Joel Jones

Organic reaction in water. Part 3¹: diastereoselectivity in Michael additions of thiophenol to nitro olefins in aqueous media

Tiofenois reagem com nitro olefinas em meio aquoso dando os correspondentes nitro-sulfetos em 58 - 95 % de rendimento. Este processo leva a formacao, predominante, de produtos anti. Para o caso da nitro olefina ciclica 1-nitro-ciclo-hexeno e observada unicamente a formacao de cis-1-nitro-2-(tio-fenil)-ciclo-hexano. Esta metodologia e interessante porque utiliza-se agua como solvente levando a minimizacao do custo, diminuindo os problemas de toxidez e poluicao ambiental

Coiodação de alquenos com nucleófilos oxigenados: reações intermoleculares

A review on the electrophilic addition of iodine to alkenes in the presence of oxygen containing nucleophiles (cohalogenation reaction) is presented. The intermolecular reactions are discussed with emphasis in methods of reaction and synthetic applications of the resulting vicinal iodo-functionalized products (iodohydrins, b-iodoethers and b-iodocarboxylates).

Cohalogenation of limonene, carvomenthene and related unsaturated monoterpenic alcohols

Cohalogenation of (R)-limonene and (R)-carvomenthene with I2/H2O/Cu(OAc)2·H 2O in aqueous dioxane followed by base treatment produced stereospecifically the corresponding trans-epoxides. Same methodology of cohalogenation applied to related monoterpenic unsaturated alcohols produced pinol derivatives [from (5R)-cis-carveol and (S)-a-terpineol] or iodohydrins [from (S)-perillyl alcohol and (5R)-trans-carveol].

Reações orgânicas em meio aquoso

The use of water as solvent in organic reactions has been uncommon for several reasons, among them the low solubility of the reactants, the incompatibility of the intermediates with water, and the competition between the desired reaction and hydrolysis. Breslow in 1980, demonstrated that the hydrophobic effect accelerates Diels-Alder reactions and gives a high endo/exo selectivity. Since then, many other reactions were studied in this medium, and below we show the principal results. Besides the academic interest, human and economic aspects are included in this study. Water as a solvent minimizes environmental impact, costs and increases operational safety.

A Novel Synthesis of 1-Acetyl-4-Isopropenyl-1-Cyclopentene by Chemoselective Cyclization of 4-Methyl-3-(Oxobutyl)-4-Pentenal: An Important Intermediate for Natural Product Synthesis

This article presents the direct oxidation of limonene-oxide 1 with KIO4 in water, which is the best way to obtain the keto-aldehyde 3, an important intermediate in natural product synthesis. The cyclization of keto-aldehyde 3 with acidic Al2O3 proceeds chemoselectively to give ketone 4. These two reactions together increase the overall yield of ketone 4 to about 70% compared to 8% previously reported in the literature1.

A Simple Method for Producing Pure (+) trans-1,2-Epoxylimonene

Abstract In this paper we report a simple methodology for obtaining (+) trans - 1,2 - epoxylimonene (1b) in high purity (>99% HRGC) and reasonable quantity. The mixture of 1a and 1b in CH2Cl2 is stirred with 1M NaHSO3 in water. Under these conditions 1a is completely destroyed, while 1b is only partially destroyed.

Chemoselective Formation of 8,9‐Epoxy‐limonene

Abstract We present here a synthetic path to produce, exclusively, 8,9-epoxy-limonene in 75% overall yields. We developed a three step synthetic route. First, the 1,2-double bond of limonene was protected by the formation of the bromo-methyl-ether by cohalogenation with NBS in MeOH. Then, this product was oxidized by m-chloro-perbenzoic acid to give the corresponding epoxides. Finally, the 1,2-double bond was restored by a reaction with NH4Cl/Zn leading to 8,9-epoxy-limonene. The great advantage of this methodology is that the intermediate purification steps are not necessary.

Simple method for monitoring enzymatic reactions by direct injection of the medium reaction in a gas chromatograph equipped with packed liner

Reduction of sulcatone, catalyzed by Thermoanaerobium brockii alcohol dehydrogenase in Tris/HCl buffer (pH 7.8) using 2-propanol 20% (v/v) as an NADPH regeneration system could be followed by using a gas chromatograph equipped with a packed liner that allowed the direct injection of the aqueous medium reaction. The time-course curve obtained by the analytical method here described and that obtained by spectrophotometric methods were similar.

Synthesis of the Four Epimeric Tosylates of (5R)-2, 3-Epoxy-5-isopropenyl-cyclohexanol

Abstract Described is the synthesis of the four optically pure epoxy-tosylates 5, 6, 9 and 12, each with four chiral centers determined, from a single starting material, (R)(-) carvone.

FUNCTIONALIZED PINOLS: 13C AND 1H NMR SPECTRA ASSIGNMENTS AND STRUCTURES

Aqueous cohalogenation reactions of cis-carveol and of α-terpineol afford respectively the 2, 6-dimethyl-6-iodomethyl-7-oxabicyclo[3.2.1]oct-2-ene and 2, 6, 6-trimethyl-7-oxabicyclo[3.2.1]octan-2-ol. Previous structural analysis involving such functionalized pinols have lacked justification of the proposed relative configuration of the substituents and detail of the 1H and 13C NMR spectra assignments. Thus, a full structure and NMR analysis for these two bicyclic compounds are presented by way of 2D NMR experiments, 1H spectra simulations and AM1 calculations.