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The reaction of phosphorus trichloride and oxygen with fluoro-olefins gives mixtures containing phosphoric and phosphonic dichlorides together with C–C cleavage products. In a wide range of compounds of the type (RO)2P-(O)·CHX·CHYCl, including products derived from these reactions, elimination of HCl occurs stereospecifically or stereoselectively, and in the case of pairs of diastereoisomers stereoconvergently, to give the olefins (RO)2P(O)-CXCHY with X and Y cis. Suggestions are made concerning correlation of ground state conformational properties determined by 1H and 19F n.m.r. studies, with observed mode of HCl elimination.

A detailed study has been made of the effects of substituents, X, upon the shielding of 19F nuclei in series of meta and para-X-fluorobenzenes, 4-X-4′-fluoro-trans-stilbenes, and 3′-fluoro-4-X-trans-stilbenes. The correlation of substituent chemical shifts for 19F nuclei in fluoroaromatic compounds with reactivity parameters is examined, and a reassessment is made of the Taft and Swain and Lupton separation of polar substituent effects into field/inductive and resonance components.

Solvent effects upon 19F shielding in some aryl fluorides are examined. A criterion is established which, it is believed, enables solvents and reference to be chosen so that interactions other than those due to ‘reaction fields’ are minimised. The reaction field model appears to work satisfactorily for 4-substituted 3′- and 4′-fluoro-trans-stilbenes, but breaks down for para-substituted fluorobenzenes.

The synthesis of several series of bridged dinuclear aromatic compounds of the type p-F·C6H4·Z·C6H4·X-p[Z = all-trans-·CHCH–CHCH·, CCH2, CH2, CH(OH), CMe(OH), –O–, or –S–; X = NH2, OMe, H, F, Cl, or NO2] is described. The 19F n.m.r. spectra of these compounds are used to examine the ‘transmission’ of electronic effects, due to the group X, across the bridge Z. A distinction is drawn between ‘transmission effects’ in which electron density may be considered to be transferred from one ring to the other and ‘relay effects’ in which there is probably no net transfer of electron density.

Norbornadiene, dimethyl acetylenedicarboxylate, and vinyl ethers react with the sulphenic acids produced by heating penicillin S-oxides. Norbornadiene, diketen (4-methyleneoxetan-2-one), and dimethyl acetylenedicarboxylate react by addition, whereas vinyl ethers, such as dihydropyran, react by substitution with loss of water. Methanolysis of the vinyl ether products can be achieved with dilute methanolic hydrochloric acid. Removal of the nitrogen-containing substituent of the β-lactam ring from the vinyl ether products has been effected via the pyrazoline route. A novel substitution reaction occurs on heating the 3-hydroxypenam (22) with acrylaldehyde : methacrylaldehyde is displaced and the 4-hydroxycepham (25) is formed. Some reactions of this cepham are reported.