[reaction: see text] A BINOLate-zinc complex prepared in situ from Et(2)Zn and 3,3'-dibromo-1,1'-bi-2-naphthol (3,3'-Br(2)-BINOL) was found to be a highly efficient catalyst for the enantioselective hetero-Diels-Alder reaction of Danishefsky's diene and aldehydes to give 2-substituted 2,3-dihydro-4H-pyran-4-one in up to quantitative yield and 98% ee.
Synthesis of aldehydes by a one-carbon homologation of ketones and aldehydes via α,β-unsaturated isocyanides
作者:Janusz Moskal、Albert M. van Leusen
DOI:10.1002/recl.19871060501
日期:——
Ketones and aldehydes react via a Wittig-Horner-Emmons reaction using diethyl (isocyanomethyl)phosphonate to form α,β-unsaturated isocyanides (4), which are either hydrolyzed as such, under acid conditions, or hydrolyzed after oxidation to α,β-unsaturated isocyanides (6) to give aldehydes containing one additional carbon atom. The scope of the reaction is demonstrated by 20 examples.
Copper(II) Acetate Mediated Synthesis of 3-Sulfonyl-2-aryl-2H-chromenes
作者:Meng-Yang Chang、Yu-Hsin Chen、Han-Yu Chen
DOI:10.1055/s-0039-1689973
日期:2019.9
two-step synthetic route, which includes (i) Cu(OAc)2/PyBOP-mediated intermolecular [4+2] annulation of substituted salicylic acids with β-sulfonylstyrenes in the presence of DMAP in refluxing DMF, and (ii) sequential O-alkylation of the resulting sulfonylflavanones with n-butyl bromide. A plausible mechanism is proposed and discussed. This protocol provides a highly effective annulation via one carbon–oxygen
The in situ generation of Ph3P=C(CF3)2. a facile one pot conversion of aldehydes to bis-trifluoromethyl olefins.
作者:Donald J. Burton、Yoshio Inouye
DOI:10.1016/s0040-4039(01)95419-x
日期:1979.1
The in situ reaction of triphenylphosphine with tetrakis(trifluoromethyl)-1,3-dithietane in the presence of aliphatic or aromatic aldehydes gives good to excellent yields of bis-trifluoromethyl olefins.
Deprotection Chemistry Mediated by ZrOCl<sub>2</sub> · 8H<sub>2</sub>O: An Efficient, Mild, and Green Method for the Conversion of Oximes to Carbonyl Compounds in Aqueous Acetone
Abstract Less-toxic, moisture-stable, inexpensive, and ecofriendly zirconium oxychloride octahydrate (ZrOCl2 · 8H2O) in aqueous acetone (1:1) mediates the conversion of oximes to carbonyl compounds in moderate to good yields. This green methodology is applicable to both aldoximes and ketoximes with tolerance to >C˭C<, -NO2, -OH, and -Cl groups. The reaction and workup are simple.