Reactions of cyclic oxalyl compounds, synthesis of functionalized hydrazono-2H-imidazol-4,5(1H, 3H)dione: Experimental data and AMI calculations

The reaction of the 4-benzoyl-5-phenylfuran-2,3-dione (1) with guanylhydrones, (2a-d) gives hydrazono-2H-imidazol-4.5-(1H,3H)-dione derivatives (4a-d) (yield ca. 30-40%). The structure of these compounds were determined by spectroscopic methods. Quantum chemical calculations were carried out for 2a-d and 4a-d by AM I method

AN IMPROVED SYNTHESIS OF 5-ALKYL-2,3-DIHYDRO-FURAN-2,3-DIONES

The synthesis of 5-tert-butyl-2,3-dihydrofuran-2,3-dione (2a) from ethenyloxysilane (3) and oxalyl chloride is reinvestigated. Apart from 2a, two other reaction products, namely furan-3-yl oxalate (6) and difuran-3-yl oxalate (7) are isolated, explaining the low yield of 2a in this process. An improved method for the preparation of 2a, and its 5-methyl analog (2b) by cyclization of acylpyruvic acids (8a,b) is described

(ALPHA)-OXOKETENES - PREPARATION AND CHEMISTRY (DEC, PG 1219, 1994)

This review describes the methods of generation of alpha-oxoketenes and their use in synthesis. While the ketenes are often generated in situ without direct proof for their existence, methods used for their direct observation are also emphasized. The most important classes of precursor molecules are 2-diazo-1,3-diketones, 1,3-dioxin-4-ones, 2,3-dihydrofuran-2,3-diones, and beta-ketoacid derivatives. Synthetically useful reactions are nucleophilic additions to give carboxylic acid derivatives which can be subjected to further functional group manipulation, [2 + 2] cycloadditions to give four-membered rings, and [2 + 4] cycloaddition chemistry with a wide variety of double-and triple-bonded dienophiles, resulting in numerous six-membered heterocyclic ring systems

A Nitroketene to Nitrile Oxide Transformation

2,3-Dihydropyrrole-2,3-diones 1 thermally extrude CO, giving imidoylketenes 2, which cyclise efficiently to 4-quinolones 3; however, the analogous nitro(imidoyl)ketene 5 eliminates CO2 and rearranges to the 3-oximino-3H-indole 9, presumably via an imidoylnitrile oxide 7