Potassium Tert-butylate Research Articles

On Radical Reactions of 1-Bromotricyclo[4.1.0.02,7]heptane with Phenylethynyl Sulfones

Phenylethynyl sulfones of the general formula RSO2C≡CPh (R = p-Tol, Ph, CH3) undergo a photochemically induced anti-stereoselective addition to the central C1–C7 bond of 1-bromotricyclo[4.1.0.02,7]heptane to form monoadducts of the bicyclo[3.1.1]heptane (norpinic) series containing a syn-sulfonyl group in position 7 and a phenylethynyl moiety on C6. Treatment of the synthesized adducts with potassium tert-butylate in THF leads to 1,3-dehydrobromination to give sulfonyl-substituted 1-(phenylethynyl)tricyclo[4.1.0.02,7]heptanes.

INVESTIGATION OF THE CATALYTIC EFFECT OF POTASSIUM TRET-BUTOXIDE IN THE AMIDATION REACTIONS OF RAPESEED OIL ACYLGLYCERIDES

Background. Alkalis and metal alkoxides are used as catalysts for the amidation of vegetable oils. However, the use of known catalysts does not always allow to soften the conditions of the processes to the required level. The use of potassium tret-butoxide as a catalyst for these reactions can serve as a solution to the problem.Objective. Verification of the use of potassium tert-butoxide as a catalyst for the amidation reaction of vegetable oil acylglycerides.Methods. To achieve this goal, a series of syntheses of the amidation of rapeseed oil with ethylenediamine, diethanolamine and dibutylamine in the presence of potassium tert-butylate was carried out. The dependences of the yields of the target product on the catalyst content, temperature and reaction time were studied.Results. It is shown that with the introduction of potassium t-butoxide in the reaction mixture in amounts from 0.1 to 1 mole percent, the reaction rate increases dramatically. A further increase in the amount of catalyst even to the molar ratio of 1/1 in the same conditions increases the yields by only 20% and is not advisable. The optimal molar ratio of rapeseed oil/t-butoxide was 1/0.01. It was found that the optimal temperature for carrying out the amidation in the presence of potassium tert-butoxide is in the range of 60–90 °C, depending on the structure of the amine used. It was revealed that the reaction also takes place at room temperature, although the yields of the target products are too low. However, the use of potassium tert-butoxide allows syntheses to be carried out under conditions in which hydroxides and other metal alkoxides are not effective. It is established that the optimal time for the amidation of rapeseed oil at the revealed temperature is on average 6–8 hours, depending on the structure of the amine. With reduced in temperature, in order to obtain a satisfactory yield, the time for synthesis should be increased.Conclusions. Studies have shown that potassium tert-butoxide exhibits a significantly greater catalytic activity in the amidation reactions of oils than other alkaline catalysts. This significantly mitigates the conditions of amidation and reduces the energy costs of the process. In addition, the data obtained make it possible to further vary the temperature and time of synthesis of vegetable oil amides, depending on the tasks.

Reactions of Ethyl 5-Methyl-4-(1,2,3-thiadiazol-4-yl)furan-2-carboxylate with Selected Bases

The reactions of 5-methyl-4-(1,2,3-thiadiazol-4-yl)furan-2-carboxylic acid ethyl ester with some bases have been studied. The opening of 1,2,3-thiadiazole ring under the action of potassium tert-butylate in tetrahydrofuran in the presence of methyl iodide has led to the corresponding 4-methylsulfanylethynylfuran derivative. Under the action of potassium carbonate in DMF with an excess of primary amines or morpholine, the starting thiadiazole has formed the corresponding thioamides of furylacetic acid. The reaction of ethyl 5-methyl-4-(1,2,3-thiadiazol-4-yl)furan-2-carboxylate with hydrazine hydrate has led to hydrazinolysis of the ester group without cleavage of the 1,2,3-thiadiazole ring.

Synthesis of 1-Naphthylacetylene Sulfides from 4-(1-Naphthyl)-1,2,3-thiadiazole

4-(1-Naphthyl)-1,2,3-thiadiazole is readily decomposed under the action of potassium tert-butylate with the release of nitrogen and the formation of potassium 2-(1-naphthyl)ethynylthiolate. Upon further treatment of the reaction mixture with excess of alkyl halide, the corresponding alkyl 2-(1-naphthyl)-1-ethynylsulfides have been obtained. In the case of the reaction with allyl bromide, the resulting sulfide has undergone rearrangement. A mixture of Z- and E-isomers of 2-(1-naphthyl)-1-ethynyl-1-propenylsulfide has been obtained as the product of allylic rearrangement instead of the expected product of the thio-Claisen rearrangement.

Straightforward access to complex isoindolinones from the Ugi reaction of o-nitrobenzoic acid derivatives.

The Ugi reaction of 2-nitrobenzoic acid derivatives has been used for a diversity oriented synthesis of complex isoindolinones via a SNAr reaction involving the peptidyl position. When the cyclization is triggered by strong bases such as potassium tert-butylate, the SNAr reaction is followed by a deamidification/oxidation sequence leading to 2-hydroxyisoindolinones. The latter may be further transformed into polycyclic fused isoindolinones via Pictet-Spengler type cyclization or O-alkylation/metathesis sequences.

Synthesis of the Derivatives of 4-(5-Aryl-3-methylfuran-3-yl)-1,2,3-thiadiazole and Functionalization of 5-Aryl-2- methylfuran via Reactions of Thiadiazole Ring

By arylation of 2-methyl-3-acetylfuran via the Gomberg–Bachmann reaction 5-(4-ethoxycarbonylphenyl)-, 5-(2-nitrophenyl), and 5-(4-nitrophenyl)-2-methyl-3-acetylfurans were synthesized. Carboethoxyhydrazones of 2-methyl-5-phenyl-3-acetylfuran and its phenyl-substituted analogs when treated with thionyl chloride form 4-(5-aryl-2-methylfuran-3-yl)-1,2,3-thiadiazoles by the Hurd–Mori reaction. Thermal stability of obtained compounds increases with the increase in electron-acceptor action of substituent in phenyl ring. Opening of thidiazole ring in the compounds synthesized under the action of potassium tert-butylate in THF in the presence of alkyl iodides leads to the corresponding alkylthioethynylfurans. Performing the reaction with potassium carbonate in DMF in the presence of excess morpholine permits the preparation of (2-methyl-5- arylfuran-3-yl)thioacetylmorpholides.

Ni(II) complex of bisthiophosphorylated thiourea prepared from the Betti base

The interaction between bisthiophosphorylated thiourea with nickel(II) nitrate in the presence of potassium tert-butylate has afforded NiL2 complex with square-planar configuration of the nickel(II) ion and the 1,3-N,S-coordination of the trans-positioned similar heteroatoms.

Thiadiazole ring opening in the derivatives of 2-substituted 5-(1,2,3-thiadiazol-4-yl)-3-furoic acid under the action of bases

Transformations of the derivatives of 2-substituted 5-(1,2,3-thiadiazol-4-yl)-3-furoic acid under the action of bases has been studied. In the presence of potassium tert-butylate in THF, the studied compounds decompose with the cleavage of the thiadiazole ring, liberation of nitrogen, and formation of labile acetylene thiolates. In the presence of methyl iodide, these salts form stable 2-methylthioethynylfurans. Under the action of sodium ethylate in ethanol, thiadiazole ring of ethyl [2-methyl-5-(1,2,3-thiadiazol-4-yl)]-3-furoate is split to form the corresponding sodium acetylene thiolate. Under the action of ethanol, two molecules of this salt give bis(furyl)dithiafulvene. In the DMF–potassium carbonate system, acetylene thiolates react with primary and secondary amines giving thioamides of (4-ethoxycarbonyl-5-methylfur-2-yl)acetic acid. Treating of ethyl 2-methyland 2-N-morpholinomethyl-5-(1,2,3-thiadiazol-4-yl)-3-furoates with hydrazine hydrate leads to hydrazinolysis of the ester group and cleavage of thiadiazole ring resulting in the formation of hydrazides of 4-hydrazinocarbonylfur-2-ylacetic acid. In the case of ethyl 2-acetoxymethyl- and 2-(4-nitrophenoxy)methyl-5-(1,2,3-thiadiazol-4-yl)-3-furoates, thiadiazole ring is retained and exclusively hydrazinolysis of the ester groups is observed.

5-Trifluoromethylfuryl derivatives of phosphocarboxylic acids

Methods of synthesis of trifluoromethylfuryl derivatives of phosphonocarboxylic acids are studied. By addition of diethyl hydrogen phosphite to alkyl 3-(5-trifluoromethylfur-2-yl)acrylate under the conditions of the Pudovik reaction the corresponding derivative of 3-phosphonopropionic acid was prepared. Diethyl (5-trifluoromethylfur-2-yl)methanephosphonate in presence of potassium tert-butylate reacts with ethyl acrylate to form trifluoromethylfuryl derivative of 4-phosphonobutyric or 4-phosphonopimelic acid depending on the reaction conditions. In the products of reaction of the alkyl 3-(5-trifluoromethylfur-2-yl)-3-(diethoxyphosphoryl) propionate with ethyl acrylate in the presence of potassium tert-butylate formation of trifluoromethylfuryl derivative of the 3-phosphonoadipic acid is detected. 3-(5-Trifluoromethylfur-2-yl)-3-(diethoxyphosphoryl) propionic acid and its acid chloride are synthesized. The latter compound is used for acylation of glycine to form the corresponding N-acyl derivative. It is suggested that such compounds may be transported in the cell using usual channels of transportation of the amino acids and short peptides.

Improved synthesis of optically active ipsdienol

In our preceding publication [1] a simple procedure was described for the preparation of both enantiomers of monoterpene alcohol ipsdienol 1, an actual pheromone component of bark beetle of genus Ips. The key synthesis stage was the resolution of the direct precursor of the ipsdienol, (±)-6-methyl-2-(2chloroethyl)hepta-1,5-dien-4-ol by its conversion into acid phthalate and the crystallization of the acid phthalate as salt with (+)or (–)-1-phenylethylamine. Then the optically active acid phthalates (S)-2 and (R)2 were treated with potassium tert-butylate in tertbutyl alcohol. By the dehydrochlorination and the simultaneous alcoholysis of the ester moiety in one stage (S)or (R)-ipsdienol was obtained in a 55% yield.

Benzimidazolium sulfonate ligand precursors and application in ruthenium-catalyzed aromatic amine alkylation with alcohols

New benzimidazolium sulfonate salts have been prepared and fully characterized. They have been associated in situ with [RuCl2(p-cymene)]2 to generate efficient catalytic systems operating at 120°C under neat conditions in the presence of potassium tert-butylate for selective N-alkylation of primary aromatic amines into secondary amines.

Reaction of potassium 2-(1-adamantyl)ethynethiolate with nitrilimines

Nitrilimines are the most active donor Huisgen 1,3-dipoles that readily are brought into the [2+3]-cycloaddition reactions with thiocarbonyl compounds. The simplest method of nitrilimines generation is the reaction of hydrazonoyl chlorides with bases [1]. It was formerly established that potassium 2-arylethynethiolates form with nitrilimines products of [2+3]-cycloaddition, 1,3,4-thiadiazolines [2]. It was proved that this reaction could proceed both as a concerted 1,3-dipolar cycloaddition and in two stages. First a linear product formed resulting from the nucleophilic attack of the thiolate on the electrophilic site of the nitrilimine that at the treatment with a methanol solution of KOH quantitatively converted into thiadiazolidine. The reaction of potassium 2-arylethynethiolates with the initial compounds for nitrilimines synthesis (hydrazonoyl chlorides) occurred exclusively as the nucleophilic substitution of the halogen by the thiolate residue [2]. At the same time the reaction of potassium 2-tertbutylethynethiolate with nitrilimines afforded only the linear product of the nucleophilic attack of the thiolate on the electrophilic site of the nitrilimine. This product did not undergo the intramolecular cyclization under the treatment with bases evidently due to the geometry of the molecule [3]. Potassium 2-(1-adamantyl)ethynethiolate (II) obtained by the treatment with such a strong base as potassium tert-butylate of 4-(1-adamantyl)-1,2,3-thiadiazole (I) [4] readily reacted with hydrazonoyl chlorides IIIa–IIIc. However the direction of the reaction is ambiguous and depends on the character of the substituents in hydrazonoyl chlorides IIIa–IIIc. For instance, the reaction of potassium 2-(1-adamantyl)-ethynethiolate (II) with hydrazonoyl chlorides IIIa, IIIb containing strond electron-withdrawing substituents MeC=O (IIIa) and CO2Me (IIIb) takes two routes. The fi rst direction consists in the nucleophilic substitution of the halogen in hydrazonoyl chlorides IIIa, IIIb by thiolate II.

New convenient method for preparation of amides of 1-adamantylthioacetic acids

The reaction of 4-(1-adamantyl)-1,2,3-thiadiazole with potassium tert-butylate followed by treating with acetyl chloride and amine results in the formation of 1-adamantylthioacetic acid amides in moderate or good yields.

New example of Ramberg-Böcklund reaction initiated by Michael addition

Only isolated cases were reported [1–4] on the synthesis of functionalized olefins from α-haloalkyl vinyl sulfones through Ramberg–Bo..cklund reaction initiated by Michael addition. The limitations of this reaction evidently depend both on the structure of the initial substrate and on the nature of the used reagent. For instance, it was established in [5] that the treatment with potassium tert-butylate, a strong base but a weak nucleophile, of α-haloalkyl vinyl sulfones containing an allyl hydrogen atom promoted the so-called vinylogic Ramberg–Bo..cklund reaction leading to the formation of conjugated dienes. For instance, by this procedure nona-1,3diene was obtained in 72% yield proceeding from 1-(bromomethylsulfonyl)oct-1-ene. We showed in [6] that the treatment with the typical Michael reagents, enolates of CH-acids, of bromomethyl β-styryl sulfone led to the cyclization initiated by Michael addition giving tetrahydrothiophene S,S-dioxide derivative. We report here that at treating 1-(bromomethylsulfonyl)cyclohex-1-ene (I) with sodium dimethyl malonate (20°C, 17 h) from the three mentioned possible reaction routes proceeds the one consisting in the Ramberg–Bocklund reaction initiated by Michael addition: The functionalized derivative of methylenecyclohexane II is obtained. Unsaturated sulfone I was obtained in a two-stage process involving the addition of BrCH2SO2Br to cyclohexene (CH2Cl2, 10°C, 24 h, no special initiation was required) and the dehydrobromination of the adduct in a water-dioxane solution of Na2CO3 at heating (50°C, 30 h). SO2CH2Br

Asymmetric synthesis of 6-18F-L-FDOPA using chiral Nickel(II) complexes

A new procedure was suggested for asymmetric synthesis of of 6-[18F]fluoro-3,4-L-dihydroxyphenylalanine (6-18F-L-FDOPA), an important radiotracer for studies of the dopaminergic system by positron emission tomography (PET). The key step of the synthesis is stochiometric asymmetric alkylation of chiral Ni(II) complexes using 3,4-methylenedioxy-6-[18F]fluorobenzyl bromide as alkylating agent. A series of Ni(II) complexes containing various substituents in the benzyl group were tested. The highest enantiomeric purity of 6-18F-L-FDOPA was attained with the complex derived from (S)-N-(2-benzoylphenyl)-1-(3,4-dichlorobenzyl)-pyrrolidine-2-carboxamide, Ni-DCBPB-Gly, under mild alkylation conditions (CH2Cl2, 40°C, potassium tert-butylate as base). Such conditions are favorable from the viewpoint of synthesis automation. The radiochemical yield of 6-18F-L-FDOPA corrected for the radioactive decay was 10–15% at a synthesis time of 120 min, including purification by semipreparative HPLC. The radiochemical and chemical purity of the product exceeded 99%, and the enantiomeric purity was as high as 95%, meeting the requirements for using 6-18F-L-FDOPA in PET practice.

Reaction with alcohols of 1-bromo(chloro)-1,2-epoxyheptafluorobutanes and 1,2-epoxyperfluorobutane. Preparation of α-bromo-, α-chloro-, and α-alkoxyhexafluorobutyric acids esters

1-Bromo(chloro)-1,2-epoxyheptafluorobutanes reacted with primary and secondary alcohols by two concurrent routes giving a mixture of esters of α-alkoxy-and α-bromo(chloro)-hexafluorobutyric acids with growing content of the latter on increasing the bulk of the nucleophilic agent. 1,2-Epoxyperfluorobutane under the same conditions was converted into α-alkoxyhexafluorobutyric acid esters. Reaction of 1-bromo-1,2-epoxyheptafluorobutane and 1,2-epoxyperfluorobutane with potassium tert-butylate in tert-butanol resulted in tert-butyl α-bromohexafluorobutyrate and heptafluorobutyrate respectively due to the forced attack of the bulky nucleophile on the terminal carbon atom of the epoxy ring.

A novel high-spin heterometallic Ni12K4cluster incorporating large Ni–azide circles and an in situ cyanomethylated di-2-pyridyl ketone

Reaction of di-2-pyridyl ketone (dpk) with nickel acetate and azide in the presence of potassium tert-butylate as a catalytic base generates the title compound, which contains the largest [Ni(mu(1,1)-N3)]6 circles in the discrete ferromagnetically-coupled M(II)-azide cluster family, and shows an unprecedented in situ cyanomethylation of ketone.

Facile synthesis of novel nonpeptide angiotensin II receptor antagonists

AbstractA series of Losartan analogues 1‐12 with different functional groups were synthesized and characterized. In comparison with the previous reports, the synthetic procedures described in this paper have been optimized as follows below: 1) preparation of aromatic amine 15 and 18 through hydrogenation by employing Raney Ni and hydrazine as catalysts in place of palladium; 2) preparation of nitro‐compound 17 by using pure fuming nitric acid at ‐20 ‐ ‐15 °C; 3) alkylation of 21 with 22 or 23 in the presence of sodium hydride in place of potassium tert‐butylate; 4) preparation of carboxylic acid 4 by ester cleavage rather than hydrolysis of cyano group.

First syntheses of 2-hydrogeno-2-oxo-1,4,2-oxazaphosphinanes via intramolecular esterification

Synthesis of 2-hydrogeno-2-oxo-1,4,2-oxazaphosphinanes via either intramolecular transesterification, using potassium tert-butylate as catalytic agent, or phosphinic acid esterification, is described for the first time.

Products of Reaction of Tricyclo[4.1.0.02,7]heptane and 1-Bromotricyclo[4.1.0.02,7]heptane with Hydrogen Sulfide, and Syntheses Based Thereon

By reactions of 1-R-tricyclo[4.1.0.02,7]heptanes (R = H, Br) with hydrogen sulfide initiated by UV irradiation endo-6-bicyclo[3.1.1]heptanethiols and bis(endo-6-bicyclo[3.1.1]heptyl) sulfides were synthesized. The sulfides were oxidized to the corresponding sulfoxides and sulfones. The results of HBr elimination from the bromine-substituted sulfoxides and sulfones effected by potassium tert-butylate are discussed. The latter reaction results in the recovery of the system of 1-substituted tricyclo[4.1.0.02,7]heptane.