David C. Forbes

Base-promoted reactions in ionic liquid solvents. The Knoevenagel and Robinson annulation reactions

Abstract When used in place of classical organic solvents, ionic liquids offer a new and environmentally benign approach toward solvation in modern synthetic chemistry. Two classical named reactions, the Knoevenagel condensation and Robinson annulation, have been studied using the ionic liquid 1-hexyl-3-methyl imidazolium hexafluorophosphate, [6-mim]PF 6 as solvent. Yields for each reaction were moderate to excellent. In each system the ionic liquid was successfully recycled for reuse in subsequent reaction runs, a factor of key importance to the ‘green’ nature of solvation with ionic liquids.

A new and efficient route toward the preparation of diazo ketones using cyanuric chloride and diazomethane

Abstract A new method for the preparation of diazo ketones has been developed. 2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride) has been found to be an excellent coupling reagent allowing for the efficient transfer of diazomethane to a carboxylic acid. Preparation of diazo ketones using carboxylic acids and triazine reagents is considerably more convenient than classical diazo transfer protocols because water does not have to be stringently removed and the entire procedure can be carried out in one-pot. Electron deficient and neutral aryl carboxylic acids were found to give better results than electron rich or aliphatic carboxylic acids.

Highly stereoselective methylene transfers onto butanediacetal-protected chiral non-racemic sulfinyl imines using S-ylide technology

Diastereomeric ratios of >95 : 5 were obtained when performing methylene transfers onto imines originating from d-mannitol and (S)-(-)-2-methyl-2-propane sulfinamide or ascorbic acid and (R)-(-)-2-methyl-2-propane sulfinamide.

(2S)-2-[(2S*,5R*,6R*)-5,6-Dimeth-oxy-5,6-dimethyl-1,4-dioxan-2-yl]-1-[(S)-1,1-dimethyl-ethylsulfon-yl]aziridine.

The reaction of a sulfur ylide with a chiral non-racemic sulfinyl imine afforded the desired aziridine in excellent yield and subsequent oxidation of the sulfinyl moiety dissolved in anhydrous dichloromethane using a 75% aqueous solution of 3-chloroperoxybenzoic acid afforded the title compound, C14H27NO6S. The configuration of the newly formed stereogenic center at the point of attachment of the 1,4-dioxane ring to the aziridine ring is S. The configurations of the pre-existing sites 2-, 5-, and 6-positions of the 1,4-dioxane ring prior to reaction of sulfinyl imine with the sulfur ylide are S, R, and R, respectively. The C—N bond lengths of the aziridine are 1.478 (2) and 1.486 (2) Å.

Phenylsulfonylacetic acid: condensations onto aryl aldehydes

A study involving scope in the condensation reaction of phenylsulfonylacetic acid with a series of carbonyl derivatives has been conducted. Reactivity trends favor formation of the corresponding vinyl sulfones when working with aryl aldehydes. Electron-deficient aryl aldehydes outperform electron-rich aryl aldehydes. Negligible differences were noted when using electron-rich and electron-deficient arylsulfonylacetic acid derivatives. Post-run analyses of the reaction mixture reveal formation of a minor product which resulted from methylidene transfer onto the carbonyl derivative. Support of a Knoevenagel-type condensation followed by decarboxylation is provided. GRAPHICAL ABSTRACT

2,6-Dichloro-1-[(1E)-2-(phenyl-sulfon-yl)ethen-yl]benzene.

In the title compound, C14H10Cl2O2S, the product of a base-catalyzed condensation followed by decarboxylation of the carboxylate group of the sulfonyl derivative, the configuration of the alkene unit is E. The torsion angle between the alkene unit and the 2,6-dichlorophenyl ring system is −40.8 (3)°. The dihedral angle between the rings is 80.39 (7)°.

(1S*,2R*,3S*,4R*,5R*)-5-Tetra­decyloxy­methyl-7-oxabicyclo­[2.2.1]heptane-2,3-dicarb­oxy­lic anhydride

In the title compound, C23H38O5, the oxabicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride unit has a normal geometry and the tetradecoxymethyl side chain is fully extended. In the crystal, molecules are linked head-to-head by C—H⋯O hydrogen bonds, forming two-dimensional networks propagating along the a and c-axis directions.

1-Diazo-2-(2-quinolinyl)-2-ethanone

Diazoketone 2 was prepared using 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride) as coupling reagent allowing for the efficient transfer of diazomethane to commercially available carboxylic acid 1 [1].[...]