Synthesis of stereoisomeric 1,3-dimethyl- and 1,2,5-trimethyl-4-acyl(benzoyl)-4-piperidinols

In order to synthesize stereoisometric 4-acyl(benzoyl)-1, 3-dimethyl and-1, 2, 5-trimethyl-4-piperidinols, the reaction of the geometrical isomers of 4-cyano-1, 3-dimethyl- and -1, 2, 5-trimethyl-4-piperidinols and the amines and imidic esters corresponding to them with some alkyl- and arylmagnesium halides, leading to the corresponding isomeric piperidinic α-ketols, has been studied. The dependence of the reactivity of the geometrical isomers of the compounds studied on the spatial orientation of their functional groups has been shown.     

Cyanoethylation of some n-substituted 2,5-dimethyl-4-piperidones

1,2,5-Trimetnyl- and 1-(-chlorocrotyl)-2,5-dimethyl-5-(-cyanoethyl)-4-piperidones were synthesized and separated into individual isomers. The corresponding isomeric 5-(-carboxyethyl)-4-piperidones were obtained by hydrolysis. The isomeric 1,2,5-trimethyl-3,5-bis(-cyanoethyl)- and 1,2,5-trimethyl-3,3,5-tris(-cyanoethyl)-4-piperidones were synthesized by subsequent cyanoethylation of the individual 1,2,5-trimethyl-5-(-cyanoethyl)-4-piperidone isomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 479–481, April, 1971.     

Esters of (1,2, 5-trimethyl-4-hydroxy-4-piperedyl)- and phenyl-(1,2, 5-trimethyl-4-hydroxy-4-piperidyl) acetic acids

The methyl ester of a new hydroxy acid of the piperidine series (-phenyl--(1,2, 5-trimethyl-4-hydroxy 4-piperidyl)acetic acid) has been prepared. Ethyl -(1,2, 5-trimethyl-4-hydroxy-4-piperidyl)acetate has been converted into the substituted pyridine, 1,1-diphenyl-2-(2-5-dimethyl-4-pyridyl)ethylene.     

Stereoselective additions to the exocyclic CC bond of some α-alkylidene-(+)-camphor derivatives

Stereoselective additions to the exocyclic CC double bond of some (1R,3E,4S)-3-alkylidene-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones and (1R,4E,5S)-4-alkylidene-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones were studied. All additions took place predominantly from the less hindered endo-face of the methylidene compounds to give the corresponding exo-adducts as the major isomers. Thus, catalytic hydrogenations afforded the α-alkylated (1R,3R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones and (1R,4R,5R)-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones in 28–100% de. Similarly, 1,3-dipolar cycloadditions of 2,4,6-trisubstituted benzonitrile oxides gave the corresponding spiro cycloadducts in 66–100% de. The structures were determined by 2D NMR techniques, NOESY spectroscopy and X–ray diffraction.     

Condensation of 1,2,5-trimethyl-4-piperidone with ethyl- and naphthylacetylenes and synthesis of substituted pyridines

The Favorskii reaction with 1,2,5-trimethyl-4-piperidone and ethyl- and naphthylacetylenes gave the corresponding piperidols, the hydrogenation of which gave 1,2,5-trimethyl-4-nbutyl(or 2-naphthylethyl)-4-piperidols. 4-Phenyl- and 4-butyl-2,5-dimethylpyridine were condensed with formaldehyde, and some of the transformations of the resulting-hydroxyethyl derivatives were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 349–352, March, 1973.     

1,4-bis(4′-hydroxy-1′,2′,5′-trimethyl-4-piperidyl)-1,3-butadiyne and its derivatives

1.4-Bis(4-hydroxy-1,2,5-trimethyl-4-piperidyl)-1.3-butadiyne has been synthesized from the individual isomers of 4-ethynyl-1,2,5-trimethyl-4-piperidol. Hydrogenation, bromination, and cleavage have given, respectively, 1,4-bis(4-hydroxy-1,2,5-trimethyl-4-piperidyl)butane, 1,4-bis(4-nydroxy-1,2,5-trimethyl-4-piperidyl)-1,2,3,4-tetrabromo-1, 3-butadiene, and 4-(1,3-butadiynyl)-1,2,5-trimethyl-4-piperidol.     

N-substituted 2, 5-dimethyl-4-ethynyl(vinyl)piperid-4-ols

They -isomers of 1-(3-chlorobuten-2-yl)- and 1-benzyl-2,5-dimethyl-4-ethynylpiperid-4-ols (I, II) and of 1-(3-chlorobuten-2-yl)-2,5-diemethyl-4-vinylpiperid-4-ol (III) and the quaternary salts of compounds I–III and of the -isomers of the 1,2,5-trimethyl-4-ethynyl-(vinyl)piperid-4-ols [1] have been synthesized.     

Peculiarities of the three-dimensional structures of isomers of 1,2,5-trimethyl-4-amino(amido)piperidines from the 1H and 13C NMR spectra

The three-dimensional structures of seven 1,2,5-trimethyl-4-amino(amido)piperidines were studied by means of the ¹H and ¹³C NMR spectra. The ³J_HH values and the ¹³C chemical shifts indicate that the substituents in the piperidine ring of all of the 2c,5c,4r isomers have a 2e,4e,5a orientation, while those in the piperidine ring of all of the 2c,5t,4r isomers have a 2e,4e,5e orientation. The conformational change (as a result of ring conversion) 2e,4a,5e 2a,4e,5a was observed for the 2t,5c,4r isomers on passing from the corresponding amine to the amide; this change is associated with striving of the more bulky amide substituent to become equatorially oriented. Retarded rotation about the C₍₄₎-N bond was observed in the 2c,5t,4r isomer of the 4-(N-phenylbenzamido) derivative; this is explained by steric hindrance due to the 5e-CH₃ group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 54–57, January, 1988.The authors thank I. I. Chervin for assistance in recording the NMR spectra with a WM-400 spectrometer.     

Synthesis and three-dimensional structures of geometrical isomers of some 4-substitute d 1,2,5-trimethyl-4-acetoxy- and 1,2,5-trimethyl-4-benzoxypiperidines

Stereoisomers of the corresponding 4-substituted 1,2,5-trimethyl-4-acetoxy- and 1,2,5-trimethyl-4-benzoxypiperidines were obtained by acylation of the geometrical isomers of 1,2, 5-trimethyl-4-piperidol and its 4-ethynyl, 4-ethyl, and 4-phenyl-substituted derivatives. The preferred conformations of the investigated esters were elucidated by means of the PMR and IR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.1, pp. 50–55, January, 1973.     

Hydrogenation of theΒ and γ isomers of 1,4-bis(4′-hydroxy-1′,2′, 5′-trimethyl-4′-piperidyl)-1,3-butadiyne

The kinetics of the hydrogenation of the and isomers of 1,4-bis(4-hydroxy-1, 2, 5-trimethyl-4-piperidyl)-1, 3-butadiyne in methanol and ethanol on the catalysts Raney nickel, platinized carbon, and palladium on supports has been studied. It has been shown that the rates of hydrogenation of the and isomers differ on all the catalysts. In the presence of platinum and nickel, hydrogenation takes place as far as the saturated compound, and in the presence of palladium to the diene.     

Reaction ofβ,β -dimethyldivinyl ketone with 2,5-dimethyl- and 1,2,5-trimethyl-4-piperidones

1-(3-Oxo-5-methyl-4-hexen-1-yl)-2,5-dimethyl-4-piperidone, 5-(3-oxo-5-methyl-4-hexen-1-yl)-2, 5-dimethyl-4-piperidone, and 5-(3-oxo-5-methyl-4-hexen-1-yl)-1,2,5-trimethyl-4-piperidone were synthesized. In the absence of a catalyst,-dimethyldivinyl ketone adds to 2,5-dimethyl-4-piperidone at the 1-position, while in the presence of alkali it adds at the 5-position.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 350–351, March, 1971.     

Synthesis of 4-hydroxy-1,2,5-trimethyl-4-piperidyl carbinols

Spatial directivity of reactions of the geometrical isomers of 4-acetyl-, 4-propionyl-, and 4-benzoyl-1,2,5-trimethyl-4-piperidols with Grignard reagents and lithium aluminum hydride has been studied. Stereospecific synthesis of some stereoisomeric 4-hydroxy-1,2,5-trimethyl-4-piperidyl carbinols has been effected and their probable spatial configurations have been discussed.     

Reaction of Zinc Enolates of Alkyl Esters of Substituted 4-Bromo-3-Oxoalkanoic Acids with Aldehydes

Zinc enolates formed from ethyl 4-bromo-2,2,4-trimethyl-3-oxopentanoate react under the conditions of one- of two-stage synthesis with aliphatic, unsaturated, or aromatic aldehydes to form 6-R-2,2,4,4-tetramethyl-2,3,5,6-tetrahydropyran-2,4-diones. Zinc enolates obtained from ethyl 4-bromo-2,2-dimethyl-3-oxopentanoate, -hexanoate, and -2,2,5-trimethyl-3-oxohexanoate under the similar conditions react with aliphatic or aromatic aldehydes to give mainly 5-R¹-6-R²-3,3-dimethyl-2,3,5,6-tetrahydropyran-2,4-diones as E or Z isomers or their mixtures. Zinc enolates generated from the ethyl 4-bromo-2,2-diethyl- or 2-benzyl-2-ethyl-3-oxobutanoates react with aromatic aldehydes to give ethyl 5-R-2-R-2-ethyl-3-oxo-4-pentenoates as E isomers.     

Reaction of dimedone with aldehydes and β-aminovinyl carbonyl compounds

The unsymmetrical condensation of dimedone, an aldehyde, and various -aminovinyl carbonyl compounds, and also bisacetonitrile, has given 3, 4-disubstituted derivatives of 2, 7, 7-trimethyl-5-oxo-1, 4, 5, 6, 7, 8-hexahydroquinoline (Va-f). Compounds Va, d, f have been oxidized with H₂CrO₄ to the corresponding 3, 4-disubstituted 2, 7, 7-trimethyl-5-oxo-5, 6, 7, 8-tetrahydroquinolines (VIa-c). The IR spectra of compounds Va-c, f and VIa and the UV spectra of compounds Va, c, f, and VIa, c have been recorded.     

1H and 13C NMR spectra and three-dimensional structures of 1,2,5-trimethyl-4-phenylaminopiperidine isomers

The three-dimensional structures of two isomers of 1,2,5-trimethyl-4-phenylaminopiperidine were established on the basis of an analysis of their ¹H and ¹³C NMR spectra. The piperidine ring has a chair conformation in both isomers. The isomer has the 1,2e,5a, trimethyl-4e-phenylaminopiperidine structure, while the isomer has the 1,2e,5e-trimethyl-4e-phenylaminopiperidine structure.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1512–1515, November, 1982.     

Cyanoethylation of 2,5-dimethyltetrahydro-4-thiopyranone isomers and selective reduction of 2,5-dimethyl-5-(β-cyanoethyl)tetrahydro-4-thiopyranone and — 4-pi pe ridone

It has been found that only the cis isomer (liquid) of 2,5-dimethyltetrahydro-4-thiopyranone is cyanoethylated under the usual conditions. 2,5-Dimethyl-5-(-carboxyethyl)tetrahydro-4-thiopyranone was synthesized by the acid hydrolysis of 2,5-dimethyl-5-(-cyanoethyl)-tetrahydro-4-thiopyranone. The selective reduction with aluminum isopropoxide of 2,5-dimethyl-5-(-eyanoethyl) tetrahydro-4-thiopyranone and of the individual isomers of 2,5-dimethyl-5-(-cyanoethyl)-4-piperidone gave the isomeric 2,5-dimethyl-5-(-cyanoethyl)-tetrahydro-4-thiopyranols and -4-piperidols. The reaction of the isomeric 5-cyanoethyl-4-piperidols with allyl bromide gave the corresponding 1-allyl-2,5-dimethyl-5(-cyanoethyl)-4-piperidols.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 12–14, January, 1972.     

An Ab initio theoretical investigation on the geometrical and electronic structures of BAun−/0 (n = 1–4) clusters

An ab initio theoretical investigation on the geometrical and electronic structures and photoelectron spectroscopies (PES) of BAu_n^?/0 (n = 1–4) auroboranes has been performed in this work. Density functional theory and coupled cluster method (CCSD(T)) calculations indicate that BAu (n = 1–4) clusters with n‐Au terminals possess similar geometrical structures and bonding patterns with the corresponding boron hydrides BH. The PES spectra of BAu (n = 1–4) anions have been simulated computationally to facilitate their future experimental characterizations. In this series, the T_d BAu anion appears to be unique and particularly interesting: it possesses a perfect tetrahedral geometry and has the highest vertical electron detachment energy (VDE = 3.69 eV), largest HOMO‐LUMO gap (ΔE_gap = 3.0 eV), and the highest first excitation energy (E_ex = 2.18 eV). The possibility to use the tetrahedral BAu unit as the building block of Li⁺[BAu₄]^? ion‐pair and other [BAu₄]^?‐containing inorganic solids is discussed. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

1H and 13C NMR spectra,isomers, and imine-enamine tautomers of N-(1,2,5-trimethyl-4-piperidylidene)aniline

The product of condensing 1,2,5-trimethylpiperidin-4-one with aniline has been investigated by NMR spectroscopy. Three isomers of N-(1,2,5-trimethyl-4-piperidylidene)aniline have been identified differing in the configuration of the methyl groups at C₂ and C₅ of the piperidine ring and the Z,E isomerism about the C=N bond. Traces of the enamine tautomeric form of the imine were also detected. , , and spin-spin couplings were used to determine the structural configuration of the isomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1405–1408, October, 1989.     

Synthesis and three-dimensional structure of the benzoates and p-nitrobenzoates of the geometrical isomers of substituted 4-hydroxypiperidines

The corresponding stereoisomeric p-nitrobenzoates were obtained by reaction of the geometrical isomers of 1,3-dimethyl-, 1,2,5-trimethyl-, and 1-tert-butyl-3-methyl-4-hydroxypiperidines with p-nitrobenzoyl chloride. The stereoisomers of the corresponding benzoates were also synthesized from the geometrical isomers of 1,3-dimethyl-4-hydroxypiperidines. The primary conformations of the investigated compounds in solution were established by means of their PMR spectra.     

New stereoselective syntheses of cis- and trans-2-methyl-4-arylpiperidines

A stereoselective approach has been developed for the synthesis of cis- and trans-2-methyl-4-arylpiperidines from a common intermediate. The Ni-catalyzed hydrogenolysis of N-Boc-2-methyl-4-aryl-4-piperidinols, obtained by addition of organometallic reagents on N-Boc-2-methyl-4-piperidone, afforded the trans derivatives with up to 95% selectivity whereas the corresponding cis isomers were obtained in the presence of palladium catalysts.