Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp<sup>3</sup>)−C(sp) Bond Activation

Kawaguchi, Yasuaki; Yabushita, Kenya; Mukai, Chisato

doi:10.1002/anie.201713096

Cited by 18 publications

(11 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The combination in a linear substrate of an allene and two alkynes is an interesting and chemoselective entry to tricyclic tetrahydropentalene derivatives 79 and cyclobuta[ a ]indenes 80 in excellent yields reported by Mukai's group relying on the steric hindrance of R 1 substituents (Scheme 24a). [ 81 ] The Rh(I) catalyzed cyclization of diyne–allene substrates bearing smaller alkyl, hydrogen and phenyl substituents and the following oxidation and hydrolysis delivered the unexpected tricyclic compounds 79 with complete chemo‐ and diastereoselectivity. In this case, due to the easy decomposition of conjugated triene‐containing tricyclic products 78 generated from Rh(I) catalysis, one‐pot, two‐step process…”

Section: Synthesis Of Carbocyclesmentioning

confidence: 99%

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

Wang

Hao

et al. 2022

Chin. J. Chem.

View full text Add to dashboard Cite

Comprehensive Summary Yne‐allenes bearing both a C—C triple bond and an allene unit are a class of focal substrates in organic synthesis, in view of their structure diversity, high reactivity and intermediate variety in the past years. Engaging yne‐allenes in numerous annulation cascades provides efficient and direct accesses to elaborate functionalized polycyclic molecular architectures in a convergent manner. There are lots of types of catalytic chemical reactions such as intramolecular cyclizations, cycloisomerizations, intermolecular annulations, and bicyclizations as well as tricyclizations with the assistance of Lewis acids, Brønsted acids, bases, transition metals, and other catalysts. This review provides an overview of the chemistry developed with transformations of yne‐allenes by discussing their general and specific reactivities, presenting and commenting on their mechanisms as well as their applications.

show abstract

Section: Synthesis Of Carbocyclesmentioning

confidence: 99%

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

Wang

Hao

et al. 2022

Chin. J. Chem.

View full text Add to dashboard Cite

show abstract

“…Thestructure of 10 was unambiguously established by X-ray crystallographic analysis of 11. [10] Interestingly,bulky R 1 substituents in 9,such as tert-butyl and TMS groups (9g and 9h), were found to change the reaction pathway,g iving rise to the six/five/four ring systems 12 g and 12 h in 98 and 66 %yield. However,this was not the case when TMS was introduced as the R 2 substituent in 9 rather than as R 1 (R 1 = nBu, R 2 = TMS).…”

Section: Yasuaki Kawaguchi Kenya Yabushita and Chisato Mukai*mentioning

confidence: 99%

“…[14] This one-pot operation was effective to exclusively produce the diol 17 a (77 %o verall yield) in ac ompletely regio-and stereoselective manner ( Table 2, entry 1). [15] When 13 b (in Scheme 4), with an electron-donating isopropyl group attached to the allene moiety,w as submitted to similar conditions,o nly an intractable complex mixture was observed. This result is in good agreement with our prediction that the phenylsulfonyl group must play as ignificant role in the differentiation of the three olefins.D iol 17 a was rather stable and could be handled without any special precaution.…”

Section: Yasuaki Kawaguchi Kenya Yabushita and Chisato Mukai*mentioning

confidence: 99%

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp³)−C(sp) Bond Activation

2018

Self Cite

View full text Add to dashboard Cite

Upon exposure to ac atalytic amount of [RhCl-(CO) 2 ] 2 in 1,4-dioxane,h omopropargylallene-alkynes underwent anovel cycloisomerization accompanied by the migration of the alkyne moiety of the homopropargyl functional group to produce six/five/five tricyclic compounds in good yields.A plausible mechanism was proposed on the basis of an experiment with 13 C-labeled substrate.T he resulting tricyclic derivatives were further converted into the corresponding bicyclo-[3.3.0] skeletons with vicinal cis dihydroxyg roups.Transition-metal-catalyzed cyclization reactions involving CÀH [1] and/or CÀC [2] bond activation steps have emerged as one of the most powerful and straightforward methods in terms of step economy for the construction of complex polycyclic frameworks.O ur recent endeavors in this field focused on the utilization of the inherent properties of the allene functional group [3] in the presence of additional p-components under rhodium catalysis as summarized in Scheme 1. [4,5] These novel rhodium-catalyzed cycloisomerization reactions of allenynes 1 [6] were tentatively surmised to proceed via the initial formation of the plausible rhodabicyclo[4.3.0] intermediates A,w hich should subse-quently collapse through several steps to various types of final products 2-6. [4,7] As af urther utilization of intermediate A,w ee nvisaged that allene-alkyne derivatives 7,with ahomopropargyl group, would produce benzocyclobutene derivatives 8 if it reacted in ap rocess similar to the conversion of 1c into 6 via intermediates A' ' and B (Scheme 2).Our initial study was carried out using 9,with adimethyl group at the allenic position to avoid unfavorable b-hydride elimination. [8] Thus as olution of 9a (R 1 = R 2 = Me) in 1,4dioxane was heated at 80 8 8Ci nt he presence of 10 mol %o f [RhCl(CO) 2 ] 2 .T he reaction reached completion within 10 min to provide the unexpected six/five/five tricyclic compound 10 a (R 1 = R 2 = Me) in 90 %y ield (Table 1, entry 1). Theexpected product 8 could not be detected in the reaction mixture.T hese conditions ([RhCl(CO) 2 ] 2 in 1,4-dioxane at 80 8 8C) were indeed found to be optimal for conversion of 9a into 10 a. [9] Thet wo derivatives 9b and 9c afforded 10 b and 10 c in 89 and 87 %yield, respectively (entries 2and 3). Upon exposure to the optimized reaction conditions,s ubstrates 9d and 9e,with aphenyl group at one of the two alkyne termini, reacted to give 10 d and 10 e in 78 and 85 %yield, respectively Scheme 1. Our previous work:R h I -catalyzed cyclization of allenynes 1.Scheme 2. This study:R h I -catalyzed cyclization of homopropargylallene-alkynes 7. Table 1: [RhCl(CO) 2 ] 2 -catalyzed cycloisomerizationo fhomopropargylallene-alkynes 9. [a] Entry 9 R 1 R 2 Product Yield [%] [b]

show abstract

“…Both cycloisomerizations include a C–H activation process. Recently, rhodium(I)-catalyzed cycloisomerizations of 1,6-allenynes involving insertion of tethered unsaturated carbon–carbon bonds were reported by Mukai and co-workers (Scheme c,d). , Despite the different tethered groups (alkene or alkyne) within 1,6-allenynes, the two novel cycloisomerization reactions can both produce 6,5,5-tricyclic compounds. Moreover, diverse polycyclic skeletons (Figure ) could be produced through modifying the substrate or changing the ligand .…”

Section: Introductionmentioning

confidence: 99%

“…The cycloisomerization reactions of 1,6-allenynes with a tethered alkene (homoallylallene–alkyne substrate, Scheme c) and alkyne (homopropargylallene–alkyne substrate, Scheme d) show similarities in substrates and products, but they differ greatly in the proposed cycloisomerization mechanisms (Figure ). , Given that the initial oxidative cyclization to a five-membered rhodacyclic intermediate ( I → II , Figure ) in rhodium(I)-catalyzed cycloisomerizations of 1,6-allenynes has been well established, − the key question is how the tethered unsaturated carbon–carbon bond reacts with rhodacyclic intermediate II . , It was proposed that in the reaction of alkene-tethered 1,6-allenyne, the five-membered rhodacycle successively undergoes alkene insertion, β-hydride elimination, alkene reinsertion, and reductive elimination to yield the 6,5,5-tricyclic product prod1 . However, in the reaction of alkyne-tethered 1,6-allenyne, II first undergoes σ-bond metathesis to form a four-membered rhodacycle VI , and then goes through alkyne insertion and reductive elimination to form product prod2 …”

Section: Introductionmentioning

confidence: 99%

Computational Study on Mechanisms and Origins of Selectivities in Rh(I)-Catalyzed Cycloisomerizations of 1,6-Allenynes with Tethered Unsaturated Carbon–Carbon Bonds

Lü

Liu

et al. 2021

ACS Catal.

View full text Add to dashboard Cite

Rhodium(I)-catalyzed cycloisomerization reactions of 1,6-allenynes with a tethered alkene (homoallylallene–alkyne substrate) or alkyne (homopropargylallene–alkyne substrate) have recently shown great potential in the construction of polycyclic skeletons. To understand the influence of the tethered unsaturated carbon–carbon bond on cycloisomerization mechanisms, density functional theory (DFT) calculations have been performed in this work. Our calculations indicate that both cycloisomerizations involve oxidative cyclization and migratory insertion but the distinct regioselectivity between alkene and alkyne insertions and the contrasting reactivity of rhodium-alkyl and rhodium-alkenyl intermediates contribute to the divergent cycloisomerization mechanisms. In the case of alkene-tethered 1,6-allenyne, both 1,2- and 2,1-insertions of alkene into the Rh–C(sp2) bond of the five-membered rhodacyclic intermediate are plausible, and the resulting rhodium-alkyl intermediates will afford cycloisomerization products through reductive elimination. In contrast, only 1,2-alkyne insertion is practical in the reaction of alkyne-tethered 1,6-allenyne, and the formed rhodium-alkenyl intermediate cannot undergo reductive elimination but rather rearranges into a reactive rhodacyclopropene, thereby releasing cyclic products through the 1,2-migration of rhodium carbene. Further distortion/interaction analysis on insertion transition states suggests that the different regioselectivity arises from the distinct features of configurational rearrangement for alkene and alkyne fragments during 1,2-migratory insertion. The computations also highlight the effects of the alkyne substituent and carbon chain length of the 1,6-allenyne reactant on the product selectivity.

show abstract

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp³)−C(sp) Bond Activation

Cited by 18 publications

References 52 publications

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp³)−C(sp) Bond Activation

Computational Study on Mechanisms and Origins of Selectivities in Rh(I)-Catalyzed Cycloisomerizations of 1,6-Allenynes with Tethered Unsaturated Carbon–Carbon Bonds

Contact Info

Product

Resources

About

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp3)−C(sp) Bond Activation

Cited by 18 publications

References 52 publications

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

Engaging Yne‐Allenes in Cycloaddition Reactions: Recent Developments

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp3)−C(sp) Bond Activation

Computational Study on Mechanisms and Origins of Selectivities in Rh(I)-Catalyzed Cycloisomerizations of 1,6-Allenynes with Tethered Unsaturated Carbon–Carbon Bonds

Contact Info

Product

Resources

About

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp³)−C(sp) Bond Activation

Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp³)−C(sp) Bond Activation