To a stirred solution of 2-(1-pyridin-2-yl-cyclopentyl)-acetamidine hydrochloride (435) (1 g, 3.55 mmol) and 2-benzyloxy-3-hydroxy-but-2-enedioic acid 4-tert-butyl ester 1-methyl ester (4) (1.638 g, 5.319 mmol) in methanol (15 mL), sodium methoxide (25% in methanol) (2.3 mL, 10.638 mmol) was dropwise added at 0° C. Then reaction mixture was allowed to stir at room temperature for 16 h. Then reaction mixture was quenched with aqueous HCl (1N; 5 mL) and the methanol was removed under reduced pressure. The residue was diluted with water (20 mL) and extracted with ethyl acetate (2×50 mL). The combined organic part was dried, concentrated and the residue was purified by nor mal silica gel (100-200 mesh) column chromatography using 30% ethyl acetate in hexane as eluent to obtain 5-benzyloxy-6-hydroxy-2-(1-pyridin-2-yl-cyclopentylmethyl)-pyrimidine-4-carboxylic acid tert-butyl ester (436) (1.2 g, 73%) as a yellow sticky liquid.
