ChemInform Abstract: Base Mediated 7-exo-Dig Intramolecular Cyclization of Ugi-Propargyl Precursors: A Highly Efficient and Regioselective Synthetic Approach Toward Diverse 1,4-Benzoxazepine-5(2H)-ones.

ChemInform ◽  
2015 ◽  
Vol 46 (1) ◽  
Author(s):  
Shashi Pandey ◽  
S. Vinod Kumar ◽  
Ruchir Kant ◽  
Prem M. S. Chauhan
Keyword(s):  
Intramolecular Cyclization ◽  
Synthetic Approach ◽  
Highly Efficient

Base mediated 7-exo-dig intramolecular cyclization of Ugi–propargyl precursors: a highly efficient and regioselective synthetic approach toward diverse 1,4-benzoxazepine-5(2H)-ones

2014 ◽  
Vol 12 (29) ◽  
pp. 5346-5350 ◽  
Author(s):  
Shashi Pandey ◽  
S. Vinod Kumar ◽  
Ruchir Kant ◽  
Prem M. S. Chauhan
Keyword(s):  
Intramolecular Cyclization ◽  
Synthetic Approach ◽  
Metal Free ◽  
Highly Efficient

A metal-free facile and efficient two-step synthetic protocol for the preparation of 1,4-benzoxazepine-5(2H)-one derivatives has been developed.

Intramolecular Diels–Alder Reactions of Oxazoles, Imidazoles, and Thiazoles

Synthesis ◽  
2020 ◽  
Author(s):  
Peter Wipf ◽  
Thanh T. Nguyen
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Acid Catalysis ◽  
Copper Catalysts ◽  
Diels Alder ◽  
Synthetic Approach ◽  
Highly Efficient ◽  
Intramolecular Cycloadditions ◽  
Western Segment ◽  
Target Molecules

AbstractThe development of the intramolecular Diels–Alder cycloaddition­ of azole heterocycles, i.e. oxazoles (IMDAO), imidazoles (IMDAI), and thiazoles (IMDAT), has had a significant impact on the efficient preparation of heterocyclic intermediates and natural products. In particular, highly efficient and versatile IMDAO reactions have been utilized as a key step in several synthetic schemes to provide alkaloids and terpenoid target molecules. More limited studies have been performed on IMDAI and IMDAT cycloadditions. Some drawbacks, such as the occasionally­ challenging preparation of IMDA precursors, are also highlighted in this review. Perspectives are provided on how IMDAI and IMDAT­ transformations can be further expanded for target-directed syntheses.1 Introduction2 Oxazoles2.1 IMDAO Approaches to Furanosesquiterpenes and Furanosteroids2.1.1 Syntheses of Highly Oxygenated Sesquiterpenes2.1.2 Syntheses of (±)-Gnididione and (±)-Isognididione2.1.3 Synthesis of (±)-Stemoamide2.1.4 Synthesis of (±)-Paniculide A2.1.5 Syntheses of (+)- and (–)-Norsecurinine2.1.6 Synthesis of Evodone2.1.7 Syntheses of (±)-Ligularone and (±)-Petasalbine2.1.8 Syntheses of Imerubrine, Isoimerubrine, and Grandirubrine2.1.9 Syntheses of Furanosteroids2.1.10 Syntheses of Substituted Indolines and Tetrahydroquinolines2.2 IMDAO Approaches to Pyridines: the Kondrat’eva Reaction2.2.1 Syntheses of Suaveoline and Norsuaveoline2.2.2 Synthesis of Eupolauramine2.2.3 Syntheses of (–)-Plectrodorine and (+)-Oxerine2.2.4 Synthesis of Amphimedine2.2.5 Synthetic Approach to the Western Segment of Haplophytine2.2.6 Synthesis of Marinoquinoline A2.2.6.1 IMDAO Approach to Marinoquinoline A2.2.6.2 Scope of Allenyl IMDAO Cycloaddition2.3 Lewis Acid Catalysis in IMDAO Reactions2.3.1 Effects of Europium Catalysts on IMDAO Reactions2.3.2 Effects of Copper Catalysts on IMDAO Reactions3 Imidazoles 4 Thiazoles4.1 Syntheses of Menthane and Eremophilane4.2 Further Comments on the Intramolecular Cycloadditions of Thiocarbonyl Ylides5 Conclusions and Outlook

Palladium-catalyzed post-Ugi arylative dearomatization/Michael addition cascade towards plicamine analogues

2021 ◽  
Author(s):  
Chao Liu ◽  
Ruiqi Zhao ◽  
Liangliang Song ◽  
Zhenghua Li ◽  
Guilong Tian ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Michael Addition ◽  
Highly Efficient ◽  
Palladium Catalyzed

A palladium-catalyzed intramolecular cyclization of Ugi-adducts via a cascade dearomatization/aza-Michael addition process has been developed. Diverse plicamine analogues are constructed in a rapid, highly efficient and step-economical manner, through the...

Synthesis of a Dihydroxy-Substituted Aminoxyl Spin Label and its Crown Ether and Cyclic Diester Derivatives

1993 ◽  
Vol 48 (4) ◽  
pp. 505-510 ◽  
Author(s):  
Yong-Kang Zhang ◽  
De-Kang Shen
Keyword(s):  
Crown Ether ◽  
Intramolecular Cyclization ◽  
Spin Label ◽  
Cyclic Ether ◽  
Synthetic Approach ◽  
Aminoxyl Radicals

A novel dihydroxy-substituted aminoxyl spin label, 4-hydroxy-3-(3'-hydroxypropyl)-2,2,6,6-tetramethylpiperidine-1-oxy (5), has been prepared. From this aminoxyl radical, a spin-labeled crown ether, 16,16,18,18-tetramethyl-2,5,8,11-tetraoxa-17-azabicyclo[ 13,4,0]-nonadecane-17-oxy (12), and a spin-labeled cyclic diester, 16,16,18,18-tetramethyl-3,10-dioxo-2,5,8,11-tetraoxa-17-azabicyclo[13,4,o]nonadecane-17-oxy (13), have been acquired. Other four new stable aminoxyl radicals 8,9,10, and 11 have also been obtained within the synthetic approach. It has been demonstrated that the cyclic ether compound (7) is generated by the reduction of its corresponding lactone which is sidely derived from the oxo-reduced species of 3 by intramolecular cyclization.

Diversity-Oriented Synthesis via Catalyst-Free Addition of Ketones to [e]-Fused 1H-Pyrrole-2,3-diones

Synthesis ◽  
2018 ◽  
Vol 50 (24) ◽  
pp. 4897-4904 ◽  
Author(s):  
Ekaterina Stepanova ◽  
Andrey Maslivets ◽  
Svetlana Kasatkina ◽  
Maksim Dmitriev
Keyword(s):  
Intramolecular Cyclization ◽  
Aromatic Hydrocarbons ◽  
Michael Addition ◽  
Aldol Reaction ◽  
Synthetic Approach ◽  
Reaction Conditions ◽  
Diversity Oriented Synthesis ◽  
Catalyst Free ◽  
Solvent Free Conditions ◽  
Reaction Proceeds

A facile synthetic approach towards two distinct pyrrole-based heterocyclic scaffolds has been developed by the interaction of 1H-pyrrole-2,3-diones fused at the [e]-side to a 1,4-benzoxazin-2-one or quinoxalin-2(1H)-one moiety with ketones. The described interaction proceeds either as an aldol reaction or as a Michael addition/intramolecular cyclization depending on the reaction conditions. The disclosed aldol reaction proceeds with good diastereoselectivity under catalyst-free conditions when the reaction is carried out in aromatic hydrocarbons. Products of the cascade Michael addition/intramolecular cyclization reaction are predominantly formed under catalyst-free and solvent-free conditions. The proposed strategy provides facile access to pharmaceutically interesting pyrrole-based polyheterocycles.

scholarly journals A Facile Synthesis of (±)-Heliannuol-D

2013 ◽  
Vol 8 (9) ◽  
pp. 1934578X1300800 ◽  
Author(s):  
Tao Zhang ◽  
Liang-Zhu Huang ◽  
You-Qiang Li ◽  
Yimg-Meng Xu ◽  
Zhen-Ting Du
Keyword(s):  
Intramolecular Cyclization ◽  
Cost Effective ◽  
Synthetic Approach ◽  
Lead Compound ◽  
Facile Synthesis ◽  
New Generation

A facile synthesis of (±)-heliannuol-D 1, which serves as an allelopathic chemical in nature and a potential lead compound in the search for new herbicides, has been achieved in a linear 11 steps, together with its epimer. The synthesis commenced with 4-methoxy-3-methyl-acetophenone, through the Baeyer-Villiger reaction, lithiation and addition, epoxidation and intramolecular cyclization to give (±)-heliannuol-D (1) and its epimer (1a) in 32.6% overall yield. Our synthetic approach is cost-effective; this will be helpful in applying this kind of compound for the development of a new generation of agrochemicals.

scholarly journals A selective and mild glycosylation method of natural phenolic alcohols

2016 ◽  
Vol 12 ◽  
pp. 524-530 ◽  
Author(s):  
Mária Mastihubová ◽  
Monika Poláková
Keyword(s):  
Synthetic Approach ◽  
Reaction Sequence ◽  
Simple Reaction ◽  
Glycoside Synthesis ◽  
Highly Efficient ◽  
Phenolic Alcohols

Several bioactive natural p-hydroxyphenylalkyl β-D-glucopyranosides, such as vanillyl β-D-glucopyranoside, salidroside and isoconiferin, and their glycosyl analogues were prepared by a simple reaction sequence. The highly efficient synthetic approach was achieved by utilizing acetylated glycosyl bromides as well as aromatic moieties and mild glycosylation promoters. The aglycones, p-O-acetylated arylalkyl alcohols, were prepared by the reduction of the corresponding acetylated aldehydes or acids. Various stereoselective 1,2-trans-O-glycosylation methods were studied, including the DDQ–iodine or ZnO–ZnCl2 catalyst combination. Among them, ZnO–iodine has been identified as a new glycosylation promoter and successfully applied to the stereoselective glycoside synthesis. The final products were obtained by conventional Zemplén deacetylation.

A highly efficient TBAF-promoted intramolecular cyclization of gem-dibromoolefins for the synthesis of 2-bromobenzofurans(thiophenes)

2011 ◽  
Vol 47 (37) ◽  
pp. 10476 ◽  
Author(s):  
Wei Chen ◽  
Yicheng Zhang ◽  
Lei Zhang ◽  
Min Wang ◽  
Lei Wang
Keyword(s):  
Intramolecular Cyclization ◽  
Highly Efficient
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