Unexpected ring opening of pyrazolines with activated alkynes: Synthesis of 1H-pyrazole-4,5-dicarboxylates and
chromenopyrazolecarboxylates Sai Teja Kolla, Nageswara Rao Rayala, Sridhar Balasubramanianand China Raju Bhimapaka CSIR-IICT, Hyderabad, India
1H-Pyrazole-4,5-dicarboxylates and chromenopyrazole carboxylates were prepared by reacting pyrazolines with activated alkynes under neat conditions without a catalyst. The products were formed via unexpected ring opening of pyrazolines with the elimination of styrene/ethylene. References 1. ( a ) C. Ma, Y. Li, P. Wen, R. Yan, Z. Ren and G. Huang, Synlett , 2011, 9 , 1321-1323; ( b ) S. Safaei, I. Mohammadpoor-Baltork, A. R. Khosropour, M, Moghadam, S. Tangestaninejad and V. Mirkhani, New J. Chem ., 2013, 37 , 2037-2042; ( c ) I. Yavari, G. Khalili and A. Mirzaei, Helv. Chim. Acta , 2010, 93 , 277-280; ( d ) B. Cheng, B. Bao, W. Xu, Y. Li, H. Li, X. Zhang, Y. Li, T, Wang and H. Zhai, Org. Biomol. Chem ., 2020, 18 , 2949-2955. 2. K. S. Teja, S. Ramya and B. C. Raju, Synth. Commun ., 2021, 51 , 145-1432. 3. L. M. Elizabeth and I. Y. Gloria, J. Org. Chem ., 2001, 66 , 2943-2947.
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