Diastereoselective synthesis of 4,5-dihydrofurans by iodoenolcyclisation of 2-allyl-1,3-dicarbonyl compounds
摘要:
A study of the stereochemical aspects of I-2-induced cyclisation of 2-alkenyl-1,3-dicarbonyl compounds reveals that the iodoenolcyclisation is strictly dependent on the dicarbonyl species and the substituents in the allylic position. (C) 2002 Elsevier Science Ltd. All rights reserved.
A new route to 2-alkenyl-1,3-dicarbonyl compounds, intermediates in the synthesis of dihydrofurans
摘要:
A two step synthetic strategy for obtaining 2-alkenyl-1,3-dicarbonyl compounds from the corresponding 1,3-dicarbonyl compounds is reported. The method is based on a Knoevenagel condensation and a Michael addition using a high order organocuprate procedure, and proves to be of general value, Obtained compounds are useful starting materials for the synthesis of furan derivatives, (C) 2002 Elsevier Science Ltd. All rights reserved.
efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π‐acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′‐dioxide–nickel(II) complex. A range of acyclic α‐allyl β‐keto esters were synthesized in high yields (up to 99 %) with good
chlorides by carbon nucleophiles and phenols, respectively. After generation of diaminocarbene species upon deprotonation by tBuOK, their association with [Cp*Ru(MeCN)3]PF6 induces a very high regioselectivity in favor of the branched isomers when cinnamyl derivatives are used as starting substrates. They also provide good regioselectivities for the allylation of phenols by unsymmetrical aliphatic allylic
New 1,2,4,5-tetrakis-(N-imidazoliniummethyl)benzene and 1,2,4,5-tetrakis-(N-benzimidazoliummethyl)benzene salts as N-heterocyclic tetracarbene precursors: synthesis and involvement in ruthenium-catalyzed allylation reactions
New tetraimidazolinium and tetrabenzimidazolium salts have been prepared. Upon reaction with tBuOK, they generate carbene ligands, which were associated in situ to [RuCp*(MeCN)3]PF6 to produce new ruthenium catalysts that are active for the substitution of allylic substrates by amines, phenols, and carbonucleophiles. The influence of the N-heterocyclic core as well as that of the N-substitutents at
Ruthenium(<scp>ii</scp>)-catalysed direct synthesis of mono-allylation products of 1,3-diketones from cinnamyl alcohols
作者:Rajesh K. Jena、Mahesh Samanta、Mohan C. Sau、Sonali Panda、Braja N. Patra、Manish Bhattacharjee
DOI:10.1039/d2nj01650h
日期:——
synthesized and structurally characterized. It crystallizes in the orthorhombic non-centrosymmetric space group P212121 and undergoes auto-resolution. The complex is an efficient catalyst for direct carbon–carbonbond-formationreactions using cinnamyl alcohols to produce enantio- and regioselective mono-allylation products of diketones in high yield. A wide range of substrates provides good to excellent
合成了复合物[Ru( p -cymene)(dppe)Cl]PF 6 ·C 7 H 8并进行了结构表征。它在正交非中心对称空间群P 2 1 2 1 2 1中结晶并经历自动分辨。该配合物是一种有效的催化剂,用于直接碳-碳键形成反应,使用肉桂醇以高收率生产二酮的对映选择性和区域选择性单烯丙基化产物。广泛的基材提供了良好的产量。吡咯烷和乙酸添加剂的使用增加了选择性并防止了不需要的副产物。
Arylboronic Acid Catalyzed <i>C</i>-Alkylation and Allylation Reactions Using Benzylic Alcohols
作者:Susana Estopiñá-Durán、Euan B. Mclean、Liam J. Donnelly、Bryony M. Hockin、James E. Taylor
DOI:10.1021/acs.orglett.0c02736
日期:2020.10.2
The arylboronic acid catalyzed dehydrative C-alkylation of 1,3-diketones and 1,3-ketoesters using secondary benzylic alcohols as the electrophile is reported, forming new C-C bonds (19 examples, up to 98% yield) with the release of water as the only byproduct. The process is also applicable to the allylation of benzylic alcohols using allyltrimethylsilane as the nucleophile (12 examples, up to 96% yield).