Enantioselective Alkynylation of Aldehydes with 1-Haloalkynes Catalyzed by Tethered Bis(8-quinolinato) Chromium Complex
摘要:
The first example of Cr-catalyzed asymmetric alkynylation of aldehydes with 1-iodo- and 1-bromoalkynes was developed. The use of tethered bis(8-quinolinato) chromium catalyst (3 mol %) allowed preparation of enantioenriched propargyl alcohols with good yields and enantioselectivities up to 92% ee. 1-Bromoalkynes can be activated by the introduction of a cobalt porphine co-catalyst, which enables shorter reaction times without any loss of enantiocontrol.
Mesoionic Carbene (MIC)-Catalyzed H/D Exchange at Formyl Groups
作者:Wei Liu、Liang-Liang Zhao、Mohand Melaimi、Lei Cao、Xingyu Xu、Jean Bouffard、Guy Bertrand、Xiaoyu Yan
DOI:10.1016/j.chempr.2019.08.011
日期:2019.9
exchange at formyl groups is the most direct approach for the synthesis of deuterated aldehydes. Platinum-group metal complexes have been employed to catalyze this transformation, with significant substrate scope limitations. Although N-heterocyclic carbenes can also activate the C–Hbond of aldehydes through the formation of Breslow intermediates, benzoin condensation and other C–C-bond-forming pathways
Access to 2-Alkyl/Aryl-4-(1<i>H</i>)-Quinolones via Orthogonal “NH<sub>3</sub>” Insertion into <i>o</i>-Haloaryl Ynones: Total Synthesis of Bioactive Pseudanes, Graveoline, Graveolinine, and Waltherione F
An efficient one-pot synthesis of 4-(1H)-quinolones through an orthogonal engagement of diverse o-haloaryl ynones with ammonia in the presence of Cu(I), involving tandem Michael addition and ArCsp2-N coupling, is presented. The substrate scope of this convenient protocol, wherein ammonium carbonate acts as both an in situ ammonia source and a base toward diverse 2-substituted 4-(1H)-quinolones, has
A tandem annulation of arylpropynols with disulfides has been developed for the synthesis of 2-sulfenylindenone derivatives. The reaction pathway involves one-pot tandem Meyer–Schusterrearrangement of arylpropynols and successive radical cyclization with disulfides. Various arylpropynols and disulfides with a number of functional groups are compatible in this reaction that affords the corresponding
Nitromethane as a Carbanion Source for Domino Benzoannulation with Ynones: One‐Pot Synthesis of Polyfunctional Naphthalenes and a Total Synthesis of Macarpine
applicability has been devised for the regioselective synthesis of polyfunctional naphthalenes by employing nitromethane and ortho‐haloaryl ynones. Utilization of nitromethane as a one carbon carbanion source that is incorporated into a variety of ynones, ends up as an aromatic nitro substituent. The application of this domino process towards a total synthesis of the polycyclic alkaloid macarpine demonstrate
的单釜,过渡金属-自由,多米诺迈克尔/ S Ñ普遍适用性的Ar协议已经通过使用硝基甲烷和设计用于多官能萘的区域选择性合成邻-haloaryl ynones。硝基甲烷作为一种碳碳负离子源的使用,并被引入到各种炔酮中,最终以芳族硝基取代基的形式出现。该多米诺法在多环生物碱马卡平的全合成中的应用证明了该方法的有效性。在概念上是简单的方法来影响ynones显示广泛的底物范围和官能团耐受性,并已与被取代的硝基甲烷实现的区域选择性,多功能benzoannulation以及与脂环ö-单倍体。
Synthesis of Phosphonylated and Thiolated Indenones by Manganese(III)-Mediated Addition of Phosphorus- and Sulfur-Centered Radicals to 1,3-Diarylpropynones
Phosphorus- or sulfur-centered radicals generated from the reaction of manganese (III) acetate with dialkyl phosphonates or arylthiols undergo selective additions to conjugated alkynes followed by cyclization and rearomatization to afford 2-phosphonyl- or 2-thioaryl-substituted indenones in fair to good yields.