Acylimines of hexafluoroacetone in cyclocondensation with C,N-binucleophiles

The reactions of acylimines of hexafluoroacetone with 1,3-C,N-binucleophiles giving rise to fluorine-containing 1,4-dihydropyrimidines, including fused compounds, were studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 706–709, April, 2006.     

The cross-aldol reaction of hexafluoroacetone (HFA) with ketones catalyzed by an acid

The cross-aldol reactions of hexafluoroacetone (HFA) and ketones using an acid catalyst are reported. When concentrated sulfuric acid was employed as the catalyst, HFA reacted regioselectively with various ketones at 50-100 °C to give the aldol adducts (6) in good yields. The reaction is initiated by an acid-catalyzed transformation of the ketone into the corresponding enol that reacts with HFA. The obtained adducts (6) can be reduced with hydrogen under a Ru/C catalyst to lead to the corresponding fluorine-containing diols (13).     

Synthesis and selective carbocupration reaction of fluorine-containing enynic esters, enynylphosphine oxides, and enynylphosphates

Some new fluorine-containing enynic esters, enynylphosphine oxides, and enynylphosphates were synthesized stereoselectively in good yields by the dehydrohalogenation reaction of fluoroalkylated 3-iodoacrylates, 2-iodovinylphosphonates, and 2-iodovinylphosphine oxides under basic conditions. These fluorine-containing enynic compounds could undergo carbocupration reaction with organocopper reagents and the vinylcopper intermediates formed in situ could further react with some electrophiles such as allyl bromide, phenylselenyl bromide, and iodine to give the corresponding polysubstituted fluorine-containing dienoic esters, phosphates, and phosphine oxides with high regio- and stereoselectivity.     

Mini Review of Sulfur Heterocyclization from π-Electron Deficient Quinones via Charge-Transfer Interaction

Abstract

This survey is mainly concerned with selected reactions of 2,3-dichloro-1,4-naphthoquinone (DHNQ), 3,4,5,6-tetrachloro-1,2-benzoquinone (o-CHL), 2,3,5,6-tetrachloro-1,4-benzoquinone (p-CHL), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as π-deficient quinones that are used or offer potential use for sulfur heterocyclic synthesis. Reaction of various donors with the π-deficient quinones are studied, especially those via charge-transfer complex formation.     

Synthesis of 1,6-dihydropyrimidines via copper-catalyzed multistep cascade reactions between O-propargylic aldoximes and isocyanates

Multi-step cascade reactions of O-propargylic oximes with isocyanates were carried out in the presence of copper catalysts to afford the corresponding 1,6-dihydropyrimidines in good yields. The multi-step reactions consisted of a 2,3-rearrangement, a [3+2] cycloaddition, decarboxylative ring opening involving a 1,4-hydrogen shift, and a 6π-electrocyclization.     

Organic reactions at high pressure. The Diels-Alder reaction of p-benzoquinone with dienic esters

The Diels-Alder reaction of $\text{p}$-benzoquinone with substituted dienoic esters affords good yields of 4a,5,8,a-tetrahydro-1,4-naphthalenediones, free from the isomeric hydroquinone. The reactions were conducted at room temperature under 15 kbar (1.5 GPa) pressure in dichloromethane solutions.     

Highly regio- and stereoselective hydrometallation reactions of fluorine-containing internal alkynes: Novel approaches to fluoroalkylated alkenes

Hydroalumination, hydrocupration, and hydroboration reactions of various fluorine-containing alkynes were investigated. The alkyne reacted smoothly with 2.0 equiv. of Red-Al at −78 °C to give the hydroaluminated adduct in a highly regio- and stereoselective manner, which was treated with iodine, the corresponding vinyliodide being produced in moderate yield. Hydrocupration of the alkynes also took place, but the resulting vinylmetal reacted with various electrophiles sluggishly. In sharp contrast, the reaction with dicyclohexylborane proceeded smoothly to afford the cis-addition products preferentially, which were subjected to Suzuki-Miyaura cross-coupling reaction, leading to trisubstituted alkenes in high yields.     

Evolution of hydrogen in the reaction of hydroheteroaromatic compounds with dehydrogenating agents

The yields of molecular hydrogen in the reactions of benzimidazolines 1,2-dihydropyrimidines with a number of dehydrogenating agents have been determined. The formation of hydrogen is due to breakdown of the cation-radicals of the hydrohetarenes formed in the first stage of the reactions. The EPR spectrum of the cation-radical from 1,3-dimethyl-2-phenylbenzimidazoline has been obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 203–208, February, 1988.     

Unexpected reaction of 2,2-dihydropolyfluoroalkylaldehydes with ammonia and aldehydes or ketones: a novel synthetic method for 4-fluoroalkyl-1,2-dihydropyrimidine

4-Fluoroalkyl-1,2-dihydropyrimidines were synthesized in good yields by the tri-component reaction of 2,2-dihydropolyfluoroalkylaldehydes, ammonia and aldehydes, ketones or enol ethers in the presence of zinc chloride under mild conditions.     

Alkoxylation of 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2-benzoquinone. New bis-1,2-benzoquinones

Alkoxylation of 3,6-di-tert-butyl-1,2-benzoquinone with a number of diols, including propane-1,3-diol, butane-1,4-diol, di-, and triethylene glycols, and cyclohexane-1,4-diyldimethanol, was studied. Nine new 4-alkoxy-3,6-di-tert-butyl-1,2-benzoquinones were synthesized, four of which were bis-1,2-benzoquinones with different tethers (6–13 atoms) between the quinone fragments. Depending on the length of the chain between the hydroxy groups in glycols, bicyclic 4,5-disubstituted 3,6-di-tert-butyl-1,2-benzoquinones were formed or their stepwise alkoxylation occurred. The newly synthesized o-benzoquinone derivatives can be reduced with alkali metals to give radical anions and converted into semiquinone chelates with manganese carbonyl.     

Synthesis and some conversions of 4-aryl-6-methyl-2-methoxy(phenyl)-5-nitro-1,4-dihydropyrimidines

The reaction of 1-arylidene-1-nitropropan-2-ones with O-methylisourea (or benzamidine) in the presence of aluminum oxide gave 4-aryl-6-methyl-2-methoxy(phenyl)-5-nitro-1,4-dihydropyrimidines. It was shown that the reactions of the compounds synthesized with electrophilic agents proceed at the exocyclic methyl group, as well as at the N₍₁₎, N₍₃₎, and C₍₅₎ atoms of the 1,4-dihydropyrimidine fragment of the molecule.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1398–1404, October, 1993.     

Reactions of N-substituted 2,6(3,5)-dialkyl-1,4-benzoquinone imines with arenesulfinic acids

The regioselectivity in the reactions of N-arylsulfonyl-2,6-dialkyl-1,4-benzoquinone imines with arenesulfinic acids (1,6-, 6,1-, or 6,3-addition) is determined by steric factor, while in the reactions of N-aroyl-1,4-benzoquinone imines electronic effect of substituents in the quinoid ring is crucial. The reactions of N-arylsulfonyl-3,5-dimethyl-1,4-benzoquinone imines with arenesulfinic acids follow mainly the 1,4-addition pattern. N-(N-Arylsulfonylbenzimidoyl)-1,4-benzoquinone imines are capable of reacting in a way similar to both N-arylsulfonyl and N-aroyl derivatives.     

Synthesis of 1,2-benzoquinones by the oxidation of 1,4-benzodioxins by peroxide derivatives

The oxidation reaction of 1,4-benzodioxin 1 by m-chloroperbenzoic acid (m-CPBA) and t-butyl hydroperoxide (t-BHP) are reported. 1,2-Benzoquinone 2 was given in moderate yields by the m-CPBA oxidation of 1,4-benzodioxin 1 , while 1,2-benzoquinone 2 was predominantly formed by t-BHP oxidation.     

Synthesis of novel 2-phenyl-5-substituted dihydropyrimidines using 2-phenyl-1,3-diaza-1,3-butadienes and electron-deficient olefins

A novel synthetic method for 2,5-disubstituted dihydropyrimidines was developed. The cyclization of 1,3-diaza-4-dimethylamino-1,3-butadienes having a N-protecting group (N-Boc, N-Cbz, N-n-C₄H₉, N-Bn or N-Ph) with electron-deficient olefins, such as α,β-unsaturated carbonyl compounds, phenyl vinyl sulfone, and acrylonitrile was studied in detail. The cyclization smoothly proceeded to afford 4-dimethylamino-1,4,5,6-tetrahydropyrimidines or 1,6-dihydropyrimidines in good yields. The isolated 4-dimethylamino-1,4,5,6-tetrahydropyrimidines were converted to 2,5-disubstituted-1,6-dihydropyrimidines through the β-elimination of the dimethylamino group. 2,5-Disubstituted-1,4(6)-dihydropyrimidines were obtained after removal of the N-Boc or N-Cbz group. Independent tautomers of the resulting dihydropyrimidines were observed.     

Fluorine-containing 1,10-phenanthrolines synthesis: an original and efficient approach by the pyridine-ring formation reaction of N-propargyl-5,7-bis(trifluoroacetyl)-8-quinolylamine with various nucleophiles

Novel fluorine-containing 1,10-phenanthrolines having a variety of substituents at the 3-position were easily synthesized in moderate yields by the pyridine-ring formation reaction of N-propargyl-5,7-bis(trifluoroacetyl)-8-quinolylamine with various amines, thiols, and phenols. Unexpectedly, the reactive intermediates 1,4-dihydro-1,10-phenanthrolin-4-ols were isolated for the first time in the reactions with dialkylamines.     

Efficient methods for the preparation of alkyl-aryl and symmetrical or unsymmetrical dialkyl ethers between alcohols and phenols or two alcohols by oxidation-reduction condensation

Oxidation-reduction condensation via alkoxydiphenylphosphines (diphenylphosphinite esters) (1), generated in situ from chlorodiphenylphosphine (2) and alcohols, 2,6-dimethyl-1,4-benzoquinone (3), and phenols proceeds smoothly to afford alkyl-aryl ethers in good to high yields under neutral conditions. In a similar fashion, a new and efficient method for the preparation of symmetrical or unsymmetrical dialkyl ethers in good to high yields is established via tetrafluoro-1,4-benzoquinone (fluoranil) (4), alcohols, and 1 formed in situ from (n)BuLi-treated alcohols and 2. This method is applicable also to the etherification of chiral secondary or tertiary alcohols with retention or inversion of configurations. The inverted ethers are afforded by treating chiral alkoxydiphenylphosphines and achiral alcohols, while the reaction of achiral alkoxydiphenylphosphines and chiral alcohols forms retained ethers.     

Reaction of N-acyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-1,4-benzoquinone monoimines with hydrazoic acid

N-Aroyl-3,5-dimethyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-3,5-dimethyl-1,4-benzoquinone monoimines react with hydrazoic acid according to the 1,4-addition pattern. N-Acyl-2,3,5,6-tetrachloro-1,4-benzoquinone monoimines take up hydrazoic acid at the double C=N bond (1,2-addition).     

Synthesis,properties, and catecholase-like activity of the [1,4-di(6′-methyl-2′-pyridyl)aminophthalazine]dimanganese(II) complex,Mn<Subscript>2</Subscript>(6′Me<Subscript>2</Subscript>PAP)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>

The preparation, spectroscopic properties, and catecholase-like activity of the dimanganese(II) complex [Mn₂(6′Me₂PAP)₂Cl₄] [6′Me₂PAP: 1,4-di(6′-methyl-2′-pyridyl)aminophthalazine] are reported. The title compound was suitable catalyst for the oxidation of 3,5-di-t-butylcatechol (3,5-DTBCH₂) to 3,5-di-t-butyl-1,2-benzoquinone (3,5-DTBQ) with dioxygen under ambient conditions in good yields. The catalytic oxidation was found to obey Michaelis–Menten type kinetics.     

6,7-Dimethoxy-3,4-dihydroisoquinolin-1(2<Emphasis Type="Italic">H</Emphasis>)-ylidenoacetonitrile in some fusion reactions

6,7-Dimethoxy-3,4-dihydroisoquinolin-1-ylacetonitrile in the enamine form readily reacts with acyl iso(thio)cyanates affording in high yields 1,2-fused oxo- and thioxodihydropyrimidoisoquinolines and thiouracyloisoquinolines. The reaction of the enamine with primary amines of diverse classes in the presence of 2 equiv of formaldehyde resulted in 1,2-fused N-substituted tetrahydropyrimidinoisoquinolines whose yields depended on the basicity and sterical accessibility of the reagent. Fused 5-hydroxyindolo-, dioxopyrrolo-, pyrroloisoquinolines formed in medium yields in the one-stage reactions of the enamine with p-benzoquinone, oxalyl chloride, and β-nitrostyrene respectively. The reaction of 1-cyanomethyl-6,7-dimethoxydihydroisoquinoline with acrylonitrile leads to the formation of 1,2-fused iminopyridinoisoquinoline easily hydrolysable to pyridine derivative and readily reacting by the amidine group with aroyl chlorides and arylsulfonyl chlorides.     

Facile synthesis of fluorine-containing 1,10-phenanthrolines by the pyridine-ring formation reaction of N-propargyl-5,7-bis(trifluoroacetyl)-8-quinolylamine with amines: isolation of the intermediates 1,4-dihydro-1,10-phenanthrolin-4-ols

Novel fluorine-containing 1,10-phenanthrolines having dialkyl-, alkyl, and arylaminomethyl substituents at the 3-position were easily synthesized in moderate yields by the pyridine-ring formation reaction of N-propargyl-5,7-bis(trifluoroacetyl)-8-quinolylamine with various amines. Unexpectedly, the reactive intermediates 1,4-dihydro-1,10-phenanthrolin-4-ols were isolated for the first time in the reactions with dialkylamines.