Merck + Co., Inc.

Torleif Utne

Ronald B Jobson

Donald F Reinhold

Gary H Rasmusson

David B Johnston

Newton L Abramson

Alfred V Lovell

A process for the preparation of (S)- or L-3-(3,4-dihydroxyphenyl)alanine (L-dopa) is described. The process utilizes water as reaction process solvent and proceeds via formation of an intermediate which can be kinetically resolved in a polar solvent to a precursor of the desired isomer and in which the undesired isomer can be efficiently racemized for reuse.

Process for L-dopa

An optically impure diastereomeric salt is purified by treating a suspension of the salt in an appropriate solvent or solvent mixture with the required amount of the desired, optically pure, acid or base.

Displacement purification of salts

A method of preparing a compound of the formula: ##STR1## where Formula (I) may also have the structure of partial Formula (III); wherein, ##STR2## R' is hydrogen or methyl; R' is hydrogen or .beta.-methyl;

Preparation of 4-aza-17-substituted-5.alpha.-androstan-3-ones useful as

Biaryl coupling, particularly to form 2,4-difluorobiphenyl, is accomplished by diazotizing an aniline and coupling the benzenediazonium salt with a second aromatic component in the presence of a strong acid, an inert finely divided solid and copper powder or a copper salt.

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Torleif Utne