18622-82-7Relevant academic research and scientific papers
Photoredox-enabled 1,2-dialkylation of α-substituted acrylatesviaIreland-Claisen rearrangement
Kleinmans, Roman,Will, Leon E.,Schwarz, J. Luca,Glorius, Frank
, p. 2816 - 2822 (2021)
Herein, we report the 1,2-dialkylation of simple feedstock acrylates for the synthesis of valuable tertiary carboxylic acids by merging Giese-type radical addition with an Ireland-Claisen rearrangement. Key to success is the utilization of the reductive radical-polar crossover concept under photocatalytic reaction conditions to force the [3,3]-sigmatropic rearrangement after alkyl radical addition to allyl acrylates. Using readily available alkyl boronic acids as radical progenitors, this redox-neutral, transition-metal-free protocol allows the mild formation of two C(sp3)-C(sp3) bonds, thus providing rapid access to complex tertiary carboxylic acids in a single step. Moreover, this strategy enables the efficient synthesis of highly attractive α,α-dialkylated γ-amino butyric acids (GABAs) when α-silyl amines are used as radical precursors - a structural motif that was still inaccessible in related transformations. Depending on the nature of the radical precursors and their inherent oxidation potentials, either a photoredox-induced radical chain or a solely photoredox mechanism is proposed to be operative.
Origins of stereoselectivity in radical additions: Reactions of alkenes and radicals bearing oxazolidine and thiazolidine amide groups
Porter, Ned A.,Rosenstein, Ian J.,Breyer, Robert A.,Bruhnke, John D.,Wu, Wen-Xue,McPhail, Andrew T.
, p. 7664 - 7676 (2007/10/02)
Single-crystal X-ray analysis of four alkenes that undergo stereoselective radical addition reactions are reported. The facial selectivity of radical additions to these alkenes is understood based upon their solid-state conformations. Alkenes which have a conformation placing a group at a position in space sterically protecting one of the faces from addition undergo radical addition with diastereofacial selectivity. The structures of the alkenes are analyzed by the polar coordinates of groups relative to the alkene center undergoing addition. The analysis of conformations of alkenes also provides a rationale for stereoselectivity in the reactions of radicals derived from the alkenes. Factors which influence the conformation of the alkene also apparently influence the conformation of analogous radicals. Several products of addition were also subjected to X-ray cryslallographic analysis, and the steric factors which influence the conformation of the reactant alkene are also observed to affect the conformation of the radical addition products.
