描述了吡咯并[2,1 - a ] isoindol-5-ones的立体选择性合成。通过串联的迈克尔加成-分子内环化反应进行合成,方法是在低温下将N-邻苯二甲酰丙氨酸甲酯与共轭受体进行碱促进的缩合反应。仅一步就以单一异构体的高收率获得所需产物。据推测,环化步骤的立体选择性是由相互作用中心之间的螯合锂物质动力学控制的。讨论了加合物的结构,并得到NMR实验和X射线晶体学的支持。
functionality has been reliably transferred into nucleophilic radicals with the loss of one molecule of formaldehyde. Intriguingly, we found that the dehydroxymethylation process can be significantly promoted by the cerium catalyst, and the stabilization effect of the fragmented radicals also plays a significant role. This operationally simple protocol has enabled the direct utilization of primary alcohols as unconventional
Efficient, direct α-methylenation of carbonyls mediated by diisopropylammonium trifluoroacetate
作者:Alejandro Bugarin、Kyle D. Jones、Brian T. Connell
DOI:10.1039/b924577d
日期:——
A very efficient method for the direct α-methylenation of carbonyl compounds, with yields up to 99%, utilizing paraformaldehyde, diisopropylammonium trifluoroacetate, and catalytic acid or base, is presented.
the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and alkylation of hydrocarbons, this reaction
Iminyl radicals: Part I. generation and intramolecular capture by an olefin.
作者:Jean Boivin、Eric Fouquet、Samir Z. Zard
DOI:10.1016/s0040-4020(01)80849-8
日期:1994.1
Slow addition of tributylstannane to sulphenylimines 2 give the corresponding Δ1- pyrrolenines 5 by an intramolecularaddition of the intermediate iminyl radical, a process which can be easily coupled to an intermolecular addition to an electrophilic olefin.
Ytterbium Triflate Catalyzed Synthesis of Alkoxy-Substituted Donor−Acceptor Cyclobutanes and Their Formal [4 + 2] Cycloaddition with Imines: Stereoselective Synthesis of Piperidines
作者:Mahmoud M. Abd Rabo Moustafa、Brian L. Pagenkopf
DOI:10.1021/ol102062t
日期:2010.11.5
A new synthesis of 2-alkoxy-1,1-cyclobutane diesters and their first use in dipolar cycloadditions is reported. Both the formation of the donor−acceptor cyclobutanes and their subsequent annulation with in situ formed imines are catalyzed by Yb(OTf)3. Cyclobutanes with carbon donor groups give piperidines with high trans stereoselectivity.