A mixture of 1 g of the compound obtained in EXAMPLE 13, 1 g of 2-dimethylamino -1,1- dimethylethylamine (synthesized according to J. Am. Chem. Soc., 1946, 68, 10-12), 1 g of BOP, 1 ml of DIPEA and 20 ml of DCM is stirred for 16 hours at RT. The reaction mixture is evaporated under vacuum, the residue is extracted with AcOEt, washed with a 1N solution of NaOH, extracted with a 6N solution of HCl, washed with AcOEt, the acidic aqueous phase is rendered alkaline by the addition of 2N NaOH, extracted with AcOEt and dried over Na2SO4 and the solvent is evaporated off under vacuum. The residue is chromatographed on silica using a DCM/MeOH mixture (99/1; v/v) as the eluent to give 0.65 g of the expected product after crystallization from iso ether. M.p.=161° C.
