Color changes induced by complexation with guest ions have been observed in special cyclic polyethers in which chromophores of various azo dyes and Phenol Blue are attached. Strongly fluorescent unbelliferone and benzothiazolylphenol groups are also used as a chromophore as well as a pair of π-electron donor and acceptor for a colored charge-transfer complex. The crown ether dyes, which have great potential utility because of their unique physicochemical properties, are surveyed here. The survey consists of the following sections : 1) principle of ion-selective coloration, 2) molecular design and synthesis, 3) metal ion-selective coloration, and 4) ion-selective fluorescent emission.
It has been known that females of the American cockroach, Periplaneta americana L. produce potent sex excitant and attractant pheromone. Extensive efforts have been made to isolate, characterize and synthesize its active components along with biochemical and behavioral studies for over 30 years, and culminated in several total syntheses of the major sex pheromone, periplanone-B with potent activity (threshold : 10-13g). These syntheses can be devided into two classes by the strategy on the preparation of its skeleton, germacrene-type ten-membered ring system; the use of oxy-Cope rearrangement or the intramolecular alkylation. This review deals mainly with these syntheses especially focussing on practically first synthesis of optically active periplanone-B by us. Proper base treatment of substituted α-phenylthioacrylate gave the desired cyclodecene ring system in good yield and reductive elimination of vicinal phenylthio-benzoate with sodium naphthalenide cleanly gave the conjugated diene. Including these key steps, the synthesis was accomplised in overall 0.5% yield through 28 steps.
Transition metal ketene complexes have drawn considerable attention as models for the possible intermediates implicated in the elementary carbon-carbon coupling step in surface-catalyzed or homogeneous carbon monoxide reduction. Although ketene chemistry has been investigated for over 80 years, there have been no review articles on chemistry of transition metal ketene complexes. Three separate aspects of transition metal ketene complexes are reviewed herein, 1) formation of ketene species on catalyst-surface, 2) the preparation and structures of transition metal ketene compexes, 3) chemical properties of transition metal ketene complexes.
The methodologies employed in the use of building blocks in the synthesis of various kinds of monofluoro molecules are reviewed in light of recent increasing interest and demand for organofluorine compounds in synthetic and biological chemistry. The building blocks were chosen with the following two criteria in mind : ease of preparation or commercial availability and wide applicability of the compounds derived therefrom. This article is organized into four sections : i) the necessity of and requirement for building blocks, ii) the building blocks for the preparation of various kinds of vinyl fluorides, iii) the building blocks for the preparation of various kinds of alkyl fluorides, and iv) versatile and practical building blocks with wide synthetic applicability.
With increasing demand for L-Phenylalanine, the enzymatic processes for the production of this amino acid have developed remarkably over the past several years. Among these processes, the followings have reached their technical levels for the commercial production : transaminase process with phenylpyruvic acid, phenylalanine dehydrogenase process with phenylpyruvic acid, phenylalanine ammonia-lyase process with trans -cinnamic acid and hydantoinase process with D, L-benzylhydantoin as substrate, respectively. Acetamidocinnamic acid, D, L-phenylalanine amide and D, L-phenyllactic acid are also useful as the substrate for enzymatic production of L-phenylalanine.
Acrylamide is industrially produced by catalytic hydration of acrylonitrile with reduced copper salts. However, the preparation and regeneration of the catalyst are laborious and the process requires a high temperature. It has therefore been considered very desirable to establish a process for producing acrylamide under moderate conditions, because compounds containing double bonds in the molecule are readily polymerizable. There is a growing interest in the synthesis of useful organic compounds by biological process for its specificity and moderate reaction condition. Therefore, we attempted to produce acrylamide from acrylonitrile using microbial enzyme and we found a bacterium having a high acrylamide producing enzyme (nitrile hydratase). This paper describes the details and merits of the development of microbial production of acrylamide.