ChemInform Abstract: Copper‐, Silver‐, and Gold‐Catalyzed Migratory Cycloisomerization Leading to Heterocyclic Five‐Membered Rings

As, Dudnik; Chernyak, Natalia; Gevorgyan,

doi:10.1002/chin.201126233

Cited by 8 publications

(9 citation statements)

References 61 publications

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“…The chemical inertness of alkynes under various reaction conditions accounts for their broad tolerance in transformations that would be problematic for other functionalities, such as carbonyls. Of course, chemical inertness can be both a blessing and a curse but, in the case of alkynes, a breakthrough that greatly facilitated their application in chemical synthesis came with the development of alkyne-selective (“alkynophilic”) π-acidic metal catalysts [32,33,34,35,36,37]. Such selective catalysts (especially, the cationic Au-species) allowed chemists to “unlock” alkyne reactivity on demand with a large degree of control.…”

Section: Alkynes In Ketal Formationmentioning

confidence: 99%

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

et al. 2019

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The high energy packed in alkyne functional group makes alkyne reactions highly thermodynamically favorable and generally irreversible. Furthermore, the presence of two orthogonal π-bonds that can be manipulated separately enables flexible synthetic cascades stemming from alkynes. Behind these “obvious” traits, there are other more subtle, often concealed aspects of this functional group’s appeal. This review is focused on yet another interesting but underappreciated alkyne feature: the fact that the CC alkyne unit has the same oxidation state as the -CH2C(O)- unit of a typical carbonyl compound. Thus, “classic carbonyl chemistry” can be accessed through alkynes, and new transformations can be engineered by unmasking the hidden carbonyl nature of alkynes. The goal of this review is to illustrate the advantages of using alkynes as an entry point to carbonyl reactions while highlighting reports from the literature where, sometimes without full appreciation, the concept of using alkynes as a hidden entry into carbonyl chemistry has been applied.

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Section: Alkynes In Ketal Formationmentioning

confidence: 99%

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

et al. 2019

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“…The thiiranium structural motif is an important cationic intermediate that is responsible for chemical transformations in the synthesis of various organosulfur compounds [ 1 , 2 ]. Thiiranium ions are highly reactive electrophiles, which can interact with diverse nucleophiles in a selective fashion that opens new horizons in the preparation of different sulfur-containing linear or heterocyclic derivatives [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. The well-known anchimeric assistance of chalcogens in case of β-haloalkyl sulfides or –selenides [ 16 ] is due to the formation of chalcogeniranium intermediates.…”

Section: Introductionmentioning

confidence: 99%

Heterocyclization of Bis(2-chloroprop-2-en-1-yl)sulfide in Hydrazine Hydrate–KOH: Synthesis of Thiophene and Pyrrole Derivatives

et al. 2022

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The article is devoted to heterocyclization of bis(2-chloroprop-2-en-1-yl)sulfide which proceeds in hydrazine hydrate–alkali medium and leads to formation of thiophene and pyrrole derivatives: previously described 4,5,9,10-tetrahydrocycloocta[1,2-c;5,8-c’]dithiophene, as well as unknown hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one and 1-amino-2-(propynylsulfanylpropenylsulfanyl)-3,5-dimethylpyrrole. Tentative mechanisms for the formation of the heterocyclic products are discussed. Obtained hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one was used for the synthesis of a range of azine derivatives and in oxidation process with SeO2. The found reactions open up expedient approaches to the formation of various hardly accessible thiophene and pyrrole compounds from 2,3-dichloropropene and elemental sulfur as starting reagents.

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“…The incorporation of molecular rearrangement into transition-metal-catalyzed cycloisomerization reactions provides a general, highly efficient, and atom-economical strategy to synthesize complex carbocyclic and heterocyclic frameworks. − Recent studies have developed various transition-metal-catalyzed heterocyclization reactions with the migration of various functional groups. − Among these, gold-catalyzed migratory cycloisomerizations are particularly beneficial for the construction of densely substituted heterocycles, and a number of heterosubstituted furans have been synthesized from various types of substrates such as alkynyl ketones, , allenyl ketones, ,, enynes, alkynyl alcohols, alkynyl epoxides, alkynyl ethers, and so on . However, well-controlled and selective formation of diverse structural motifs is still a challenge that as yet requires further attention, mainly due to the limited understanding of the detailed mechanisms of individual transformations, which are often complicated in nature and sensitively depend on reaction parameters, such as the metal catalyst, ligand, counterion, and additives.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Insight into Ligand- and Counterion-Controlled Regiodivergent Reactivity in Synthesis of Borylated Furans: 1,2-H vs 1,2-B Migration

Yang

Zhu

et al. 2018

ACS Catal.

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Divergent catalytic reactions provide quick access to diverse molecular scaffolds through controlled reaction pathways by tuning the catalytic conditions, especially changing auxiliary ligands and/or counterions. This study presents a computational study of Au(I)-catalyzed regiodivergent cycloisomerizations of boron-containing alkynyl epoxides toward C2- and C3-borylated furans. The calculations clarified the mechanistic details of the reaction and the regiodivergence induced by two gold catalysts. The proposed catalytic cycle involves two major stages: ring expansion of alkynyl epoxide accompanied by B(MIDA) group migration to form a m-boron furyl heterocyclic intermediate and a formal 1,2-H or a 1,2-B migration to form a C3- or C2-borylated furan. The former is identified as the bottleneck of the reaction, which proceeds via σ activation of the oxirane moiety rather than π activation of the alkynyl moiety proposed in experimental work, and the latter controls the regiodivergence. Calculations show that the counterion and ligand in the gold catalyst play a less important role in the ring expansion, but they are crucial for the divergent formation of borylated furans: an OTf– counterion with an (ArO)3P ligand favors the 1,2-H migration, leading to the formation of C3-borylated furan, whereas an SbF6 – anion with an IPr ligand promotes the 1,2-B migration, supporting the predominant formation of C2-borylated furan. The theoretical results rationalize the observed regioselectivity and provide key insights into the mechanism of the migratory cycloisomerization of boron-containing alkynyl epoxides.

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ChemInform Abstract: Copper‐, Silver‐, and Gold‐Catalyzed Migratory Cycloisomerization Leading to Heterocyclic Five‐Membered Rings

Cited by 8 publications

References 61 publications

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

Heterocyclization of Bis(2-chloroprop-2-en-1-yl)sulfide in Hydrazine Hydrate–KOH: Synthesis of Thiophene and Pyrrole Derivatives

Theoretical Insight into Ligand- and Counterion-Controlled Regiodivergent Reactivity in Synthesis of Borylated Furans: 1,2-H vs 1,2-B Migration

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