the organic solution is evaporated at low pressure until dry to obtain 8 07 g of 3 in the form of a white solid 10 0 g of compound 16 is suspended in 100 ml of absolute ethanol the suspension obtained is cooled to 0 u00b0 c and 6 0 ml of triethylamine and 5 2 ml of isobutyl chloroformate are added at a rate such that the inner temperature does not exceed 5 u00b0 c after 1 5 hours the suspension is filtered and the solid washed with absolute ethanol 2 u00d7 and dried to give 8 36 g of compound 3 in the form of a white crystalline solid yield 88 9 8 5 g of palladium on 5 wet charcoal 50 water is added in an inert atmosphere to a mixture of 11 33 g of 3 chloro 6 methyl benzo b thiophene 2 carboxylic acid 18 135 ml of n n dimethylformamide 15 ml of 3 3 m naoh and 40 ml of methanol water 9 1 after repeated vacuum hydrogen cycles the suspension is maintained under stirring in a hydrogen atmosphere at ambient temperature for 20 24 hours the mixture is then rendered inert and filtered through a celite bed and the catalyst is washed with 150 ml of methanol the filtrate is evaporated until dry 500 ml of water and 40 ml of 1n hcl are added and the solution is maintained under stirring for 1 hour the suspension is filtered and the solid washed with 200 ml of water and dried after drying 8 71 g of compound i is obtained in the form of a white solid yield 90 6 hplc purity 99 3 1 h nmr.