Reaction of 2,3-dimethyl-and 1,2,3-trimethyl-6-aminoindoles with ethyl 4,4,4-trifluoroacetoacetate

The comparative reactivity of 2,3-dimethyl-and 1,2,3-trimethyl-6-aminoindoles in the reaction with ethyl trifluoroacetoacetate has been studied with the aim of developing the synthesis of corresponding trifluoromethylpyrroloquinolines. Depending on the amine used, the reaction proceeds differently both at the initial stage of the formation of amides and during their transformation into trifluoropyrroloquinolines.     

Peculiarities of three-component cyclization of ethyl 4,4,4-trifluoroacetoacetate and 1,2-ethanediamines with 3-methylbutan-2-one

The peculiarities of the three-component cyclization of ethyl 4,4,4-trifluoroacetoacetate and 1,2-ethanediamines with 3-methylbutan-2-one into hexahydroimidazo[1,2-a]pyridin-5-ones were studied. The reactions proceeded under mild conditions. The use of methyl ketone with a bulky isopropyl substituent increased the stereoselectivity of the transformations, but the reaction with 1,2-diaminopropane was accompanied by the formation 4-[(1-ammoniopropan-2-yl)amino]-1,1,1-trifluoro-4-oxobut-2-en-2-olate as a by-product.

     

葡萄汁酵母SW-58不对称还原4，4，4-三氟乙酰乙酸乙酯的研究

对实验室保藏菌种进行筛选,得到一株葡萄汁酵母Saccharoinyces uvarum SW-58,能够催化还原4,4,4-三氟乙酰乙酸乙酯生成(R)-4,4,4-三氟-3-羟基丁酸乙酯。在优化条件下,摩尔转化率达到77.0%,产物的对映体纯度88.9%e.e.,产物浓度达到15.7 g/L,产物浓度得到了显著的提高,达到优化前的3.3倍。     

Direct catalytic asymmetric aldol-type reaction of aldehydes with ethyl diazoacetate

The direct aldol-type condensation of aldehydes with ethyl diazoacetate catalyzed by the chiral complex of BINOL derivatives-Zr(O(t)Bu)(4) gave beta-hydroxy alpha-diazo carbonyl compounds with moderate enantioselectivities (53-87% ee). [reaction: see text]     

NMR study of the keto-enol equilibrium of ethyl γ,γ,γ-trifluoroacetoacetate and its reaction with water and alcohols

The keto-enol equilibrium of the title compound 1 has been studied by ¹⁹F NMR spectroscopy at variable temperature. The results found are in agreement with those reported by previous authors using ¹H NMR. In addition, the reaction of 1 with water and alcohols, and the equilibrium of the starting keto-enol forms with the corresponding hydrate and hemiketals has been investigated. Some interesting features of the ¹H and ¹⁹F NMR spectra of these compounds are also discussed.     

Piperidine promoted aldol reaction of alkynyl aldehydes and ethyl diazoacetate

Complex diazo compounds containing propargyl alcohol functional group were prepared by an efficient aldol reaction of alkynyl aldehydes and ethyl diazoacetate in good yields. Piperidine was utilized as a base to catalyze this transformation. The aldol reaction showed broad substrate scopes and good functional group compatibility.     

Reinvestigation of the condensation of 2-hydrazinobenzothiazole with ethyl acetoacetate

The reaction of 2-hydrazinobenzothiazole (1) with ethyl acetoacetate has twice been reported to yield a fused triazepinobenzothiazolone, namely, 3-methyl[1,2,4]triazepino[3,4-b]benzothiazol-5(4H)-one (4). We have repeated this work and reassigned the reaction product as 2-(2-benzothiazolyl)-1,2-dihydro-5-methyl-3H-pyrazol-3-one (5) on the basis of X-ray crystallography.     

Addition of thiols to ethyl 4,4,4-trifluorocrotonate

Ethyl 4,4,4-trifluorocrotonate 1 readily adds aliphatic and aromatic thiols and aminothiols at the double bond in the presence of catalytic amounts of alkylamines and ammonia to give 3-thiolation products. Thiolacetic acid reacts with ester 1 in the absence of a catalyst at 100 °C.     

Catalytic aldol-type reaction of aldehydes with ethyl diazoacetate using quarternary ammonium hydroxide as the base

The direct aldol-type condensation of aldehydes with ethyl diazoacetate (EDA) promoted by an organic base and non-metallic catalyst such as tetrabutylammonium hydroxide (TBAOH) gave β-hydroxy-α-diazocarbonyl compounds with moderate to excellent yields. Furthermore, the reactivity and scope of various phase-transfer catalysts as well as electronically divergent aldehydes are discussed.     

Study on the reactions of ethyl 4,4,4-trifluoro-3-oxobutanoate with arylidenemalononitriles

In the presence of a catalytic amount of NEt₃, ethyl 4,4,4-trifluoro-3-oxobutanoate 1 reacted readily with arylidenemalononitriles 2 in ethanol at room temperature. It gave two products 2-trifluoromethyl-3,4-dihydro-2H-pyran derivatives 3 and 2-(trifluoromethyl)piperidine derivatives 4, the ratio of 3 and 4 was depended on the substrates 2 and reaction solvents. Reflux of the ethanol solution of 4 with a catalytic amount of NEt₃ afforded 2-trifluoromethyl-1,4,5,6-tetrahydropyridine derivatives 5 in moderate to good yields. The structures of new compounds 3, 4 and 5 were determined by spectral methods, microanalysis and X-ray diffraction analysis. A possible reaction mechanism for the formation of 3, 4 and 5 was presented.     

DMAP-catalyzed cyanation of aldehydes and ketones with ethyl cyanoformate

The cyanation of carbonyl compounds with ethyl cyanoformate is catalyzed by 4-dimethylaminopyridine (DMAP) to afford the corresponding cyanohydrin carbonates in excellent yields. The system provides a convenient method for cyanation of carbonyl compounds without using metal catalysts or solvents.     

Lewis acid-promoted Baylis-Hillman-type reaction of alpha,beta-unsaturated ethyl thioester with aldehydes without the use of a Lewis base

The Baylis-Hillman-type reaction of alpha,Beta-ethyl thioacrylate with aldehydes has been achieved using diethylaluminium iodide as the promoter without the direct use of any Lewis bases. The reaction provides an effective access to various alpha-methylene-Beta-hydroxy thioesters.     

Unusual transformations of lithium enolate of ethyl 4,4,4-trifluoro-3-oxobutanoate

The present paper describes unusual reactions of lithium enolate of ethyl 4,4,4-trifluoro-3-oxobutanoate with ammonium acetate and 1-aminonaphthalene. These reactions produce 4-amino-2,6-bis(trifluoromethyl)pyridine and 4-trifluoromethyl-2-[(Z)-1,1,1-trifluoroprop-1-en-2-ol-1-yl]benzo[h]quinoline, respectively. The reaction of 1,1,7,7,7-hexafluoroheptane-2,4,6-trione hydrate with 1-naphthylamine gives a mixture of 4-trifluoromethyl-2-[(Z)-1,1,1-trifluoroprop-1-en-2-ol-1-yl]benzo[h]quinoline and N,N??-bis(naphth-1-yl)-2,6-bis(trifluoromethyl)pyridine-4(1H)-imine, respectively.     

alpha-Aminoallylation of aldehydes in aqueous ammonia

alpha-Aminoallylation of aldehydes in aqueous ammonia has been developed; commercial aqueous ammonia was successfully used, and this method does not require anhydrous conditions thus leading to easy and practical operations.     

Stereoselection in the condensation between ethyl propionate and aldehydes

Ethyl propionate can be converted stereoselectively into geometrical isomers of O-ethyl-O-trimethylsilylmethylketene acetal ($\text{5}$). The E-isomer of $\text{5}$ condenses with aldehydes by titanium tetrachloride to give stereoselectively the threo isomers of ethyl 2-methyl-3-hydroxy carboxylates.     

Reinvestigation of the grignard reactions with formic acid. A convenient method for preparation of aldehydes

Grignard reagents react with formic acid in tetrahydrofuran to produce aldehydes in relatively good yields Various aldehydes such as alkyl, aryl, allyl, benzyl and vinyl aldehydes were prepared from the corresponding Grignard reagents. The reaction with vinyl Grignard reagents proceeded with retention of configuration.