Catalyst-Free Synthesis of Chromane-Type N,O-Acetals via Intramolecular Addition of Phenols to Enamines
作者:Vitaly A. Osyanin、Dmitry V. Osipov、Irina V. Melnikova、Kirill S. Korzhenko、Irina A. Semenova、Yuri N. Klimochkin
DOI:10.1055/s-0040-1707209
日期:2020.12
Abstract A new strategy to 2-aminochromanes through catalyst-free cascade reaction of 3-trifluoroacetyl-4H-chromenes and 4H-chromene-3-carbaldehydes with cyclic secondary amines is presented. The reaction proceeds through subsequent 1,4- and 1,2-additions of amine, bimolecular elimination of trifluoroacetamide or formamide, and 6-exo-trig cyclization. The latter stage is a very rare example of addition
Convenient one-step synthesis of 4-unsubstituted 2-amino-4H-chromene-2-carbonitriles and 5-unsubstituted 5H-chromeno[2,3-b]pyridine-3-carbonitriles from quaternary ammonium salts
作者:Vitaly A. Osyanin、Dmitry V. Osipov、Yuri N. Klimochkin
DOI:10.1016/j.tet.2012.04.065
日期:2012.7
We have reported DBU catalyzed synthesis of 4-unsubstituted 2-amino-4H-chromene-2-carbonitriles in water under reflux. The attractive features of this process are mild reaction conditions, short reaction times, easy isolation of products and good yields. 5H-chromeno[2,3-b]pyridine-3-carbonitriles were obtained by refluxing excess of malononitrile and quaternary ammonium salts in ethanol in the presence
我们已经报道了DBU在回流下在水中催化4-未取代的2-氨基-4 H-亚甲基-2-腈的合成。该方法的吸引人的特征是反应条件温和,反应时间短,产物易于分离和产率高。在NaOH为催化剂的情况下,通过将过量的丙二腈和季铵盐在乙醇中回流,得到5 H -chromeno [2,3 - b ]吡啶-3-腈。据信这些反应的机理涉及邻醌甲基化物中间体的形成。
Conversions of Mannich Phenol Bases; II. Synthesis of 2-Thioxo-2<i>H</i>-3,4-dihydro-1,3-benzoxazine Derivatives
作者:Jacek ARCT、Elżbieta JAKUBSKA、Grażyna OLSZEWSKA
DOI:10.1055/s-1977-24375
日期:——
Arct,J. et al., Synthetic Communications, 1978, vol. 8, p. 143 - 149
作者:Arct,J. et al.
DOI:——
日期:——
Potassium Trinitromethanide as a 1,1-Ambiphilic Synthon Equivalent: Access to 2-Nitroarenofurans
作者:Vitaly A. Osyanin、Dmitry V. Osipov、Maxim R. Demidov、Yuri N. Klimochkin
DOI:10.1021/jo402543s
日期:2014.2.7
The first example of the use of potassium trinitromethanide as a 1,1-ambiphilic synthon equivalent for the construction of a benzofuran moiety mediated by triethylamine has been developed. The method tolerates a variety of functional groups on the starting quaternary ammonium salt and has been successfully extended to polysubstituted benzofurans. Formation of an o-quinone methide intermediate is postulated as a key to the mechanism of this cascade process.