Dess−Martin Periodinane Oxidation of Alcohols in the Presence of Stabilized Phosphorus Ylides: A Convenient Method for the Homologation of Alcohols via Unstable Aldehydes

An efficient fructose-1,6-bisphosphate aldolase mediated synthesis of new aminocyclitol analogues of valiolamine is described. The one-pot process where four stereocentres are created involves the formation of two carbon–carbon bonds. One is catalysed by the aldolase, coupling dihydroxyacetone phosphate to nitrobutyraldehydes. The other is the result of a highly stereoselective intramolecular Henry reaction occurring on the intermediate nitroketones. Depending on the configuration of the hydroxyl which is α to the nitro group, two series of configuration are accessible. The lipase resolution of the nitroalcohol ketal, precursor of the nitroaldehyde, is presented. The inhibition properties of the aminocyclitols obtained after the reduction of the nitro group are evaluated towards five commercial glycosidases

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Straightforward chemo-enzymatic synthesis of new aminocyclitols, analogues of valiolamine and their evaluation as glycosidase inhibitors

One-pot oxidation and wittig olefination of alcohols using o-iodoxybenzoic acid and stable wittig ylide*

Extremely Expanded Tetrathiafulvalenes with Polyene Spacers. Carotinoid Tetrathiafulvalenes. Polymethin-Tetracyanotetrathiafulvalene Radical Cations, a New Class of Violenes



The synthesis of extended tetrathiafulvalenes 11 with di-, tetra-, hexa-, octa-, deca- and dodecamethine spacers is described by a PPh3-induced Wittig-reaction-like condensation of the corresponding polyenedials 10 with 2-thio-1,3-dithiole-4,5-dicarbonitrile (9). By the same procedure, the dimethyloctamethine- and the tetramethyl-hexadecamethine-tetrathiafulvalenes 14 and 15, respectively, were obtained. The extended tetrathiafulvalenes represent multistep vinylogous redox systems of the ‘violene type’. They can be oxidized to give the cyanine-like radical cations, e.g.11sem, 14sem, and 15sem, and the dications, e.g.11ox, 14ox, and 15ox; their UV/VIS/NIR spectra are reported. The crystal and molecular structure of (all-E)-2,2′-(octa-2,4,6-trien-1,8-diylidene)bis[1,3-dithiole-4,5-dicarbonitrile] (11e) was determined: it is a rod-like, planar molecule; in the crystal, it forms staples along the longest molecule axis. The CV measurements confirm that the redox potentials of 11, 14, and 15 decrease asymptotically with the increasing length of the spacer. Because of the close relationship of the extended tetrathiafulvalenes (ETTF's) to the carotinoids, they are named ‘caroviologenes’; they formally belong to the class of molecular wires.

Extrem aufgeweitete Tetrathiafulvalene mit Polyen-Spacern. Carotinoide Tetrathiafulvalene. Polymethin-tetracyanotetrathiafulvalen-Radikalkationen, eine neue Klasse von Violenen†

Synthesis of Ethyl 6-Bromosorbate

1.

Three ways of synthesizing polyenic dicarboxylic acids having even numbers of double bonds are proposed.




2.

A new method of synthesizing corticrocin diethyl ester is described.




3.

The difficulty with which the cis bond in 6-cis-corticrocin diethyl ester is isomerized is pointed out.

Chemistry of polyenic and polyacetylenic compounds communication 8. Methods of synthesizing polyenic dicarboxylic acids having even numbers of double bonds and also polyenynic dicarboxylic acids

Chemistry of acetals: Communication 11. Some reactions of 3-ethoxyacrolein and 3, 3-diethoxypropionaldehyde

General method of synthesizing esters of ω-nitropolyenic acids

Some symmetrical and unsymmetrical bifunctional polyenic compounds were synthesized; they included diphenyl polyenes, polyenic diketones and dinitriles, dibromo polyenic dicarboxylic esters, polyenic cyano acetals and keto acetals, polyenic keto esters, and cyano polyenic carboxylic esters.

Chemistry of acetals Communication 16. Ways of synthesizing symmetrical and unsymmetrical bifunctional polyenic compounds

1.

The reaction of the diethyl ester of carbethoxymethylphosphinic acid with aldehydes proceeds stereospecifically and leads to unsaturated esters with a trans-configuration of the double bond that arises.




2.

The reaction of carbethoxymethylenetriphenylphosphorane and the diethyl ester of carbethoxymethylphosphinic acid with sterically unhindered ketones leads to a mixture of cis-trans isomers.




3.

The results obtained agree with the generally accepted scheme of the Wittig reaction.

L. A. Yanovskaya

Papers

Chemistry of polyenic and polyacetylenic compounds communication 8. Methods of synthesizing polyenic dicarboxylic acids having even numbers of double bonds and also polyenynic dicarboxylic acids

Chemistry of acetals: Communication 11. Some reactions of 3-ethoxyacrolein and 3, 3-diethoxypropionaldehyde

General method of synthesizing esters of ω-nitropolyenic acids

Chemistry of acetals Communication 16. Ways of synthesizing symmetrical and unsymmetrical bifunctional polyenic compounds

Reaction of carbethoxymethylenetriphenylphosphorane and the diethyl ester of carbethoxymethylphosphinic acid with certain aldehydes and ketones