1408251-00-2Relevant articles and documents
p-TSA-Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2-Alkynyl-(hetero)-arylcarboxylates: an Alternative Access to 6-Substituted 3,4-Fused 2-Pyranones
Curti, Fabiola,Tiecco, Matteo,Pirovano, Valentina,Germani, Raimondo,Caselli, Alessandro,Rossi, Elisabetta,Abbiati, Giorgio
, p. 1904 - 1914 (2019/02/26)
In this paper, we describe the use of p-TSA based Deep Eutectic Solvents (DESs) as alternative environmental-friendly “active” solvents for the microwave-mediated synthesis of 6-substituted 3,4-fused 2-pyranones, and in particular isocoumarins, starting from 2-alkynyl-(hetero)arylcarboxylates. When the alkyne terminus bears a neutral or an electron-donating group (EDG), the reactions are fast, clean and highly regioselective, to give the 6-endo-dig cyclization products in good to excellent yields. For substrates bearing an electron-withdrawing group (EWG) on the alkyne end, the regioselectivity can be tuned by adding a small amount of silver(I) triflate as co-catalyst. DES was demonstrated to be reusable without loss of efficiency in terms of reaction yields. Based on experimental evidence and previous findings, two competitive mechanisms working simultaneously are proposed to explain the outcomes and the regioselectivity issues.
Palladium-catalyzed carbonylative synthesis of isocoumarins and phthalides by using phenyl formate as a carbon monoxide source
Yuan, Qing,Chen, Zhen-Bang,Zhang, Fang-Ling,Zhu, Yong-Ming
, p. 1628 - 1635 (2017/02/23)
A simple and efficient palladium-catalyzed intramolecular carbonylative synthesis of isocoumarins and phthalides from the easily available starting materials by employing phenyl formate as a CO surrogate has been achieved. The approach affords target compounds in good to excellent yields with the advantages of lower toxicity, milder conditions, easy operation and wide functional group tolerance.
Palladium-catalyzed synthesis of isocoumarins and phthalides via tert -butyl isocyanide insertion
Fei, Xiang-Dong,Ge, Zhi-Yuan,Tang, Ting,Zhu, Yong-Ming,Ji, Shun-Jun
, p. 10321 - 10328 (2013/01/15)
A novel and highly efficient strategy for the synthesis of isocoumarins and phthalides through a palladium(0)-catalyzed reaction incorporating tert-butyl isocyanide has been developed. This process, providing one of the simplest methods for the synthesis of this class of valuable lactones, involves two steps including cyclization reaction and simple acid hydrolysis. The methodology is tolerant of a wide range of substrates and applicable to library synthesis.