14604-46-7Relevant articles and documents
Vinylcyclobutanols: A composite functional group?
Trost, Barry M.,Chen, Deborah W. C.
, p. 12541 - 12554 (1996)
The effect of small strained rings on chemical reactivity was probed by the examination of the behavior of vinylcyclobutanols as terminators in cyclization reactions. The substrates were readily available by the addition of vinyllithium reagents bearing acetals as cyclization initiators to cyclobutanone. Bronsted and Lewis acids both promoted cyclization in contrast to vinylcyclopropanol terminators for which Bronsted acids failed. The products are spirocycles consisting of a cyclopentanone derived from ring expansion of the cyclobutanol and the second ring derived by attack of the terminator on the initiator. Spirocyclization to [4.5] and [4.6] systems proceeded smoothly, whereas spirocyclization to a [4.7] system failed. Attaching the cyclization termini to a preexisting ring system (whereby tricycles consisting of a fused bicycle and a spirocycle are formed) expands the scope of the cyclization to include the [4.7] ring system even at 0.01 M, a rather high concentration for such an unfavorable ring system. The diastereoselectivity generally placed the initiator substituent and the carbon-carbonyl bond of the cyclopentanone ring trans on the newly formed ring. Cyclic acetals and the free aldehyde also served as initiators. The mechanistic implications of these observations are discussed.
ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
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Paragraph 0013; 0028, (2021/01/29)
An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
Copper-Catalyzed Oxidative Fragmentation of Alkynes with NFSI Provides Aryl Ketones
Chen, Hanfei,Cheng, Hao,Huang, Yifan,Jin, Chaochao,Song, Weihan,Tan, Chen,Tan, Jiajing,Tang, Lin,Yang, Fang,Zhang, Shuaifei
supporting information, (2020/11/03)
A copper-catalyzed oxidative cleavage reaction of alkynes using NFSI and TBHP was described. Various terminal and internal alkyne substrates were employed to render quick access to aryl ketone products in moderate to good yields. NFSI not only functioned as N-centered radical precursors but also engaged in the aryl group migration. Mechanistic studies also suggested the important role of water in the title reactions.
Conversion of Aldehydes to Branched or Linear Ketones via Regiodivergent Rhodium-Catalyzed Vinyl Bromide Reductive Coupling-Redox Isomerization Mediated by Formate
Swyka, Robert A.,Shuler, William G.,Spinello, Brian J.,Zhang, Wandi,Lan, Chunling,Krische, Michael J.
supporting information, p. 6864 - 6868 (2019/05/10)
A regiodivergent catalytic method for direct conversion of aldehydes to branched or linear alkyl ketones is described. Rhodium complexes modified by PtBu2Me catalyze formate-mediated aldehyde-vinyl bromide reductive coupling-redox isomerization to form branched ketones. Use of the less strongly coordinating ligand, PPh3, promotes vinyl-to allylrhodium isomerization en route to linear ketones. This method bypasses the 3-step sequence often used to convert aldehydes to ketones involving the addition of pre-metalated reagents to Weinreb or morpholine amides.