188014-56-4Relevant academic research and scientific papers
Metal-Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde-Derived Silyl Enol Ethers
Roy, Avijit,Oestreich, Martin
supporting information, p. 8273 - 8276 (2021/05/11)
Little-explored hydrosilylation of ketenes promoted by main-group catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enol ethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using dihydrosilanes. The related trityl-cation-initiated hydrosilylation involving self-regeneration of silylium ions is far less effective.
Photoinduced Copper-Catalyzed Asymmetric Decarboxylative Alkynylation with Terminal Alkynes
Dong, Xiao-Yang,Du, Xuan-Yi,Fang, Jia-Heng,Gu, Qiang-Shuai,Li, Zhong-Liang,Liu, Xin-Yuan,Wang, Li-Lei,Xia, Hai-Dong
supporting information, p. 16926 - 16932 (2020/08/25)
We describe a photoinduced copper-catalyzed asymmetric radical decarboxylative alkynylation of bench-stable N-hydroxyphthalimide(NHP)-type esters of racemic alkyl carboxylic acids with terminal alkynes, which provides a flexible platform for the construction of chiral C(sp3)?C(sp) bonds. Critical to the success of this process are not only the use of the copper catalyst as a dual photo- and cross-coupling catalyst but also tuning of the NHP-type esters to inhibit the facile homodimerization of the alkyl radical and terminal alkyne, respectively. Owing to the use of stable and easily available NHP-type esters, the reaction features a broader substrate scope compared with reactions using the alkyl halide counterparts, covering (hetero)benzyl-, allyl-, and aminocarbonyl-substituted carboxylic acid derivatives, and (hetero)aryl and alkyl as well as silyl alkynes, thus providing a vital complementary approach to the previously reported method.
Carbonylative Transformation of Allylarenes with CO Surrogates: Tunable Synthesis of 4-Arylbutanoic Acids, 2-Arylbutanoic Acids, and 4-Arylbutanals
Wu, Fu-Peng,Li, Da,Peng, Jin-Bao,Wu, Xiao-Feng
supporting information, p. 5699 - 5703 (2019/08/01)
In this Communication, procedures for the selective synthesis of 4-arylbutanoic acids, 2-arylbutanoic acids, and 4-arylbutanals from the same allylbenzenes have been developed. With formic acid or TFBen as the CO surrogate, reactions proceed selectively and effectively under carbon monoxide gas-free conditions.
N-heterocyclic carbene-mediated enantioselective addition of phenols to unsymmetrical alkylarylketenes
Concellon, Carmen,Duguet, Nicolas,Smith, Andrew D.
supporting information; experimental part, p. 3001 - 3009 (2010/03/26)
Chiral N-heterocyclic carbenes (NHCs) mediate the enantioselective addition of 2-phenylphenol to unsymmetrical alkylarylketenes, delivering α-alkyl-α-arylacetic acid derivatives with good levels of enantiocontrol (up to 84% ee). Enantiodivergent stereochemical outcomes are observed using 2-phe-nylphenol and benzhydrol in the NHC-promoted esterification reaction using a triazolium precatalyst derived from pyroglutamic acid, consistent with distinct mechanistic pathways operating within these processes.
Asymmetric dimerization of disubstituted ketenes catalyzed by N-heterocyclic carbenes
Lv, Hui,Zhang, Yan-Rong,Huang, Xue-Liang,Ye, Song
supporting information; experimental part, p. 2715 - 2718 (2009/10/20)
A series of chiral N-heterocyclic carbenes (NHCs), derived from L-pyrogutamic acid, were found to be efficient catalysts for the asymmetric dimerization of alkylarylketenes to give the corresponding α-quaternary β-alkylidenyl-β-lactones in good yields with up to 97% ee. A chiral NHC with a proximal hydroxy group is superior in comparison with the corresponding NHC with its hydroxy group protected.
