A Novel Heterocycle-Stabilized Allylic Anion Route to Cyclopropanes, 1-Ethoxy-1-vinylethylene Oxides, 1-Hydroxyalkyl 2-Methoxyethyl Ketones, 1-Hydroxyalkyl Vinyl Ketones, .beta.-Ethoxy-.beta.-vinylalkyl Alcohols, .gamma.-Lactones, and .beta.,.gamma.-Unsaturated Carboxylic Acids
摘要:
Treatment of N-(alpha-ethoxyallyl)benzotriazole (8) with butyllithium followed by alpha,beta-unsaturated esters at -78 degrees C formed the 1,1-adducts 11 which underwent internal displacement of the benzotriazolyl group at 20 degrees C to give cyclopropanecarboxylic esters 14 and 15. In the presence of ZnBr2, addition of anion 13 to cyclic and methyl ketones gave 1-ethoxy-1-vinylethylene oxides 25 in good yields. Epoxides 25 were subsequently converted to 1-hydroxyalkyl 2-methoxyethyl ketones 24, 1-hydroxyalkyl vinyl ketones 26, and beta-ethoxy-beta-vinylalkyl alcohols 27. Treatment of anion 13 with aromatic ketones or sterically hindered aliphatic ketones produced gamma-alkylated adducts 31 which were hydrolyzed to beta,gamma-unsaturated carboxylic acids 32 (R(1), R(2) = aromatic) or gamma-lactones 33 (R(1), R(2) = aliphatic).
Organocatalytic Michael Addition of Unactivated α-Branched Nitroalkanes to Afford Optically Active Tertiary Nitrocompounds
作者:Beñat Lorea、Ane García-Urricelqui、José M. Odriozola、Jesús Razkin、Maialen Espinal-Viguri、Mikel Oiarbide、Antonia Mielgo、Jesús M. García、Claudio Palomo
DOI:10.1021/acs.orglett.3c03340
日期:2023.12.8
The direct, asymmetric conjugateaddition of unactivated α-branched nitroalkanes is developed based on the combined use of chiral amine/ureidoaminal bifunctional catalysts and a tunable acrylate template to provide tertiary nitrocompounds in 55–80% isolated yields and high enantioselectivity (e.r. up to 96:4). Elaboration of the ketol moiety in thus obtained adducts allows a fast entry to not only
Development of an α′-hydroxy enone for the aminocatalytic asymmetric formal conjugate addition of aldehydes to acrylates, vinyl ketones and acrolein
作者:José M. Odriozola、Jesús Razkin、Beñat Lorea、Antonia Mielgo、Jesús M. García、Mikel Oiarbide、Claudio Palomo
DOI:10.1039/d3ob00475a
日期:——
conjugate addition of aldehydes to Michael acceptors is a well established C–C bond forming methodology. However, various acrylic-type acceptors, including acrylic acid derivatives and acrolein, remain reluctant. Here we demonstrate that the internal H-bonding self-activation in α′-hydroxy enones allows them to react smoothly with enolizable aldehydes using commercially available aminocatalysts to afford
Thermoplastische Formmassen aus Polyamiden, Pfropfprodukten aus gegebenenfalls substituiertem Polybutadien und Estern der (Meth)acrylsäure und gegebenenfalls Styrol und Acrylnitril und für Polyamide üblichen Weichmachern.
Three-carbon annelations. Regiocontrolled reactivity of trimethylsilyl- and ethoxyethyl-protected cyanohydrins. Versatile homoenolate and acyl anion equivalents
作者:Richard M. Jacobson、George P. Lahm、John W. Clader