Copper-Catalyzed Intramolecular Hydroalkoxylation of α-(1-Hydroxy-1-alkyl- and -aryl)methylallenoates by a 5-Endo Mode for Preparation of 2-Alkyl- and 2-Aryl-2,5-dihydrofurans
摘要:
Ethyl alpha-(1-hydroxy-1-alkyl)methylallenoates and alpha-(1-hydroxy-1-aryl)methylallenoates containing not only electron-donating groups but also an electron-withdrawing group on the aryl group at the alpha-position have been shown to undergo an efficient and selective copper-catalyzed intramolecular hydroalkoxylation to give functionalized 3-ethoxycarbony1-2-alkyl- and -aryl-2,5-dihydrofurans in good to excellent yields through a 5-endo mode.
β-unsaturated aldehydes and α-acetyl-β-aryl-α,β-unsaturated esters in excellent diastereo- and enantioselectivity. Three continuous stereocenters were controlled by diphenylprolinolsilyl ether-mediated domino Michael/Michaelreaction, followed by epimerization to thermodynamically favored compound.
iminyl‐radical formation has been established for the construction of pyridines, quinolines, and phenanthridines from acyl oximes. With fac‐[Ir(ppy)3] as a photoredox catalyst, the acyl oximes were converted by 1 e− reduction into iminyl radical intermediates, which then underwent intramolecular homolytic aromatic substitution (HAS) to give the N‐containing arenes. These reactions proceeded with a broad
已经建立了涉及可见光诱导的亚胺基自由基形成的统一策略,用于从酰基肟中构建吡啶,喹啉和菲啶。用FAC - [的Ir(ppy)3 ]作为催化剂photoredox,酰基肟通过1e中转化-还原成亚氨基自由基中间体,然后行分子内均裂芳族取代(HAS),得到含有N-芳烃其中。这些反应在室温下以宽范围的底物以高收率进行。这种可见光诱导的亚胺基自由基形成策略已成功地应用于五步精简合成苯并[ c ]菲啶生物碱。
Organocatalytically Enantioselective Approach to Polysubstituted Tetrahydropyridines and Piperidines
作者:Fang Yu、Xiaojing Zhang、Yongwen Jiang
DOI:10.1002/cjoc.201180327
日期:2011.9
2,3,4,5‐pentasubstituted tetrahydropyridines and piperidines was developed. This method relies on preparing the required enantiopure cyclic semi‐acetals via an organocatalyzed Michael addition/cyclization cascadereaction of aldehydes and α‐keto‐α,β‐unsaturated esters, and subsequent reductive amination/condensation with primary amines.
Reaction of Corey Ylide with α,β-Unsaturated Ketones: Tuning of Chemoselectivity toward Dihydrofuran Synthesis
作者:Alexey O. Chagarovsky、Ekaterina M. Budynina、Olga A. Ivanova、Elena V. Villemson、Victor B. Rybakov、Igor V. Trushkov、Mikhail Ya. Melnikov
DOI:10.1021/ol500877c
日期:2014.6.6
A straightforward, efficient, and reliable approach to synthetically valuable 2,3-dihydrofurans via a reaction between Corey ylide and α,β-unsaturated ketones has been developed. The use of simple and widely spread starting materials as well as mild reaction conditions and scalability provide a broad scope of 2,3-dihydrofurans.
A facile synthesis of trisubstituted alkenes from β-diketones and aldehydes with AlCl3 as catalyst
作者:Zheng-Nan Li、Xiao-Liang Chen、Yu-Jie Fu、Wei Wang、Meng Luo
DOI:10.1007/s11164-011-0322-y
日期:2012.1
Preparation of trisubstitutedalkenesfrom low-activity β-diketones and aldehydes with aluminum chloride as catalyst has been studied. The frequently used catalyst AlCl3 is used for the first time to promote this condensation. The procedure is a convenient, low toxicity, and highly efficient method for industrial synthesis of trisubstitutedalkenes in high yield.