Silylcarbocyclizations of 1,6-Diynes

Ojima, Iwao; Zhu, Jian‐Bo; Vidal, Ephraim S.; Kass, Dora Fracchiolla

doi:10.1021/ja980907l

Cited by 75 publications

(25 citation statements)

References 36 publications

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“…Various functional groups, e.g., ether, ester, hydroxyl, and sulfonamide, and heteroatoms in the backbone of enediynes 14 are well tolerated in this reaction to give the corresponding fused 5-7-5 tricyclic products 15 in good to excellent isolated yields [10]. Other rhodium catalysts, Rh(acac)(CO) 2 , Rh 4 (CO) 12 , and [Rh(CO) 2 Cl] 2 , show similar efficacy. As hydrosilane, PhMe 2 SiH is the best, but Ph 2 MeSiH, (EtO) 3 SiH, and Et 3 SiH can also be used.…”

Section: Carbonylative Carbotricyclization Of Enediynesmentioning

confidence: 94%

“…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 (1) which enable the reaction to proceed at ambient temperature and completes mostly within a minute.…”

Section: Silylcarbocyclizations (Sicacs)mentioning

confidence: 99%

“…Other Rh catalysts such as Rh(acac)(CO) 2 are also effective for this reaction, but require 65-70 °C to promote the reaction efficiently. Although CO is not incorporated into the SiCaC products, the cluster catalysts require CO atmosphere to stabilize the active catalyst species [1][2][3].…”

Section: Silylcarbocyclizations (Sicacs)mentioning

confidence: 99%

“…The SiCaC reactions that accompany subsequent hydrosilylation (SiCaC-HS) have also been studied [2]. We have also discovered and developed novel Rh-catalyzed silylcarbobicyclization (SiCaB) of 1,6-diynes, which gives the corresponding 2-silylbicyclo[3.…”

Section: Silylcarbocyclizations (Sicacs)mentioning

confidence: 99%

“…Under optimized conditions using Rh 4 (CO) 12 as the catalyst and 2 equiv of hydrosilane to 6 at 22 °C, fused tricyclic silylbenzene 7 was obtained in excellent yield with 84-93% selectivity. Several Rh complexes were found to be effective in the SiCaT reaction, which are Rh(acac)(CO) 2 nitrogen atoms in the backbone are proven to be good substrates for this process. Fused tricyclic benzene 8 was formed exclusively using exactly stoichiometric amount of PhMe 2 SiH.…”

Section: Cascade Silylcarbocyclizationsmentioning

confidence: 99%

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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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Section: Carbonylative Carbotricyclization Of Enediynesmentioning

confidence: 94%