Ruthenium catalyzed β-selective alkylation of vinylpyridines with aldehydes/ketones <i>via</i> N<sub>2</sub>H<sub>4</sub> mediated deoxygenative couplings
作者:Leiyang Lv、Chao-Jun Li
DOI:10.1039/d0sc06586b
日期:——
aldehyde/ketones via N2H4 mediated deoxygenative couplings. Compared with one-electron umpolung of carbonyls to alcohols, this two-electron umpolung strategy realized reductive deoxygenation targets, which were not only applicable to the regioselective alkylation of a broad range of 2/4-alkene substituted pyridines, but also amenable to challenging 3-vinyl and steric-embedded internal pyridines as well as their
Magnesium-promoted reductivesilylation of 2- and 4-vinylpyridines with chlorotrialkylsilanes in N-methylpyrrolidinone at room temperature led to the selective formation of a variety of the corresponding β-mono-silylated compounds at the terminal carbon atom in good to excellent yields, whereas silylation of 3-vinylpyridine under the same reduction conditions failed to give a complex mixture of silylated
Photosensitized [4+2]‐ and [2+2]‐Cycloaddition Reactions of <i>N</i>‐Sulfonylimines
作者:Wang Wang、M. Kevin Brown
DOI:10.1002/anie.202305622
日期:2023.8.7
Dearomative [4+2]-cycloadditions and azetidine-forming [2+2] cycloadditions (aza-Paternó-Büchi reactions) of sulfonylimines are presented. The divergent reactivity was achieved though substrate modulation. In both cases, the reactions lead to the synthesis of complex polycyclic scaffolds from simple components. The mechanistic details and the utility of the products are described.
Selective introduction of a trifluoroacetyl group onto 4-vinylpyridines through magnesium-promoted reduction
作者:Hirofumi Maekawa、Yutaro Nishiyama
DOI:10.1016/j.tet.2015.07.046
日期:2015.9
Magnesium-promoted reductive coupling of 4-vinylpyridines and ethyl trifluoroacetate in the presence of chlorotrimethylsilane in N-methyl-2-pyrrolidone resulted in selective formation of the tri-fluoroacetylated compounds at the beta-olefinic carbon of the pyridine ring, the electron deficient carbon in good yields. In particular, 4-vinylpyridine with an aromatic ring at the beta-olefinic position of the pyridine ring gave higher yield of the trifluoroacetylated compound. The nitrogen atom of the pyridine ring may play an important role in the regioselectivity of the product. (C) 2015 Elsevier Ltd. All rights reserved.