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Palladium-Catalyzed Sequential Hydroamination and Hydroxylation of 1,3-Enynes with 2-Aminophenols
Zonglin Ma1, Qian Wang1, Xihang Lu1
1State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China.
Abstract:
We herein present an atom- and step-economic palladium-catalyzed sequential hydroamination and hydroxylation of readily available 1,3-enynes with 2-aminophenol derivatives. This strategy provides an efficient and redox-neutral route for the synthesis of 3,4-dihydro-2H-1,4-benzoxazines with good to high yields, demonstrating broad substrate scope, excellent regioselectivities, and high E-selectivities. Unlike prior reports, no acidic or basic additives are required for this process. The practicality of this protocol is further highlighted by the gram-scale reaction and rapid access to functionalized 3,4-dihydro-2H-1,4-benzoxazines.
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