Preparation of naphthoquinone compounds using 2,3-dihalonaphthoquinone

A process for the preparation of 2-cyclohexyl-1,4-naphthoquinones compounds of Formula III and its isomers,

• wherein, R3 is selected from the group consisting of C1-6 alkoxy;
• aralkoxy;
• C1-6 alkyl-C1-6 alkoxy;
• hydrogen;
• unsubstituted phenyl;
• phenyl substituted by one or more groups, preferably selected from halogens;
• C1-6 linear or branched alkyl, halogen and perhalo-C1-6 alkyl;
• R4 is selected from the group comprising consisting of hydroxyl;
• a group OCOR5, wherein R5 is a C1-10 alkyl group, a C3-10 cycloalkyl group, a C1-10 alkoxy group, or a phenyl or naphthyl group, each such R5 group being optionally substituted e.g. by amino, mono or di-C1-4 alkylamino, carboxy or hydroxy;
• a group OR6 or SR6, wherein R6 is an optionally substituted C1-10 alkyl, C3-10 cycloalkyl, phenyl or naphthyl group as defined for R5 or a group NR7R8, wherein R7 and R8 each independently represent hydrogen or C1-4 alkyl, or the group NR7R8 which represents a 5-7 membered saturated heterocyclic ring, which may optionally contain a further heteroatom selected from nitrogen, oxygen or sulfur,
• comprising the steps of:
• (i) condensing 2,3-dihalonaphthoquinone compounds of Formula I
• wherein R1 and R2 are leaving groups selected from the group consisting of Cl, Br, I and F and the R1 and R2 may be the same halogen or may contain different halogen groups, or sulphonyl groups, and physiologically acceptable salts and other physiologically functional derivatives thereof, with
• wherein R is selected from the group consisting of H,
• to prepare napthoquinone compounds of Formula IA;
• wherein X is any aryl, heteroaryl, alkyl, cyclohexyl, substituted cylohexyl groups;
• (ii) treating napthoquinone compounds of Formula IA with base in a suitable solvent to form the 2-cyclohexyl-1,4-naphthoquinones compounds of Formula III.