HCID 10107954, compound → HCID 10015281, compound

Participants

Reaction Steps

The t-butyl 5-(2-ethoxycarbonylethyl)-2-thiophenecarboxylate (7.6 g, 26.8 mmol) prepared in the Preparative Example 15 was partially hydrolyzed in an ethanol/1N sodium hydroxide mixture at room temperature to give 6.1 g of 3-(5-t-butoxycarbonylthiophen-2-yl)propionic acid. This acid was dissolved in anhydrous tetrahydrofuran and the obtained solution was dropped into a solution of borane in tetra-hydrofuran, which had been preliminarily prepared from sodium borohydride (3.37 g, 89 ml) and trifluoroborane-diethyl ether complex (16.9 g, 119 mmol), under cooling with ice in about 30 minutes. The obtained mixture was stirred for 30 minutes, followed by the gradual dropwise addition of methanol. After the generation of hydrogen gas had discontinued, the reaction mixture was filtered and the filtrate was evaporated to dryness. Methanol was added to the residue to remove the boron compound by azeotropic distillation. The residue was dissolved in diethyl ether and the obtained solution was washed with a dilute hydrochloric acid and an aqueous solution of common salt, dehydrated and distilled to remove the solvent. The residue was evaporated to dryness in a vacuum to give 6.0 g of the compound.

Provenance & Evidence