One-Pot Quinine-Catalyzed Synthesis of α-Chiral γ-Keto Esters: Enantioenriched Precursors of <i>cis</i>
-α,γ-Substituted-γ-Butyrolactones
作者:Sara Meninno、Chiara Volpe、Alessandra Lattanzi
DOI:10.1002/adsc.201600427
日期:2016.9.1
enantioselective one‐pot synthesis of important building blocks, α‐chiral γ‐keto esters, has been developed by combining a quinine‐catalyzed Michael addition of malononitrile to trans‐enones followed by magnesium monoperoxyphthalate (MMPP) oxidation. These synthons proved to be useful reagents for a simple access to challenging cis‐α,γ‐disubstituted γ‐butyrolactones in good diastereoselectivity and
conjugate addition of malononitrile to trans-chalcones has been investigated as a case study using easily available α,α-L-diaryl prolinols as promoters. Both experimental and computational results are consistent with a bifunctional noncovalent mode of activation of the reactive partners, provided by the secondary amine and hydroxyl groups of the promoter as generalbase and acid catalysis. This most
丙二腈与反式查耳酮的对映选择性共轭加成已作为案例研究,使用容易获得的 α,α-L-二芳基脯氨醇作为促进剂。实验和计算结果都与反应伙伴的双功能非共价活化模式一致,由作为一般碱和酸催化的促进剂的仲胺和羟基提供。这种最能负担得起的途径预测了 R 型加合物的主要形成,这与实验结果一致。本研究首次解决了脯氨酸衍生物通过非共价催化辅助产物形成的能力,类似于金鸡纳生物碱的典型作用模式。
Chloramphenicol base chemistry. Part 11: 1 chloramphenicol base-derived thiourea-catalyzed enantioselective Michael addition of malononitrile to α , β -unsaturated ketones
The first chloramphenicol base-derived thiourea-catalyzed enantioselective Michael addition of malononitrile to alpha,beta-unsaturated ketones is reported. The Michael adducts were obtained in good to excellent yields (up to 98% yield) and enantioselectivities (up to 94% ee). This reaction has a broad substrate scope to various alpha,beta-unsaturated ketones. With this in mind, this methodology was successfully applied to the synthesis of a chiral piperidone, an advanced building block for dihydropyridinone P2X(7) receptor antagonists. (C) 2017 Published by Elsevier Ltd.
Organocatalytic Enantioselective Decarboxylative Michael Addition of β-Keto Acids to Dicyanoolefins and Disulfonylolefins
作者:Yi Wei、Ran Guo、Yanfeng Dang、Jing Nie、Jun-An Ma
DOI:10.1002/adsc.201600485
日期:2016.9.1
A convenient organocatalyticenantioselective decarboxylative Michaeladdition of β‐keto acids to dicyanoolefins and disulfonylolefins is realized. In the presence of saccharide‐derived chiral amino thioureas, the reaction proceeded smoothly to afford a wide range of the Michael adducts in 62–99% yield with 70–94% ee. Moreover, one of the chiral adducts obtained could be readily converted into the