John Edward Glyn Kemp

Nucleophilic SN2 displacements on penicillin-6- and cephalosporin-7- triflates; 6β-iodopenicillanic acid, a new β-lactamase inhibitor

Abstract Triflate or nonaflate esters of alkyl 6α (or β) hydroxypenicillanates are substituted (with inversion) by the soft nucleophiles iodide, bromide, chloride, azide, arylselenoxide, 1 thiocyanate, thiols, and thiolacids; carbon nucleophiles fail. Methoxide (hard) attacks the lactam bond, opening both rings to give a known 11 1,4 thiazine. Iodide substitutes 7α-trifloxycephalosporins, giving 7β-iodocephalosporins.

Penicillin N-cyanosulphilmines; cyanamide/iodobenzene diacetate, a convenient cyanonitrene reagent for N-cyano sulphilmines, sulphoximines, phosphinimines and aziridines

Abstract Cyanamide with iodobenzene diacetate give cyanonitrene adducts of sulphides, sulphoxides, phosphines, and olefins. Penicillins give N -cyanosulphilimines, shown by intramolecular N-H...N hydrogen bonding or NMR ASIS to have β(S) stereochemistry.

Rational resolution of the isosteric enantiomers of 6,11-dihydrodibenzo[b,e]thiepin-11-ol and conversion to the two isosteric diastereoisomers of the calcium channel blocker UK-74,756

Abstract Sulfoxidation of the (+)-Noe-lactol derivative of racemic 6,11-dihydrodibenzo[b,e]thiepin-11-ol broke the isosterism and converted an inseparable mixture of two compounds into a separable mixture of four. X-Ray structural determination on one of these and subsequent manipulation provided resolved 6,11-dihydrodibenzo[b,e]thiepin-11-ol and all four sulfoxides in known configurations, and enabled the resolution by synthesis of the two isosteric diastereoisomers of the calcium channel blocker UK-74,756.

Penicillin and cephalosporin sulphoximines

Abstract Penicillin N -cyanosulphoximines are obtained by permanganate oxidation of the sulphilimines. Phthalimidosulphoximines are obtained from penicillin or cephalosporin sulphoxides are phthalimidonitrene (from N -aminophthalimide with lead tetraacetate).