Search

Investigation of Iresine pringlei led to the identification of the pentacyclic triterpene friedelin (III) (in the stem), ceryl alcohol (IV), as well as the steroids stigmastanol (VIII), stigmasterol (XI), β-sitosterol (V) and α-spinasterol (XII). From Iresine calea were isolated ceryl alcohol and β-sitosterol.

Au cours de l'isolement de l'iresine (I) a partir de Iresine celosioides L, un examen minutieux des extraits a permis de deceler la presence de trois sesquiterpenes apparentes. En plus de la dihydroiresine (VI) deja connue, la dihydroiresone (III) et l'isoiresine (VIII) ont ete isolees. Leur structure et stereochimie sont determinees. Le schema de cyclisation a partir d'un precurseur du type farnesique souligne l'importance de ces sesquiterpenes du point de vue biogenetique.

Working in the early 1950s with Syntex S.A. in Mexico City, Carl Djerassi with colleagues first synthesized 19nor-17a-ethynyltestosterone (VIII in the figure), which came to be known as norethindrone or norethisterone. This steroid, derived from a wild and inedible yam of the genus Dioscorea, proved to be the most effective orally administered progestational agent discovered to that time. After demonstration of the effectiveness of this compound as an oral contraceptive in rabbits, the first clinical trials were conducted by the endocrinologist Gregory Goodwin Pincus (1903-1967) of the Worcester Foundation, Shrewsbury, Mass, and the gynecologist John Rock (1890-1984) of Harvard University. The subsequent use and misuse of ‘‘the Pill,’’ its societal effects, and politics and public-policy consequences have been described in a flood of articles and books. Without question, Djerassi’s first synthesis of an oral contraceptive has played a critical role in the reproductive revolution of the later half of the 20th century. Djerassi, born in Vienna, Austria, obtained his doctorate in chemistry at the University of Wisconsin. After his seminal work with Syntex, Djerassi moved to Stanford University as Professor of Chemistry. Later, he embarked on a career as social historian, novelist, playwright, and poet. Amember of the National Academy of Sciences and the American Academy of Arts and Sciences, Djerassi was honored with the National Medal of Science (1973), the National Medal of Technology (1991), and numerous other awards, including 20 honorary doctorates.

The effective separation of sex (‘in bed’) and fertilization (‘under the microscope’) has already been practised successfully for the past 25 years by well over one million people – virtually all of them suffering from infertility problems. But why, where and when will fertile people resort to assisted reproductive techniques to become parents? And why are the prospects for fundamentally new methods of birth control so dim?

Just because a play contains some allusions or even a few deliberate references to science does not make it 'science-in-theatre'. For this definition to fit, the play itself in terms of plot and preferably also characters should focus on science. Until recently, there was considerable doubt whether this genre was theatrically viable—at least in the contemporary commercial theatre—but current trends point towards a more positive prognosis. Almost by definition, such science-in-theatre has pedagogic components that constitute both an advantage and a burden, as shown by brief excerpts from some contemporary plays. Presenting science in dialogic form also has interesting implications for classroom instruction.

In his famous 1936 essay, The work of art in an age of mechanical reproduction, Walter Benjamin stated: “The technique of reproduction detaches the reproduced object from the domain of tradition.” But if “The work of art” is replaced by “Sex” in the title, and “reproduced object” by “off spring” in the quotation, a much deeper issue is illustrated: detachment of the child from trad itional procreation may well be the most fundamental ethical issue raised by techniques of assisted reproduction. Neither science nor society has so far adequately prepared us for that consequence of sex in an age of mechanical reproduction.

A recent report by an Institute of Medicine (IOM) committee on contraceptive research and development (RD not one seems to sell contraceptive drugs or devices. The pharmaceutical market, which has changed dramatically during the past decade, has spoken. It now focuses on blockbuster drugs dealing with diseases of aging or deterioration in the increasingly geriatric populations of affluent Japan, North America, and Europe, not the needs of the poor pediatric societies of Latin America, Asia, and Africa. An item in the same issue (Random Samples, 31 May, p. 1269) features the ominous trends for infectious diseases, listing the four biggest global killers: acute respiratory infections, diarrheal diseases, tuberculosis, and malaria. If we again consider the minute fraction of the huge R&D budgets of the top eight pharmaceutical companies dedicated to these fields, we see that unmet burning societal needs do not necessarily equal financial returns. The most important point missed by the IOM committee is that the features of a truly novel contraceptive (say, a contraceptive vaccine or a once-a-month anti-implantation or menses-inducer pill) associated with major societal advantages (for example, low cost and long duration for a vaccine; short action and minimal pill consumption involving 13 pills per year for a menses-inducer versus 250 or more pills per year for current oral contraceptives) are precisely the economic disincentives keeping companies, which search for billion-dollar drugs used daily, from reentering the contraceptive field. The proposal “that commitments [by international aid agencies] to buy large volumes of contraceptives would induce companies to develop low-cost products” is a pipe dream. The only reason why some of the current oral contraceptive manufacturers will sell monthly pill regimens at 20 cents a package in lots of multimillion units to the Agency for International Development is the fact that an affluent American woman buying the same product in a drugstore pays more than 100 times that price. Absent that latter market, a pharmaceutical company would go broke if it focused on the low-cost public-sector market for a new contraceptive. More realistic, though politically unpopular, incentives for industrial involvement have been suggested earlier ([1][2]). 1. 1.[↵][3]1. C. Djerassi , Science 245 356 1989); ibid . 166, 468 (1969); ibid . 169, 941 (1970). [OpenUrl][4][Abstract/FREE Full Text][5] [1]: /lookup/doi/10.1126/science.272.5266.1258a [2]: #ref-1 [3]: #xref-ref-1-1 "View reference 1. in text" [4]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DDjerassi%26rft.auinit1%253DC%26rft.volume%253D245%26rft.issue%253D4916%26rft.spage%253D356%26rft.epage%253D361%26rft.atitle%253DThe%2Bbitter%2Bpill%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.2667135%26rft_id%253Dinfo%253Apmid%252F2667135%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [5]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEyOiIyNDUvNDkxNi8zNTYiO3M6NDoiYXRvbSI7czoyNToiL3NjaS8yNzIvNTI3MC8xODU3LjQuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9

The application of the reduction of aldehdyes and ketones has been reviewed in an earlier chapter (The Meerwin-Pondorff-Verley reduction). The reversible nature of the reaction was demonstrated by Verley, but it was not until 1937 that Oppenauer showed that unsaturated steroid alcohols could be oxidized to the corresoponding ketones in excellent yield using aluminum t-butoxide. In the presence of a large amount of acetones. Acetone functions as the hydrogen acceptor and the large excess serves to shift the equilibrium into the desired direction. This reaction is called the Oppenauer reaction hand is useful in steroid chemistry. The Oppenauer oxidation employs mild conditions so it will undoubtedly find use in synthetic organic chemistry. The recent experimental modifications are discussed here. Keywords: Oppenauer oxidation; alcohols; aldehydes; aluminum alkoxides; hydrogen acceptors; Steroids; catalysts; side reactions; experimental procedures

The kinetic HH/HD/DH/DD isotope effects of an intramolecular reversible nondegenerate double proton transfer reaction are described. The molecule studied is 8-acetyl-3,13,17-tris(2-(methoxycarbonyl)ethyl]-2,7,12,18-tetramethyl-(21H,23H)-porphyrin (acetylporphyrin, ACP) dissolved in CD 2 Cl 2 . As a thermodynamic and kinetic method we used dynamic 1 H and 13 C NMR spectroscopy of suitably 2 H, 15 N, and 13 C labeled ACP. The 15 N label was introduced at the 21, 23, and 24 positions, the 13 C label at the 6- and 7-methyl positions, and 2 H at the central proton sites, respectively