The Dow Chemical Company

Schering Corporation

Antibioticos

Charles R Martin

Haiyan Zhang

Loris Sogli

Junning Lee

Ermanno Bernasconi

Derek Walker

Vinod Parakkal Menon

Robert B Moore, Iii

Reginald M Penner

Mark W Espenscheid

A process is described for preparing 3-exomethylene cephalosporanic acid derivatives for use in the synthesis of cephalosporin antibiotics such as ceftibuten. The process comprises electrochemical reduction of a compound of the formula (IV) ##STR1## wherein: R.sup.3 is ##STR2## is an optional sulfoxide group; n is 2 or 3; R.sup.1 is H and R is H or NHR.sup.2, where R.sup.2 is H or a protecting group selected from C.sub.6 H.sub.5 CH.sub.2 OC(O)--, C.sub.6 H.sub.5 C(O)-- or C.sub.1 -C.sub.6 alkoxy-C(O)--; or wherein R and R.sup.1 together with the carbon atom to which they are attached comprise --C(O)--, and produces the desired 3-exomethylene compounds with low levels of the corresponding 3-methyl tautomers.

Process for the preparation of intermediates useful in the synthesis of

A process is described for preparing 3-exomethylene cephalosporanic acid derivatives for use in the synthesis of cephalosporin antibiotics such as ceftibuten. The process comprises electrochemical reduction of a compound of the formula (IV) ##STR1## wherein: R.sup.3 is CH.sub.3 C(O)--; ##STR2## is an optional sulfoxide group; n is 2 or 3; R.sup.1 is H and R is H or NHR.sup.2, where R.sup.2 is H or a protecting group selected from C.sub.6 H.sub.5 CH.sub.2 OC(O)--, C.sub.6 H.sub.5 C(O)-- or C.sub.1 -C.sub.6 alkoxy-C(O)--; or wherein R and R.sup.1 together with the carbon atom to which they are attached comprise --C(O)--, and produces the desired 3-exomethylene compounds with low levels of the corresponding 3-methyl tautomers.

A process is described for preparing 3-exomethylene cephalosporanic acid derivatives for use in the synthesis of cephalosporin antibiotics such as ceftibuten. The process comprises electrochemical reduction of a compound of the formula (IV) ##STR1## wherein: R.sup.3 is CH.sub.3 C(O)--; ##STR2## is an optional sulfoxide group; n is 2 or 3; R.sup.1 is H and R is H or NHR.sup.2, where R.sup.2 is H or a protecting group selected from C.sub.6 H.sub.5 CH.sub.2 OC(O)--, C.sub.6 H.sub.5 C(O)-- or C.sub.1 -C.sub.6 alkoxy--C(O)--; or wherein R and R.sup.1 together with the carbon atom to which they are attached comprise --C(O)--, and produces the desired 3-exomethylene compounds with low levels of the corresponding 3-methyl tautomers.

A composite membrane suitable for separations of fluid components by electropolymerization of a discrimination layer on an electrically conductive porous support.

Ultrathin-film composite membrane

An ultramicroelectrode assembly which generally comprises an electrically nonconducting host membrane having a plurality of micro-sized pores extending through the membrane, and a macro-sized substrate electrode in contact with this host membrane. The host membrane has its pores impregnated with an electrically conductive medium, and the substrate electrode is in electrical contact with the impregnated pores of the host membrane. The electrically conductive medium is a carbon paste, and the substrate electrode includes a confined volume of such carbon paste in contact with an interior surface of the impregnated membrane.

Ultramicroelectrode ensembles

The invention is a method for forming a perfluorosulfonate ionomer film comprising:

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Fort Collins, CO, United States of America

Charles R Martin