Ron Caple

Controlled one-pot sequence of three AdE reactions as a novel protocol for the synthesis of polyfunctional compounds

Abstract Various silyl-capped nucleophiles have been shown to be reactive as the final components in ArS mediated coupling of two alkyl vinyl ether units and carbon nucleophile and thus a fairly general procedure for the assemblage of polyfunctinal compounds from simple precursors has been elaborated.

Reaction of vinyl ethers with ArSCl adducts of d-glucal

Abstract Lewis acid mediated reactions of vinyl ethers with ArSCl adducts of benzyl protected D-glucal followed by quenching of the five-membered sulfonium salt intermediates with external nucleophiles, H2O, MeOH, and n-Bu4NBH4, lead to a highly stereoselective formation of β-C-glucopyranosides with different functional groups in the lateral chain.

Structure and reactivity of thiophanium salts, the elusive intermediates in ArS+-mediated one-pot sequence of three AdE reactions

Abstract The structure of the previously postulated cationoid intermediate, presumably formed in ArS + -mediated coupling of two vinyl ether units, was firmly established as (1R * ,2R * ,4S * ) -2,4-dimethoxy-3,3-dimethyl-1- p -tolylthiophanium salt and its reactivity was elucidated.

Use of Volatile Chloroorganics as a Measure of the Rehabilitation of the St. Louis River and Bay

Abstract A major source of chloroorganic discharge into the St. Louis River system is a pulp mill located 33 km upstream from Lake Superior. The effect of diverting the pulp mill effluent to an advanced secondary treatment plant, located 33 km downstream, was examined using a “chloroform monitoring technique.” Chloroform, formed during the bleaching of pulp, was used as a tracer substance to follow the movement of the chloroorganic effluent plume originating from the pulp mill. The treatment plant was shown to be only partially effective in removing chloroorganics, indicating that the point source of chloroorganic discharge into the St. Louis River system has only been relocated.

Tandem sequence of ArSCl initiated AdE reactions resulting in formation of two C–C bonds

A one-pot procedure for the sequence of reactions between arylsulfanyl chloride, vinyl ether-I, vinyl ether-II and organomagnesium reagents has been developed for assembling polyfunctional compounds from simple precursors. 2,3-Dihydropyran and various vinyl ethers have been used as VE-I and/or VE-II. The dependence of the stereochemical course of the carbon–carbon bond formation step upon the Lewis acid has been studied. In the case of the sequence p-toiylsulfanyl chloride, 2,3-dihydropyran, 1-methoxy-2-methylpropene and Grignard reagent the reaction initiated with TiCl4 takes place with a very high diastereoselectivity ( > 95%).

Polyfunctional adducts assembled with the help of a one-pot sequence of three AdE reactions as synthetically useful intermediates. The course of the Lewis acid induced transformations of the 4,6-dialkoxy-7-arylthioheptene moiety

Abstract Data on the selectivity of the Lewis acid induced transformations of the title adducts are presented and the routes leading to formation of products containing either cyclohexane or 1,3-dienes units are described.

Bacterial Degradation of Selected Organics in Natural Waters of Northeastern Minnesota

Abstract An evaluation of a standardized kinetic procedure that determines the ability of bacteria to degrade organic pollutants was conducted using natural water samples from the Lake Superior watershed in northern Minnesota. Second-order rate constants for the degradation of butoxyethyl and butoxypropyl esters of 2,4-dichlorophenoxyacetic acid, methyl 2,4-dichlorobenzoate, ethyl-2,4-dichlorobenzoate, and p-nitrophenyl ether were determined using three different bacterial enumeration methods. The reproducibility of the bacterial enumeration method is especially important if reliable degradation kinetics are to be obtained. Comparisons of lipopolysac-charide measurements, epifluorescence counts, and standard plate counts to enumerate bacteria suggest bacterial stabilization has a minor, yet notable, effect on kinetic results.