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

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Reaction Steps

Compounds of structure (III) with R2 as carbonitrile, and R1 and R3 as defined above were also prepared from intermediate 4-chloro-6-oxo-6,7-dihydro-thieno[2,3-b]pyrdine-5-carbonitrile, depicted by formula (50). Intermediate 4-chloro-6-oxo-6,7-dihydro-thieno[2,3-b]pyridine-5-carbonitrile, depicted by formula (50), was reacted with tert-butyl-1-piperazine carboxylate to yield 4-(5-cyano-6-oxo-6,7-dihydro-thieno[2,3-b]-pyridine-4-yl)-piperazine-1-carboxylic acid tert-butyl ester, depicted by formula (53). This intermediate was either reacted with an appropriate halide (R1—X) or boronic acid (R1—B(OH)2) to yield an intermediate of structure (54), 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 carbonitrile, and R1 and R3 as defined above, as shown in Scheme 28.

Provenance & Evidence