Carbene Cyclization Cycloaddition Research Articles

ChemInform Abstract: Further Studies on Sultones Derived from Carbene Cyclization Cycloaddition Cascades.

AbstractThe rhodium‐catalyzed carbene cyclization‐cycloaddition cascade of a tosyl‐substituted diazoketone derivative to a polycyclic sultone is described.

Further studies on sultones derived from carbene cyclization cycloaddition cascades

A sulfonyl-stabilized diazoketone underwent an efficient rhodium-catalyzed cascade reaction with an internal vinylsulfonate unit to give a tricyclic sultone as a single diastereomer. Nucleophilic addition of a vinyl Grignard reagent to the ketone of the resultant arylsulfonyl-substituted cycloadduct was stereocomplementary with respect to vinyl Grignard addition to corresponding ester-substituted substrates. The latter tricyclic compounds were chemoselectively transformed into vinylsultones via β-elimination in good yield.

Total synthesis of (-)-dolastatrienol.

The first asymmetric total synthesis of the tricyclic diterpenoid natural product (-)-dolastatrienol has been accomplished using a rhodium(II)-catalyzed carbene cyclization cycloaddition cascade reaction as the key step to construct the [5.4.0]carbobicyclic core. An intramolecular Heck reaction furnished the tricyclic skeleton and a challenging methylenation completed the synthesis of the target.

The Rhodium‐Catalyzed Carbene Cyclization Cycloaddition Cascade Reaction of Vinylsulfonates

AbstractVinylsulfonates have proved to be excellent dipolarophiles for carbonyl ylides derived from diazoketones in rhodium‐catalyzed intramolecular cycloadditions. Polyfunctional substrates, such as 8 and (+)‐15, were readily available from hydroxy esters, e.g. 1 and the cyclopenta‐1,3‐dione 10, respectively, and the resulting polycyclic sultones were formed under mild reaction conditions in high yields with very good diastereoselectivities. A ruthenium‐catalyzed asymmetric transfer hydrogenation was found to desymmetrize the meso‐cyclopenta‐1,3‐dione 12 efficiently.

ChemInform Abstract: Asymmetric Total Synthesis of (‐)‐Indicol by a Carbene Cyclization—Cycloaddition Cascade Strategy.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Asymmetric Total Synthesis of (−)‐Indicol by a Carbene Cyclization–Cycloaddition Cascade Strategy

The first total synthesis of a secodolastane, (-)-indicol, has been accomplished. The key reaction is a rhodium(II)-mediated carbene cyclization-cycloaddition cascade, by which the core bicyclo[5.4.0]undecane skeleton was assembled. In this one-pot reaction, a domino series of transformations resulting in the construction of three sigma bonds and three stereocenters was realized in good yield.

Total Synthesis of Pseudolaric Acid A

The antiangiogenic and cytotoxic natural product pseudolaric acid A ((−)-1) has been obtained by a 26-step synthetic route. This enantioselective synthesis employed an intramolecular carbene cyclization cycloaddition cascade reaction as the key step to construct the carbocyclic framework. PMB=para-methoxybenzyl.

Allenes as Dipolarophiles in the Intramolecular Carbene Cyclization—Cycloaddition Cascade Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Allenes as Dipolarophiles in the Intramolecular Carbene Cyclization-Cyclo­addition Cascade Reaction

Intramolecular carbene cyclization-cycloaddition cascade reactions with allenes occur efficiently in the presence of dirhodium catalysts to afford oxatricyclic products as single dia­stereomers.

Application of the Carbene Cyclization—Cycloaddition Cascade in Total Synthesis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Application of the carbene cyclization-cycloaddition cascade in total synthesis

Abstract The title reaction is a key transformation that has been applied to the synthetic studies of the antitumor and antifungal compounds, the pseudolaric acids.

A Tandem Metal Carbene Cyclization—Cycloaddition Approach to the Pseudolaric Acids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A tandem metal carbene cyclization-cycloaddition approach to the pseudolaric acids.

An approach toward the synthesis of the antifungal and cytotoxic pseudolaric acids based on the tandem metal carbene cyclization-cycloaddition reaction is described. Using this strategy, the advanced intermediate 3a bearing three of the four stereocenters of the target molecules has been synthesized. The substrate-controlled diastereoselectivity of the tandem carbene cyclization-cycloaddition was preferential for the undesired diastereomer, but reagent control through the use of Hashimoto's chiral rhodium catalyst Rh(2)(S-BPTV)(4) reversed the selectivity in favor of 3a. Ring opening of the oxabicyclic nucleus to give a hydroxycycloheptene has been demonstrated in a model study.

ChemInform Abstract: A Rhodium Carbene Cyclization—Cycloaddition Cascade Strategy Toward the Pseudolaric Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A rhodium carbene cyclization-cycloaddition cascade strategy toward the pseudolaric acids.

A rhodium carbene intramolecular cyclization-cycloaddition cascade was employed as the key reaction in the synthesis of the nucleus of the cytotoxic diterpenoids pseudolaric acids A and B.