I2/DMSO-Promoted the synthesis of chromeno[4,3‑b]quinolines through an imine formation/aza-Diels-Alder/aromatization tandem reaction under metal-catalyst and photosensitizer-free conditions

Synthesis ◽  
2021 ◽  
Author(s):  
Angelica Peñaranda ◽  
Carlos Eduardo E. Puerto Galvis ◽  
Mario Alberto Macias ◽  
Cristian Ochoa-Puentes ◽  
Vladimir V. Kouznetsov
Keyword(s):  
Lewis Acid ◽  
Molecular Iodine ◽  
Diels Alder ◽  
Metal Catalyst ◽  
Tandem Reaction ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Heterocyclic Molecules ◽  
Dmso System ◽  
Tandem Process

A tandem approach was developed for the efficient synthesis of substituted chromeno[4,3-b]quinolines from arylamines and O-cinnamyloxy salicylaldehydes under metal-catalyst and photosensitizer-free reaction conditions. Our protocol is based on an inexpensive I2/DMSO system in which molecular iodine first acts as a Lewis acid to promote the formation of the corresponding imine bearing the alkene moiety, then, this species fulfills a second role by catalyzing the intramolecular aza-Diels-Alder cycloaddition to generate the respective tetrahydro-chromenoquinolines as an intermediates. Finally, the dual behaviour of DMSO as an oxidant and as a solvent resulted crucial at this stage, allowing the regeneration of I2 and promoting the aromatization of the tetrahydro-chromenoquinoline intermediates to yield the desired 7-aryl-6H-chromeno[4,3-b]quinolines. This protocol features by being mild, easy to perform, high step-economy (tandem process) and for providing a new access to biologically important nitrogen and oxygen containing heterocyclic molecules.

scholarly journals Efficient synthesis of dihydropyrimidinones via a three-component Biginelli-type reaction of urea, alkylaldehyde and arylaldehyde

2013 ◽  
Vol 9 ◽  
pp. 2846-2851 ◽  
Author(s):  
Haijun Qu ◽  
Xuejian Li ◽  
Fan Mo ◽  
Xufeng Lin
Keyword(s):  
Molecular Iodine ◽  
Tandem Reaction ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
One Pot ◽  
Type Reaction ◽  
Reaction Proceeds ◽  
Phosphoric Acids ◽  
Substituted Urea

A one-pot three-component synthesis of dihydropyrimidinones via a molecular iodine-catalyzed tandem reaction of simple readily available mono-substituted urea, alkylaldehyde, and arylaldehyde has been developed. The reaction proceeds with high chemo- and regioselectivity to give highly diverse dihydropyrimidinones in reasonable yields under mild reaction conditions. Moreover, the first catalytic enantioselective version of this reaction was also realized by using chiral spirocyclic SPINOL-phosphoric acids.

Metal and Non-Metal Catalysts in the Synthesis of Five-Membered S-Heterocycles

2019 ◽  
Vol 16 (2) ◽  
pp. 258-275 ◽  
Author(s):  
Navjeet Kaur
Keyword(s):  
Organic Synthesis ◽  
Biological Activities ◽  
Reaction Times ◽  
Research Field ◽  
Environmentally Benign ◽  
Metal Catalyst ◽  
Efficient Synthesis ◽  
Heterocyclic Molecules ◽  
The Past ◽  
Harsh Conditions

Background:A wide variety of biological activities are exhibited by N, O and S containing heterocycles and recently, many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and non-metal catalyst has become a highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of S-heterocylces in the presence of metal and non-metal catalyst. The synthesis of five-membered S-heterocycles is described here.Objective:There is a need for the development of rapid, efficient and versatile strategy for the synthesis of heterocyclic rings. Metal, non-metal and organocatalysis involving methods have gained prominence because traditional conditions have disadvantages such as long reaction times, harsh conditions and limited substrate scope.Conclusion:The metal-, non-metal-, and organocatalyst assisted organic synthesis is a highly dynamic research field. For ßthe chemoselective and efficient synthesis of heterocyclic molecules, this protocol has emerged as a powerful route. Various methodologies in the past few years have been pointed out to pursue more sustainable, efficient and environmentally benign procedures and products. Among these processes, the development of new protocols (catalysis), which avoided the use of toxic reagents, are the focus of intense research.

Intramolecular Diels–Alder reactions of 2H-thiopyran dienes

1996 ◽  
Vol 74 (7) ◽  
pp. 1418-1436 ◽  
Author(s):  
Dale E. Ward ◽  
Thomas E. Nixey ◽  
Yuanzhu Gai ◽  
Matthew J. Hrapchak ◽  
M. Saeed Abaee
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Thermal Conditions ◽  
Sigmatropic Rearrangement ◽  
Diels Alder ◽  
Methyl Groups ◽  
Type Ii ◽  
Reaction Conditions ◽  
Terminal Olefin ◽  
High Stereoselectivity

A systematic survey of IMDA reactions of 4-[tris(2-methylethyl)silyl]oxy-2H-thiopyran derivatives with potential dienophiles tethered at the C-2, C-3, C-5, and C-6 positions is presented. Cycloaddition was not observed with a C3 or C4 tether and an unactivated terminal olefin as dienophile. IMDA adducts could be obtained when dienophiles activated by a carbomethoxy group were employed. Compounds having the activated dienophile attached via a C3 tether to C-2 of the 2H-thiopyran gave adducts with high stereoselectivity. Substrates having the dienophile attached to C-3 with a C3 or C4 tether cyclized readily. With an (E)-enoate as the dienophile, the stereoselectivity was poor (endo:exo = 1.1–2.5:1) and essentially independent of reaction conditions (i.e., thermal vs. Lewis acid mediated). With the(Z)-enoate, a 7:1 mixture of endo:exo IMDA adducts was obtained under thermal conditions; with Lewis acid catalysis, isomerization of the dienophile was competitive with cycloaddition. Type II IMDA adducts were not observed with C-5 tethered substrates. Compounds having the dienophile attached to C-6 via a C3 or a five-atom tether also failed to give IMDA adducts. No evidence for isomerization of the 2H-thiopyran dienes by [1,5] sigmatropic rearrangement was observed. The endo adducts from IMDA reactions of the C-3 tethered substrates can be desulfurized to obtain synthetically useful trans-fused hydrindans and decalins with angular methyl groups. Key words: intramolecular Diels–Alder, 2H-thiopyran, cis-substituted 1,3-diene surrogate, trans-octahydro-3a-methyl-1H-indene derivatives, trans-decahydro-4a-methylnapthalene derivatives.

Prochiral alkyl-aminomethyl ketones as convenient precursors for efficient synthesis of chiral (2,3,5)-tri-substituted pyrrolidines via an organo-catalysed tandem reaction

RSC Advances ◽  
2016 ◽  
Vol 6 (61) ◽  
pp. 55764-55767 ◽  
Author(s):  
Yuming Song ◽  
Ke Li ◽  
Tao Shu ◽  
Yamei Xie ◽  
Yixin Zhang ◽  
...  
Keyword(s):  
Secondary Amine ◽  
Tandem Reaction ◽  
Efficient Synthesis ◽  
Tandem Process ◽  
High Yields

2-Alkanoyl-3-aryl-5-hydroxy pyrrolidines were prepared in high yields and ees via a secondary amine catalyzed tandem process.

Asymmetric Inverse-Electron-Demand Diels–Alder Reactions of 2-Pyrones by Lewis Acid Catalysis

Synlett ◽  
2021 ◽  
Author(s):  
Quan Cai ◽  
Xu-Ge Si ◽  
Zhi-Mao Zhang
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Diels Alder ◽  
Enantioselective Synthesis ◽  
Natural Product Synthesis ◽  
Lewis Acid Catalysis ◽  
Reaction Conditions ◽  
Inverse Electron Demand ◽  
Bicyclic Lactones ◽  
Electron Demand

AbstractDiels–Alder reactions of 2-pyrones with alkenes can provide highly functionalized [2,2,2]-bicyclic lactones under mild reaction conditions. Synthetic utilizations of these reactions have been well demonstrated in natural-product synthesis. Although several catalytic asymmetric strategies have been realized, current research in this area is still largely underdeveloped. Recent advances in enantioselective inverse-electron-demand Diels–Alder reactions with Lewis acid catalysis are reviewed.1 Introduction2 State of the Art of Enantioselective Diels–Alder Reactions of 2-Pyrones by Lewis Acid Catalysis3 Enantioselective Synthesis of Arene cis-Dihydrodiols by Diels–­Alder/Retro-Diels–Alder Reactions of 2-Pyrones4 Enantioselective Synthesis of cis-Decalin Derivatives by Diels–­Alder Reactions of 2-Pyrones5 Conclusions

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