Diastereoselective allylation of aldehydes with an enantiopure 2-sulfinylallyl halide under environmentally friendly Barbier-type conditions

[reaction: see text] A simple, efficient, and diastereoselective zinc-promoted allylation of aldehydes with enantiopure (Ss)-3-chloro-2-(p-tolylsulfinyl)-1-propene [(Ss)-1] under aqueous Barbier conditions is described. The observed diastereoselectivity can be explained via an acyclic antiperiplanar transition state model.     

Lead-promoted Barbier-type reaction of aldehydes with propargyl bromides in aqueous media

This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media.The selectivity and possible mechanism of these reactions are discussed.The yields of products for reaction of propargyl bromide are 31~71%.The ratios of al-lenyl alcohol and homopropargyl alcohol are 1:1.5 to 1:3.The product for reaction of phenyl propargyl bromide is allenyl alcohol and the yields are 52~84%.     

6-Magnesiated purines: preparation and reaction with aldehydes

[reaction: see text] Halogen-metal exchange reaction of 9-benzyl-6-iodopurine with iPrMgCl in toluene at -80 degrees C proceeds almost quantitatively. Such a purine-derived Grignard reagent reacts selectively with aldehydes in toluene, giving the corresponding alcohols in 25-62% yield, while other functional groups such as ketones, esters, and nitriles do not react under these conditions. The reaction can be extended to protected 6-iodopurine ribonucleoside.     

A facile synthesis of N-sulfonyl and N-sulfinyl aldimines under Barbier-type conditions

A convenient synthesis of N-sulfonyl- and N-sulfinylimines by the condensation of aldehydes with sulfonyl or sulfinyl amides in the presence of benzyl bromide and zinc dust at room temperature under the Barbier-type conditions is reported. The procedure is lauded by its simplicity and adaptability to aromatic, alpha,beta-unsaturated, and aliphatic aldehydes.     

Reaction of 3,3-dichloropentane-2,4-dione with aromatic aldehydes under the conditions of Darzens reaction

3,3-Dichloropentane-2,4-dione reacts with aromatic aldehydes under the conditions of Darzens reaction to give 4-acetoxy-4-aryl-3,3-dichlorobutan-2-ones, the products of insertion into the -C-C bond. The reaction of ethyl dichloroacetylacetate with benzaldehyde yields a derivative of tricyclo[5.1.0.0^3,5]octane, rather than 2,6-bis(1-chlorobenzylidene)cyclohexane-1,4-dione, as the by-product.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1294–1298, July, 1995.     

Reaction of nitriles under acidic conditions. Part I. A general method of synthesis of condensed pyrimidines

Nitriles are known to give rise to salts of different compositions with halogen acids. Many of the reactions undergone by nitriles under the influence of halogen acids are, in many cases, assumed to proceed via the intermediate formation of highly reactive imidoyl derivatives. The intermediates produced, in situ, by the reaction of nitriles with hydrogen chloride should, in principle, be capable of reacting with compounds containing appropriately placed nucleophilic and electrophilic centers leading to the formation of a heterocycle incorporating the C=N of the nitrile. Thus, the reaction of aliphatic, aromatic and heterocyclic nitriles with a variety of ortho aminocarbonyl derivatives such as nitriles, amides, esters and ketones of benzene, thiophen, furan, pyrrole, benzothiophene and pyridothiophene have been found to yield the corresponding condensed pyrimidines in fair to good yields. This constitutes a facile and versatile one-pot synthesis of condensed pyrimidines.     

Highly chemoselective and efficient Strecker reaction of aldehydes with TMSCN catalyzed by MgI2 etherate under solvent-free conditions

Abstract

Strecker reaction of various substituted aromatic aldehydes, heteroaromatic aldehydes, aliphatic aldehydes and α,β-unsaturated aldehydes with trimethylsilyl cyanide (TMSCN) was realized in the presence of 5?mol % of MgI₂ etherate in a mild, efficient and highly chemoselective manner under solvent-free conditions.     

A convenient preparation of nitriles by reaction of free sulfimide with aldehydes

Diphenyl free sulfimide was found to react readily with aldehydes affording the corresponding nitriles in high yields.     

Copper-catalyzed alkyne-aryne coupling reaction under microwave conditions: preparation of unsymmetric and symmetric di-substituted alkynes

Several unsymmetric and symmetric alkynes were prepared excellent to modest yields by generating benzyne from the reaction of 2-(trimethylsilyl)phenyl triflate with CsF in the presence of CuI and terminal alkyne under microwave heating for 30 min at 150 °C. Using conventional heating, the reactions required 24 h reaction time.     

Erlenmeyer azlactone synthesis with aliphatic aldehydes under solvent-free microwave conditions

2-Phenyl-5(4H)-oxazolone (azlactone) reacts with aliphatic aldehydes upon adsorption on neutral alumina and irradiation with microwaves (<2 min). The corresponding condensation products are obtained in good yields (62-78%), indicating the satisfactory resolution of a long-standing problem plaguing the classical Erlenmeyer synthesis (poor results with aliphatic aldehydes). Plausible mechanistic reasons for the success of the procedure are discussed.     

Studies on oxidations with IBX: oxidation of alcohols and aldehydes under solvent-free conditions

A variety of allylic and benzylic alcohols are oxidized to their respective carbonyl compounds with IBX under solvent-free conditions at ca. 60-70 °C. It has also been found that some of the aromatic aldehydes also undergo oxidation when heated with IBX at 90 °C under solvent-free conditions; notably, this transformation does not occur under the otherwise identical but heterogeneous conditions.     

The reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions

Russian Chemical Bulletin - 3,5-Disubstituted 1,2,4-oxadiazoles were synthesized by the reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions (10 kbar). The...     

Indium-mediated asymmetric Barbier-type propargylations: additions to aldehydes and ketones and mechanistic investigation of the organoindium reagents

We report a simple, efficient, and general method for the indium-mediated enantioselective propargylation of aromatic and aliphatic aldehydes under Barbier-type conditions in a one-pot synthesis affording the corresponding chiral alcohol products in very good yield (up to 90%) and enantiomeric excess (up to 95%). The extension of this methodology to ketones demonstrated the need for electrophilic ketones more reactive than acetophenone as the reaction would not proceed with just acetophenone. Using the Lewis acid indium triflate [In(OTf)(3)] induced regioselective formation of the corresponding homoallenic alcohol product from acetophenone. However, this methodology demonstrated excellent chemoselectivity in formation of only the corresponding secondary homopropargylic alcohol product in the presence of a ketone functionality. Investigation of the organoindium intermediates under our reaction conditions shows the formation of allenylindium species, and we suggest that these species contain an indium(III) center. In addition, we have observed the presence of a shiny, indium(0) nugget throughout the reaction, irrespective of the stoichiometry, indicating disproportionation of indium halide byproduct formed during the reaction.     

Direct oxidative amidation of aldehydes with anilines under mechanical milling conditions

Oxone is found to be an effective oxidant for the oxidative amidation of aldehydes with anilines to furnish amides in a one-pot process under mechanical milling conditions.