A photoresponsive crown ether which combines within a molecule both a crown ether and a photoisomerizable functional group changes the conformation of the crown ring in response to photoirradiation. Thus, many chemical and physical functions of the crown ether family can be controlled by on-off light switch. The syntheses and the functions (ion extraction, ion transport, etc.) of following photoresponsive crown ethers are described : azobenzene-bridged crown ethers, crown ethers containing azobenzene as a ring member, azobis (benzocrown ether) s, and anthracenecontaining crown ethers. In relation to the cis-trans isomerism of azobenzene, the mechanism of thermal cis-to-trans isomerization is discussed.
This article describes the synthesis of bioactive natural products such as phytotoxins, inhibitors of plant growth and seeds germination, antitumor and antibiotic compounds, efficiently utilizing the Diels-Alder and the retro-Diels-Alder reactions. The target compounds are classified into four sections according to their chemical structure, i. e. highly oxygenated cyclohexane derivatives, α, β-unsaturated γ-lactones, pyranojuglone derivatives, and coronafacic acid as an 1-indanone derivative.
The direct amination of some quinones promoted by metal salts was developed as a substitute for the Ullmann amination to prepare aminoquinone dyes. α-Aminoanthraquinones reacted readily with alkylamines to give 4- (or 2, 4-bis) aminated products. 2-Alkylamination of quinizarin proceeded quantitatively in the presence of copper chlorides. Possible mechanism, which involves the formation of the metal complexes followed by a nucleophilic attack of amines, was studied in details. The direct photo-aminations of some quinones were also studied. A number of new aminoanthraquinones and aminonaphthoquinones as dye were synthesized by both the metal-promoted direct amination and the direct photo-amination.
The characteristic reaction of Schiff bases and a variety of related compounds with carbon disulfide leading to N-substituted β-imino-dithiocarboxylic acids or the related derivatives was investigated especially by R. Mayer, R. Gompper, and their co-workers. The reaction of ketimines having no substituent on the nitrogen atom, however, had not been explored until 1966 when we started the title investigation. We outline here the essentials of our investigation originated in the synthesis of N-unsubstituted, β-imino-dithiocarboxylic acids. Our finding was that the syntesis required no isolations of ketimines ; the reaction of ketones with carbon disulfide in the presence of aqueous ammonia alone sufficed. Special mention may be made of stereochemical relationships in the syntheses and reactions of the acids, involving a novel mode of ring opening in the synthesis from 2-methylcyclopentanone. Synthetic applications are described together with a variety of new type compounds obtained. In addition, we referred to the reaction of acid amide-type compounds with carbon disulfide. Finally, we touched on some of our future projects, and, further, potentiality of powerful chemotherapeutic agents in this area.
The synthesis and biological activities of 1-β-D-arabinofuranosylcytosine (Ara C) and related compounds are reviewed and discussed under following headings : 1. Synthesis of 1-β-D-arabinofuranosylcytosine. 1-1 synthesis from uridine ; 1-2 synthesis from cytidine ; 1-3 synthesis via coupling of bases with suitably protected sugars ; 1-4 synthesis via D-arabinose oxazoline derivative. 2. Biological activities of 1-β-D-arabinofuranosylcytosine and related compounds. 2-1 antitumor and antiviral activities ; 2-2 biological activation of 1-β-D-arabionfuranosylcytosine in vivo and its mode of biological actions ; 2-3 inhibition of DNA polymerases by Ara CTP 2-4 other arabinofuranosyl nucleosides. 3. Some derivatives of 1-β-D-arabinofuranosylcytosine. 3-1 modifications on cytosine moieties; 3-2 sugar-modified derivatives; 3-3 depot form of Ara C and Ara CMP. 4. Scope and limitation of cancer chemotherapy using 1-β-D-arabinofuranosylcytosine and related compounds are also finally discussed.
Organometallic intramolecular-coordination compounds containing a nitrogen donor ligand generally have five-membered ring structure, and few compounds have three, four and six-membered ring structures. These compounds have been prepared mainly by orthometallation, transmetallation, insertion and ligand exchange reaction. New methods have recently been developed to prepare ortho-substituted derivatives of the starting aromatic compounds using organometallic intramolecular-coordination compounds as the synthetic intermediate.