tert-Butyl piperazine-1-carboxylate → 4-(4-Tert-butoxycarbonyl-piperazin-1-yl)-6-oxo-6,7-dihydro-thieno[2,3-b]-pyridine-5-carboxylic acid ethyl ester

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Reaction Steps

In another method, intermediate 4-chloro-6-oxo-6,7-dihydro-thieno[2,3-b]pyrdine-5-carboxylic acid ethyl ester, depicted by formula (42), was reacted with tert-butyl-1-piperazine carboxylate to yield 4-(4-tert-butoxycarbonyl-piperazin-1-yl)-6-oxo-6,7-dihydro-thieno[2,3-b]-pyridine-5-carboxylic acid ethyl ester, depicted by formula (45). This intermediate was either reacted with an appropriate halide (R1—X) or boronic acid (R1—B(OH)2) to yield intermediate of structure (46), which was deprotected and reacted with an appropriate acid chloride (R3—COCl) or acid (R3—COOH) to yield target compounds of structure (III) with R2 as ethyl carboxylate, and R1 and R3 as defined above, as shown in Scheme 24.

Provenance & Evidence