Search results for "Tertiary alcohols"
showing 6 items of 6 documents
Diastereoselective synthesis of enantiomeric tertiary alcohols via nucleophilic additions to protected D- and L-erythrulose derivatives
1992
Abstract The diastereoselectivity of the addition of several organometallic reagents to the carbonyl group of protected D - and L -erythrulose derivatives has been investigated. Tertiary alcohols are stereoselectively formed, the diastereomeric ratio being markedly dependent on the reagent type, solvent and temperature.
Stereoselectivity in the Addition of Organotitanium Reagents to Carbonyl Compounds
1986
Although great strides have been made in the area of stereoselective C—C bond forming reactions [1], many problems persist. Early studies concerning chemo- selective reactions of organotitanium reagents (Chapter 3) suggested that they might also behave stereoselectively in relevant cases. In fact, the first such observation goes back to 1979 when it was noted that dichlorodi- methyltitanium (2) adds to the ketone 1 in CH2C12 to produce a mixture of tertiary alcohols 4/5 instead of the desired (±) cuparene (3) [2, 3]. The striking aspect of this transformation is the high disastereoselectivity in favor of 4. Methyllithium shows the opposite stereoselectivity (4:5 = 34:66), in line with the s…
Organocatalytic Enantioselective Vinylogous Henry Reaction of 3,5-Dimethyl-4-nitroisoxazole with Trifluoromethyl Ketones
2017
The enantioselective vinylogous Henry reaction of 3,5-dimethyl-4-nitroisoxazole with trifluoromethyl ketones employing a bifunctional squaramide organocatalyst has been developed. A series of isoxazole bearing trifluoromethyl-substituted tertiary alcohols, 2-substituted (R)-1,1,1-trifluoro-3-(3-methyl-4-nitroisoxazol-5-yl)propan-2-ols, were obtained under these mild reaction conditions in good yields and moderate to good enantioselectivities
Enantioselective Synthesis of Tertiary Alcohols through a Zirconium-Catalized Friedel-Crafts Alkylation of Pyrroles with alpha-Ketoesters
2011
Chiral complexes of 1,10-bi-2-naphthol-based ligands with zirconium tert-butoxide catalyze the Friedel Crafts alkylation of pyrroles with R-ketoesters to afford tertiary alcohols in good yields and ee up to 98%. The reaction is also of application to 4,7-dihydroindole to give C2-alkylated indoles after oxidation with p-benzoquinone.
ChemInform Abstract: Enantioselective Synthesis of Tertiary Alcohols Through a Zirconium-Catalyzed Friedel-Crafts Alkylation of Pyrroles with α-Ketoe…
2011
Chiral complexes of 1,1′-bi-2-naphthol-based ligands with zirconium tert-butoxide catalyze the Friedel–Crafts alkylation of pyrroles with α-ketoesters to afford tertiary alcohols in good yields and ee up to 98%. The reaction is also of application to 4,7-dihydroindole to give C2-alkylated indoles after oxidation with p-benzoquinone.
Water compatible gold(III)-catalysed synthesis of unsymmetrical ethers from alcohols.
2008
An efficient and broad-scoped method for the preparation of unsymmetrical ethers from alcohols catalysed by the simplest and least expensive gold catalyst, NaAuCl 4 , is described for the first time. The procedure enables the etherification of benzylic and tertiary alcohols with moderate to good yields under mild conditions with low catalyst loading. Symmetrical ethers, the usual side products in the etherification of alcohols, were not detected in this case. The formation of the racemic ether from a chiral benzyl alcohol suggests the intermediacy of a carbocation, which has not previously been postulated for gold-catalysed reactions involving alcohols.