in situ chemical sulfonation procedure.

A process for the manufacture of a compound of formula IIa: ** ** Formula wherein R is a suitable sulphonate ester; from compound 4-piperidinecarboxylate (C1-C6) Formula III: Formula ** ** alkyl (C1-C6) process comprising the steps of: (a) reacting compound 4-piperidinecarboxylate alkyl (C1-C6) Formula III with di-tert-butyl in the presence of toluene or xylene to form a first mixture comprising toluene or xylene, tert -butanol and a compound of formula IV: Formula ** ** alkyl ( C1-C6) (b) substantially removing the tert-butanol from the first mixture; (C) reacting the compound of Formula IV with a suitable reducing agent in situ in the presence of toluene or xylene to form a second mixture comprising toluene, byproducts reduction including byproducts spirits and a compound of Formula V: ** ** Formula (d) removing byproducts sustancialmentelos alcoholics from the second mixture; and (e) reacting the compound of formula V with a suitable sulphonylating agent in situ to form a sulphonate ester in the presence of a suitable base and toluene to form the compound of formula IIa.