1-(tert-Butoxycarbonyl)-5'-methyl-4',5'-dihydrospiro[piperidine-4,7'-thieno[2,3-c]pyran]-2'-carboxylic acid 5g

1-(tert-Butoxycarbonyl)-5'-methyl-4',5'-dihydrospiro[piperidine-4,7'-thieno[2,3-c]pyran]-2'-carboxylic acid 5g