Sandor Karady

Enantioretentive alkylation of acyclic amino acids

Abstract A stereospecific method is described for the alkylation of acyclic amino acids (alanine and phenylalanine) which proceeds with retention of configuration. The method involves a) conversion of the amino acid to the predominantly cis 2-aryl-3-carbobenzyloxy oxazolidinones (2 and 8), b) alkylation of the potassium enolate with CH3I or PhCH2Br, c) Base hydrolysis and hydrogenolysis to afford the alkylated amino acid.

Mass spectrometry of the trimethylsilyl ethers of 2-ketohexoses

Abstract The mass spectra of the trimethylsilyl ethers of d -fructose, l -sorbose, methyl- d -fructopyranose and methyl- l -sorbofuranose are presented. The interpretation of the fragmentation is supported by the use of deuterium labelled analogues. The preparation of 1,1-d2 and 6,6-d2- l -sorbose is reported. The mass spectra of the trimethylsilyl ethers offers a method to distinguish 2-ketohexoses from aldohexoses, and to identify the existing ring structure. The characteristic peaks are 2-ketohexoses m/e 437; aldohexoses m/e 435, pyranose ring m/e 204, furanose ring m/e 217.

Diarryl-a-heteroarylmalonates from Cerium(IV)-promoted Reactions of Dialkyl Malonates with Heterocyclic Compounds

Thiophenes, furans and their benzo analogs undergo facile malonylation in the 2-position on reaction with dialkyl malonate radicals generated with cerium (IV) reagent

Anodic N-dearylation of 2-azetidinones

Abstract N-Methoxyphenyl-2-azetidinones are dearylated under mild conditions via anodic oxidation.

Cyclization of electrochemically generated nitrogen radicals. A novel synthesis of 11-substituted dibenzo[a,d]cycloheptenimines

Abstract A novel and convenient synthesis of 11-substituted dibenzo[a,d]cyclo-heptimines 10 via annelatlon of electrochemically generated aminium radicals derived from substituted 5-hydroxylamino-5-methyl-5H-dibenzo[a,d]cycloheptenes 14 is described. The scope and limitations of the reaction as well as the effects of reactor design, current density and electrode material on the yield of 10 and the carbocation rearrangement by-product 28 are discussed.

Annelation of aromatic oxo compounds

Abstract The silyl enol ether of α-diazoacetoacetate is used for the annelation of aromatic oxo compounds. The method involves condensation with the oxo compound in the presence of TiCl4 followed by rhodium octanoate-catalyzed ring closure to afford furan derivatives by direct carbene isertion and β-naphthol esters by a Wolff rearrangement pathway.

In situ NMR spectroscopic studies of aniline ortho acylation (“sugasawa reaction”): The nature of reaction intermediates and Lewis acid influence on yield

Abstract Ortho acylation of anilines by nitriles in the presence of BCl 3 and a second Lewis acid appear to proceed through an intermediate “supercomplex” including all four components. Yield improvements were obtained based on recognition that chloride affinity of the second Lewis acid governs supercomplex formation. Aniline protonation was found to be the cause of incomplete reaction.

Cyclization of electrochemically generated nitrogen radicals. : A novel synthesis of 11-substituted dibenzo[a,d]cycloheptenimine derivatives

Abstract A novel and convenient synthesis of 11-substituted dibenzo[a,d]cyclo-heptimines 10 via annelatlon of electrochemically generated aminium radicals derived from substituted 5-hydroxylamino-5-methyl-5H-dibenzo[a,d]cycloheptenes 14 is described. The scope and limitations of the reaction as well as the effects of reactor design, current density and electrode material on the yield of 10 and the carbocation rearrangement by-product 28 are discussed.

A Practical Process for the Preparation of Azetidine-3-carboxylic Acid

Abstract A practical and convenient synthesis of azetidine-3-carboxylic acid (1) that proceeded in 55% overall yield from commercially available diethylbis(hydroxymethyl)malonate (3) is reported. Azetidine ring-formation was achieved in high yield by cyclization of bistrifiate of the diol (3) and benzylamine. Decarboxylation under carefully pH-controlled conditions gave the mono acid azetidine that was hydrogenated to give the title compound.

A direct preparation of silyl oxazoles: a dramatic chemoselectivity difference between R3SiOTf and R3SiCl

Abstract General, highly selective silylation conditions for the ambident oxazole anion (isocyano enolate) have been found. The chemoselectivity between O -silylation and C -silylation changed from 99:1 upon switching from R 3 SiCl to R 3 SiOTf.