Condensation of aldehydes and ketones

The Mannich reaction with methylene- and benzylidenediacetophenones has given: 1,3-dibenzoyl-4-piperidinobutane, 1,3-dibenzoyl-4-morpholinobutane, 1,3-dibenzoyl-4-diethylamino-2-phenylbutane, 1,3-dibenzoyl-2-phenyl-4-piperidinobutane, 1,3-dibenzoyl-4-diethylaminobutane, and 1,3-dibenzoyl-4-dimethylamino-2-phenylbutane. From the latter two compounds, 3-diethylaminomethyl-2,6-diphenylpyridine and 3-dimethylaminomethyl-2,4,6-triphenylpyridine have been obtained.For part XVII, see [7].     

Condensation of aldehydes and ketones

The alkaline condensation of β-aceto-and β-propionaphthalenes with furfural has given, respectively, 2-(α-furfuryl)-1, 3-di(β-naphthoyl)-propane and 3-(α-furyl)-2,4-di(β-naphthoyl)pentane; both δ-diketones have also been obtained by the Michael condensation. Under more severe conditions, two molecules of furfural condense with three molecules of β-acetonaphthalene to form 2, 4-di(α-furyl)-1, 3, 5-tri(β-naphthoyl)pentane. Under similar conditions, benzaldehyde exhibits only a feeble capacity for triketone condensation with β-acetonaphthalene. The condensation of β-propionaphthalene with furfural has given the new compound furylidenepropionaphthalene. It has been shown that both under the conditions of the improved Chichibabin pyridine synthesis and under the conditions of the Leuckhardt reaction, 3-(α-furyl)-1, 3-di(β-naphthoyl)propane gives 4-(α-furyl)-2, 6-di(β-naphthyl)pyridine.     

Condensation of acetals of aromatic β-keto aldehydes with ketones and phenols

Pyrylium salts with a free (active) position and different kinds of substituents in the, positions of the pyrylium ring were obtained by the reaction of acetals of aroylacetaldehydes with ketones and phenols.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1163–1165, September, 1972.     

The chemistry of sym-tetracyanoethane. 1. Condensation of sym-tetracyanoethane with aldehydes and ketones

In an aqueous dioxane solution sym-tetracyanoethane adds to aldehydes and ketones with subsequent cyclization to 3,3,4-tricyano-5-amino-2,3-dihydrofurans.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 744–746, June, 1981.     

Acetylene derivatives Communication 174. Condensation of aldehydes and ketones with acetylene under pressure. II

Summary A further study was made of a new method of synthesizing secondary and tertiary acetylenic alcohols by the condensation of aldehydes and ketones with acetylene under pressure in presence of potassium hydroxide powder.     

Magnesium-catalysed hydroboration of aldehydes and ketones

The heteroleptic magnesium alkyl complex [CH{C(Me)NAr}(2)Mg(n)Bu] (Ar = 2,6-(i)Pr(2)C(6)H(3)) is reported as a highly efficient pre-catalyst for the hydroboration of aldehydes and ketones with pinacolborane.     

Radical cations of aldehydes and ketones

We confirm the observation made by Snow and Williams in the previous letter that the quartet substructure observed in the ESR spectrum of acetaldehyde is due to hyperfine coupling to a single chlorine nucleus of the solvent, fluorotrichloromethane. Reasons for this reversible interaction, and its absence for other similar cations are discussed.     

Zinc-catalyzed allenylations of aldehydes and ketones

The general zinc-catalyzed allenylation of aldehydes and ketones with an allenyl boronate is presented. Preliminary mechanistic studies support a kinetically controlled process wherein, after a site-selective B/Zn exchange to generate a propargyl zinc intermediate, the addition to the electrophile effectively competes with propargyl-allenyl zinc equilibration. The utility of the methodology was demonstrated by application to a rhodium-catalyzed [4+2] cycloaddition.     

TBD-catalyzed cyanosilylation of aldehydes and ketones

This study examines the catalytic efficacy of 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) in the cyanosilylation of aldehydes and ketones. In an aldehyde reaction, the corresponding products were obtained at high yield using minimal TBD (0.01?mol%). TBD was similarly effective in various ketone reactions.     

Organocatalytic asymmetric alpha-bromination of aldehydes and ketones

The first organocatalytic enantioselective alpha-bromination of aldehydes and ketones is presented; a C2-symmetric diphenylpyrrolidine catalyst afforded the alpha-brominated aldehydes in good yields and up to 96% ee, while ketones were alpha-brominated by a C2-symmetric imidazolidine in up to 94% ee; furthermore, the organocatalytic enantioselective alpha-iodination of aldehydes is also demonstrated to proceed with up to 89% ee.     

Calcium-promoted Pictet-Spengler reactions of ketones and aldehydes

Calcium bis-1,1,1,3,3,3-hexafluoroisopropoxide is shown to be an effective catalyst for Pictet-Spengler reactions of 3-hydroxyphenethylamine and 3-hydroxy-4-methoxyphenethylamine with various aldehydes and ketones. Previous Lewis acid catalyzed Pictet-Spengler reactions of unactivated ketones typically require two separate reactions (imine formation, cyclization) to obtain the same results. The reactions described within directly provide 1,1'-disubstituted tetrahydroisoquinolines from the corresponding amine and ketone. These rare examples of Pictet-Spengler reactions of unactivated ketones demonstrate the unique nature of calcium as a Lewis acid catalyst.     

Condensation of acetylenic acetals with ketones

Summary A study was made of the reaction of propargylaldehyde acetal with a number of ketones under the influence of BF₃ etherate. With acetone and methyl ethyl ketone the reaction goes with the cleavage of 1 mole of alcohol and the formation of the corresponding ethoxyacetylenic ketones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1070–1072, June, 1965     

Reductive one-carbon homologation of aldehydes and ketones

[reaction: see text] A rhodium-catalyzed methylenation-hydrogenation cascade process allows the homologation of carbonyl compounds to lead to the corresponding alkanes in high yields.     

Catalytic hydroboration of aldehydes and ketones with sodium hydride: Application to chemoselective reduction of aldehydes over ketones

Sodium hydride-promoted catalytic hydroboration of aldehydes and ketones with pinacolborane (HBpin) was examined, and 10?mol% of NaH was found to cause the HBpin to participate in hydroboration in a convenient and efficient manner at mild reaction conditions. Further chemoselective hydroboration of aldehyde over ketone functionality was also analyzed. In addition, no hydroboration was observed form ester, acyl chloride, amide, nitrile, alkene, alkyne, alkyl halide and epoxide functional groups indicate that present system (HBpin, NaH) is highly selective for aldehydes and ketones.     

Electroreductive crossed pinacol coupling of aromatic ketones with aliphatic ketones and aldehydes

The intermolecular crossed pinacol coupling of aromatic ketones with aliphatic aldehydes and ketones was effected by electroreduction in the presence of chlorotrimethylsilane. The best result was obtained using a Pb cathode in Bu₄NPF₆/THF. The electroreduction of aromatic 1,4-, 1,5-, and 1,6-diketones under the same conditions gave four-, five-, and six-membered 1,2-diols with trans-stereoselectivity, while the reduction of these diketones with TiCl₄-Zn produced the cis-isomers of the same intramolecular crossed pinacol coupling products predominantly.