86633-09-2Relevant articles and documents
Synthesis of Di-tert-butyl Methylenemalonate, a Sterically Hindered 1,1-Dicarbonyl Alkene
Ballesteros, Paloma,Roberts, Brian W.,Wong, Janice
, p. 3603 - 3605 (1983)
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Dehydroxymethylation of Alcohols Enabled by Cerium Photocatalysis
Zhang, Kaining,Chang, Liang,An, Qing,Wang, Xin,Zuo, Zhiwei
supporting information, p. 10556 - 10564 (2019/08/28)
Dehydroxymethylation, the direct conversion of alcohol feedstocks as alkyl synthons containing one less carbon atom, is an unconventional and underexplored strategy to exploit the ubiquity and robustness of alcohol materials. Under mild and redox-neutral reaction conditions, utilizing inexpensive cerium catalyst, the photocatalytic dehydroxymethylation platform has been furnished. Enabled by ligand-to-metal charge transfer catalysis, an alcohol functionality has been reliably transferred into nucleophilic radicals with the loss of one molecule of formaldehyde. Intriguingly, we found that the dehydroxymethylation process can be significantly promoted by the cerium catalyst, and the stabilization effect of the fragmented radicals also plays a significant role. This operationally simple protocol has enabled the direct utilization of primary alcohols as unconventional alkyl nucleophiles for radical-mediated 1,4-conjugate additions with Michael acceptors. A broad range of alcohols, from simple ethanol to complex nucleosides and steroids, have been successfully applied to this fragment coupling transformation. Furthermore, the modularity of this catalytic system has been demonstrated in diversified radical-mediated transformations including hydrogenation, amination, alkenylation, and oxidation.
Enhanced stereoselectivity of a Cu(II) complex chiral auxiliary in the synthesis of Fmoc-L-γ-carboxyglutamic acid
Smith, Daniel J.,Yap, Glenn P.A.,Kelley, James A.,Schneider, Joel P.
supporting information; experimental part, p. 1513 - 1520 (2011/06/20)
L-γ-Carboxyglutamic acid (Gla) is an uncommon amino acid that binds avidly to mineral surfaces and metal ions. Herein, we report the synthesis of N-R-Fmoc-L-γ-carboxyglutamic acid γ, γ0-tert-butyl ester (Fmoc-Gla(OtBu)2-OH), a suitably protected analogue for Fmoc-based solid-phase peptide synthesis. The residue was synthesized using a novel chiral Cu(II) complex, whose structurebased design was inspired by the blue copper protein rusticyanin. The five-coordinate complex is formed by Shiff base formation between glycine and the novel ligand (S)-2-(N-(2-methylthio)benzylprolyl) aminobenzophenone in the presence of copper. Michael addition of di-tert-butyl methylenemalonate to the R-carbon of the glycine portion of the complex occurs in a diastereoselective fashion. The resulting (S,S)-complex diastereomer can be easily purified by chromatography. Metal complex decomposition followed by Fmoc protection affords the enantiomerically pure amino acid. With the use of this novel chiral complex, the asymmetric synthesis of Fmoc-Gla(OtBu)2-OH was completed in nine steps from thiosalicylic acid in 14.5% overall yield.
