Synthesis of 5,6-Dihydropyrazolo[5,1-<i>a</i>]isoquinolines through Indium(III)-Promoted Halocyclizations of <i>N</i>-Propargylic Sulfonylhydrazones

Li, Ren‐Hao; Ding, Cheng‐Ke; Jiang, Yanan; Ding, Zong‐Cang; An, Xiao-Ming; Tang, Hai‐Tao; Jing, Qiwei; Zhan, Zhuang‐Ping

doi:10.1021/acs.orglett.6b00534

Cited by 16 publications

(3 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zhan and co-workers reported a cascade sequence involving an alkynyl aza-Prins reaction as one of the key steps in forming functionalized 5,6-dihydropyrazolo[5,1-a]isoquinolines (Scheme 19). 44…”

Section: Scheme 18 Removal Of No-acetal To Form Iminium Electrophilementioning

confidence: 99%

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

Abdul-Rashed¹,

Holt²,

Frontier³

2020

Synthesis

View full text Add to dashboard Cite

This review focuses on alkynyl Prins and alkynyl aza-Prins cyclization processes, which involve intramolecular coupling of an alkyne with either an oxocarbenium or iminium electrophile. The oxocarbenium or iminium species can be generated through condensation- or elimination-type processes, to achieve an overall bimolecular annulation that enables the synthesis of both oxygen- and nitrogen-containing saturated heterocycles with different ring sizes and substitution patterns. Also discussed are cascade processes in which alkynyl Prins heterocyclic adducts react to trigger subsequent pericyclic reactions, including [4+2] cycloadditions and Nazarov electrocyclizations, to rapidly construct complex small molecules. Finally, examples of the use of alkynyl Prins and alkynyl aza-Prins reactions in the synthesis of natural products are described. The review covers the literature through the end of 2019.1 Introduction1.1 Alkyne-Carbonyl Coupling Pathways1.2 Coupling/Cyclization Cascades Using the Alkynyl Prins Reaction2 Alkynyl Prins Annulation (Oxocarbenium Electrophiles)2.1 Early Work2.2 Halide as Terminal Nucleophile2.3 Oxygen as Terminal Nucleophile2.4 Arene as Terminal Nucleophile (Intermolecular)2.5 Arene Terminal Nucleophile (Intramolecular)2.6 Cyclizations Terminated by Elimination3 Synthetic Utility of Alkynyl Prins Annulation3.1 Alkynyl Prins-Mediated Synthesis of Dienes for a [4+2] Cyclo- addition-Oxidation Sequence3.2 Alkynyl Prins Cyclization Adducts as Nazarov Cyclization Precursors3.3 Alkynyl Prins Cyclization in Natural Product Synthesis4 Alkynyl Aza-Prins Annulation4.1 Iminium Electrophiles4.2 Activated Iminium Electrophiles5 Alkynyl Aza-Prins Cyclizations in Natural Product Synthesis6 Summary and Outlook

show abstract

Section: Scheme 18 Removal Of No-acetal To Form Iminium Electrophilementioning

confidence: 99%

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

Abdul-Rashed¹,

Holt²,

Frontier³

2020

Synthesis

View full text Add to dashboard Cite

show abstract

“…N -Sulfonyl iminium ions are the last class of electrophiles that have been employed in alkynyl aza-Prins chemistry. In these cyclizations, sulfonamide reactants are leveraged for the preparation of functionalized pyrazoles, indoles, indolines, and piperidines. , Recently, a report by Hou et al shows the use of bromotrimethylsilane (TMSBr) to promote the reaction of a sulfonamide 8 and a carbonyl coupling partner 9 to make tosyl-piperidines like 11 via N -tosyl iminium intermediate 10 (Scheme C).…”

Section: Introductionmentioning

confidence: 99%

Alkynyl Halo-Aza-Prins Annulative Couplings

Hernandez,

Lawrie,

Frontier

2023

J. Org. Chem.

View full text Add to dashboard Cite

This article is a comprehensive report describing our studies in the field of aza-alkynyl Prins chemistry, comparing and contrasting the different reaction partners and reactivities observed during method development. The synthetic strategies combine an alkynyl aza-Prins coupling with an annulation, enabling the preparation of different nitrogen-containing heterocycles. Different iminium ions are explored as viable electrophiles for an alkynyl Prins cyclization, terminated by capture with a halogen nucleophile to form a vinyl halide. The synthetic utility of this functional handle is exploited through a number of Suzuki cross-couplings, allowing for the preparation of a modest library of compounds. In most cases, the Prins couplings are highly selective for the vinyl halides with E geometry, resulting from anti-addition across the alkyne.

show abstract

“…This approach needs a large amount of excess TiCl 4 /Fe 3 or excess SnCl 2 /PhSH and TsCl for two-step synthesis 4 of the fused skeleton. The other approach is indium-promoted halocyclization of N -propargylic sulfonylhydrazones, 5 and the reaction was conducted in 1,2-dichloroethane at reflux with the use of stoichiometric indium( iii ) halides. On the other hand, transition-metal catalyzed intermolecular cross-coupling reactions have been developed for the synthesis of 5,6-dihydropyrazolo[5,1- a ]isoquinolines, such as palladium-catalyzed/norbornene-mediated C–H activation of N -bromoalkyl pyrazoles and aryl iodides, 6 and three-step synthesis starting from acetophenones and hydrazines 7 (Scheme 1a).…”

Section: Introductionmentioning

confidence: 99%

Catalyst-free and oxidant-free tandem aza-Mannich/cyclization/aromatization of C,N-cyclic azomethine imines with enamides: facile synthesis of 5,6-dihydropyrazolo[5,1-a]isoquinolines

et al. 2022

View full text Add to dashboard Cite

show abstract

Synthesis of 5,6-Dihydropyrazolo[5,1-a]isoquinolines through Indium(III)-Promoted Halocyclizations of N-Propargylic Sulfonylhydrazones

Cited by 16 publications

References 36 publications

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

Alkynyl Halo-Aza-Prins Annulative Couplings

Catalyst-free and oxidant-free tandem aza-Mannich/cyclization/aromatization of C,N-cyclic azomethine imines with enamides: facile synthesis of 5,6-dihydropyrazolo[5,1-a]isoquinolines

Contact Info

Product

Resources

About