Regioselective synthesis of biologically interesting pentacyclic polyheterocycles by sequential thio-Claisen and AlCl3 catalyzed oxy-Claisen rearrangement of 4-(4′-aryloxybut-2′-ynylthio)-1-phenyl-1,8-naphthyridin-2(1H)-one

2006 ◽  
Vol 84 (12) ◽  
pp. 1632-1639 ◽  
Author(s):  
K C Majumdar ◽  
R Islam
Keyword(s):  
Lewis Acid ◽  
Claisen Rearrangement ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Acid Catalyst ◽  
Sigmatropic Rearrangement ◽  
Regioselective Synthesis ◽  
X Ray ◽  
Lewis Acid Catalyst ◽  
Acid Catalyzed

A number of 4-aryloxymethyl-6-phenyl-2H-thiopyrano[3,2-c][1,8]naphthyridin-5(6H)-ones were regio selectively synthesized in 82%–95% yields by the thermal Claisen rearrangement of 4-(4′-aryloxybut-2′-ynylthio)-1-phenyl-[1,8]naphthyridin-2(1H)-ones. These products were then subjected to a second Claisen rearrangement in the presence of a Lewis acid catalyst, anhyd. AlCl3, to give hitherto unreported pentacyclic heterocycles in 75%–90% yields. The same final products were also obtained in low yield upon refluxing 4-aryloxymethyl-6-phenyl-2H-thio pyrano-[3,2-c][1,8]naphthyridin-5(6H)-ones in N,N-diethyl aniline for 12–14 h. This method was found to be more effective than thermal Claisen rearrangement.Key words: [3,3] sigmatropic rearrangement, regioselective synthesis, phase transfer catalysis, sequential Claisen rearrangement, Lewis acid catalyzed Claisen rearrangement, single crystal X-ray.

Lewis acid catalyzed Claisen rearrangement: Regioselective synthesis of oxygen, nitrogen, and sulfur heterocycles

2008 ◽  
Vol 86 (1) ◽  
pp. 72-78 ◽  
Author(s):  
K C Majumdar ◽  
A K Pal
Keyword(s):  
Lewis Acid ◽  
Claisen Rearrangement ◽  
Sigmatropic Rearrangement ◽  
Regioselective Synthesis ◽  
Aluminium Chloride ◽  
Sulfur Heterocycles ◽  
Acid Catalyzed

Regioselective synthesis of pentacyclic heterocycles containing oxygen, nitrogen, and sulfur has been achieved in good to excellent yields by the sequential Claisen rearrangement of but-2-ynyl ethers and sulfides containing quinolone moiety. The substrates ethers and sulfides were prepared from 1-aryloxy-4-chlorobut-2-ynes with N-alkyl-4-hydroxyquinoline-2(1H)-ones.Key words: regioselectivity, [3,3] sigmatropic rearrangement, nucleophilicity of sulfur, aluminium chloride, heterocycles.

An acyl-Claisen approach to the synthesis of lignans and substituted pyrroles

2012 ◽  
Vol 84 (7) ◽  
pp. 1557-1565 ◽  
Author(s):  
David Barker ◽  
Benjamin Dickson ◽  
Nora Dittrich ◽  
Claire E. Rye
Keyword(s):  
Lewis Acid ◽  
Nucleophilic Addition ◽  
Claisen Rearrangement ◽  
Acid Catalyst ◽  
Protecting Groups ◽  
Organometallic Reagent ◽  
Wacker Oxidation ◽  
Lewis Acid Catalyst ◽  
Substituted Pyrroles

The acyl-Claisen rearrangement, also called a zwitterionic aza-Claisen rearrangement, allows for the synthesis of 2,3-syn-substituted morpholine pent-4-eneamides with high levels of diastereoselectivity. A wide variety of alkyl and aryl substituents can be introduced with yields highly dependent on the stoichiometry of the Lewis acid catalyst. The use of these morpholine amides in the synthesis of the tetrasubstituted tetrahydrofuran lignans fragransin A2, talaumidin, and galbelgin is summarized. The conversion of the Claisen-derived amides into aryl tetraline and 1,1-diarylbutanol lignans via alteration of the protecting groups is also described. Nucleophilic addition of an organometallic reagent to the morpholine amide followed by Wacker oxidation of the alkene gives highly substituted 1,4-diketones, which can be easily converted into fully substituted pyrroles.

Development of a New Lewis Acid-Catalyzed [3,3]-Sigmatropic Rearrangement:  The Allenoate-Claisen Rearrangement

2002 ◽  
Vol 124 (46) ◽  
pp. 13646-13647 ◽  
Author(s):  
Tristan H. Lambert ◽  
David W. C. MacMillan
Keyword(s):  
Lewis Acid ◽  
Claisen Rearrangement ◽  
Sigmatropic Rearrangement ◽  
Acid Catalyzed

scholarly journals Development of a New Lewis Acid Catalyzed [3,3]-Sigmatropic Rearrangement: The Allenoate-Claisen Rearrangement.

ChemInform ◽  
2003 ◽  
Vol 34 (10) ◽  
Author(s):  
Tristan H. Lambert ◽  
David W.C. MacMillan
Keyword(s):  
Lewis Acid ◽  
Claisen Rearrangement ◽  
Sigmatropic Rearrangement ◽  
Acid Catalyzed

scholarly journals BX3-Mediated Intermolecular Formation of Functionalized 3-Halo-1H-indenes via Cascade Halo-Nazarov-Type Cyclization

Synthesis ◽  
2020 ◽  
Vol 52 (15) ◽  
pp. 2245-2258
Author(s):  
Rodney A. Fernandes ◽  
Anupama Kumari
Keyword(s):  
Lewis Acid ◽  
Acid Catalyst ◽  
Dual Role ◽  
Regioselective Synthesis ◽  
Lewis Acid Catalyst

A BX3-promoted, intermolecular regioselective synthesis of 3-halo-functionalized 1H-indenes from 4-oxo-4H-chromene-3-carb­aldehydes and alkynes has been developed. BX3 displays a dual role of Lewis acid catalyst and halide source for haloallyl cation formation for the intended halo-Nazarov-type cyclization. The overall transformation represents an efficient cascade annulation that employs readily available starting materials, inexpensive reagents and a convenient and mild reaction procedure to generate halo-functionalized indenes (45 examples). The reaction was also extended to 8-formylcoumarins to deliver coumarin-based 3-halo-1H-indenes in 79–95% yield (6 examples). The reaction involves conversion of the aldehyde into an sp3 carbon with two new C–C bonds and additionally a C–X bond is formed (X = halide).

Mechanism of Lewis-acid-catalyzed intramolecular coupling of sp3C–H bond and alkene: A theoretical investigation

2014 ◽  
Vol 13 (02) ◽  
pp. 1450015
Author(s):  
Miaoqiang Ye ◽  
Rongfu Liu ◽  
Hui Zeng ◽  
Kai Tan ◽  
Xin Lu
Keyword(s):  
Carbon Atom ◽  
Lewis Acid ◽  
Density Functional ◽  
Substituent Effects ◽  
Hydride Transfer ◽  
Acid Catalyst ◽  
First Principle ◽  
Lewis Acid Catalyst ◽  
Acid Catalyzed ◽  
Rate Limiting

First-principle density functional calculations have been carried out to explore the mechanism of the BF 3-catalyzed intramolecular coupling between a C ( sp 3)- H bond in the α-position of such heteroatom as O and an electron-deficient alkene that has an electron-withdrawing substitute, e.g. acetal or carbonyl [McQuaid KM, Sames D, J Am Chem Soc131:402, 2009]. The computations not only confirmed the previously proposed mechanism that coordination of BF 3 (as Lewis acid catalyst) to the acetal oxygen atom triggers 1,5-hydride transfer from the α- C ( sp 3)- H bond to the alkenic carbon, followed by 1,6-cyclization ( C – C bond formation) between the carbon atom of the as-formed oxacarbenium and another alkenic carbon atom, but also disclosed that the 1,5-hydride transfer step is rate-limiting and the cyclization step accounts for the stereoselectivity. In addition, the following substituent effects were disclosed, i.e. the efficacy of intramolecular coupling can be significantly improved by introducing a more electron-donative amino group as the closest neighbor of the hydride donor, but retarded by introducing a less electron-withdrawing – CO 2 Me group as the closest neighbor of the hydride acceptor or by introducing an aromatic phenyl linkage, instead of the saturated linkages exploited in experiments, between the two reacting groups.

Computationally-Guided Investigation of Dual Amine/pi Lewis Acid Catalysts for Direct Additions of Aldehydes and Ketones to Unactivated Alkenes and Alkynes

2020 ◽  
Author(s):  
Eric Greve ◽  
Jacob D. Porter ◽  
Chris Dockendorff
Keyword(s):  
Lewis Acid ◽  
Density Functional ◽  
Acid Catalyst ◽  
Metal Catalyst ◽  
Catalyst Poisoning ◽  
Lewis Acid Catalysts ◽  
Metal Ligands ◽  
Aldehydes And Ketones ◽  
Lewis Acid Catalyst ◽  
Catalyst Systems

Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehyde/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that PyBOX-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan’s imidazolidinone organocatalyst for aldehyde/ketone activation to facilitate desirable C-C bond formations, and certain reactions were calculated to be more exergonic than catalyst poisoning pathways. As calculated, preformed enamines generated from the MacMillan imidazolidinone did not displace ethylene from a biscationic (<i>t</i>-Bu)PyBOX-Pt<sup>2+</sup>complex, but neither were the desired C-C bond formations observed under several different conditions.

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