R. Caple

Dramatic acceleration of the Diels-Alder reaction by adsorption on chromatography adsorbents

Abstract The development of a new method for effecting [4+2] cycloadditions on the surface of chromatographic adsorbents in the absence of solvents that leads to a moderation of the reaction conditions and an increase in selectivity is described.

New route to the synthesis of polycyclic compounds based on a stepwise AdE-reaction of dicobalt hexacarbonyl complexes of conjugated enynes with a subsequent intramolecular Khand-Pauson type reaction.

Abstract The stepwise AdE-reaction of dicobalt hexacarbonyl complexes of conjugated enynes has been extended to include unsaturated electrophiles and nucleophiles to produce products with an orientation conducive to a subsequent conversion into polycyclic compounds via an intramolecular Khand-Pauson type reaction.

Adsorption effects on the efficiency of cobalt-mediated cyclizations of allylpropargyl ethers into derivatives of 3-oxabicyclo[3.3.0]oct-5-en-7-one

Abstract Thermolysis in an adsorbed state under oxygen is shown to be a mild and general method for promoting a Khand-Pauson cyclization of dicobalt hexacarbonyl complexes of allylpropargyl ethers into derivatives of 3-oxabicyclo[3.3.0]oct-5-en-7-one.

Aqueous chlorination and ozonation studies I. Structure-toxicity correlations of phenolic compounds to Daphnia magna

A correlation showing the dependency of the observed biological activity (LC50) of a series of phenols to the free energy related terms, π, F and R (field and resonance), which are specific for each compound, has been observed for the freshwater invertebrate, Daphnia magna. A series of 14 phenols was investigated and with F and R considered to be additive terms the following correlation was obtained. Log 1/c = 0.500 π + 0.453 F + 0.636 R + 3.731 r = 0.978 In those phenols containing chlorine it was noted the toxicity increased with increased chlorine content.

Novel reagents containing hypervalent iodine and their use for electrophilic additions to olefins

Abstract A series of novel I(III) containing reagents have been developed and their electrophilic reactions with olefins giving vic -disubstituted derivatives (including vic -ditriflates) are described.

An efficient protocol for the synthesis of fenestrane derivatives

Abstract A short route for the synthesis of several fenestrane derivatives is suggested based on the sequence: ( A ) etherification of μ-cobaltcarbonyl complexes of 1,6-enyn-5-ols with unsaturated alcohols, ( B ) intramolecular Khand-Pauson reaction and, ( C ) [2+2] photocycloaddition.

Discrete introduction of the electrophile and nucleophile in AdE -reactions of dicobalt hexacarbonyl complexes of conjugated enynes.

Abstract The dicobalt hexacarbonyl complex of the enyne isopropenylacetylene ( 1 ) is effective in permitting stepwise Ad E reactions to the double bond of 1 via stabilization of the intermediate carbenium ion.

An unusual case of Khand-Pauson cyclization involving the participation of a conjugated double bond. A promising sequence for the assemblage of polycyclic framework

Abstract A short and convergent route for the synthesis of polycyclic linearly and/or angularly fused compounds is proposed based on the intramolecular alkyne-alkene-carbonyl cycloaddition with participation of the double bond bearing an electron withdrawing group.

Reaction of phIO·HBF4/silyl enol ether adduct with olefins as general approach to carbon-carbon bond formation in AdE reactions using hypervalent iodine reagents

A simple method for method for new carbon-carbon bond formation in AdE reactions using the PhIO·HBF4 complex and silyl enol ethers has been developed.

Iodosobenzene tetrafluoroborate: First example of a stable electrophilic hypervalent iodine reagent without nucleophilic ligands

Abstract Iodosobenzene tetrafluoroborate 1 ha been prepared by the reaction of PhI(OAc) 2 and aquenous HBF 4 , and its reactions with alkenes, silyl enol ethers, and acetylenes have been studied.