Patents by Inventor Francis J. Taplin

Francis J. Taplin 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).

  • Process for the preparation of optically pure 1,2,3,4-tetrahydro-3-isoquinolinecarboxylic acid and its derivatives
    Patent number: 5627282
    Abstract: This invention relates to the preparation of optically pure tetrahydro-3-isoquinolinecarboxylic acid derivative of formula (III) which comprises the reaction of optically pure phenylalanine derivative of formula (I) with a formaldehyde precursor, such as formaline, trioxane, dialkoxymethane, or paraformaldehyde, for about 10 hours to 60 hours at about 40 .degree. C. to about 60 .degree. C. in concentrated hydrochloric acid to give the compound of formula (II), followed by neutralization in hot water at about 70 .degree. C. to about 100 .degree. C. with a base, such as ammonium hydroxide, potassium carbonate, sodium carbonate, sodium hydroxide or potassium hydroxide, according to the following reaction scheme.
    Type: Grant
    Filed: January 3, 1996
    Date of Patent: May 6, 1997
    Assignee: Yukong Limited
    Inventors: Taesoo Kwon, Francis J. Taplin