A rapid and mild esterification method using carboxylic 2,4,6-trichlorobenzoic anhydrides in the presence of 4-dimethylaminopyridine was developed. The method was also successfully applied to the synthesis of large-ring lactones, including DL-2,4,6-tridemethyl-3-deoxymethynolide.

A rapid esterification by means of mixed anhydride and its application to large-ring lactonization.

Many systems that exhibit nonmonotonic behavior have been described and studied already in the literature. The general notion of nonmonotonic reasoning, though, has almost always been described only negatively, by the property it does not enjoy, i.e. monotonicity. We study here general patterns of nonmonotonic reasoning and try to isolate properties that could help us map the field of nonmonotonic reasoning by reference to positive properties. We concentrate on a number of families of nonmonotonic consequence relations, defined in the style of Gentzen. Both proof-theoretic and semantic points of view are developed in parallel. The former point of view was pioneered by D. Gabbay, while the latter has been advocated by Y. Shoham in. Five such families are defined and characterized by representation theorems, relating the two points of view. One of the families of interest, that of preferential relations, turns out to have been studied by E. Adams. The "preferential" models proposed here are a much stronger tool than Adams' probabilistic semantics. The basic language used in this paper is that of propositional logic. The extension of our results to first order predicate calculi and the study of the computational complexity of the decision problems described in this paper will be treated in another paper.

Nonmonotonic Reasoning, Preferential Models and Cumulative Logics

13 EADERS of Mr. Bertrand Russell's philosophical £v works know that one of his pupils before the outbreak of the war, an Austrian, Mr. Ludwig Wittgenstein, caused him to change his views in some important particulars. Curiosity can now be satisfied. The “Tractatus Logico-Philosophicus “which Mr. Ogden has included in his new library of philosophy is a remarkable and strikingly original work. It is published in German and English in parallel pages. It is difficult to appreciate the reason for this, seeing that the author is evidently familiar with our language and has himself carefully revised the proofs of the translation. Also we should have liked to have the Tractatus without Mr. Russell's Introduction, not, we hasten to add, on account of any fault or shortcoming in that introduction, which is highly appreciative and in part a defence of himself, in part explanatory of the author, but for the reason that good wine needs no bush and that Mr. Russell's bush has the unfortunate effect of dulling the palate instead of whetting the appetite. In his penultimate sentence Mr. Russell says; “To have constructed a theory of logic which is not at any point obviously wrong is to have achieved a work of extraordinary difficulty and importance.” We agree, but how uninspiring when compared with Mr. Wittgenstein's own statement of aim: “What can be said at all can be said clearly, and whereof one cannot speak, thereof one must be silent.” Tractatus Logico-Philosophicus. By Ludwig Wittgenstein. (International Library of Psychology, Philosophy and Scientific Method.) Pp. 189. (London: Kegan Paul and Co., Ltd.; New York: Harcourt, Brace and Co., Inc., 1922.) 10s. 6d. net.

Tractatus Logico-Philosophicus

Erythromycin inhibits protein synthesis by its effect on ribosome function (14, 118, 119) The metabolic modifications that enable cells to cope with the inhibitory action of erythromycin fall under major headings that include (i) target site alteration, (ii) antibiotic modification, and (iii) altered antibiotic transport This minireview concentrates on target site alteration, which for erythromycin is the 50S subunit of the ribosome The first clinical isolates of macrolide-resistant staphylococci were described in reports from France, England, Japan, and the United States shortly after the introduction of erythromycin into clinical practice in 1953 On the basis of current understanding of the biochemistry of erythromycin’s action, resistance in most of the strains that were described in early reports can be ascribed to a posttranscriptional modification of the 23S rRNA by an adenine-specific N-methyltransferase (methylase) specified by a class of genes bearing the name erm (erythromycin ribosome methylation) The last decade has seen the isolation and characterization of approximately 30 erm genes from diverse sources, ranging from clinical pathogens to actinomycetes that produce antibiotics; for many of these genes, both the respective nucleotide sequences that encode the methylases as well as the flanking sequences that control their expression have been determined A tabulation of the erm genes that have been described is presented in Table 1 Any discussion of mechanisms of resistance to macrolide antibiotics must include the chemically distinct, but functionally overlapping, lincosamide and streptogramin B families as well This type of resistance has therefore also been referred to as MLS resistance Members of the MLS antibiotic superfamily include, among the macrolides, carbomycin, clarithromycin, erythromycin, josamycin, midecamycin, mycinamicin, niddamycin, rosaramicin, roxithromycin, spiramycin, and tylosin; among the lincosamides, celesticetin, clindamycin, and lincomycin; and among the streptogramins, staphylomycin S, streptogramin B, and vernamycin B The streptogramin family is subdivided into A and B groups or alternatively into M and S groups, respectively Methylation of A2058 confers resistance to the Band S-group streptogramins but not to the Aand M-group streptogramins The reason for this grouping was originally based on empirical observations from clinical bacteriology that resistance to one class often involved resistance to the other two classes (11, 16, 35, 39, 41, 135); however, (i) the three classes of antibiotics interact competitively when binding to the 50S subunit, and only one antibiotic molecule can bind per 50S subunit (129, 130); this suggests that the binding sites for these antibiotics overlap or at least functionally interact (ii) Nucleotide alterations in 23S rRNA, both mutational and posttranscriptional, that confer coresistance to MLS antibiotics appear to cluster in the peptidyltransferase region in 23S rRNA domain V, providing a physical basis and a common location for their sites of action (50, 101–104, 109, 110, 128) (Fig 1 and Table 2), and (iii) footprinting experiments show that the nucleotides in 23S rRNA domain V are protected by bound MLS antibiotics against modification by agents such as dimethyl sulfate (DMS) and kethoxal that can derivatize purine and pyrimidine bases in single-stranded DNA or RNA (26, 76) (Table 3) The erm family of genes is not alone in conferring clinical resistance to macrolide antibiotics A notable early exception to the established MLS resistance pattern was the MS pattern reported by Janosy and coworkers (58, 59), who described clinical isolates that were coresistant to erythromycin and streptogramin B but that remained susceptible to lincosamide antibiotics The molecular basis for resistance in these strains was subsequently shown by Ross et al (94) to involve the active efflux of erythromycin and streptogramin B but not clindamycin Additional mechanisms of macrolide resistance, all associated with the acquisition of new genetic information, including structural modification of erythromycin by phosphorylation (82), glycosylation (60), and lactone ring cleavage by erythromycin esterase (2, 83), have been added to the list Mechanisms involving mutational alteration of genes that normally reside in the host and that encode either ribosomal protein or rRNA have also been described and will be discussed below in detail Reviews of erythromycin resistance that relate to material covered in the present work have been presented previously (4, 18, 20, 21, 28, 29, 133) Recent developments in the synthetic chemistry of semisynthetic macrolides, including the biological and clinical aspects of their actions, have been reviewed by Kirst (65, 66) A forthcoming review covers the inducible nature of MLS resistance and its implications for the mechanism of action of erythromycin (134)

Erythromycin resistance by ribosome modification.

This account examines double asymmetric induction from theoretical and practical viewpoints. In the context of four major organic reactions-the aldol, Diels-Alder, catalytic hydrogenation, and epoxidation-it is shown that a double asymmetric induction can be analyzed in terms of the single asymmetric reactions of each of the two chiral reactants. A rule which qualitatively relates the results of these single asymmetric reactions with the outcome of the double asymmetric reaction is proposed. A powerful new strategy based on this rule for the predictable creation of new chiral centers is discussed and the use of this strategy for the synthesis of sugars and macrolides is presented.

Double Asymmetric Synthesis and a New Strategy for Stereochemical Control in Organic Synthesis

Published with the aid of a grant from the National Endowment for the Humanities. Contains the only complete English-language text of The Concept of Truth in Formalized Languages. Tarski made extensive corrections and revisions of the original translations for this edition, along with new historical remarks. It includes a new preface and a new analytical index for use by philosophers and linguists as well as by historians of mathematics and philosophy.

Logic, Semantics, Metamathematics: Papers from 1923 to 1938

In this manuscript, published here for the first time, Tarski explores the concept of logical notion. He draws on Klein's Erlanger Programm to locate the logical notions of ordinary geometry as those invariant under all transformations of space. Generalizing, he explicates the concept of logical notion of an arbitrary discipline.

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What are logical notions

The progress of macrolide chemistry and biochemistry over the past several years has indeed been remarkable. This review attempts to cover the important contributions which have been made in the fields of structural and synthetic chemistry as well as in the biosynthesis and mode of antimicrobial activity of the “polyoxo” macrolide antibiotics. Emphasis has been placed on the recent synthetic achievements in this field.

Macrolides. Recent progress in chemistry and biochemistry.

In previous articles ([4], [5]) it has been shown that the deductive system developed by Aristotle in his “second logic” (cf. Bochenski [2, p. 43]) is a natural deduction system and not an axiomatic system as previously had been thought [6]. It was also pointed out that Aristotle's logic is self-sufficient in two senses: First, that it presupposed no other logical concepts, not even those of propositional logic; second, that it is (strongly) complete in the sense that every valid argument formable in the language of the system is demonstrable by means of a formal deduction in the system. Review of the system makes the first point obvious. The purpose of the present article is to prove the second. Strong completeness is demonstrated for the Aristotelian system.

/pdf/completeness-of-an-ancient-logic-2i1dkaa94t.pdf

Completeness of an ancient logic

In the present article we attempt to show that Aristotle’s syllogistic is an underlying logic which includes a natural deductive system and that it is not an axiomatic theory as had previously been thought. We construct a mathematical model which reflects certain structural aspects of Aristotle’s logic and we examine both the mathematical properties of the model and the relation of the model to the system of logic envisaged in certain scattered parts of Prior and Posterior Analytics.

/pdf/aristotle-s-natural-deduction-system-80z069iowt.pdf

John Corcoran

Papers

Logic, Semantics, Metamathematics: Papers from 1923 to 1938

What are logical notions

Macrolides. Recent progress in chemistry and biochemistry.

Completeness of an ancient logic

Aristotle’s Natural Deduction System