Ramamoorthy Sivaramakrishnan

Preparation of lactones via tricarbonyliron–lactone complexes

A number of tricarbonyliron–lactone complexes have been prepared from vinyl oxirans by treatment with pentacarbonyliron. In certain cases two η3-allyl complexes were isolated from a single vinyl oxiran. Oxidation of the complexes by cerium(IV) ammonium nitrate in acetonitrile leads predominantly to β-lactones. The stereochemical integrity of the initial complexes is reflected in the formation of the oxidation products. Reduction of these products with lithium aluminium hydride gave the expected diols.

Isolation, Characterisation and Oxidation of Isomeric Ferrelactone Complexes.

Abstract Irradiation of 1,2-epoxy-l-vinylcyclopentane (1) in the presence of Fe(CO)5 leads to the formation of isomeric syn -and anti - ferrelactones (2) and (3). The structures of these complexes were determined by X-ray crystallographic methods and on oxidation gave different ratios of β- and δ-lactones.

Oxidation of bis(2-hydroxy-1-naphthyl)methane and similar bisnaphthols with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Structure and synthesis of novel products

Oxidation of bis(2-hydroxy-1-naphthyl)methane (4a) with 2,3-dichloro-5,6-dicyano-1,4-benzoqui-none (DDQ) has been shown to give the novel compounds, cis- and trans-dispiro{naphthalene-1,2′(1′H)-naphtho[2,1-b]pyran-3′,1″-naphthalene}-2(1H),2″(1″H)-dione (12a) and (13a) together with the quinone methide dimer (6a) and the spiroketone (5a). Compounds (12a) and (13a) were characterised on the basis of their spectral properties and the structures were finally confirmed by an X-ray crystal structure analysis of (12a). Hydrogenation of compounds (12a) and (13a) has been shown to give the dihydroxy compound (14) via C–C bond cleavage. An alternative synthesis of the dispironaphthalenones (12a) and (13a) was achieved by oxidation of the dihydroxy compound (14), prepared by an independent method. The generality of the oxidation of bisnaphthols of type (4a) to give novel products of the type (12a) and (13a) has been shown by studying the oxidation of the variously substituted bisnaphthols (4b–d,f) with DDQ. A mechanism has been proposed invoking the intermediacy of the quinol ethers (22) and (24).

Oxidation of bis-(2-hydroxy-1-naphthyl)methane with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. X-Ray crystal structure of a novel product

A novel compound obtained by the oxidation of the title compound with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone has been assigned structure (5) on the basis of spectral data and X-ray crystal structure analysis.

Oxidation of Abel's ketone and similar spiroketones with 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ). Synthesis of novel tropone derivatives

The structure of the novel product obtained from the oxidation of Abels ketone (1a) and similar spiroketones (1b–d) with 2, 3-dichloro-5, 6-dicyano-1,4-benzoquinone has been determined on basis of spectral data (i.r., n.m.r., and mass)

Thermal rearrangement reactions of tricarbonyliron lactone complexes

A variety of tricarbonyliron lactone complexes (1)–(12) undergo thermal decomposition upon warming in deoxygenated solvents to give products arising from decarbonylation, decarboxylation, and rearrangement pathways. The products of the reactions were characterised by spectroscopic or X-ray crystallographic methods, or in some cases, by independent synthesis. Mechanisms to account for the various transformations are also proposed.

Thermal decomposition of tricarbonyliron lactone complexes

Tricarbonyliron lactones, on warming in tetrahydrofuran or benzene, afford products derived from decarbonylation, decarboxylation, and rearrangement pathways.