Stericallyhinderedporphyrins with four bulky aryl groups in the β-positions are prepared by the reduction of ethyl 3-aryl-4-alkylpyrrole-2-carboxylate with LiAIH4 followed by treatment with an acid and an oxidizing agent.
Synthesis of 2 or 3-(hetero)aryl pyrazolo[1,5-a]pyridines through [3 + 2] cycloaddition ofN-aminopyridine with β-nitrostyrenes followed byin situdenitration under metal-free and mild conditions are described.
Proton Magnetic Resonance Spectra of Some Amphetamines and Related Compounds and Observations on Rotamer Populations
作者:K. Bailey、A. W. By、K. C. Graham、D. Verner
DOI:10.1139/v71-524
日期:1971.10.1
β-nitro-α-phenyl-propanes having methyl or methoxy substituants on the phenyl ring (37 compounds in all) are presented. The α and β protons of the side-chain give a pattern usually analyzable as ABX. The data are discussed in terms of correlations of coupling constants and chemicalshifts with electronegativity of the substituent groups, steric and electronic effects, and apparent changes in rotamer
Squaramide-catalysed enantio- and diastereoselective sulfa-Michael addition of thioacetic acid to α,β-disubstituted nitroalkenes
作者:Wen Yang、Da-Ming Du
DOI:10.1039/c2ob26068a
日期:——
A highly enantio- and diastereoselective sulfa-Michael addition of thioacetic acid to α,β-disubstituted nitroalkenes catalysed by a chiral squaramide organocatalyst has been described. This organocatalytic reaction at an extremely low catalyst loading (0.2 mol%) furnished synthetically useful β-nitro sulfides in excellent yields with good diastereoselectivities and high enantioselectivities (up to 94â:â6 dr, 95% ee). In addition, the catalytic reaction can be performed on a 10 gram scale, and facile transformation into taurine derivative is also presented.
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