Electroorganic chemistry has been now an important technique to synthesize heterocycles particularly in aspects of regio- and stereo-selective reactions. As the recent developments in this field have been already excellently reviewed, this paper mostly deals with the works done in the author's laboratory, which are in the following items. (1) Utilization of anodic oxidation for the synthesis of various plant alkaloids. (2) The synthesis of heterocycles with Ni0-complexes prepared by cathodic reduction. (3) The facile removal of arenesulfonyl groups from sulfonamides by cathodic reduction in a doubly mediatory system.
While many valence-bond isomers had been proposed as intermediates of photoisomerization of five-membered heterocyclic compounds such as furan, pyrrole, and thiophene, few had been isolated. Recently, we isolated a Dewar thiophene and Dewar pyrroles stabilized by trifluoromethyl groups. In this report, we review mainly the chemistry of these compounds and the development of the chemistry of valence-bond isomers of five-membered heterocyclic compounds.
Cyclodextrins form molecular inclusion complexes with certain guest molecules of appropriate size. In some special occasions, two different guest molecules are bound to a single cyclodextrin molecule. Formation of the inclusion complexes often lead to very efficient and specific catalysis. Especially when cyclodextrins modified with one or two functional groups at appropriate positions are used, specificity and efficiency of the catalysis are markedly enhanced.
Several 1, 4-diaminocyclitol-containing aminoglycoside antibiotics have been discovered by four Japanese research groups during the past five years. Fortimicin A, C, D and KG3 produced by Micromonospora, sporaricin A and C by Saccharopolyspora, istamycin A, B, C and A2, 2″- N-form-imidoylistamycin A and B by Streptomyces, and dactimicin by Dactylosporangium inhibit strongly the growth of Grampositive and -negative bacteria including most aminoglycosides-resistant strains. These antibiotics are pseudodisaccharides consisting of a diaminosugar and a 1, 4-diaminocyclitol acylated with glycine at the 4-methylamino group. Fortimicin A and some derivatives of this group antibiotics have been evaluated their clinical usefulness. In this review, chemical studies and structure-activty relationships of the 1, 4-diaminocyclitol-aminoglycoside antibiotics are discussed.
Since the original trial by Westheimer in 1962, photoaffinity labeling has evolved into one of major techniques for studying molecular interactions in biological systems. The method has been used to investigate enzymes, antibodies, receptors, transport proteins, and membrane structure and function. The properties of various photo-labile groups and reagents are evaluated, while their applications are discussed to highlight the potential of the method.
This atricle is concerned with the reactions of the phosphonium salts derived from the oxidation of phosphites and from nonoxidative cleavage of the P-O- (C) bonds facilitated by tertiary amines and metal salts, and with their application to polymer syntheses by the direct polycondensations of dicarboxylic acids and diamines, of free amino acids, and of carbon dioxide and diamines. Initiation and propagation in the polycondensation and their significant effects on the molecular weight of the resulting polymers are discussed. The preparation of polyesters by use of phosphorus chlorides is also described.
Chrysanthemic acid (2, 2-dimethyl-3- (2-methyl-1-propenyl) cyclopropanecarboxylic acd) is an acid component of pyrethroidal insecticides. There exist four optical isomers originated from two asymmetric carbon atoms at the C-1 and C-3 positions. Insecticidal activities of the synthetic pyrethroids derived from these optical isomers are shown as follows : 1 R-trans≥1 R-cis>>1 S-trans1 S-cis. Optical resolution of racemic mixture of chrysanthemic acid conveniently gives each isomer in optically pure from. Highly efficient epimerization at the position of C-1, C-3 and racemization were achieved as the method for the conversion of ineffective isomers into effective ones. Secondly, the relationship between stereochemical interconversion and regioselective ring opening of chrysanthemic acid derivatives was investigated. Some of the ring opening products were successfully converted into optically active form of tetrahydrolavandulol and tetralin musks.
This article describes the novel active transport membranes having a fixed carrier, which is a specific functional group that could interact with ions. After a brief introduction of the synthetic membrane, the active and selective transport of anions and cations through synthetic polymer membranes are presented.
A major product of the Vilsmeier reaction on 3- (2, 2, 2-trifluoroethyl) guaiazulene, which was prepared from 3-trifluoroacetylguaiazulene by reduction using LiAlH4-AlCl3 mixture, was confirmed to be 2-formyl-4- (1-formyl-2-dimethylaminovinyl) -7-isopropyl-1-methy-3- (2, 2, 2-trifluoroethyl) azulene. And a 4-formylmethyl derivative and four kinds of 2-formyl derivatives were also isolated as minor products.