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L D Hatfield

Publications and source records attributed to L D Hatfield.

4 recordsLinked to original sources
PubMed1980

Cephalosporanic acids: a new look at reactions at the C-3' position.

Nucleophilic displacement of the acetoxy group of cephalosporanic acids by thiols in aqueous solution at neutral pH provides 3-thiomethyl-substituted compounds with a broad spectrum of antibiotic activity. The aqueous displacement reaction is often destructive of much of the cephalosporanic acid, and products generally require extensive purification. Displacements at a lower pH are complicated by unwanted lactone formation. However, reactions conducted under acid conditions in a variety of anhydrous organic solvents give 3-thiomethyl-substituted compounds in very high yield and quality; no lactone formation is observed. The kinetics of the reaction support an SN1 mechanism. Protonation of the departing acetoxy group appears therefore critical; the more basic solvents, e.g. dimethylsulphoxide and N,N-dimethylformamide, significantly retard the rate of reaction.

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