1,1,1-Trifluoro-3-(2-thenoyl)acetone in Reactions with Hydrazines

Properties of 1,1,1-trifluoro-3-(2-thenoyl)acetone and its reactions with hydrazine hydrate, 2,4-dinitrophenylhydrazine, and 1,1-dimethylhydrazone are studied.     

Reactions of 1,1,1-trihalo-3-nitrobut-2-enes with enamines derived from cycloalkanones. Rearrangement of trifluoromethylated 1,2-oxazine N-oxide into 1-pyrroline N-oxides and stereochemistry of the products

1,2-Oxazine N-oxides derived from (E)-1,1,1-trifluoro-3-nitrobut-2-ene and cyclohexanone enamines underwent spontaneous rearrangement with ring contraction to give 1-pyrroline N-oxides. Reactions of (E)-1,1,1-trifluoro(trichloro)-3-nitrobut-2-enes with N-cyclopent-enylmorpholine resulted in a series of novel CX₃-containing nitroalkyl enamines and g-nitro ketones; the stereochemistry of the synthesized compounds were studied by NMR spectroscopy and X-ray diffraction.     

Synthesis of chiral 2-(anilinophenylmethyl)pyrrolidines and 2-(anilinodiphenylmethyl)pyrrolidine and their application to enantioselective borane reduction of prochiral ketones as chiral catalysts

Chiral diamines, 2-(anilinophenylmethyl)pyrrolidines and 2-(anilinodiphenylmethyl)pyrrolidine, were prepared from N-(tert-butoxycarbonyl)pyrrolidine or (S)-proline as a starting material, respectively. These chiral diamines were efficient for the catalytic enantioselective borane reduction of acetophenone. Using (S)-2-(anilinodiphenylmethyl)pyrrolidine, chiral secondary alcohols were obtained from prochiral ketones with good to excellent enantiomeric excesses (up to 98% ee).     

Synthesis and Characterization of Novel 2-(1,2,3-Triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles and 2-(4,5-Dihydro-1H-pyrazol-1-yl)-4-(1H-1,2,3-triazol-4-yl)thiazoles

Reactions of 1-(5-methyl)-1H-1,2,3-triazol-4-yl)ethan-1-ones and benzaldehydes in ethanol under basic conditions gave the corresponding chalcones. Reactions of the chalcones combined with thiosemicarbazide in dry ethanol containing sodium hydroxide afforded the corresponding pyrazolin-N-thioamides. Reactions of the synthesized pyrazolin-N-thioamides and several ketones (namely, ethyl 2-chloro-3-oxobutanoate, 2-bromoacetylbenzofuran, and hydrazonoyl chloride) gave the corresponding novel 2-(1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles in high yields (77–90%). Additionally, 2-(4,5-dihydro-1H-pyrazol-1-yl)-4-(1H-1,2,3-triazol-4-yl)thiazoles were obtained in high yields (84–87%) from reactions with N-pyrazoline-thioamides and 4-bromoacetyl-1,2,3-triazoles under basic conditions. The structures of six of the newly synthesized heterocycles were confirmed by X-ray crystallography.     

Oxidative addition of trifluoromethanesulfonamide to cycloalkadienes

Reactions of trifluoromethanesulfonamide with cyclopentadiene, cyclohexa-1,3- and -1,4-dienes, cyclohepta-1,3,5-triene, and cycloocta-1,3-diene in the presence of t-BuOCl-NaI were studied. Trifluoromethanesulfonamide added at one double bond of cyclopentadiene and cyclohexa-1,3-diene in regio- and stereoselective fashion to give N-(5-iodocyclopent-2-en-1-yl)trifluoromethanesulfonamide and trans-N,N′-cyclohex-3-ene-1,2-diylbis(1,1,1-trifluoromethanesulfonamide), respectively. The reaction with cyclohexa-1,4-diene involved both isolated double bonds to produce N,N′-(2-chloro-5-iodocyclohexane-1,4-diyl)bis(1,1,1-trifluoromethanesulfonamide) which underwent halophilic reduction of the CHI group by the action of NaI and elimination of HCl, leading to N,N′-(cyclohex-2-ene-1,4-diyl)bis(1,1,1-trifluoromethanesulfonamide). Under analogous conditions, cyclohepta-1,3,5-triene was oxidized to benzaldehyde, while no reaction with trifluoromethanesulfonamide occurred.     

Synthesis of 2,3-bis(perfluoroalkyl)quinoxalines and 2,3-bis(perfluoroalkyl)-1,4-benzoxazines from oxides of internal perfluoroolefins

The reactions of oxides of internal trans-, cis-perfluoroolefins with o-phenylenediamine and 2-aminophenol in dioxane gave 2,3-bis(perfluoroalkyl)quinoxalines and 2,3-bis(perfluoroalkyl)-2H-1,4-benzoxazin-2-ols respectively in yields of 23-67%. When N,N-dimethylacetamide was used as a solvent an anionic isomerization of the oxides into ketones, which further yielded 2-(perfluoroalkyl)benzimidazoles in the case of o-phenylenediamine and 2-hydroxy-N-perfluoroalkanoylanilines in the case of 2-aminophenol, became the main path of these reactions. Unusual cyclization resulting in 2-pentafluoroethyl-2-pentafluoropropanoylbenzoxazolidine occurs on interaction between dodecafluoro-3,4-epoxyhexane and 2-aminophenol in N,N-dimethylacetamide.     

Synthesis and reactions with <Emphasis Type="Italic">N</Emphasis>-nucleophiles of 1-(thien-2-yl)- and 1-(4-hydroxyphenyl)-3,4,4-trichloro-3-buten-1-ones

Acylation of thiophene and phenol with 3,4,4-trichloro-3-butenoyl chloride afforded the corresponding 1-(thien-2-yl)- and 1-(4-hydroxyphenyl)-3,4,4-trichloro-3-buten-1-ones, whose reaction with amines led to the formation of 3-amino-1-(thien-2-yl, 4-hydroxyphenyl)-4,4-dichloro-2-buten-1-ones The heterocyclization of the initial ketones into pyrazole structure was not observed, and the reaction with hydrazine hydrate provided bispyrazole products, N,N′-bis(5-thien-2-yl)- and N,N′-bis[5-(4-hydroxyphenyl)-1H-pyrazol-3-ylmethylene]hydrazines.     

Diastereoselective route to (2R,5S)- and (2S,5S)-2-methyl-1,6-dioxaspiro[4.5]decane, a pheromone component of the wasp Paravespula vulgaris

A diastereoselective approach to (2R,5S)- and (2S,5S)-2-methyl-1,6-dioxaspiro[4.5]decane 1 and 1a is described. The route starts with an alkylation reaction among the cyclopentanone N,N-dimethylhydrazone 6 and the chiral iodides (R)-3 or (S)-3, derived from the enantiomers of ethyl β-hydroxybutyrate, controlling the estereocenter at C-2 of the molecules. The alkylated products 7 and 7a were easily transformed into the 1,8-O-TBS-1,8-dihydroxy-5-nonanones 9 and 9a in four steps, and a subsequent stereoselective spiroketalization, in acidic media, afforded a Z:E mixture (1:2) of compounds 1 and 1a.     

Synthesis of aryl 3-(2-imidazolyl)propyl ketones

The approach to the title compounds was via lithiation-substitution of N-methyl or N-(triphenylmethyl)-imidazole by some iodo ketals. 4-Chloro-4′-halobutyrophenones (halo = F, Cl, Br) were converted by sodium iodide to the corresponding aliphatic iodides which were subsequently ketalized with ethylene glycol to provide the corresponding iodo ketals. Lithiation of either 1-methyl- or 1-(triphenylmethyl)imid-azole with N-butyllithium generated the corresponding 2-lithioimidazoles, in situ, which were then reacted with these iodo ketals to form the corresponding C-2 substituted imidazoles. Dilute aqueous acid hydrolysis released the ketone from the ketal. For N-triphenylmethyl protected imidazoles, the triphenylmethyl group was also hydrolyzed to give triphenylmethanol and 3-(2-imidazolyl)propyl 4-haloaryl ketones. These N-unsubstituted imidazolyl ketones can be alkylated independently with triphenylmethyl chloride to form the corresponding N-triphenylmethyl imidazole derivatives.     

A simple and convenient synthesis of 4-methyl-3-nitro-2-trihalomethyl-2H-chromenes from N-unsubstituted imines of 2-hydroxyacetophenones and trichloro(trifluoro)ethylidene nitromethanes

The reaction of N-unsubstituted imines of 2-hydroxyacetophenones with trichloro(trifluoro)ethylidene nitromethanes in the presence of DABCO proceeds via tandem oxa-Michael/aza-Henry additions (in dichloromethane) or aza-Michael addition (in benzene) to give 4-methyl-3-nitro-2-trichloro(trifluoro)methyl-2H-chromenes or 1,1,1-trichloro(trifluoro)-3-nitro-N-[1-(2-hydroxyaryl)ethylidene]propan-2-amines, respectively.     

Transformations of 2-(phenylethynyl)isocamphanol under acid catalysis

2-exo-(Phenylethynyl)isocamphanol prepared from lithium phenylacetylide and isocamphanone suffered under conditions of Ritter reaction a conversion predominantly into a mixture of 2-(benzoylmethylene)isocamphane and 2-(benzoylmethylene)bornane that formed as a result of rearrangements of the initial acetylene alcohol by Meyer-Schuster and partially by Wagner-Meerwein. The enones ratio depends on the reaction conditions and varies from 5:4 to 1:3. The product of nucleophilic substitution, N-(4-benzoylmethyl-2-isobornyl)acetamide, formed in a yield no higher than 10%. Analogous rearrangements occurred at treating 2-phenylethynylisocamphanol with formic acid; here the mixture of the above enones formed in a ratio 1:2. The initial acetylene alcohol treated with Beckmann mixture gave rise to the same enones in a ratio 1:1, and the target 2-endo-(phenylethynyl)isocamphanol acetate formed as minor product (～15%). The individual α,β-unsaturated ketones under the Ritter reaction conditions were selectively converted into N-(4-benzoylmethyl-2-isobornyl)acetamide.     

(N-Isocyanimino)triphenylphosphorane-Mediated,One-Pot,Efficient Synthesis of Sterically Congested 1,1,1-Trifluoro-2-(5-aryl-1,3,4-oxadiazol-2-yl)-2-propanol Derivatives via Intramolecular Aza-Wittig Reaction

Reactions of (N-isocyanimino)triphenylphosphorane with 1,1,1-trifluoroacetone in the presence of aromatic (or heteroaromatic) carboxylic acids (3-methylbenzoic acid, 1-naphthalenecarboxylic acid, 2-naphthalenecarboxylic acid, 2-furancarboxylic acid, and 2-thiophenecarboxylic acid) proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,1,1-trifluoro-2-(5-aryl-1,3,4-oxadiazol-2-yl)-2-propanol derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Experimental and theoretical investigation of self-association in inert environment of new triflamide derivatives

According to the data of IR spectroscopy and quantum chemical calculations N-(2-phenylethyl) trifluoromethanesulfonamide exists in an inert solvent CCl₄ as an equilibrium mixture of the monomer and chain associates; in contrast, N-(5-iodocyclopentenyl)-1,1,1-trifluoromethanesulfonamide under the same conditions is prone to the formation of cyclic self-associates. The behavior of N,N′-(cyclohexenediyl)-bis(1,1,1-trifluoromethane sulfonamide) in the same medium is far more complicated: apart from the monomer with intramolecular hydrogen bonds (HB), it forms only cyclic self-associates with eight-membered and eleven-membered rings.     

Preparation of dimethyl (R)- and (S)-2-(2-aminophenyl)-2-hydroxyethylphosphonate from anthranilic acid

An efficient synthesis of both enantiomers of dimethyl δ-amino-β-hydroxyethylphosphonate 6 has been achieved starting from anthranilic acid, through the resolution of dimethyl (±)-2-(2-N,N-dibenzylaminophenyl)-2-hydroxyethylphosphonate 9 with (S)-O-methylmandelic acid. The absolute configuration of the enantiomers 9 was assigned by the Dale and Mosher approach using the extended Newman projections and molecular mechanics.     

Preparation,molecular structures,and characteristic properties of (E)-1-(2-furyl)- and (E)-1-(2-thienyl)-2-(3-guaiazulenyl)ethylenes and (E)-1-(3-furyl)- and (E)-1-(3-thienyl)-2-(3-guaiazulenyl)ethylenes

Wittig reactions of 2-furaldehyde (20) [and thiophene-2-carbaldehyde (21)] with (3-guaiazulenylmethyl)triphenylphosphonium bromide (19) in ethanol containing NaOEt at 25 °C for 24 h under argon give (E)-1-(2-furyl)-2-(3-guaiazulenyl)ethylene (22E) and (E)-1-(2-thienyl)-2-(3-guaiazulenyl)ethylene (23E) in 53 and 36% yields. Similarly, Wittig reactions of 3-furaldehyde (29) [and thiophene-3-carbaldehyde (30)] with 19 under the same reaction conditions as for 20 and 21 afford (E)-1-(3-furyl)-2-(3-guaiazulenyl)ethylene (31E) and (E)-1-(3-thienyl)-2-(3-guaiazulenyl)ethylene (32E) in 32 and 46% yields. Molecular structures and characteristic properties as well as preparation of the title E (i.e., one of the geometrical isomers) forms, with a view to comparative study, are reported. Moreover, reactions of those conjugated π-electron systems with TCNE (=tetracyanoethylene) in benzene [and in DMF (=N,N-dimethylformamide)] at 25 °C for 24 h under argon yield unique products, possessing interesting molecular structures, respectively, whose characteristic properties and crystal structures are documented, also.     

Reaction of 2-(2-oxo-2-arylethylidene)-2,3-dihydropyrimidine-4(1H)-ones with aldehydes

2-(2-Oxo-2-arylethylidene)-2,3-dihydropyrimidine-4(1H)-ones react with aromatic and heteroaromatic aldehydes to form the unsaturated ketones, whereas in the case of 3- and 4-benzaldehydes the corresponding trans-2-styrylpyrimidine-4(3H)-ones were obtained. A possible mechanism of hydrolytic cleavage of the product of condensation of 2-(2-oxo-2-phenylethylidene)-2,3-dihydropyrimidine-4(1H)-one with paraformaldehyde under acid catalysis and mechanochemical activation has been discussed.     

Reactions of epoxides derived from internal perfluoroolefins with o-phenylenediamine and 2-aminophenol

The reactions of epoxy derivatives of internal perfluoroolefins with o-phenylenediamine and 2-aminophenol in dioxane gave 23–67% of the corresponding 2,3-bis(perfluoroalkyl)quinoxalines and 2,3-bis(perfluoroalkyl)-2H-1,4-benzoxazin-2-ols, respectively. When N,N-dimethylacetamide was used as a solvent, the main reaction pathway was anionic isomerization of epoxides into ketones which were then converted into 2-perfluoroalkylbenzimidazoles (in the reactions with o-phenylenediamine) or 2-hydroxy-N-perfluoroalkanoylanilines (in the reactions with 2-aminophenol). The reaction of 3,4-epoxydodecafluorohexane with 2-aminophenol in N,N-dimethylacetamide was accompanied by unusual cyclization to afford 2-pentafluoropropanoyl-2-pentafluoroethyl-1,3-benzoxazolidine.     

Studies of reactions of dimethylphosphoramidic difluoride withtrans-2-(N,N-dialkylamino)cycloalkanols in the presence of various sulfur-containing nucleophiles

The reactions of dimethylphosphoramidic difluoride (1) withtrans-2-(N,N-dialkylamino)cycloalkanols were studied in the presence of various sulfur-containing nucleophiles and Et₃N. WhenO,O-diisopropyl thiophosphoric acid was used as a nucleophile, the correspondingO,O-diisopropylS-[2-(N,N-dialkylamino)cycloalkyl] thiophosphates were obtained in satisfactory yields. The direction of this reaction in the presence ofO-isopropyl toluenephosphonothioic acid depends on the pK _a of aminoalcohol, namely, the amount ofO-isopropyl tolylphosphonofluoridate that was formed along withO-isopropylS-[2-(N,N-dialkylamino)cycloalkyl] tolylphosphonothioates was increased as the pK _a increased. The reactions of compound1 withtrans-2-(N,N-dialkylamino)cycloalkanols and thioacetic acid afforded 2-(N,N-dialkylamino)cycloalkanethiols, certain of which were readily oxidized to the corresponding disulfides. In the case of potassium ethyl xanthate, the composition of the reaction products depends on the nature of aminoalcohol. X-ray diffraction analysis ofS-(2-piperidinocyclohexyl)N,N-dimethyldithiocarbamate demonstrated that this compound exists as thetrans isomer. This fact supports the reaction mechanism, which we have suggested previously and which involves the formation of aziridinium cations followed by their opening under the action of nucleophilic agents.     

Condensation of <Emphasis Type="Italic">N</Emphasis>-(2-vinyloxyethyl)ethane-1,2-diamine with carbonyl compounds

Condensation of N-(2-vinyloxyethyl)ethane-1,2-diamine with aromatic aldehydes gave mixtures of 2-aryl-1-(2-vinyloxyethyl)imidazolidines and N-arylmethylidene-N′-(2-vinyloxyethyl)ethane-1,2-diamines in an overall yield of 79–84%, while analogous condensation with cyclic and acyclic ketones resulted in the formation of only the corresponding Schiff bases (yield 53–83%).     

Ring opening of 2-(cyanomethyl)aziridines by acid chlorides: synthesis of novel 4-amino-2-butenenitrile derivatives through intermediate aziridinium salts

1-Arylmethyl-2-(cyanomethyl)aziridines were transformed into novel N-arylmethyl-N-(2-chloro-3-cyanopropyl)amides as the major reaction products upon treatment with acid chlorides in CH₂Cl₂ through the ring opening of intermediate aziridinium salts. Subsequently, N-arylmethyl-N-(2-chloro-3-cyanopropyl)amides were converted into stable N-arylmethyl-N-(3-cyano-2-propenyl)amides for the first time by means of a dehydrochlorination mediated by Et₃N in CH₂Cl₂.