Cycloheptadiene Derivatives Research Articles

ChemInform Abstract: Rhenium(I)‐Catalyzed Generation of α,β‐Unsaturated Carbene Complex Intermediates from Propargyl Ethers for the Preparation of Cycloheptadiene Derivatives.

AbstractThe rhenium(I)‐catalyzed generation of αβ‐unsaturated carbene complex intermediates from easily available propargyl ethers is achieved for the concise construction of cycloheptadiene derivatives through the formal [4+3] cycloaddition reaction with siloxydienes.

Rhenium(I)‐Catalyzed Generation of α,β‐Unsaturated Carbene Complex Intermediates from Propargyl Ethers for the Preparation of Cycloheptadiene Derivatives

AbstractThe rhenium(I)‐catalyzed generation of α,β‐unsaturated carbene complex intermediates from easily available propargyl ethers was achieved for the concise construction of cycloheptadiene derivatives through the formal [4+3] cycloaddition reaction with siloxydienes.

Rhenium(I)-Catalyzed Generation of α,β-Unsaturated Carbene Complex Intermediates from Propargyl Ethers for the Preparation of Cycloheptadiene Derivatives.

The rhenium(I)-catalyzed generation of α,β-unsaturated carbene complex intermediates from easily available propargyl ethers was achieved for the concise construction of cycloheptadiene derivatives through the formal [4+3] cycloaddition reaction with siloxydienes.

Rhodium‐Catalyzed [3+2+2] and [2+2+2] Cycloadditions of Two Alkynes with Cyclopropylideneacetamides

AbstractIt has been established that a cationic rhodium(I)/H8‐binap complex catalyzes the [3+2+2] cycloaddition of 1,6‐diynes with cyclopropylideneacetamides to produce cycloheptadiene derivatives through cleavage of cyclopropane rings. In contrast, a cationic rhodium(I)/(S)‐binap complex catalyzes the enantioselective [2+2+2] cycloaddition of terminal alkynes, acetylenedicarboxylates, and cyclopropylideneacetamides to produce spiro‐cyclohexadiene derivatives which retain the cyclopropane rings.

Rhodium-Catalyzed [3+2+2] and [2+2+2] Cycloadditions of Two Alkynes with Cyclopropylideneacetamides.

It has been established that a cationic rhodium(I)/H8 -binap complex catalyzes the [3+2+2] cycloaddition of 1,6-diynes with cyclopropylideneacetamides to produce cycloheptadiene derivatives through cleavage of cyclopropane rings. In contrast, a cationic rhodium(I)/(S)-binap complex catalyzes the enantioselective [2+2+2] cycloaddition of terminal alkynes, acetylenedicarboxylates, and cyclopropylideneacetamides to produce spiro-cyclohexadiene derivatives which retain the cyclopropane rings.

ChemInform Abstract: Rhodium‐Catalyzed Tandem Cyclopropanation/Cope Rearrangement of 4‐Alkenyl‐1‐sulfonyl‐1,2,3‐triazoles with Dienes.

AbstractThis method uses 4‐alkenyl‐1,2,3‐triazoles as alkenylcarbene precursors which undergo a formal [4 + 3] cycloaddition to give substituted cycloheptadiene derivatives in high yields and with good enantioselectivities.

Palladium‐Mediated Phosphine‐Dependent Chemoselective Bisallylic Alkylation Leading to Spirocarbocycles

Cycles everywhere: The selectivity in the transformations of 1,3-diones to carbocycles by palladium-catalyzed bisallylic alkylations is strongly dependent on the phosphine that is employed. Moreover, synthesized vinylcyclopentenes can be easily transformed into cycloheptadiene derivatives through a carbon-carbon allylic bond cleavage.

Thermal and catalytic isomerization of exomethylenecycloheptadienes. Experimental and theoretical studies

The intermolecular [3+2+2] cycloaddition reaction of ethyl cyclopropylideneacetate with alkynes proceeded in the presence of a Ni(0)/PPh 3 catalyst, and cycloheptadiene derivatives were obtained. However, in the reaction of 1-cyclopropylidene-2-propanone with phenylacetylene, a cycloheptatriene derivative was isolated. It was anticipated that the isomerization of the initially formed cycloheptadiene derivative led to the formation of the cycloheptatriene derivative. In this paper, we report the isomerization of cycloheptadiene derivatives under thermal, acidic and basic conditions. The stability of the products was also studied by theoretical calculations. The effects of substituents and the mechanism of the isomerization were discussed.

Ni-catalyzed [3+2+2] cycloaddition of ethyl cyclopropylideneacetate and 1,3-diynes. Application to the three-component cycloaddition

The Ni-catalyzed [3+2+2] cocyclization between ethyl cyclopropylideneacetate ( 1) and 1,3-diynes afforded cycloheptadiene derivatives. The three-component reaction of 1, 1,3-diynes, and alkynes proceeded with good yield and high selectivity. Scope of the substrates was studied, and the origin of chemo- and regioselectivity of the reaction is discussed.

Nickel-Catalyzed Intermolecular [3 + 2 + 2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes. Synthesis of Seven-Membered Carbocycles

The [3 + 2 + 2] cocyclization of ethyl cyclopropylideneacetate (1a) and various alkynes proceeded smoothly in the presence of Ni(cod)2-PPh3. The cycloheptadiene derivatives were synthesized in highly selective manners. The unique reactivity of 1a was essential for the progress of the reaction. The observed regioselectivity of the product formation and the mechanism of the reaction are discussed.

Nickel‐Catalyzed Intermolecular [3 + 2 + 2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Nickel-catalyzed intermolecular [3 + 2 + 2] cocyclization of ethyl cyclopropylideneacetate and alkynes.

The [3 + 2 + 2] cocyclization of ethyl cyclopropylideneacetate (1a) and terminal alkynes (2) proceeded smoothly in the presence of 10 mol % "Ni(PPh3)2", which was prepared in situ from Ni(cod)2 and PPh3. The high reactivity of 1a, which was induced by the introduction of an electron-withdrawing group, is very important for the progress of this reaction. The cycloheptadiene derivatives were synthesized in highly selective manner in good yields.

Ruthenium‐Catalyzed Cyclopropanation of Alkenes Using Propargylic Carboxylates as Precursors of Vinylcarbenoids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Ruthenium-catalyzed cyclopropanation of alkenes using propargylic carboxylates as precursors of vinylcarbenoids.

Intermolecular cyclopropanation reactions of various alkenes with propargylic carboxylates 1 are catalyzed by [RuCl2(CO)3]2 to give vinylcyclopropanes 2 in good yields. The key intermediate of the reaction is a vinylcarbene complex generated in situ by nucleophilic attack of a carbonyl oxygen of the carboxylates to an internal carbon of the alkyne activated by the ruthenium complex. A variety of transition-metal compounds other than the Ru compound can also be employed in this system. Similar cyclopropanation proceeds with conjugated dienes as well to give trans-vic-divinylcyclopropane derivatives and cycloheptadiene derivatives 5, the latter being thermally derived from the initially formed cis-vic-isomers via Cope-type rearrangement. The present reaction is chemically equivalent to the transition metal-catalyzed cyclopropanation reaction using alpha-diazoketones as carbenoid precursors.

Cyclopropanation with Fischer Acyloxycarbene Complexes: Preparation of Cyclopropane and Cycloheptane‐Fused γ‐Lactones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cyclopropanation with Fischer acyloxycarbene complexes: preparation of cyclopropane and cycloheptane-fused gamma-lactones.

[reaction: see text] A sequential acylation-intramolecular cyclopropanation reaction takes place upon treatment of a series of tetraalkylammonium acylchromates with beta,gamma-unsaturated acyl chlorides at -10 degrees C. The reaction leads to 2-oxabicyclo[3.1.0]hexan-3-ones with exo selectivity in good yields. The diastereoselectivity of the reaction allows the preparation of cis-divinyl cyclopropanes, which evolve via Cope sigmatropic reaction toward cycloheptadiene derivatives. Furthermore, the aromatic Cope rearrangement of a series of cis-aryl vinyl cyclopropanes prepared by means of this methodology has been studied.

Regiocontrolled functionalization of seven-membered ring via nucleophilic cycloheptenyl-η3-allyltitanium complexes

A new "electron-reversed" method for the functionalization of a seven-membered ring is developed. Cycloheptenyl-η3-allyltitanocene complexes derived from cycloheptatriene react with aldehydes or carbon dioxide to afford, respectively, the mixture of isomeric 1,4- and 1,3-cycloheptadienyl carbinols 3a–e and 2a–e or methyl esters 7 and 6. The 3/2 and 7/6 ratios increase with increasing steric hindrance in the electrophile. Moreover, these may be significantly increased by introducing tert-butyl substituents on the Cp rings of the starting titanocene dichloride. The regiochemistry of the reaction was rationalized in terms of the equilibrium between the two envisageable allylic complexes. The reaction constitutes the first direct entry to functionalized 1,4-cycloheptadienes, some of which are related to biologically active compounds. Keywords: η3-allyltitanium complexes, cycloheptadiene derivatives, regiocontrol, electron reversal.