1 63 eq was added dropwise and the mixture was directly stirred for 30 min thereafter a solution of 5 bromomethylthiophene 2 carboxylic acid methyl ester in cyclopentyl methyl ether cpme gross 95 43 g net 33 86 g 144 0 mol was added and the mixture was stirred for 1 hr water 169 ml was added and the mixture was extracted with heptane 339 ml washed with a mixture of ethanol 112 ml and water 223 ml and concentrated to give the title compound gross 59 28 g net 37 10 g yield 86 3 1 h nmr 400 mhz chloroform d u03b4 7 62 d j 3 8 hz 1h 6 79 d j 3 8 hz 1h 3 85 s 3h 3 04 s 2h 1 45 s 9h 1 18 s 6h to 5 2 tert butoxycarbonyl 2 methylpropyl thiophene 2 carboxylic acid methyl ester gross 59 28 g net 37 10 g 124 3 mmol were added water 80 2 ml and ethanol 111 3 ml and 6 n naoh aqueous solution 31 1 ml 1 5 eq was added and the mixture was stirred at 30 u00b0 c for 16 hr after completion of the reaction and the mixture was neutralized with 6 n hcl 31 1 ml 1 5 eq and extracted with cyclohexane 371 ml after washing with a mixture.