Synthesis of Derivatives of ω-Isocyanato-α-methylamino, ω-Ureido-α-methylamino,and N<Superscript>α</Superscript>-Methyl-α, ω-diamino Acids

Summary.  Homochiral N^α-methyl-2,3-diaminopropionic and N^α-methyl-2,4-diaminobutyric acid derivatives 8a,b were obtained via a stereoconservative four-step synthesis starting from hexafluoroacetone protected L-aspartic and L-glutamic acid 2a,b, respectively. Hexafluoroacetone protected ω-isocyanato-α-methylamino acids 4a,b– the key intermediates of the synthesis – are versatile building blocks for amino acid and peptide modification and promising candidates for combinatorial chemistry. Upon reaction with alcohols, compounds 4 give activated N ^ω-urethane protected ω-amino-α-methylamino acid derivatives 5–7; upon reaction with amines, ω-ureido-α-methylamino acid derivatives 10–12 and 3-methylamino-pyrrolidin-2-ones 13 are available. Received November 17, 1999. Accepted November 26, 1999     

Reductive activation of arenes 22. Reactions of the terephthalonitrile radical anion and dianion with α,ω-dibromoalkanes. New evidence for the charge transfer complex as a key intermediate in the reactions of the dianion

The major products of reactions of the terephthalonitrile radical anion with α,ω-dibromoalkanes Br(CH₂)_nBr (n = 3–5) were 4-(ω-bromoalkyl)benzonitriles. Analogous reactions of the terephthalonitrile dianion mainly yielded α,ω-bis(4-cyanophenyl)alkanes. Both transformations are convenient one-step routes to otherwise not easily accessible compounds that are valuable as versatile building blocks. The results of alkylation allow one to suggest that reactions of the dianion with intermediate 4-(ω-bromoalkyl)benzonitriles proceed more rapidly than those with the starting α,ω-dibromoalkanes. This was confirmed by competitive reactions of the dianion with 4-(ω-bromoalkyl)benzonitriles and the corresponding alkyl bromides. To explain such a ratio of the reaction rates, a mechanism was proposed for the reaction of the dianion with 4-(ω-bromoalkyl)benzonitriles. According to this mechanism, a charge transfer complex is a key reaction intermediate. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1069–1077, June, 2007.     

Synthesis of α,ω-dihalopermethyloligosilanes and silane-siloxane copolymers

α,ω-Dibromopermethyloligosilanes, Br(SiMe₂) _n Br (n=2–4, 6), were prepared by the reaction of dodecamethylcyclohexasilane with bromine. The reaction of (Me₂Si)₆ with MCl₄ (M=Sn, Ti) proceeds with the cleavage of Si−Si- and Si−C-bonds with the formation of α,ω-dichloropermethyloligosilanes, Cl(SiMe₂) _n Cl (n=2–4, 6), and chloro derivatives of cyclohexasilane, Cl _m Si₆Me_12−m (m=1, 2). Silane-siloxane copolymers of regular structure were obtained by heterofunctional copolycondensation of α,ω-dihalopermethyloligosilanes with 1,5-dihydroxyhexamethyltrisiloxane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1513–1517, August, 1997.     

Synthesis of new cyclolinear permethyloligosilane-siloxanes

α,ω-Bis(heptamethylcyclotetrasiloxanyloxy)oligodimethylsilanes were synthesized for the first time by heterofunctional condensation of hydroxyheptamethylcyclotetrasiloxane with α,ω-dichloropermethyloligosilanes, Cl(Me₂Si) _n Cl (n=2, 4, or 6). The compounds obtained were characterized by spectroscopic methods. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 544–545, March, 1998.     

Effect of the temperature on the composition and ratio of hydrolysis products of 1,2-dichlorotetramethyldisilane

The hydrolysis of 1,2-dichlorotetramethyldisilane was studied at different temperatures. At reduced temperatures, the hydrolysis gave permethylcyclo(oxadisilanes) [(Me₂Si)₂O]_n (n = 2 and 3) and α,ω-dihydroxypermethyloligo(oxadisilanes) HO[(SiMe₂)₂O]_mH (m = 1–5). The formation of the latter was proved by the GC-MS method. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 722–724, April, 2006.     

Two-fragment α-adrenolytics

Dialkyl β-(2-aroxyethylamino)ethylphosphonates,N-[β-(2-methoxyphenoxy)ethyl]-N′-[β-(diethoxyphosphoryl)ethyl]-α,ω-diaminoalkanes, and diethyl β-(N-arylpiperazino)ethyl-phosphonates were synthesized by the reactions of dialkyl vinylphosphonates with β-aroxyethylamines,N-[β-(2-methoxyphenoxy)ethyl]-α,ω-diaminoalkanes, andN-aryl-piperazines, respectively. The compounds synthesized exhibit hypotensive and α-adrenolytic activities. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 987–991, May 1999.     

Reformatsky-type addition of esters of α-halogeno carboxylic acids to aldehydes and ketones in the presence of Fe(CO)5

Reformatsky-type addition of esters of α-halogeno carboxylic acids to aldehydes and ketones in the presence of Fe(CO)₅ and an activating agent (CBrCl₃ or I₂) afforded the corresponding esters of β-hydroxy acids in good yields. Possible reaction mechanisms are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1132–1138, June, 1999.     

New transformation of cycloalkanone acetals by peracids α,ω-dicarboxylic acids synthesis

A new process of oxidation of cycloalkanone acetals under the action of in situ generated performic acid has been found. The main products of the reaction are α, ω-dicarboxylic acids obtained with the yield up to 77% depending on the size of acetals ring. The process has been explored and optimized on the example of the dodecanedioic acid synthesis (a valuable industrial product).     

Reaction of N-Acyl-α-triphenylphosphonio-α-amino Acid Esters with Organic Bases: Mechanism of the Base-Catalyzed Nucleophilic Substitution of the Triphenylphosphonium Group

Summary.  Reactions of N-acyl-α-triphenylphosphonio-α-amino acid methyl esters with organic bases (triethylamine or DBU) were investigated as the crucial step of the base-catalyzed displacement of the triphenylphosphonium group by nucleophiles. It was proved that N-acyl-α-triphenylphosphonioglycinates are transformed to an equilibrium mixture of the corresponding N-acyliminoacetates and N-acyl-α-triphenylphosphoranylidene glycinates by bases. In the case of N-acyl-α-triphenylphosphonio-α-amino acid esters with quaternary α-carbon, the α-substituted homologues of the N-acyliminoacetates were detected to be the only primary reaction product which, however, can undergo further tautomerization to the corresponding α,β-dehydro-α-amino acid derivatives. In both these cases the reaction of N-acyl-α-triphenylphosphonio-α-amino acid esters with nucleophiles proceeds via the addition of a nucleophile to the activated C=N double bond of the N-acylimino intermediate. Corresponding author. E-mail: romanm@zeus.polsl.gliwice.pl Received October 31, 2001. Accepted (revised) December 17, 2001     

Applications of HPLC with evaporative light scattering detection in fat and carbohydrate chemistry

Summary The advantages of an evaporative light scattering detector in HPLC are demonstrated using the separation of α, ω-dicarboxylic and hydroxycarboxylic acids, alkyl glucosides and mono-, di- and triglycerides as examples. By using this detector reversed phase as well as normal phase gradient HPLC becomes possible for substances with no UV absorption. Presented at the 17th International Symposium on Chromatography, September 25–30, 1988, Vienna, Austria.     

Polynuclear branched tetrazole systems. 3. Acidity of α,ω-ditetrazol-5-ylalkanes

α,ω-Ditetrazol-5-ylalkanes with 1 to 5 methylene groups in the alkyl fragment display the properties of dibasic heterocyclic NH acids with pK_a values lying in the range 3.4–6.1. The pK_a values of these compounds are in a linear dependence on the values of the dielectric permeability of the medium, on the chemical shifts of the signals of the endocyclic carbon atom, and of the carbon atom of the α-methylene group in the ¹³C NMR spectra. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 535–541, April. 2006.     

Complexes of αω-bis(3,3-dialkyldiaziridin-1-yl)alkanes and their bis(2-arylcarbamoyl) derivatives with cadmium and nickel salts

Complexes of αω-bis(3,3-dialkyldiaziridin-1-yl)alkanes and their bis(2-arylcarbamoyl) derivatives with Cd²⁺ and Ni²⁺ salts were synthesized. The X-ray diffraction study showed that only one molecule of the starting bis-diaziridine is involved in the complexation. The Cd²⁺ complexes have octahedral geometry. The Ni²⁺ complexes are either square-planar or octahedral. One of the octahedral Ni²⁺ complexes crystallizes in the chiral space group P2₁. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 53–59, January, 2008.     

Synthesis and electrochemistry of (5Z,5′Z)-2,2′-(alkane-α,ω-diyldisulfanyldiyl)-bis(5-(2-pyridylmethylene)-3,5-dihydro-4H-imidazol-4-one) complexes with cobalt(II ) chloride

A series of S-alkylated 2-thiohydantoin derivatives containing two 5-(2-pyridylmethylene)-2-sulfanyl-3,5-dihydro-4H-imidazol-4-one moieties linked through a polymethylene bridge with different numbers of carbon atoms was synthesized for the first time. These compounds were obtained by the alkylation of 3-phenyl-5-(2-pyridylmethylene)-2-thiohydantoin or 3-methyl-5-(2-pyridylmethylene)-2-thiohydantoin with different α,ω-dibromoalkanes in acetone or DMF in the presence of potassium carbonate. Complexes of these compounds (L) with CoCl₂ were synthesized. In all cases, the complexes L(CoCl₂)₂ were formed regardless of the ratio of L and inorganic salt introduced into the reaction. According to electronic spectroscopic data, the cobalt atom in the complexes has a tetrahedral coordination environment. The synthesized ligands and complexes were electrochemically studied by cyclic voltammetry. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Deceased. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2099–2104, September, 2005.     

Homolytic addition of dithiols to alkynes: A new approach to the construction of dithiacyclanes and crown thioethers

A novel general approach to the construction of sulfur-containing heterocyclic compounds and crown thioethers based on one-pot “assembling” of their molecules from α,ω-dithiols and alkynesvia homolytic cycloaddition has been developed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1256–1267, July, 1997.     

Spiro[4H-chromene-4,5′-isoxazolines] and related compounds: Synthesis and reactivities

Reactions of chromones with methyl ketoximes in the presence of lithium diisopropylamide follow the nucleophilic 1,2-addition mechanism to give spiro[4H-chromene-4,5′-isoxazolines] in good yields. The isoxazoline ring in spiro[4H-chromene-4,5′-isoxazolines] undergoes opening under the action of conc. H₂SO₄, yielding α,β-unsaturated oximes. Their nitrosation and bromination lead to the corresponding spiroisoxazolines, while the Beckmann rearrangement, to α,β-unsaturated amides. The latter are also formed directly from spiro[4H-chromene-4,5′-isoxazolines] under the action of PCl₅. N-Substituted acetophenone hydrazones in the presence of lithium diisopropylamide react at the C(4) atom of 2-trifluoromethylchromone, while acetophenone anil under the same conditions, at the C(2) atom. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 516–522, March, 2006.     

Chemical Constituents of Brown Rice Grain (<Emphasis Type="Italic">Oryza sativa</Emphasis>)

One new compound 3,7,11,15,19-pentamethyl-9α,10α,11α,17α,18α-pentahydroxy-n-tetracosan-1-oxy-p-hydroxycaffeoate (oryzaterpenyl caffeoate) (1), together with three known fatty acids linoleic acid, stearic acid and myristic acid were isolated and identified from the rice grain of Oryza sativa. The structure of the new compound was elucidated by 1D and 2D NMR spectroscopic techniques (¹H-¹HCOSY, ¹H-¹³C HETCOR) aided by EI-MS, and IR spectra. __________ Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 535–537, November–December, 2005.     

Micelle formation of a nonamphiphilic poly(vinylphenol)-<Emphasis Type="Italic">block</Emphasis>-polystyrene diblock copolymer in ethyl acetate

The micelle formation of a poly(vinylphenol)-block-polystyrene diblock copolymer was studied in ethyl acetate, a nonselective solvent using α,ω-diamine. The copolymer formed micelles in ethyl acetate in the presence of a small amount of the α,ω-diamine. Light scattering studies demonstrated that the micellization was dependent on the grade, the bulkiness, and the conformation of the diamines. The copolymer needed more diamine with the increasing grade of the diamine, due to a decrease in the basicity of the diamine. The bulkiness of the diamines also reduced the efficiency of the micellization by hindering the formation of the hydrogen bond cross-linking. Similarly, the conformation of the diamine affected the micellization, since the conformation determined the intramolecular spatial distance between the animo groups. Trans-1,2-cyclohexanediamine was more effective than the cis-isomer to produce the micelles. Furthermore, (1S,2S)-(+)-1,2-cyclohexanediamine, one of the mirror image isomers composing the trans-isomer, was more effective in producing the micelles than the trans-isomer. The interaction between the mirror image isomers also obstructed the micellization. The micellization, coupled with the thermoresponsivity of the micelles, were influenced by the solvent quality. The dissociation of the micelles into unimers was suppressed in ethyl acetate, while the reconstruction was promoted, in comparison with those in 1,4-dioxane and THF.     

Synthesis of unsaturated dibasic acid esters from five-, six-, and seven-membered cycloalkanones

A new route to diesters of symmetrical octene-, decene-, and dodecenedioic acids was proposed. The ratio of the cis/trans-isomers was 1: 4. The synthesis involved oxidative splitting of five-, six-, and seven-membered cycloalkanones with hydrogen peroxide into the corresponding ω-alkenoic acids followed by esterification and metathesis over Re₂O₇/B₂O₃-Al₂O₃-SnMe₄. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1942–1944, November, 2006.     

Synthesis and mass spectrometric study of α,ω-bis(heptamethylcyclotetrasiloxanyloxy)oligodimethylsilanes

α,ω-Bis(heptamethylcyclotetrasiloxanyloxy)oligodimethylsilanes were synthesized by the reaction of dichlorodimethylsilane and 1,3-dichlorohexamethyltrisilane with hydroxyheptamethylcyclotetrasiloxane. The peculiarities of fragmentation of the compounds obtained by electron impact mass spectrometry are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1729–1733, September, 1999.     

Preparation of micelles with azo dye and UV absorbent at their cores or coronas using non-amphiphilic block copolymers

Micelles with azo dye and UV absorbent at their cores or coronas were prepared from non-amphiphilic random diblock copolymers by α,ω-diamine. Poly[4-(phenylazophenoxymethyl)styrene-ran-4-(2-hydroxybenzophenoxymethyl)styrene-ran-vinylphenol]-block-polystyrene (P(AS-r-HBS-r-VPh)-b-PSt) and poly(vinylphenol)-block-poly[4-(phenylazophenoxymethyl)styrene-ran-4-(2-hydroxybenzophenoxymethyl)styrene-ran-styrene] (PVPh-b-P(AS-r-HBS-r-St)) diblock copolymers were prepared by living radical polymerization mediated by 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The former copolymer had a molecular weight of Mn[P(AS-r-HBS-r-VPh)-b-PSt] = 10,000-b-250,000 by ¹H NMR and a molar ratio of AS:HBS:VPh = 0.01:0.01:0.98, while the latter had a molecular weight of Mn[PVPh-b-P(AS-r-HBS-r-St)] = 10,000-b-111,000 and a molar ratio of AS:HBS:St = 0.02:0.03:0.95. The copolymers showed no self-assembly in 1,4-dioxane because this solvent was non-selective to the copolymers. Dynamic light scattering demonstrated that the copolymers formed micelles in the solvent in the presence of α,ω-diamine. The hydrodynamic radii of the micelles slightly increased with the copolymer concentration decrease, while the aggregation numbers were almost independent of the copolymer concentration. It was found that P(AS-r-HBS-r-VPh)-b-PSt formed smaller micelles with a lower aggregation number than PVPh-b-P(AS-r-HBS-r-St) because of the steric hindrance of the AS and HBS units present at the micellar coronas.