Synthesis of (2S,3R)-[3',3',3'-2H3]-valine and (2S,3S)-4-fluorovaline

A new synthesis of (2S,3R)-[3',3',3'-2H3]-valine has been completed and (2S,3S)-4-fluorovaline has been synthesised for the first time. Both compounds have been prepared by routes involving stereoselective addition to the (S)-pyroglutamate derivative and are available for studies in several areas of bio-organic chemistry.     

Condensation of 5-bromo-, 3-bromo-, and 3-iodoacenaphthenequinones with 3-hydroxythionaphthene and its derivatives

The oxidation of 3-bromo-and 3-iodoacenaphthene has given 3-bromo-and 3-iodoacenaphthenequinones. The condensation of 5-bromo-, 3-bromo-, and 3-iodoacenaphthenequinones with 3-hydroxythionaphthene and its derivatives has yielded indigoid dyes, and the main light absorption maxima of these dyes have been determined.     

Condensation of 5-bromo-, 3-bromo-, and 3-iodoacenaphthenequinones with 3-hydroxythionaphthene and its derivatives

The oxidation of 3-bromo-and 3-iodoacenaphthene has given 3-bromo-and 3-iodoacenaphthenequinones. The condensation of 5-bromo-, 3-bromo-, and 3-iodoacenaphthenequinones with 3-hydroxythionaphthene and its derivatives has yielded indigoid dyes, and the main light absorption maxima of these dyes have been determined.     

Preparation and oxidation of 3-methylene-, 3-Oxo- and 3-hydroxy-bicyclo[2,2,1]heptane-2, 6-carbolactones

3-methylenebicyclo[2,2,1]heptane-2,6-carbolactone (previously incorrectly claimed) has now been prepared and converted to the 3-oxo-lactone. Some 3-hydroxy-bicyclo-[2,2,1]heptane-2,6-carbolactones have been prepared and their rates of oxidation with chromic acid determined. The results do not support a theory about the mechanism of oxidation, involving a dipolar interaction from the lactone.     

2, 5-Dialkyl-1, 3, 4-oxadiazoles

A single stage method has been developed for the preparation of 2, 5-dialky-1, 3, 4-oxadiazoles from aliphatic carboxylic acids, by boiling with hydrazine hydrochloride in phosphoryl chloride. A mechanism for the synthesis is suggested. The oxadiazoles are characterized, and the group refractivity of the 1, 3, 4-oxadiazole ring has been determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1171–1175, September, 1970.     

Thio effects on the departure of the 3'-linked ribonucleoside from diribonucleoside 3',3'-phosphorodithioate diesters and triribonucleoside 3',3',5'-phosphoromonothioate triesters: implications for ribozyme catalysis

To provide a solid chemical basis for the mechanistic interpretations of the thio effects observed for large ribozymes, the cleavage of triribonucleoside 3',3',5'-phosphoromonothioate triesters and diribonucleoside 3',3'-phosphorodithioate diesters has been studied. To elucidate the role of the neighboring hydroxy group of the departing 3'-linked nucleoside, hydrolysis of 2',3'-O-methyleneadenosin-5'-yl bis[5'-O-methyluridin-3'-yl] phosphoromonothioate (1 a) has been compared to the hydrolysis of 2',3'-O-methyleneadenosin-5'-yl 5'-O-methyluridin-3'-yl 2',5'-di-O-methyluridin-3'-yl phosphoromonothioate (1 b) and the hydrolysis of bis[uridin-3'-yl] phosphorodithioate (2 a) to the hydrolysis of uridin-3'-yl 2',5'-di-O-methyluridin-3'-yl phosphorodithioate (2 b). The reactions have been followed by RP HPLC over a wide pH range. The phosphoromonothioate triesters 1 a,b undergo two competing reactions: the starting material is cleaved to a mixture of 3',3'- and 3',5'-diesters, and isomerized to 2',3',5'- and 2',2',5'-triesters. With phosphorodithioate diesters 2 a,b, hydroxide-ion-catalyzed cleavage of the P--O3' bond is the only reaction detected at pH >6, but under more acidic conditions desulfurization starts to compete with the cleavage. The 3',3'-diesters do not undergo isomerization. The hydroxide-ion-catalyzed cleavage reaction with both 1 a and 2 a is 27 times as fast as that compared with their 2'-O-methylated counterparts 1 b and 2 b. The hydroxide-ion-catalyzed isomerization of the 3',3',5'-triester to 2',3',5'- and 2',2',5'-triesters with 1 a is 11 times as fast as that compared with 1 b. These accelerations have been accounted for by stabilization of the anionic phosphorane intermediate by hydrogen bonding with the 2'-hydroxy function. Thio substitution of the nonbridging oxygens has an almost negligible influence on the cleavage of 3',3'-diesters 2 a,b, but the hydrolysis of phosphoromonothioate triesters 1 a,b exhibits a sizable thio effect, k(PO)/k(PS)=19. The effects of metal ions on the rate of the cleavage of diesters and triesters have been studied and discussed in terms of the suggested hydrogen-bond stabilization of the thiophosphorane intermediates derived from 1 a and 2 a.     

3, 3, 3-Trifluoropropyl(methyl)cyclosiloxanes

The catalytic rearrangement of the cyclopentasiloxanes Φ_mD_5-m, where Φ represents a 3, 3, 3-trifluoropropyl(methyl)siloxane link and D a dimethylsiloxane link, and m=2–5 has been studied by the method described previously [1]. The rate of rearrangement and the rate of formation of a linear polysiloxane rise with an increase in m from 2 to 4. The equilibrium concentration of the linear polysiloxane formed from Φ_mD_5-m and from Φ_mD_4-m (m=0–4) [1] is inversely proportional to the molar fraction of Φ links in the ring and rises with an increase in the total concentration of siloxane links in solution. Results have been obtained on the kinetics of the formation of the cyclosiloxanes Φ_mD_n (where m=0–5, n=0–5, and m+n=3-6) during the rearrangement of the cyclopentasiloxanes Φ_mD_5-m. It has been established that at equilibrium a mixture of cyclosiloxanes Φ_mD_n containing practically constant ratios of tetramers, pentamers, and hexamers (m+n=4, 5, and 6) is obtained, regardless of the composition and structure of the initial cyclosiloxane and of the conditions of rearrangement (polymerization). The cyclopentasiloxanes Φ_mD_5-m are less active in the process of rearrangement than the cyclotetrasiloxanes Φ_mD_4-m. The activity of the cyclosiloxanes in rearrangement in the presence of a base rises in the sequence D₄?ΦD₃ ≈ Φ₂D₃<Φ₃D₂<Φ₄D < Φ₂D₂ < Φ₃D.     

Synthesis of 3-cyano-4, 6-diaryl-3, 4-dihydropyridine-2-thionks

3-Cyano-4, 6-diaryl-3, 4-dihydropyridine-2-thiones have been synthesized for the first time by the condensation of arylideneacetophenones or 1-piperidino-1-phenyl-2-benzoylethane with cyanothioacetamide and the 1, 1-dicyano-2-aryl-3-benzoylpropane with hydrogen sulfide in the presence of bases. It has been established by PMR spectroscopy that 3-cyano-3,4-dihydropyridine-2-thiones exist in solutions in the form of mixture of cis and trans isomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1515–1520, November, 1983.     

3-间硝基苯基/对硝基苯基-6-芳基-1, 2, 4-三唑并[3, 4-b]-1, 3, 4-噻二唑衍 生物的合成

报道了以3-间硝基苯基/对硝基苯基-4-氨基-5-巯基-1,2,4-三唑与芳酸在磷酰氯的作用下,合成了16个标题化合物,并研究了合成反应的条件。观察了部分标题化合物对金黄色葡萄球菌和大肠杆菌有明显的抑菌作用。     

3, 3, 3-Trifluoropropyl(methyl)cyclosiloxanes

The influence of the number of 3, 3, 3-trifluoropropyl(methyl)siloxane links (Φ/Φ) in the cyclotetrasiloxanes Φ_mD_4-m, where D represents the dimethylsiloxane link and m=0–4, on the rearrangement of these compounds in acetone solution under the action of sodium siloxanolate has been studied. The rearrangement takes place with the formation of a linear polysiloxane the degradation of which yields, in addition to the initial ring, cyclosiloxanes with a different structure. The rate of rearrangement of Φ_mD_4-m and of the formation of a linear polysiloxane rises with an increase in m from 0 to 3. The equilibrium concentration of the linear polysiloxane formed from Φ_mD_4-m is inversely proportional to m. Results have been obtained on the kinetics of the formation of the cyclosiloxanes Φ_mD_n, where m=0–5, n=0–5, and m+n=3–6, in the rearrangement of the rings ΦD₃, Φ₂D₂, Φ₃D, and Φ₄. The reactivity of the siloxane links rises in the sequence ～ (CH₃)₂Si-O-Si(CH₃)₂ ～<～ (CF₃CH₂CH₂)-(CH₃) Si-O-Si(CH₃)₂ ～<(CF₃CH₂CH₂) (CH₃)Si-O-Si(CH₃) (CH₂CH₂CF₃) ～. Because of the negative inductive effect transferred through the siloxane links, the 3, 3, 3-trifluoropropyl groups strongly activate the siloxane ring with respect to nucleophiiic reagents.     

Synthesis and Luminescent Properties of Eu 3+ , Gd 3+ , and Tb 3+ Complexes with Quinoline-4-carboxylic Acids

New complex compounds LnL3·nH2O (n = 5–10) have been synthesized on the basis of Eu3+, Gd3+, and Tb3+ salts and quinoline-4-carboxylic acid derivatives obtained via the Pfitzinger reaction. Composition and structure of the ligands and the resulting complex compounds have been confirmed by NMR and IR spectroscopy, thermogravimetry, and complexometric titration. Europium complex with 1,2,3,4-tetrahydroacridine-9-carboxylic acid has exhibited efficient luminescence.     

Floating spherical gaussian orbital model study of some organometallic systems. I. LiCH3, HBeCH3, and CH3BeCH3

The floating spherical Gaussian orbital method has been used to study the equilibrium geometries and electronic structures of some organometallic systems like LiCH₃, HBeCH₃, and CH₃BeCH₃. The predicted geometries are in good agreement with other theoretical estimates and available experimental results. Electron transfer values from carbon to metal atom and bond energies of Li? C and Be? C bonds are estimated and discussed. The wave functions obtained here have also been used to predict the electron momentum distributions and Compton profiles for LiCH₃, HBeCH₃, and CH₃BeCH₃.     

The reductive repair of 1, 3-dhnethylthymine bromohydrin into 1, 3-dimethylthymine by 1, 5-dihydro-5-deazaflavin or 1, 4-dihydroquinoline

The reductive conversion of 1, 3-dimethylthymine bromohydrin into 1, 3-dimethylthymine by 10-ethyl-3-methyl-1, 5-dihydro-5-deazaflavin or 1-benzyl-3-carbamoyl-1, 4-dihydroquinoline has been achieved in the presence of trifluoroacetic acid.     

Derivatives of 2-(3'-coumarinyl)-1, 3-indandione

The possibility of the direct preparation of 2-(3'-coumarinyl)-1,3-indandione and its derivatives by condensing phthalic and substituted phthalic anhydrides with 3-coumarinylacetic acid in acetic anhydride solution in the presence of triethylamine has been shown. The bromination and hydroxymethylation of 2-(3'coumarinyl)-1,3-indandione and its substituted derivatives have been performed.     

3,3,6,6-四甲基-9-邻氯苯基-1,8-二氧代-3,4,5,6,7,9-六氧化氧杂蒽的合成和晶体结构

标题化合物C23H25对O3Cl是由邻氯苯甲醛与5，5-二甲基1，3-环己二酮在N，N-二甲基甲酸腹中反应而得。结构通过单晶X-射线衍射法确定，其晶体属于单科晶系，空间群=1632。晶体结构用直接法解出，使用全矩阵最小二乘法对原子参数进行修正，最后的偏离因子为R=0．054，Rw一0．063。在晶体结构中，吡喃环与苯环之间的两面角为92．43°。     

Gas phase structure of Ruppert's reagent, CF3SiMe3

CF3SiMe3 (Ruppert's reagent) has been investigated by gas phase electron diffraction, microwave spectroscopy and quantum chemical methods, deriving structural parameters and the barrier height for the methyl torsion. The bond length of the Si-CF3 bond, 1.941(3) A, is the longest Si-C bond observed so far in the gas phase. The V3 barrier for the methyl group torsion (V3= 5.71 kJ/mol) is only slightly lower than barriers determined for other trimethylsilane compounds.     

CRYSTAL AND MOLECULAR STRUCTURE OF SUEFATOAQUO-2, 3-DIMETHYL-2, 3-BUTYLDIAMINEPLATINUM

[PtDMBA(SO4)H2O]H2O crystals belong to the orthorhombic system,a=11.073(3),b=9.672(2),c=21.156(7)A,space group C2cb,z=8.The diffraction data (Moka) were collected with Nicolet R3 four-circle di-ffractometer.The structure was determined by heavy atom method and refined by the least square program,R=0.0716.In the systematic study of anticancer action of a series of platinum compounds,our Coordination Chemistry Research Institute has synthesized PtDMBASO4 2H2O(where DMBA=2,3-dimethyl-2,3-butyldiamino) and found it has antitumor activity against L-1210 in mice.In order to study the relationship between the structure and the anticancer effects of the platinum compounds,the crystal structure of the compound has been determined.     

Synthesis of new 2',3'-dideoxy-6',6'-difluoro-3'-thionucleoside from gem-difluorohomoallyl alcohol

[reaction: see text] 2',3'-Dideoxy-6',6'-difluoro-3'-thionucleoside 1b, an analogue of 3Tc that has high biological activities against HIV and HBV, has been synthesized from gem-difluorohomoallyl alcohol 3 in an efficient way. The key intermediate 4-amino-3,3-difluorotetrahydrothiophen-2-ylmethyl benzoate 15 was prepared from 2,2-difluoro-1-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl]but-3-en-1-ol 3 in 11 steps. The construction of pyrimidine ring with the amino group of compound 15 gave the target compound 1.     

Bonding and Reactivity in RB-As R Systems(R=H,F,OH,CH_3,CMe_3,CF_3,SiF_3,BO): Substituent Effects

Density functional theory-based calculations have been carried out to study the bonding and reactivity in RB-As R(R=H,F,OH,CH3,CMe_3,CF_3,SiF_3,BO)systems.Our calculations demonstrated that all the studied systems adopted bent geometry(DR-B-As≈180°andDB-As-R≈90°or less).The reason for this bending was explained with the help of a valence-orbital model.The potential energy surfaces for three possible isomers of RB-As R systems were also generated,indicating that the RB-As R isomer was more stable than R_2B-As R when R=SiF_3,CMe_3,and H.The B-As bond character was analyzed using natural bond orbital(NBO)and Wiberg bond index(WBI)calculations.The WBI values for B-As bonds in F3Si B-As SiF_3 and HB-As H were 2.254 and 2.209,respectively,indicating that this bond has some triple-bond character in these systems.While the B centers prefer nucleophilic attack,the As centers prefer electrophilic attack.