Imidazol-1-YL-oxo-acetic acid tert-butyl ester → 2-Amino-7-(1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-3,6-dicarboxylic acid di-tert-butyl ester

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Reaction Steps

To a solution of the above mixture of 2-amino-5-(4-benzyloxy-1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-3,6-dicarboxylic acid di-tert-butyl ester and 2-amino-7-(4-benzyloxy-1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-3,6-dicarboxylic acid di-tert-butyl ester (0.15 g, 0.24 mmol) in distilled dichloromethane (4 ml) under nitrogen was added imidazol-1-yl-oxo-acetic acid tert-butyl ester (0.14 g, 0.72 mmol) and the reaction mixture was stirred at ambient temperature for 1.5 h. The volatiles were evaporated in vacuo and the crude residue was purified by silica gel chromatography using dichloromethane as eluant. Pure fractions were collected and the solvent evaporated in vacuo affording 50 mg of 2-(tert-butoxyoxalyl-amino)- (4-benzyloxy-1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-3,6-dicarboxylic acid di-tert-butyl ester (A) and 50 mg of 2-(tert-butoxyoxalyl-amino)-7-(4-benzyloxy-1,3-dioxo-1,3-dihydro-isoindol-2-ylmethyl)-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-3,6-dicarboxylic acid di-tert-butyl ester (B). Another 50 mg remained as a mixture of the two isomers (A) and (B).

Provenance & Evidence