John N. Marx

DETERMINATION OF HYDROGEN PEROXIDE BY PHOTOINDUCED FLUOROGENIC REACTIONS

Abstract 4-Hydroxyproline, 8-hydroxyquinoline, 4-hydroxyquinoline-2-carboxylic acid and 4-hydroxyphenylacetic acid (HPA) react with H2O2 when irradiated with UV light to yield fluorescent products. Sub-micromolar detection limits of H2O2 are possible with HPA. The fluorescent product is the same as that formed in the peroxidase enzyme-mediated H2O2 oxidation of HPA. Several compounds that participate in the photomediated reaction do not react in the enzyme-mediated system. A mechanism for the photomediated reaction involving an aryloxy radical derived from the substrate is suggested. Although the limits of detection for H2O2 do not equal the best achievable with the enzyme-mediated systems, the simplicity of a single-step reaction and an ability to “photodevelop” the product offer a range of novel analytical possibilities.

Simple, high yielding synthesis of trifunctional fluorescent lanthanide chelates

Abstract In an effort to produce strong fluorophores which are conjugated to biologically active substrates, we report a facile, high yielding synthesis of conjugable lanthanide chelates based on the cyclen (1,4,7,10-tetraazacyclododecane) macrocycle.

A simple and convenient synthesis of β-haloketones

Abstract A new rapid quantitative method to synthesize β-halo-ketones is described (eqn 2) which utilizes the reaction of an enone with a tetraalkyl ammonium halide in anhydrous trifluoro acetic acid. The method is especially convenient for the preparation of β-iodoketones.

2-Carbomethoxycyclopentenone as a synthon. synthesis of sarkomycin☆

Abstract The first regiospecific synthesis of sarkomycin (II), a compound active against ascites-type tumors, is reported. Treatment of 2-carbomythoxycyclopentenone (I) with Et 2 AlCN generated the carbon skeleton; aelective functional group manipulations then gave the keto lactone X and the protected hydroxy acid XI; and mild acid treatment of these led to sarkomycin.

A new synthesis of theaspirone, an odiferous principle of tea

Abstract A new synthesis of theaspirone ( 10 ) is recorded. The key step involves coupling between the organolithium reagent 6 , derived from 4-bromo-2-butanol ( 4 ), and the monoketal of 4-ketoisophorone ( 3 ). Removal of protecting groups and ether cyclization then gave theaspirone 10 and its diastereoisomer 11 .

Synthesis of dihydroarbiglovin and stereochemistry of arbiglovin

Abstract Dihydroarbiglovin (III) has been synthesized by a stereoselective route starting with photolysis of santonin. The synthesis determines the stereochemistry at C-1 and C-10 as shown for arbiglovin (I).

Spectrophotometric determination of H2O2 with 1-anilinonaphthalene-8-sulfonic acid and 4-aminoantipyrine with hematin as catalyst

A spectrophotometric flow injection method for the determination of H(2)O(2) in aqueous solution is presented. The technique is based on the oxidative condensation reaction between 1-anilinonaphthalene-8-sulfonic acid (ANSA) and 4-aminoantipyrine (AAP) in the presence of H(2)O(2). Hematin is a good peroxidatic catalyst for this reaction; its effectiveness is significantly enhanced in an ammoniacal medium. If the yellow product formed in the alkaline medium is acidified, a blue chromophore (lambda(max) 592 nm) is formed; a surfactant is necessary to keep the blue compound in solution. Chemical and instrumental parameters for FIA were evaluated and optimized. A detection limit of 0.3muM was achieved with a linear dynamic range extending to 50muM. The typical relative standard deviation is 1.5% or better. The structure of the reaction product has been identified.

Cobaloxime template reactions I. The formation of N-nitrosamines

Abstract The synthesis of a potent carcinogen, N -nitroso- N -methylaniline, employing a bis(dimethylglyoximato)cobaltate template is described. Carbon bonded N -methyleneaniline adducts of cobaloxime with pyridine, NO - 2 or CN - in the basal (sixth) coordination position of the cobalt atom were prepared and isolated. These cobaloxime methyleneaniline adducts were found to readily undergo nitrosation when treated with nitrous acid. The resulting N -nitrosamine adducts were characterized by IR, NMR and mass spectroscopy. Interesting trans effects of the basal substituents are noted. Final template reaction products were identified by thermal degradation and chemical cleavage with Cr 2+ .

A stereoselective total synthesis of (−)-rishitin

Abstract A new synthesis of (−)-rishitin (1) is reported, starting with chiral pool molecules. The crucial step is a stereoselective vinyl radical cyclization, which gives a 10:1 ratio of 21 to 22.

Acid catalyzed rearrangements of 4-methyl-4-cyanocyclohexadienone

Abstract Acid-catalyzed dienone-phenol rearrangement reactions of 4-methyl-4-cyanocyclohexadienone occur very slowly and give either fragmentation or methyl group migration, not cyano group migration, under non-nucleophilic strongly acidic conditions.