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Hydroamination of Dihapto-Coordinated Benzene and Diene Complexes of Tungsten: Fundamental Studies and the Synthesis of γ-Lycorane
Helvetica Chimica Acta ( IF 1.8 ) Pub Date : 2021-08-10 , DOI: 10.1002/hlca.202100103
Katy B Wilson 1 , Hannah S Nedzbala 1 , Spenser R Simpson 1 , Megan N Ericson 1 , Karl S Westendorff 1 , Mahendra D Chordia 1 , Diane A Dickie 1 , W Dean Harman 1
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Reactions are described for complexes of the form WTp(NO)(PMe3)(η2-arene) and various amines, where the arene is benzene or benzene with an electron-withdrawing substituent (CF3, SO2Ph, SO2Me). The arene complex is first protonated to form an η2-arenium species, which then selectively adds the amine. The resulting η2-5-amino-1,3-cyclohexadiene complexes can then be subjected to the same sequence with a second nucleophile to form 3-aminocyclohexene complexes, where up to three stereocenters originate from the arene carbons. Alternatively, 1,3-cyclohexadiene complexes containing an ester group at the 5 position (also prepared from an arene) can be treated with acid followed by an amine to form trisubstituted 3-aminocyclohexenes. When the amine is primary, ring closure can occur to form a cis-fused bicyclic γ-lactam. Highly functionalized cyclohexenes can be liberated from the tungsten through oxidative decomplexation. The potential utility of this methodology is demonstrated in the synthesis of the alkaloid γ-lycorane. An enantioenriched synthesis of a lactam precursor to γ-lycorane is also described. This compound is prepared from an enantioenriched version of the tungsten benzene complex. Regio- and stereochemical assignments for the reported compounds are supported by detailed 2D-NMR analysis and 13 molecular structure determinations (SC-XRD).

中文翻译:

钨的二重配位苯和二烯配合物的加氢胺化:基础研究和 γ-Lycorane 的合成

描述了 WTp(NO)(PMe 3 )(η 2 -芳烃)形式的配合物和各种胺的反应,其中芳烃是苯或具有吸电子取代基的苯 (CF 3、SO 2 Ph、SO 2 Me )。芳烃络合物首先质子化以形成 η 2 -芳烃物质,然后选择性地添加胺。结果 η 2然后,-5-氨基-1,3-环己二烯配合物可以与第二个亲核试剂进行相同的序列以形成 3-氨基环己烯配合物,其中多达三个立体中心源自芳烃碳。或者,在 5 位含有酯基的 1,3-环己二烯配合物(也由芳烃制备)可以先用酸处理,然后用胺处理,形成三取代的 3-氨基环己烯。当胺为伯胺时,可发生闭环形成顺式-稠合双环γ-内酰胺。高度官能化的环己烯可以通过氧化解络合从钨中释放出来。这种方法的潜在效用在生物碱 γ-lycorane 的合成中得到证明。还描述了 γ-lycorane 的内酰胺前体的对映体富集合成。该化合物由对映体富集的钨苯络合物制备。详细的 2D-NMR 分析和 13 分子结构测定 (SC-XRD) 支持报告化合物的区域和立体化学分配。
更新日期:2021-10-19
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