Direct Bis-Arylation of Cyclobutanecarboxamide via Double C–H Activation: An Auxiliary-Aided Diastereoselective Pd-Catalyzed Access to Trisubstituted Cyclobutane Scaffolds Having Three Contiguous Stereocenters and an All-<i>cis</i> Stereochemistry
作者:Ramarao Parella、Bojan Gopalakrishnan、Srinivasarao Arulananda Babu
DOI:10.1021/jo4019733
日期:2013.12.6
An auxiliary-aided Pd-catalyzed highly diastereoselective double C–H activation and direct bis-arylation of methylene C(sp3)–H bonds of cyclobutanecarboxamides and the syntheses of several novel trisubstituted cyclobutanecarboxamide scaffolds having an all-cis stereochemistry are reported. Extensive screening of various auxiliaries and reaction conditions was performed to firmly establish the optimized
辅助辅助Pd催化的高度非对映双C-H活化和亚甲基(SP的C直接双-芳基化3)-H cyclobutanecarboxamides的键和若干新颖的合成三取代环丁烷支架具有清一色顺式立体化学被报告。对各种助剂和反应条件进行了广泛的筛选,以牢固地建立实现环丁烷甲酰胺的单或双CH芳基化所需的优化反应条件。由助剂如8-氨基喹啉,2-(甲硫基)苯胺和N ',N制备的辅助连接的环丁烷甲酰胺15a,15g和15h发现'-二甲基乙烷-1,2-二胺经历了有效的直接双芳基化。N-(喹啉-8-基)环丁烷甲酰胺15a与一当量或更多的芳基碘化物经Pd催化的芳基化反应,得到相应的双芳基化环丁烷甲酰胺16a - y。尽管如此,的Pd催化的芳基化部15a与仅0.5当量的芳基碘的13A,13B,13E,和13米,选择性地得到相应的monoarylated cyclobutanecarboxamides 17A - 17D。P