This review describes the reactions of pyrylium, thiopyrylium and selenopyrylium salts with a variety of nucleophiles involving CN-, active methylene compounds and organometallic compounds, and further the hydrolysis, reduction, oxidation and photochemical reaction, some of which can be synthetically utilized for preparing compounds not readily obtainable by the other methods.
Recently γ-exomethylene-γ-butyrolactones and related compounds are widely studied. In the present review the syntheses, some reactions and spectral features of γ-exomethylene-γ-butyrolactones, γ-ylidenebutenolides, γ-ylidenetetronic acids, and phthalides are described, and naturally occurring exoenol lactones and its biological activities are also summarized.
Aminohaloboranes, easily prepared from anilines, imines, ketones or alkylnitriles, and boron trichloride or diethylaminodichloroborane, were found to be a convenient species for C-C bond formation reaction in both aromatic and aliphatic series. Namely, N-anilinophenylchloroboranes and N- alkylaminodichloroboranes reacted smoothly in the presence of triethylamine with benzaldehydes and isonitriles, probably via a cyclic transition state giving 2-aminobenzhydrols and 2-N-alkylaminobenzaldehydes, respectively. A simple directed aldol reaction using vinylaminodichloroboranes and diethylaminovinyloxychloroboranes and a unique aldol-type reaction of alkylnitriles using diethylaminodichloroborane were performed under mild conditions. Using chiral vinylaminodichloroboranes made possible a very simple enantioselective aldol condensation reaction.
Hexafluoropropene (HFP) oligomers composed of two dimers (D -1 and D-2) and three trimers (T-1, T-2, and T-3), which are readily obtained by having the monomer oligomerize in the presence of a fluoride ion or a tert-amine in a polar solvent, have been revealed to be unique perfluoro - inner - alkenes. Characteristic reactivities of these C6 and C9 oligomers with various nucleophiles, such as alcohols, phenols, thiols, amines and organolithium or -magnesium compounds, have thoroughly been investigated. The scope, limitation and mechanisms of these reactions of the oligomers are discussed.
Synthesis and biological activity of several chiral pheromones are discussed with emphasis on the synthetic strategies such as derivation from optically active natural products, optical resolution of intermediates and asymmetric synthesis using biochemical systems.
“Synthetic Methods of Organic Chemistry” by Theilheimer is well known as secondary sources of organic reactions. In 1975, a British company, Derwent published “Journal of Synthetic Method” as a part of Chemical Reactions Documentation Service (CRDS) system. On-line retrieval of CRDS by telephone line has been available in Japan and even Theilheimer can be retrieved on the same system. In addition to the above, in 1979, ISI published “Current Chemical Reactions” in U. S. A., thus secondary sources of organic reactions have been gradually developed. The present article reviews secondary sources which have seldom been reported before.
The effects of polyethyleneglycol dialkyl ethers as solvents in the reaction of potassium 3-aminophenoxide with isopropyl chloride were studied. The reactions using the polyethyleneglycol dialkyl ethers as solvents gave O- isopropylated 3-aminophenol in higher yields than using small amounts of dibenzo-18- crown-6 or the polyethyleneglycol dialkyl ethers as solvents.