The iodolactonization of 3-alkynylthiophene-2-carboxylic acids and 3-alkynylpicolinic acids has been investigated. Using I2 as the iodine source and NaHCO3 as the base in MeCN, the process took place smoothly to afford thienopyranones and pyranopyridinones, respectively, from 6-endo-dig cyclization. The method also worked nicely for the transformation of 2-(phenylethynyl)thiophene-3-carboxylic acid and 3-(phenylethynyl) isonicotinic acid into 7-iodo-6-phenyl-4H-thieno[3,2-c]- pyran-4-one and 4-iodo-3-phenyl-1H-pyrano[4,3-c]pyridin-1- one, respectively. Although with some 3-alkynylpicolinic acids the process led to a mixture of the 6-endo-dig and 5-exo-dig products, it could be still made selective toward the pyranopyridinone compound working in 1-ethyl-3-methylimidazolium ethyl sulfate as the solvent. On the other hand, the exclusive formation of the 5-exo-dig product was observed in N-ethyl-Nmethylmorpholinium dicyanamide starting from 3-(3,3-dimethylbut- 1-yn-1-yl)picolinic acid. Some representative iodinated thienopyridinone products were successfully used as substrates for Pd-catalyzed Suzuki and Sonogashira reactions.

Mancuso, R., Novello, M., Russo, P., Palumbo Piccionello, A., Gabriele, B. (2020). Iodolactonization of 3-Alkynylthiophene-2-Carboxylic and 3-Alkynylpicolinic Acids for the Synthesis of Fused Heterocycles. EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, 2020(24), 3712-3725 [10.1002/ejoc.202000468].

Iodolactonization of 3-Alkynylthiophene-2-Carboxylic and 3-Alkynylpicolinic Acids for the Synthesis of Fused Heterocycles

Palumbo Piccionello, Antonio;
2020-01-01

Abstract

The iodolactonization of 3-alkynylthiophene-2-carboxylic acids and 3-alkynylpicolinic acids has been investigated. Using I2 as the iodine source and NaHCO3 as the base in MeCN, the process took place smoothly to afford thienopyranones and pyranopyridinones, respectively, from 6-endo-dig cyclization. The method also worked nicely for the transformation of 2-(phenylethynyl)thiophene-3-carboxylic acid and 3-(phenylethynyl) isonicotinic acid into 7-iodo-6-phenyl-4H-thieno[3,2-c]- pyran-4-one and 4-iodo-3-phenyl-1H-pyrano[4,3-c]pyridin-1- one, respectively. Although with some 3-alkynylpicolinic acids the process led to a mixture of the 6-endo-dig and 5-exo-dig products, it could be still made selective toward the pyranopyridinone compound working in 1-ethyl-3-methylimidazolium ethyl sulfate as the solvent. On the other hand, the exclusive formation of the 5-exo-dig product was observed in N-ethyl-Nmethylmorpholinium dicyanamide starting from 3-(3,3-dimethylbut- 1-yn-1-yl)picolinic acid. Some representative iodinated thienopyridinone products were successfully used as substrates for Pd-catalyzed Suzuki and Sonogashira reactions.
Settore CHIM/06 - Chimica Organica
Mancuso, R., Novello, M., Russo, P., Palumbo Piccionello, A., Gabriele, B. (2020). Iodolactonization of 3-Alkynylthiophene-2-Carboxylic and 3-Alkynylpicolinic Acids for the Synthesis of Fused Heterocycles. EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, 2020(24), 3712-3725 [10.1002/ejoc.202000468].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/429120
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