term u201c halo u201d means fluoro chloro bromo or iodo preferably chloro or bromo u201c alkali metal u201d or u201c alkali u201d refers to lithium sodium potassium rubidium and caesium preferable alkali metal is lithium or sodium of these sodium is most preferred u201c c 1 c 8 alkyl u201d refers to a branched or straight hydrocarbon chain of one to eight carbon atoms such as methyl ethyl n propyl isopropyl n butyl isobutyl sec butyl t butyl pentyl hexyl and heptyl c 1 c 6 alkyl is preferred u201c c 3 c 6 cycloalkyl u201d refers to a single saturated carbocyclic ring such as cyclopropyl cyclobutyl cyclopentyl and cyclohexyl u201c c 1 c 6 alkyllithium u201d is understood as being an c 1 c 6 alkyl as defined above substituted by a lithium atom such as butyllithium hexyllithium sec butyllithium u201c secondary amine u201d refers to an amine of formula hnr 2 r 3 wherein r 2 and r 3 may be the same or different and are independently selected from c 1 c 6 alkyl or c 3 c 6 cycloalkyl or r 2 and r 3 taken together with the nitrogen atom to which they are attached obtain a c 4 c 8 heterocycloalkane optionally containing an additional heteroatom selected from o or n representative examples include but are not limited to piperidine 4 methyl piperidine piperazine pyrrolidine morpholine dimethylamine diethylamine diisopropylamine dicyclohexylamine ethylmethylamine ethylpropylamine and methylpropylamine preferably the secondary amine is chosen from diethylamine diisopropylamine dicyclohexylamine ethylmethylamine ethylpropylamine methylpropylamine and morpholine the more preferred secondary amine is diethylamine or diisopropylamine most preferred diethylamine u201c c 4 c 8 heterocycloalkane u201d refers to a saturated non aromatic cyclic compound of 4 to.