Stevens Rearrangement of Ammonium Salts Containing 3-Methyl-3-ethoxycarbonylbutanon-2-yl Group

Ammonium salts containing alongside 3-methyl-3-ethoxycarbonylbutanon-2-yl also 2-alkenyl or benzyl groups under the treatment with Na₂CO₃·10H₂O afford products resulting from Stevens rearrangement. In the mentioned salts the ketoester group on treatment with sodium ethylate suspension in ether or benzene suffers partial or total acid cleavage, and then the Stevens 3,2-rearrangement takes place.     

Synthesis of Allyl 2-Dialkylamino-4-pentenoates and Their Analogs via Stevens Rearrangement

Stevens rearrangement of ammonium salts containing an allyloxycarbonylmethyl group in benzene in the presence of sodium phenoxide yields allyl 2-dialkylamino-4-pentenoates. The rearrangement in the presence of sodium methoxide is accompanied by transesterification to afford methyl 2-dialkylamino-4-pentenoates.     

Intramolecular Cyclization of Furfuryl 2-Propynyl Ether

Intramolecular cyclization of furfuryl 2-propynyl ether in the presence of a catalytic amount ofpotassium tert-butoxide in tert-butyl alcohol gives 3a'6-epoxy-1'3-dihydro-6H-isobenzofuran. The cyclizationis presumed to be favored by preliminary isomerization of the 2-propynyl group into allenyl. Heating of thecyclization product with excess potassium tert-butoxide in tert-butyl alcohol results in cleavage of the epoxybridge with formation of 6-hydroxy-1'3-dihydroisobenzofuran.     

Stevens Rearrangement of Anilinium Salts By the Action Sodium Carbonate Hexahydrate

Anilinium salts containing an allyl-like group together with various functionally substituted receiving groups undergo Stevens rearrangement by the action of sodium carbonate hexahydrate in the absence of a solvent. As a result, both N-methylaniline derivatives and nucleophilic substitution products are formed.     

Reactions of 4-halo-2-alken(arylen)ylphosphonium salts with binucleophiles

Phosphonium salts with a 4-bromo-3-chlorobut-2-enyl or a 3-chlorobuta-1,3-dienyl group react with phenylhydrazine to give phenylhydrazones of corresponding 4-phospohonio-substituted 2-chloro-2-butenals. Reactions of phosphonium salts containing a 4-bromo-3-chlorobut-2-enyl group with a series of binucleophiles were studied. Under the action of urea, 1,4-dehydrobromination takes place to form a salt with a conjugated diene group, which undergoes partial 3,4-3,4-cyclization under the reaction conditions. Nucleophilic substitution reactions of [o-(bromomethyl)benzyl]triphenylphosphonium bromide with binucleophiles were also carried out.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 1992–1997.Original Russian Text Copyright © 2004 by Ovakimyan, Barsegyan, Pogosyan, Kikoyan, Panosyan, Indzhikyan.This revised version was published online in April 2005 with a corrected cover date.     

The Synthesis and Reactions of 1-(2-Propynyl)pyidinium Salts

The synthesis of 1-(2-propynyl)pyridinium salts 3 described. Compounds 3 react with a second pyridine molecule, in the presence of the corresponding hydrochloride, to form products of type 4, Certain bases cause the 1-(2-propynyl)pyridinium salts 3 to rearrange into 1-propadienylpyridinium salts. 5 . Diethylamine converts compounds 3 into 1-acetonylpyridinium salts 8 . Moreover, treatment of 3 or 5 with sodium methoxide gives enol ether sof type 9, which can be hydrolyzed to teh ketones 8 . Addition of bromine to some of teh unsaturated compounds is also reported.     

Rearrangement-Cleavage of Ammonium Salts Containing a 3-Methyl-2-naphthylmethyl Group

The example of the rearrangement-cleavage under the action of 25% aqueous potassium hydroxide at 90-92°C of ammonium salts containing both 3-methyl-2-naphthylmethyl and 2-bromoethyl, allyl, methallyl, 2-bromoallyl, 3-phenylallyl, 2-propynyl, or 3-phenylphenyl-2-propynyl groups was used to show that the reaction always involves the aromatic ring of the 3-methyl-2-naphthylmethyl group. Along with rearrangement-cleavage, nucleophilic substitution of the 2-naphthylmethyl group takes place.     

On the Mechanism of Intramolecular Cyclization of Dialkyl(2-propynyl)[3-alkenyl(or aryl)-2-propynyl]-ammonium Salts

Given are experimental data indicating that base-catalyzed intramolecular cyclization of ammonium salts containing a 2-propynyl-like group together with a 3-alkenyl- or 3-aryl-2-propynyl group follows a concerted mechanism involving the 3-alkenyl- or 3-aryl-2-propynyl moiety as π⁴-fragment.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 369–371.Original Russian Text Copyright © 2005 by E. Chukhadzhyan, Gevorkyan, El. Chukhadzhyan, Kinoyan.     

Production of Biodiesel Fuel by Transesterification of Triglycerides in the Presence of Sodium Pyrophosphate

The possibility of using anhydrous sodium pyrophosphate and its decahydrate in transesterification of triacyl glycerides (with sunflower and rapeseed oils as examples) with methanol to obtain biodiesel fuel was examined. As shown by gas-chromatographic analysis, at the vegetable oil to methanol ratio of 1: 12, temperature of 65°C, reaction time of 2 h, and catalyst concentration of no less than 6 wt %, the maximal yield of methyl esters of fatty acids (biodiesel) was 93 and 69% when using Na₄P₂O₇ and Na₄P₂O₇·10H₂O, respectively. The catalytic effect of sodium pyrophosphate in the transesterification of triacyl glycerides was attributed to its methanolysis with the formation of sodium methylate. Water present in sodium pyrophosphate decahydrate causes hydrolysis of the formed sodium methylate; therefore, the yield of methyl esters of fatty acids is lower than with anhydrous pyrophosphate. Anhydrous sodium pyrophosphate can be used repeatedly no less than five times without significant decrease in the yield of methyl esters of fatty acids. Sodium pyrophosphate can be recommended for use in transesterification with other esters and alcohols.

     

Synthesis of polystyrene–poly(tert‐butyl methacrylate)–poly(ethylene oxide) triarm star block copolymers

Three alternative routes, using the heterobifunctional macroinitiator technique, have been developed to obtain polystyrene–poly(tert‐butyl methacrylate)–poly(ethylene oxide) triarm star block copolymers. Only the route showing the reverse initiation of tert‐butyl methacrylate on potassium alkoxide leads to the pure star, whereas the other strategies lead to incomplete initiation because of either an increase in the side reactions, such as transesterification, or a decrease in the accessibility toward bulky catalysts. These limits are linked to the particular location of the initiating group at the junction of the two blocks of the copolymer precursor. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1745–1751, 2004     

1,2,3‐ and 1,2,4‐triazolium salts,pyrazoles, and quinoxalines from diarylnitrilimines and isocyanides: A study of the scope

Formation of the four title compounds has been found to be strongly dependent on substituents: 1,2,3‐Triazolium salts 6 do not arise from nitrilimines 2 that have an electron‐acceptor attached to either the C‐ or the N‐phenyl group. Likewise tert‐butyl and aryl isocyanides do not afford this class of compounds; from the former isocyanide, dequaternization products 7 are obtained instead, whereas from the latter 1,2,4‐triazolium salts 11 are formed. Compounds 11 with tert‐butyl group at the ring are unstable too, giving rise to triazoles 13 . Pyrazole formation (analogues of 14 ) is completely suppressed when both tert‐butyl and aryl isocyanides are used, whereas access to this ring system works best with see‐alkyl isocyanides (the influence of substituents of 2 being almost negligible in this case). Formation of quinoxalines 23 which arise from intermediary 1,2‐diazets 22 by ring expansion is much favoured on employment of 2 that bears a donator substituent at the N‐phenyl group, and under this premise ring closure to 22 is virtually independent on the nature of the isocyanide. Formation of 23 is not observed with 2 having acceptor groups.     

Trisubstituted 1,3,5-Triazines. 6. Synthesis of 2,4,6-Tris(acetonyl)-1,3,5-triazine

Acylation of 2,4,6-tris(tert-butoxycarbonylmethyl)-1,3,5-triazine with acetic anhydride in the presence of lithium hydride with subsequent removal of the tert-butoxycarbonyl groups with trifluoroacetic acid leads to 2,4,6-tris(acetonyl)-1,3,5-triazine, the cyclic analog of -cyanoacetone. The special spectral features of this compound compared with triazines obtained previously are discussed.     

Acetylenchemie 12. Mitt.: Weitere studien über die phasentransfer-katalysierte umsetzung des 9(10H)-acridinons mil alkinylhalogeniden

By the phase transfer catalyzed reaction of 9(10H)-acridinone with 1-bromo-2-propyne, 10-(2-propynyl)-9(10H)-acridinone is synthesized. As prototropic rearrangement products of this 10-(1,2-propadienyl)-9(10H)-acridinone and 10-(1-propynyl)-9(10H)-acridinone are obtained, Under the given conditins 1-bromo-2butyne leads to 10-(2-butynyl)-9(10H)-acridinone and 2-chloro-3-butyne leads to 10-(1-methyl-1,2-propddienyl)-9(10H)-acridinone, 10-(1-methyl-2-propynyl)-9(10H)-acridinone, 9-(1-methyl-2-propynyloxy)acridine and 10-[1-methyl-3-(3,4-dimethylphenyl-2-propynyl)]-9(10H)-acridinone. The formation of the products is experimentally confirmed and with published work compared.     

Alkylation of cyclic mannich bases,derivatives of thiourea and simple amino acids

Aminomethylation of thiourea with aqueous formaldehyde and simple amino acids (glycine, β-alanine, γ-aminobutyric acid) have resulted in the formation of (4-thioxo-1,3,5-triazinan-1-yl)-substituted acetic, propionic, and butyric acids, respectively. By alkylation of these compounds corresponding S-methyl and S-ethyl iodides were obtained, and by the action of tert-butylamine, the corresponding salts. The same salts were obtained by the reaction of amine exchange between 5-tert-butyl-1,3,5-triazinan-2-thione and these amino acids in water. As a result of neutralization of S-methyl iodides with tert-butylamine in 2-propanol or aqueous 2-propanol zwitterionic [4-(methyl-sulfanyl)-3,6-dihydro-1,3,5-triazin-1(2H)-yl] derivatives of these acids were isolated. From aqueous solutions of S-methyl iodides and tert-butylamine ion associates of the corresponding zwitter-ions and tert-butylammonium iodide have crystallized. The same associates have formed at treating S-methyl iodides with tert-butylamine or diethylamine in the absence of a solvent.     

Syntheses of polymerizable hydroquinone derivatives

Several polymerizable hydroquinone derivatives were prepared by the Williamson synthesis. Thus, hydroquinone mono(p-vinylbenzyl) ether (III-1), hydroquinone methyl p-vinylbenzyl ether (III-4), and hydroquinone benzyl p-vinylbenzyl ether (III-5), tert-butylhydroquinone mono(p-vinylbenzyl) ether (III-2), and 2,5-di-tert-butylhydroquinone mono(p-vinylbenzyl) ether (III-3) were synthesized by the reactions of p-chloromethylstyrene with the corresponding hydroquinone derivatives in alcoholic potassium hydroxide or with their potassium salts in dipolar aprotic solvents. All monomers were found to polymerize by free-radical initiation except III-3, which required a cationic initiator.     

Preparation of two triflate precursors for <Emphasis Type="Italic">O</Emphasis>-(2-[<Superscript>18</Superscript>F] fluoroethyl)-<Emphasis Type="Italic">L</Emphasis>-tyrosine used in positron emission tomography (PET)

Two novel triflate precursors for radiolabelling of L-tyrosine in positron emission tomography (PET) for tumor imaging, O-(2-trifluoromethanesulfonyloxyethyl)-N-(tert-butoxycarbonyl)-L-tyrosine methyl ester 9a and O-(2-trifluoromethanesulfonyloxyethyl)-N-(tert-butoxycarbonyl)-L-tyrosine tert-butyl ester 9b, are synthesized. The triflate agent, 9a or 9b, is prepared by esterification of methanol or transesterification of tert-butyl acetate with L-tyrosine, protection of the amine group with di-tert-butyl dicarbonate, alkylation with chlorohydrin, and triflation with trifluoromethanesulfonic anhydride in four steps with overall yields of 30% and 15%, respectively.     

Prototropic Rearrangement of 2-Propynyl(methyl)amino, 2-Propynyloxy,and 2-Propynylsulfanyl Derivatives of Hetarenes under Conditions of Phase-Transfer Catalysis: Mechanism and Limitations

2-Propynyl derivatives of N-methylaniline, phenol, benzenethiol, 2-pyridinethiol, 2-pyrimidinethiol, and 1,3-benzoxazole-2-thiol were synthesized. Under conditions of phase-transfer catalysis, phenyl 2-propynyl sulfide is converted into allenyl phenyl sulfide and phenyl 1-propynyl sulfide. The rearrangement mechanism was studied by the AM1 quantum-chemical method.     

Prostanoids: XC. Extension to the Synthesis of Enprostil of the <Emphasis Type="Italic">o</Emphasis>-Nitrophenylsulfonylhydrazine Method for Transformation of 2-Propynyl Alcohols into Allenes

A potential precursor of enprostil, (±)-9-acetoxy-11,15-di-O-(tert-butyldimethylsilyl)-2-decarboxy-6-hydroxy-16-phenoxy-2-triphenylmethyloxymethyl-4,4,5,5-tetradehydro-17,18,19,20-tetranorprostaglandin F1α, was synthesized. This compound remained unchanged under the conditions for generation of allenes from 2-propynyl alcohols by the action of the system diisopropyl azodicarboxylate-triphenylphosphine-o-nitrophenylsulfonylhydrazine.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 7, 2005, pp. 988–994.Original Russian Text Copyright © 2005 by Vostrikov, Vasikov, Miftakhov.     

Study on 1,3,5‐Triazine Chemistry in Dehydrocondensation: Gauche Effect on the Generation of Active Triazinylammonium Species

The reaction of 2‐chloro‐4,6‐dimethoxy‐1,3,5‐triazine (CDMT) with various nitrogen‐containing compounds, particularly tertiary amines (tert‐amines), has been studied for the preparation of 2‐(4,6‐dimethoxy‐1,3,5‐triazinyl)trialkylammonium salts [DMT‐Am(s)]. DMT‐Ams derived from aliphatic tert‐amines exhibited activity for the dehydrocondensation between a carboxylic acid and an amine to form an amide in a model reaction. Based on a conformational analysis of DMT‐Ams and tert‐amines by NMR and X‐ray diffraction methods, we concluded that a β‐alkyl group maintained in a gauche relationship with the nitrogen lone pair of tert‐amines significantly hinders the approach of CDMT to the nitrogen. Thus, trimethylamine and quinuclidine without such alkyl groups readily react with CDMT whereas triethylamine, possessing two or three such gauche β‐alkyl groups in the stable conformations, does not react at all. The theory of “gauche β‐alkyl group effect” proposed here provides useful guidelines for the preparation of DMT‐Ams possessing various tertiary amine moieties. An investigation of the dehydrocondensation activity of tert‐amines in a CDMT/tert‐amine system that involves in situ generation of DMT‐Am, showed that the gauche effect of the β‐alkyl group becomes quite pronounced; the yield of the amide decreases significantly with tert‐amines possessing an unavoidable gauche β‐alkyl group. Thus, the tert‐amine/CDMT systems are useful for judging whether tert‐amines can readily react with CDMT without isolation of DMT‐Ams.     

The Synthesis of (3,5-DI-tert-butyl-4-hydroxyphenyl)methyl-(3-pyridylalkyl)-ethers via 1-(3,5-Di-tert-butyl-4-hydroxyphenyl)methyl Pyridinium Salts.

The rearrangement of 1-(3,5-di-tert-butyl-4-hydroxyphenyl)methyl pyridinium salts under basic conditions is described. A method for the synthesis of (3,5-di-tert-butyl-4-hydroxyphenyl)methyl-(3-pyridylalkyl)-ethers is elaborated.