New cascade silylcarbocyclization (SiCaC) of enediynes

Ojima, Iwao; McCullagh, James V.; Shay, William R.

doi:10.1016/0022-328x(96)06359-0

Cited by 40 publications

(20 citation statements)

References 23 publications

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“…It was hoped that the alkyl-[Rh] species A arising from the initial silylcarbocyclization would be trapped by another alkene moiety to give bicyclization product 64, but the attempted process did not proceed as designed and gave functionalized tetrahydrofurans 65 (in hexane, 1 atm of CO, 95%) or 66 (in THF, 2.6 atm of CO, 60%) (Scheme 24). The observed failure for the bicyclization can be ascribed to the trans juncture of the tether, which keeps [Rh] and the olefin moiety rather remote, hence the competing reductive elimination or CO insertion prevails [73]. The first cascade SiCaC reaction was observed when enediyne 67 was employed as substrate, which gave bicyclization product 68 (Scheme 25) [73].…”

Section: Polyheterocycle Synthesis By Cascade Silylcarbonylation and mentioning

confidence: 95%

“…The observed failure for the bicyclization can be ascribed to the trans juncture of the tether, which keeps [Rh] and the olefin moiety rather remote, hence the competing reductive elimination or CO insertion prevails [73]. The first cascade SiCaC reaction was observed when enediyne 67 was employed as substrate, which gave bicyclization product 68 (Scheme 25) [73]. The analysis of the reaction mechanism indicated a definite possibility that the vinyl- freedom of the C-C bond connecting the two cyclopentyl moieties were restricted (Scheme 25) [73].…”

Section: Polyheterocycle Synthesis By Cascade Silylcarbonylation and mentioning

confidence: 98%

“…The first cascade SiCaC reaction was attempted on dienyne 63 (Scheme 24) [73]. It was hoped that the alkyl-[Rh] species A arising from the initial silylcarbocyclization would be trapped by another alkene moiety to give bicyclization product 64, but the attempted process did not proceed as designed and gave functionalized tetrahydrofurans 65 (in hexane, 1 atm of CO, 95%) or 66 (in THF, 2.6 atm of CO, 60%) (Scheme 24).…”

Section: Polyheterocycle Synthesis By Cascade Silylcarbonylation and mentioning

confidence: 99%

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Synthesis of Heterocycles Through Hydrosilylation, Silylformylation, Silylcarbocyclization and Cyclohydrocarbonylation Reactions

Varchi

Ojima

2006

COC

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Section: Polyheterocycle Synthesis By Cascade Silylcarbonylation and mentioning

confidence: 95%

Section: Polyheterocycle Synthesis By Cascade Silylcarbonylation and mentioning

confidence: 98%

Section: Polyheterocycle Synthesis By Cascade Silylcarbonylation and mentioning

confidence: 99%

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Synthesis of Heterocycles Through Hydrosilylation, Silylformylation, Silylcarbocyclization and Cyclohydrocarbonylation Reactions

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Ojima

2006

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“…[91][92][93][94][95][96] Most of them occur via the insertion of the CC bond into the M-Si bond followed by the insertion of CO into the metalvinyl bond.…”

Section: Silylformylation Of Alkynesmentioning

confidence: 99%

Silicometallics and catalysis

Marciniec

2000

Appl. Organometal. Chem.

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Several processes of silicon substrates (such as hydrosilylation, dehydrogenative silylation and double silylation of alkenes and alkynes, silylative coupling versus cross-metathesis of vinylsilanes with alkenes, polycondensation of divinylsubstituted silicon compounds versus ADMET polymerization, dehydrocoupling of hydrosilanes and silylformylation of acetylene) by transition-metal complexes are briefly overviewed. All the reactions occur via a mechanism involving intermediates containing metal-silicon (i.e. silicometallics versus organometallics) and metal-hydrogen bonds, only occasionally accompanied (sided) by intermediates including metal-carbon bonds.

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“…For example, the reaction of dodec-6-ene-1,11-diyne 4 with PhMe 2 SiH catalyzed by Rh(acac)(CO) 2 at 50 °C and atmospheric pressure of CO gives bis(exo-methylenecyclopentyl) 5 (eq. 3) [7]. The reaction is stereospecific, i.e., (6E)-and (6Z)-dodec-6-ene-1,11-diynes, (E)-4 and (Z)-4, afford (R*,R*)-5 and (S*,R*)-5, respectively.…”

Section: Cascade Silylcarbocyclizationsmentioning

confidence: 99%

New cyclization reactions in organic syntheses

Ojima

2002

Pure and Applied Chemistry

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Recent development in the transition metal-catalyzed cyclization reactions for organic syntheses in the author's laboratories is summarized, which includes (i) novel silylcarbocyclizations (SiCaCs) and carbonylative carbotricyclizations, (ii) intramolecular silylformylations and desymmerization of siloxydiynes by sequential double silylformylation, (iii) efficient total synthesis of (+)-prosopinine, (iv) enantioselective desymmetrization of aminodienes, and (iv) new and efficient routes to 1-azabicyclo[x.y.0]alkane amino acids. All these processes are catalyzed by Rh or Rh-Co complexes, and useful for rapid and efficient construction of a variety of heterocyclic and carbocyclic compounds. Mechanisms of these new carbocyclization and cyclohydrocarbonylation reactions are also discussed.It has been the central focus in modern organic synthesis to develop highly efficient catalytic processes for the syntheses of natural and unnatural compounds of medicinal interest or intermediates useful for functional materials. One of the most attractive approaches to such aims is to apply transition metal-catalyzed cyclization reactions for the transformations of simple starting materials into monocyclic, bicyclic, and polycyclic scaffolds that can be further elaborated into specific targets.This account describes new and useful cyclization processes based on silylcarbocyclization (SiCaC), silylformylation, and cyclohydrocarbonylation reactions, which have recently been developed in these laboratories and will find many applications in organic syntheses. SILYLCARBOCYCLIZATIONS (SiCaCs)The first silylcarbocyclization was discovered serendipitously during our detailed product analysis of the silylformylation of 1-hexyne catalyzed by Rh and Rh-Co carbonyl clusters, which gave dibutylcyclopentenone by incorporating two molecules of 1-hexyne, one molecule of hydrosilane, and one molecule of CO. Following up this discovery, we have investigated the intramolecular version of this reaction using a variety of 1,6-enynes, which led to the discovery of novel silylcarbocyclization (SiCaC) reaction (eq. 1) [1][2][3]. The SiCaC reaction of 1,6-enynes is catalyzed by Rh 4 (CO) 12 and Rh 2 Co 2 (CO) 12 , *Lecture presented at the

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New cascade silylcarbocyclization (SiCaC) of enediynes

Cited by 40 publications

References 23 publications

Synthesis of Heterocycles Through Hydrosilylation, Silylformylation, Silylcarbocyclization and Cyclohydrocarbonylation Reactions

Synthesis of Heterocycles Through Hydrosilylation, Silylformylation, Silylcarbocyclization and Cyclohydrocarbonylation Reactions

Silicometallics and catalysis

New cyclization reactions in organic syntheses

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