Palladium??Catalyzed Monoselective Halogenation of C H Bonds: Efficient Access to Halogenated Arylpyrimidines using Calcium Halides

B Song, X Zheng, J Mo, B Xu

Index: Song, Bingrui; Zheng, Xiaojian; Mo, Jun; Xu, Bin Advanced Synthesis and Catalysis, 2010 , vol. 352, # 2-3 p. 329 - 335

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Citation Number: 60

Abstract

We initiated our study with electron-deficient substrate 1a in the presence of CuCl 2 6e or NCS,6f however, low yield and monoselectivity of 2a were observed (Table 1, entries 1–3). Use of CaCl 2 and Cu(OTFA) 2 in acetic acid led to improvements of both yield and monoselectivity (entry 6 vs. entries 3–5), although a long reaction time was needed to reach completion. To our delight, CaCl 2 (6.0 equiv.) and Cu(OTFA) 2 (1.0 equiv.) turned out to be the best choice ...