65145-55-3

Upstream product

• 3481-02-5 cyclopropyl phenyl ketone 
• 4009-98-7 (methoxymethyl)triphenylphosphonium chloride 

Downstream Products

• 123078-49-9 2-cyclopropyl(phenyl)ethanoic acid 
• 128871-23-8 cyclopropyl phenyl ketene 
• 133658-79-4 Cyclopropyl-phenyl-acetyl chloride 
• 133658-89-6 {1-[1-Cyclopropyl-1-phenyl-meth-(Z)-ylidene]-2,2-dimethyl-propoxy}-trimethyl-silane 
• 133658-92-1 (E)-1-cyclopropyl-3,3-dimethyl-1-phenyl-2-trimethylsilyloxy-1-butene 
• 16282-50-1 2-cyclopropyl-2-phenylacetaldehyde 

Relevant academic research and scientific papers

An Asymmetric SN2 Dynamic Kinetic Resolution

The SN2 reaction exhibits the classic Walden inversion, indicative of the stereospecific backside attack of the nucleophile on the stereogenic center. Observation of the inversion of the stereocenter provides evidence for an SN2-type displacement. However, this maxim is contingent on substitution proceeding on a discrete stereocenter. Here we report an SN2 reaction that leads to enantioenrichment of product despite starting from a racemic mixture of starting material. The enantioconvergent reaction proceeds through a dynamic Walden cycle, involving an equilibrating mixture of enantiomers, initiated by a chiral aminocatalyst and terminated by a stereoselective SN2 reaction at a tertiary carbon to provide a quaternary carbon stereocenter. A combination of computational, kinetic, and empirical studies elucidates the multifaceted role of the chiral organocatalyst to provide a model example of the Curtin-Hammett principle. These examples challenge the notion of enantioenriched products exclusively arising from predefined stereocenters when operating through an SN2 mechanism. Based on these principles, examples are included to highlight the generality of the mechanism. We anticipate the asymmetric SN2 dynamic kinetic resolution to be used for a variety of future reactions.

Copper-catalyzed vinylogous aerobic oxidation of unsaturated compounds with air

A mild and operationally simple copper-catalyzed vinylogous aerobic oxidation of β,γ- and α,β-unsaturated esters is described. This method features good yields, broad substrate scope, excellent chemo- and regioselectivity, and good functional group tolerance. This method is additionally capable of oxidizing β,γ- and α,β-unsaturated aldehydes, ketones, amides, nitriles, and sulfones. Furthermore, the present catalytic system is suitable for bisvinylogous and trisvinylogous oxidation. Tetramethylguanidine (TMG) was found to be crucial in its role as a base, but we also speculate that it serves as a ligand to copper(II) triflate to produce the active copper(II) catalyst. Mechanistic experiments conducted suggest a plausible reaction pathway via an allylcopper(II) species. Finally, the breadth of scope and power of this methodology are demonstrated through its application to complex natural product substrates.

Cyclopropylketenes: preparation and nucleophilic additions

Phenylcyclopropylketene (4), tert-butylcyclopropylketene (5), and dicyclopropylketene (6) were formed by dehydrochlorination of the corresponding acyl chlorides by Et3N in THF, and are the first cyclopropylketenes to be isolated and purified.Reaction of 4 with n-BuLi and capture of the intermediate enolates with Me3SiCl gave the stereoisomeric silyl enol ethers c-PrCPh=C(OSiMe3)-n-Bu with a 79:21 preference for formation of the Z isomer resulting from nucleophilic attack syn to cyclopropyl, whereas the corresponding reaction of t-BuLi gave 9:91 preference for attackanti to cyclopropyl.Some isopropyl-, cyclopentyl-, and cyclohexylketenes gave comparable results.Analyses of the relative sizes of the ketene substituents in the ground state by steric parameters, and of the product stabilities by molecular mechanics, both fail to predict the observed similarities in the results with different secondary alkyl groups.The hydration reactivities of 4 and 6 show that, in neutral H2O/CH3CN, c-PrCPh=C=O is more reactive than i-PrCPh=C=O, a result ascribed as mainly due to the smaller size of cyclopropyl. c-Pr2C=C=O has the same reactivity in neutral water as Et2C=C=O, but is 22 times less reactive with acid, a result attributed to the inability of the β-cyclopropyl groups to directly stabilize the cationic transition state for protonation. Key words: cyclopropylketenes, ketenes, nucleophilic addition, hydration kinetics.