Search results for "Alkylation"

1983

Introduction des groupes alkyl dans le polyamide commercial Trogamid T. Formation d'anions polyamides par l'hydrure de sodium puis alkylation par les bromures d'alkyle

ChemInform Abstract: Enantioselective Synthesis of α-Quaternary Amino Acids by Alkylation of Deprotonated α-Aminonitriles.

2015

An α-alkylation of deprotonated α-amino nitriles, prepared from chiral phenyldioxanamine (I) by Strecker reaction, leads to α-quaternary arylglycines with high optical purity after hydrolysis and oxidative cleavage of the chiral auxiliary.

Lewis Acid-Catalyzed Stereoselection on Carbohydrate Templates

1989

The chirality and the complexing abilities of carbohydrates are utilized for chemical stereoselection in different reactions. In this sense, the carbohydrates are investigated as the chiral auxiliaries in alkylation reactions and in Michael additions of ester enolates. Furthermore, carbohydrates are demonstrated to be efficient chiral matrices in Lewis acid-catalyzed Diels-Alder reactions. They also effect stereoselection in a new synthesis of β-branched carboxylic acid derivatives. O-Acylated glycosylamines are shown to be potent chiral templates in the Strecker synthesis and in the Ugi four-component condensation to give α-amino acid derivatives in high yield and diastereoselectivity. In …

Alkylation of acidic organic compounds for gas chromatographic analysis

1973

A new alkylation method is proposed. Organic solutions of fatty acids, phenols or barbituric acids are refluxed with an alkylating reagent and solid K2CO3. The reaction mixture is injected directly into the gas chromatograph. The scope of this convenient method for quantitative and qualitative analyses is considerable as different classes of alkylating agents can be used.

Structural selectivity provided by starburst dendrimers as pseudostationary phase in electrokinetic chromatography

1995

Abstract Starburst dendrimers (SBDs) were used as a pseudostationary phase in electrokinetic chromatography (EKC) of hydrophobic compounds. The selectivity of SBD-mediated EKC (SBD-EKC) was different from those in micellar EKC (MEKC) systems, in spite of the apparent structural resemblance between micelles and SBDs. The SBDs provided similar selectivity as polymer gel packing materials in reversed-phase liquid chromatography (RPLC), showing little selectivity for alkyl groups and clear preference for aromatic compounds, especially for rigid, planar polynuclear aromatic hydrocarbons. The alkylation of SBDs resulted in the increased retention and hydrophobic selectivity while maintaining the …

New ferrocene-containing copolyesters

1995

We have synthesized four new ferrocene monomers (three diols and one diester). The redox potential of these ferrocene derivatives varies between 0 mV and 230 mV due to different degrees of ring alkylation. Amorphous and liquid crystalline copolyesters were prepared with these monomers in the polymer main chain. Cyclovoltammetric measurements show that the redox potential of the ferrocene units is increased by about 40 mV upon polymer formation (esterification). Since the ester group is 4 to 6 σ-bonds away from the ferrocene unit this increase is probably caused by some charge-transfer interaction through space. First rheological measurements show an unusual rubber-like behaviour of the ferr…

Nucleophilic benzoylation using lithiated methyl mandelate as a synthetic equivalent of the benzoyl carbanion. Oxidative decarboxylation of α-hydroxy…

2001

Abstract The synthesis of alkyl aryl ketones using lithiated methyl mandelate as a synthetic equivalent of the benzoyl carbanion is reported (Umpolung). The methodology involves alkylation of methyl mandelate, hydrolysis of the ester group and oxidative decarboxylation of the resulting α-hydroxyacids. The last step is carried out in a catalytic aerobic way using a Co(III) complex in the presence of pivalaldehyde under very mild and advantageous conditions. The procedure is also applied to methyl mandelates substituted on the aromatic ring.

Stable 17-electron Mo(III) complexes containing alkyl ligands

1999

Abstract The alkylation of the half-sandwich complex CpMoCl 2 ( η 4 -diene) (diene=C 4 H 6 , 2,3-Me 2 C 4 H 4 ) affords the first thermally stable 17-electron compounds containing Mo(III)–alkyl bonds.

Lithium enediolates and dienediolates of carboxylic acids in synthesis: Alkylation with secondary halides

1998

Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.

ChemInform Abstract: Lithium Enediolates and Dienediolates of Carboxylic Acids in Synthesis: Alkylation with Secondary Halides.

2010

Abstract High yields in the alkylation of dianions of α,β-unsaturated carboxylic acids with secondary halides can be obtained despite elimination reactions occurring. α-Regioselectivity for the alkylation of but-2-enoic acids ( 1–4 ) is seldom obtained. Although double bond stereoselectivity is higher than 99% for γ-alkylated products, stereoselectivity is rather poor for most of the α-alkylated products.