Low-temperature matrix isolation technique has been developed to permit the spectroscopic study of extremely unstable species. Its usefulness in organic chemistry is shown in detecting reaction intermediates and preparing unstable molecules. A brief summary of the experimental approach and the characteristics of low-temperature photochemistry is presented. The low-temperature photochemical reactions directed toward organic synthesis are discussed by the illustrative examples which can provide high selectivity or specificity.
Recent development in 77Se NMR spectroscopy is reviewed and the information available therefrom is critically discussed. After brief discussion on the technical problems inherent in the measurement, an NMR chart is given which illustrates relationship between structures and chemical shifts having the range as wide as 2, 000 ppm. Spin-spin coupling constants pertaining to 77Se can be informative of stereochemistry. Contribution of dipolar interaction between nuclear spins to the total spin-lattice relaxation is negligible in 77Se NMR. Spin rotation and/or chemical shift anisotropy are shown to be important here. Recent high research activities in organoselenium chemistry will be strongly aided by this new methodology.
The synthesis of organic acetates with the liquid-phase oxidation of hydrocarbons by transition metals is reviewed. This article described three reactions, i. e., a side-chain acetoxylation of methylbenzenes, a nuclear acetoxylation of aromatic compounds and an acetoxylation of olefins. According to the function of the transition metals, the reaction was divided into two types; a direct activation and an indirect activation of a substrate by the transition metals. In the former, the co-ordination of a substrate and oneelectron-transfer are included. The metal ions in the latter act as an oxidizing agent of halogen ions to its active species which reacts with a substrate to the acetate. On the basis of the distribution of the reactions, the action of the transition metals in an individual reactin was discussed.
2-Methyleneglutaronitrile (MGN) is a unique trifunctional compound because of the combination of the vinylidene group with the two cyano groups. It is a useful intermediate in organic syntheses for making polymers, pharmaceuticals and other special chemicals. Since the early 1960's the catalytic dimerization of acrylonitrile (AN) to MGN has been actively investigated using mainly trivalent phosphorus compounds. However, until a few years ago, MGN had not been industrially used, because an economical way for its production on a large scale did not exist. We now produce MGN on a commercial scale by the dimerization of AN with a catalyst consisting of metal halide and tertiary amine. This paper describes the preparation and chemistry of MGN with the intention of stimulating future applications. The physical and toxicological properties of MGN are also mentioned briefly.
Preparation and formation reactions of organic sulfides have been reviwed covering the later half of 1978 to 1980. The literatures were classified by the sulfur materials used for the preparations. (141 ref.)
Synthesis of naturally occurring diamino sugars and their stereoisomers are reviewed. Preparation of stereoisomers of the following diamino sugars are described together with some synthetic problems : 2, 4-diamino-2, 3, 4, 6-tetradeoxyhexose via 3, 6-dideoxy-2, 4-di-O-mesylhexopyranosides, 2, 4-diamino-2, 4-dideoxypentose via 2, 3-anhydro-4-azido-4-deoxypentopyranosides, and 2, 3- diamino- 2, 3- dideoxypentose via 2, 3- epimino- 2, 3- dideoxypentopyranosides.
Contents-1. Prologue-2. Hyper-modified nucleoside Q : 2. 1. Discovery and Structure de-termination of nucleoside Q; 2.2. Total synthesis of nucleoside Q; 2.3. Biosynthesis of nucleoside Q; 2. 4. Synthesis of Q base, pre Q1 base, and pre Q0base; 2. 5. Nucleoside Q-3. Hyper-modified nucleoside Yt : 3. 1. Discovery of the nucleoside Y group and structure determination of the Y base group; 3.2. Structure determination of nucleoside Yt by synthesis; 3. 3. Total synthesis of nucleoside Yt- 4. Epilogue.
The reactions of γ-thiobutyrolactone with primary amines (methylamine, butylamine, octylamine, aniline) afforded corresponding 4-mercaptobutanamides in 50%, 76%, 86%, 82% yield, respectively. The reactions with secondary amines (morpholine, pyrrolidine, diethylamine) also afforded corresponding 4-mercaptobutanamides in high yields, respectively. Furthermore, the reaction of two equivalents of 1-thiobutyrolactone with ethylenediamine gave N, N'-ethylenedi-4-mercaptobutanamide in 64 % yield. The mercapto compounds thus obtained were oxidized to the corresponding disulfides by dimethyl sulfoxide.
3-Acetyltropolone 1 and 3-acetyl-2-methoxytropone 2a reacted with semicarbazide to afford their semicarbazone (3 and 5) and 3-methyl-1, 8-dihydrocycloheptapyrazol-8-one 4. 2-Acetyl-7-methoxytropone 2b gave 4. The reactions of 1 with thiosemicarbazide gave its thiosemicarbazone 6 and 4. Both of 2a and 2b reacted with thiosemicarbazide to afford 4.