Patents by Inventor Hendrik A. Witkamp

Hendrik A. Witkamp has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Cephem derivatives
    Patent number: 5359058
    Abstract: A cephalosporin compound substituted in the 7-position with a (cyclo)alkylideneammonio group of formula (II) ##STR1## wherein X' is an anion from an acid HX, R.sub.1 and R.sub.2 are individually a C.sub.1 -C.sub.16 alkyl group, or R.sub.1 and R.sub.2 together with the carbon atom to which they are attached form a cycloalkylidene ring with up to 8 carbon atoms and a process for the preparation which compounds are useful intermediates.
    Type: Grant
    Filed: April 27, 1992
    Date of Patent: October 25, 1994
    Assignee: Gist-Brocades, N.V.
    Inventors: Jan Verweij, Henri G. J. Hirs, Hendrik A. Witkamp, Everardus J. A. M. Leenderts, Jan J. Dekoning, Herman H. Grootveld
  • Cephalosporin derivatives
    Patent number: 5164494
    Abstract: Process for the preparation of 7.beta.-amino-3-substituted methyl-3-cephem-4-carboxylic acid derivatives, new intermediates comprising 7.beta.-(cyclo)alkylideneammonio-3-halomethyl-3-cephem-4-carbox ylic acid derivatives and 7.beta.-amino/ammonio-3-bromomethyl-3-cephem-4-carboxylic acid derivatives and the processes for the preparation of these intermediates.
    Type: Grant
    Filed: March 23, 1989
    Date of Patent: November 17, 1992
    Assignee: Gist-Brocades N.V.
    Inventors: Hendrik A. Witkamp, Jan J. DeKoning, Jan Verwej, Herman H. Grootveld, Everardus J. A. M. Leenderts
  • Process for the preparation of 3-exomethylene cepham derivatives
    Patent number: 5109132
    Abstract: A process is provided for the preparation of 3-methylene and 3-halomethylene cepham derivatives via 3-phosphoniomethyl-3-cephem derivatives, which in turn can be prepared from 3-halomethyl-3-cephem derivatives. The preparation can be carried out with or without isolating the intermediate phosphonium cephem compounds. The 3-methylene and 3-halomethylene cepham derivatives and in particular the 1-oxo and 1,1-dioxo cepham compounds are also prepared by reducing a 3-halomethyl-3-cepham derivative with activated metal, preferably zinc or magnesium.
    Type: Grant
    Filed: September 10, 1990
    Date of Patent: April 28, 1992
    Assignee: Gist-Brocades N.V.
    Inventors: Jan Verweij, Jan J. De Koning, Hendrik A. Witkamp
  • Cepham derivatives
    Patent number: 4994454
    Abstract: A process is provided for the preparation of 3-methylene and 3-halomethylene cepham derivatives via 3-phosphoniomethyl-3-cephem derivatives, which in turn can be prepared from 3-halomethyl-3-cephem derivatives. The preparation can be carried out with or without isolating the intermediate phosphonium cephem compounds. The 3-methylene and 3-halomethylene cephem derivatives and in particular the 1-oxo and 1,1-dioxo cephem compounds are also prepared by reducing a 3-halomethyl-3-cephem derivative with activated metal, preferably zinc or magnesium.
    Type: Grant
    Filed: December 27, 1989
    Date of Patent: February 19, 1991
    Assignee: Gist-Brocades N.V.
    Inventors: Jan Verweij, Jan J. DeKoning, Hendrik A. Witkamp
  • Process for the preparation of 3-exomethylene cepham derivatives
    Patent number: 4985554
    Abstract: A process is provided for the preparation of 3-methylene and 3-halomethylene cepham derivatives via 3-phosphoniomethyl-3-cephem derivatives, which in turn can be prepared from 3-halomethyl-3-cephem derivatives. The preparation can be carried out with or without isolating the intermediate phosphonium cephem compounds. The 3-methylene and 3-halomethylene cepham derivatives and in particular the 1-oxo and 1,1-dioxo cepham compounds are also prepared by reducing a 3-halomethyl-3-cephem derivative with activated metal, preferably zinc or magnesium.
    Type: Grant
    Filed: February 15, 1989
    Date of Patent: January 15, 1991
    Assignee: Gist-Brocades N.V.
    Inventors: Jan Verweij, Jan J. De Koning, Hendrik A. Witkamp
  • Process for the preparation of cephem compounds
    Patent number: 4921954
    Abstract: Process for the preparation of 7.beta.-amino-3-substituted methyl-3-cephem-4-carboxylic acid derivatives, new intermediates comprising 7.beta.-(cyclo)alkylideneammonio-3-halomethyl-3-cephem-4-carbox ylic acid derivatives and 7.beta.-amino/ammonio-3-bromomethyl-3-cephem-4-carboxylic acid derivatives and the processes for the preparation of these intermediates.
    Type: Grant
    Filed: July 8, 1988
    Date of Patent: May 1, 1990
    Assignee: Gist-Brocades N.V.
    Inventors: Hendrik A. Witkamp, Jan Verweij, Jan J. DeKoning, Herman H. Grootveld, Everardus J. A. M. Leenderts