Regiodivergent construction of medium-sized heterocycles from vinylethylene carbonates and allylidenemalononitriles |
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| Authors: | Xiang Zhang Xiang Li Jun-Long Li Qi-Wei Wang Wen-Lin Zou Yan-Qing Liu Zhi-Qiang Jia Fu Peng Bo Han |
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| Institution: | West China School of Pharmacy, Sichuan University, Chengdu 610041 China.; State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137 China.; Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 China ; Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052 China |
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| Abstract: | Medium-sized heterocycles exist in a broad spectrum of biologically active natural products and medicinally important synthetic compounds. The construction of medium-sized rings remains challenging, particularly the assembly of different ring sizes from the same type of substrate. Here we report palladium-catalyzed, regiodivergent 5 + 4] and 5 + 2] annulations of vinylethylene carbonates and allylidenemalononitriles. We describe the production of over 50 examples of nine- and seven-membered heterocycles in high isolated yields and excellent regioselectivities. We demonstrate the synthetic utility of this approach by converting a nine-membered ring product to an interesting polycyclic caged molecule via a 2 + 2] transannulation. Mechanistic studies suggest that the 5 + 2] annulation proceeds through palladium-catalyzed ring-opening/re-cyclization from the 5 + 4] adducts.Here we report palladium-catalyzed, regiodivergent 5 + 4] and 5 + 2] annulations of vinylethylene carbonates and allylidenemalononitriles affording over 50 medium-sized heterocycles in high isolated yields with excellent regioselectivities. |
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