chemical record, almost unique in its scope and depth, was constructed, the molecule was transformed and rent asunder in innumerable directions, and the fascination and intricacy of the chemistry of chlorophyll and its congeners was fully revealed. These massive contributions were crowned by the proposal, in 1940, of a structure which was complete except for stereochemical detail. Finally, in a series of elegant investigations completed only during the last few years, Linstead and his associates at Imperial College were able to solve the stereochemical problem and to provide definitive confirmatory detail in respect of the number and disposition of saturated carbon atoms within the nuclear framework. Half a century of structural study had culminated in the complete formula (I) for chlorophyll aI, 8. Our active interest in chlorophyll was initiated four years ago, in 1956. The first questions we asked were very general ones. The structural investigations had been carried out almost entirely during the twilight of the classical period of organic chemistry. Only the very simplest basic * A brief communication recording the results on which this lecture is based has appeared in
. Can. J. Chem. 70, 2526Chem. 70, (1992. Tridzoderma longibrnchiaturn Rifai aggr. is a fungus reported to be antagonistic to the fungus Mycenn citricolor, the causative agent of the American leaf spot disease of coffee. We have investigated the metabolites produced when T. lorzgibrachiat~~rn is grown in liquid culture and have isolated the known compounds sorbicillin (Z), bisvertinol (3), and bisvertinolone (4) as well as several new compounds including trichodimerol (I), an interesting new natural product possessing a proper axis of symmetry. The structure of trichodimerol (1) was determined by a combination of spectroscopic techniques, including 'H and "C nuclear magnetic resonance, infrared, ultraviolet, circular dichroism, optical rotatory dispersion, and mass spectrometry, and by transformation to octahydrotrichodimerol (6) and symmetrical and unsymmetrical derivatives thereof. The relative stereochemistry of bisvertinol (3) and bisvertinolone (4) has been revised. The metabolites described are not biologically active against Mycena citricolor.ROMANO ANDRADE, WILLIAM A. AYER et PAUL P. MEBE. Can. J. Chem. 70, 2526 (1992) Le Trichodertna longibrachiatum Rifai aggr. est un champignon qui serait antagoniste du champignon Mycerla citricolor, l'agent causant des taches sur les feuilles de cafe amtricain. On a examint les mttabolites produits par culture liquide du T. longibrachiaturn et on a identifie la sorbicilline (Z), le bisvertinol (3) et la bisvertinolone (4), des composes connus, ainsi que plusieurs nouveaux compods, dont le trichodimCrol (I), un nouveau produit nature1 inttressant possCdant un axe de symttrie propre. On a determine la structure du trichodimCrol (1) par une combinaison de techniques spectroscopiques, dont la resonance magnttique nucltaire du 'H et du I3c, l'infrarouge, I'ultraviolet, le dichroi'sme circulaire, la dispersion rotatoire optique et la spectrometrie de masse ainsi que par la transformation de 1 en octahydrotrichodimCrol (6) et en des dtrivts symttriques et asymCtriques de ce dernier. On a revist la sttrtochimie relative du bisvertinol (3) et de la bisvertinolone (4). Les mttabolites dCcrits ne sont pas biologiquement actifs contre la Mycena citricolor.[Traduit par la redaction]
The metabolites produced when Monocillium nordinii (Bourchier) W. Gams, a destructive mycoparasite of pine stem rusts, is grown in liquid culture have been separated and identified. The metabolites include the known compound monorden (1) and five new substances, monocillin I (2), monocillin II (4), monocillin III (3), monocillin IV (5), and monocillin V (6). Structural assignments and chemical correlations of the five new compounds are reported and the absolute configuration of monorden is assigned. The antifungal spectra of the three major metabolites are reported. Monorden and monocillin I show pronounced activity against a wide variety of fungi, including Ceratocystis ulmi, the cause of Dutch elm disease. Extraction of the mycelium yielded averufin (13), along with a pigment C18H12O6, as yet unidentified.
Chlorophyll a, the major green pigment of the plant world, is certainly the most widespread and conspicuous of organic natural products. Few can be unaware of its decorative function, and all are beneficiaries of its central role in transforming sunlight into substance and sustenance. Yet the fruitful chemical study of this green badge of life did not commence until fairly recent times. For chlorophyll a is a very reactive, sensitive, and complicated substance. Only when, early in this century, the genius of Willstatter applied itself to the problem, were the first sure steps taken. That great investigator isolated the pigment-and its closely related frequent minor concomitant chlorophyll b as well-in the pure state, established correctly the empirical formula of the substance, and laid down a sound and extensive preliminary basis of transformation and degradation. These achievements can be measured against the fact that the isolation of chlorophyll in a state of purity is even now, after more than fifty years, no mean feat, and, further, that the empirical formula defined by Willstatter, repeatedly called into question by subsequent investigators, has stood the test of time. For some period after this solid foundation had been laid by Willstatter there was little activity until three new groups took the field late in the 1920s. Stoll, who had played a prominent role in the early studies as a collaborator of Willstatter, took up the work anew, and made important contributions, as did Conant in the United States. But by far the greatest contribution was made by Hans Fischer and his collaborators at Munich. Fresh from his dramatic conquest of the blood pigment, Fischer hurled his legions into the attack on chlorophyll, and during a period of approximately fifteen years, built a monumental corpus of fact. As this chemical record, almost unique in its scope and depth, was constructed, the molecule was transformed and rent asunder in innumerable directions, and the fascination and intricacy of the chemistry of chlorophyll and its congeners was fully revealed. These massive contributions were crowned by the proposal, in 1940, of a structure which was complete except for stereochemical detail. Finally, in a series of elegant investigations completed only during the last few years, Linstead and his associates at Imperial College were able to solve the stereochemical problem and to provide definitive confirmatory detail in respect of the number and disposition of saturated carbon atoms within the nuclear framework. Half a century of structural study had culminated in the complete formula (I) for chlorophyll aI, 8. Our active interest in chlorophyll was initiated four years ago, in 1956. The first questions we asked were very general ones. The structural investigations had been carried out almost entirely during the twilight of the classical period of organic chemistry. Only the very simplest basic * A brief communication recording the results on which this lecture is based has appeared in
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