Structure Of 5'-Deoxy-5',6-Epithio-5,6-Dihydro-2',3'-O-Isopropylideneuridine, C12h16n2o5s

Mr=300.33 , triclinic, P1, a=5.635 (2), b=11.077(2), c=11.582(2)A, a= 70.48 (1), fl= 88.16 (3), y=80.56(3) ° , V= 670.325 A3, Z=2, D x = 1.49 Mg m -3, Cu Ka, n= 1.54184 ,A, g = 2.308mm -1, F(000)=316, T=301K, R=0.054, R w = 0.093 for 1944 observed counter reflections. The sulphur position with respect to the dihydrouracil ring, which is of possible relevance to the action of thymidylate synthetase, is axial in molecule A and equatorial in B. Both molecules show the anti conformation about the glycosidic bond [torsion angle C(6)-N(1)-C(1')-O(4'), 2'CN = 21.6 (9) and 29.4 (10) °] and have the C(4')-endo, O(4')-exo (40T) sugar conformation. The dioxolane-ring conformation is O(2')-endo in A and C(7)-endo in B. The dihydrouracil rings show self base pairing with hydrogen bondsN(3A)...O(ZB) and N(3B)...O(ZA).

Structure of a thionucleoside: 5'-deoxy-5',6-epithio-5,6-dihydro-2',3'-O-isopropylidene-3-methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3'-O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Structure Of A Thionucleoside - 5'-Deoxy-5',6-Epithio-5,6-Dihydro-2',3'-Ortho-Isopropylidene-3-Methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3' O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Synthesis and Isolation of 5,6-Dihydro-4H-1,3-Oxazine Hydrobromides by Autocyclization of N-(3-Bromopropyl)amides

5,6-Dihydro-4H-1,3-oxazine hydrobromides have been synthesized by the nucleophilic autocyclo-O-alkylation of N-(3-bromopropyl)amides under neutral conditions in chloroform. It is found that electron-donating amide alpha-substituents influence the autocyclization efficiency.

Synthesis of 5-p-hydroxybenzyl-5,6-dihydro-2-naphthol, (+/-)-sequirin-d

A high-yield six-step synthesis of sequirin D (1a), a naturally occurring norlignan, is described. Michael addition of deoxyanisoin (2) to acrylonitrile gives a ketonitrile (3), which on Wolff–Kishner reduction is reduced and hyrolysed in situ to 4,5-bis-p-methoxyphenylpentanoic acid (4). Cyclodehydration of (4) with polyphosphoric acid, followed by borohydride reduction and dehydration furnishes di-O-methylsequirin D (1b) which affords on demethylation sequirin D (1a) in an overall yield from (2) of 60%. The key synthon (4) has also been prepared by three other routes.

Total synthesis and determination of the absolute configuration of 5,6-Dihydro-alpha-pyrone natural product synargentolide B

Enantiospecific total synthesis and determination of the absolute stereochemistry of the alpha-pyrone-containing natural product synargentolide B were accomplished. The absolute stereochemistry of the natural product was established by synthesizing the possible diastereomers and comparison of the data with those reported for the natural product. During the process, total synthesis of the putative structure of related natural product 6R-1S,2R,SR,6S-(tetraacetyloxy)-3E-heptenyl]-5,6-dihydro-2H-pyran-2-o ne was also accomplished and confirmed by X-ray crystal structure analysis. Wittig-Horner reaction of a chiral phosphonate derived from (S)-lactic acid and ring-closing metathesis were the key reactions during the course of the total synthesis.

Synthesis of 5,6-dihydro-4H-1,3-thiazine containing peptide mimics from N-(3-hydroxypropyl)thioamides and epimerization studies

The first synthesis of 1,3-thiazine fused peptide mimics is described from N-(3-hydroxypropyl)thioamides under MsCl/NEt3 conditions. The method is amenable to oligopeptidomimics with polar and apolar side chains. Substantial epimerization occurs at chiral C(2) exo methines in non-Pro fused mimics even under neutral conditions. H-1 NMR and crystal structure analyses indicate that the Thi analogues primarily associate with each other through intermolecular hydrogen bonds, involving the nitrogen of 1,3-thiazine and the N-H of the fused residue, which may be the basis for enamination-racemization process in these peptide mimics. (C) 2014 Elsevier Ltd. All rights reserved.

A New Method For The Generation Of 5,6-Quinolinedione 5-Methide .5. Synthesis Of Polycyclic Heteroaromatics

Reaction of 6-acetoxy-5-bromomethylquinoline (1c) and 2-bromomethyl-4-(2'-pyridyl)phenyl acetate (2b) with tetrachlorocatechol in acetone in the presence of anhydrous potassium carbonate resulted in the formation of diastereomeric products 3c, 3d, 4e and 4f.

A thermal molecular migration in the solid-state - structures of isomeric 5-amino-4-(2,6-dichlorophenyl)-1-(2-nitrophenyl)-1h-1,2,3-triazole (yellow form i) and 4-(2,6-dichlorophenyl)-5-(2-nitroanilino)-2h-1,2,3-triazole (red form-ii), c14h9cl2n5o2

Yellow form (I): Mr= 350.09, monoclinic, P2Jn, Z--4, a=9.525(1), b=14.762(1), c= 11.268(1),/t, fl= 107.82 (1) o , V= 1508.3 A 3 , Din(flotation in aqueous KI)= 1.539 (2), D x= 1.541 (2) g cm -3, #(Cu Ka, 2 = 1.5418 A) = 40.58 cm -~, F(000) = 712, T= 293 K, R = 8.8% for 2054 significant refections. Red form (II): Mr= 350.09, triclinic, Pi, Z=2, a=9.796(2), b= 10.750 (2), c= 7.421 (1)A, a= 95.29 (2), fl= 0108-2701/84/111901-05501.50 70.18 (1), y = 92-.76 (2) °, V= 731.9 A 3, Din(flotation in KI) = 1.585 (3), D x = 1.588 (3) g cm -3, ~t(Cu Ka, 2 = 1.5418/~) = 40.58 cm -1, F(000) = 356, T=293 K, R = 5.8% for 1866 significant reflections. There are no unusual bond distances or angles. The triazole and two phenyl rings are planar. On the basis of packing considerations the possibility of intermolecular interactions playing a role in the reactivity of the starting material is ruled out.

Zeeman effect of chlorine nuclear quadrupole resonance and hydrogen bonding in 2,6-, 2,5- and 3,5-dichlorophenols

The Zeeman effect of chlorine nuclear quadrupole resonance in polycrystalline samples of 2,6-, 2,5 and 3,5-dichlorophenol has been investigated at room temperature in order to study the effect of hydrogen bonding on the electric field gradient asymmetry parameter n. While the two n.q.r. lines in 3,5-dichlorophenol gave an asymmetry parameter of 10%, those in 2,6- and 2,5-dichlorophenol gave different values of n for the two chlorines. The chlorine atom which is ortho to the OH group and involved in hydrogen bonding (i.e., corresponding to the low frequency line) gave an asymmetry parameter of 0.21 in 2,6-dichlorophenol and 0.17 in 2,5-dichlorophenol while the other chlorine (i.e., corresponding to the high frequency line) gave a lower value of 0.12 in 2,6-dichlorophenol and 0.11 in 2,5-dichlorophenol. These values of n are discussed in terms of hydrogen bonding and bond parameters.

Evaluation Of Diffusion-Coefficient And Ionic Mobility In (Nh4)4fe(Cn)6.1.5 H2o

The diffusion coefficient, D, and the ionic mobility, μ, in the protonic conductor ammonium ferrocyanide hydrate have been determined by the isothermal transient ionic current method. D is also determined from the time dependence of the build up of potential across the samples and theretical expressions describing this build up in terms of double exponential dependence on time are obtained. The values obtained are D=3.875×10−11m2s−1 and μ=1.65×10−9 m2V−1s−1.

Synthesis of 4,6-(and 5,7-)dimethoxy-3,3-dimethyl-1-indanones

Grignard reaction of ethyl 3-(3,5-dimethoxyphenyl)-propionate (4) followed by cyclodehydration of the carbinol (5) with conc H2SO4 gave 4,6-dimethoxy-3,3-dimethylindane (6). Oxidation of the indane (6) with CrO3-pyridine complex in methylene chloride gave 4,6-dimethoxy-3,3-dimethylindan-1- one (1) in high yield. Conjugate addition of methyl magnesium iodide to methyl α-cyano-β-methyl-3,5-dimethoxycinnamate (11), prepared from 3,5-dimethoxyacetophenone (10) by Knoevenagel condensation, resulted in methyl 2-cyano-3-(3,5-dimethoxyphenyl)-3,3-dimethylpropionate (12). Refluxing the ester (12) with aq DMSO containing sodium chloride gave the corresponding nitrile (15) which underwent Höesch reaction to yield 5,7-dimethoxy-3,3-dimethylindan-1-one (2).

Microwave spectrum and structure of C(6)H(5)CCH center dot center dot center dot H(2)S complex

Rotational spectra of C(6)H(5)CCH center dot center dot center dot H(2)S, C(6)H(5)CCH center dot center dot center dot H(2)(34)S, C(6)H(5)CCH center dot center dot center dot HDS, C(6)H(5)CCH center dot center dot center dot D(2)S and C(6) H(5)CCD center dot center dot center dot H(2)S complexes have been observed using a pulsed nozzle Fourier transform microwave spectrometer. The observed spectrum is consistent with a structure in which hydrogen sulfide is located over the phenyl ring pi cloud and the distance between the centers of masses of the two monomers is 3.74 +/- 0.01 angstrom. In the complex, the H(2)S unit is shifted from the phenyl ring center towards the acetylene group. The vibrationally averaged structure has an effective Cs symmetry. Ab initio calculations were performed at MP2/aug-cc-pVDZ level of theory to locate the possible geometries of the complex. The calculations reveal the experimentally observed structure to be more stable than a coplanar arrangement of the monomers, which was observed for the C(6)H(5)CCH center dot center dot center dot H(2)O complex. Atoms in molecule theoretical analysis shows the presence of S-H center dot center dot center dot pi hydrogen bond. For the parent isotopologue, each transition frequency was found to split into two resulting from an interchange of the equivalent hydrogens of H(2)S unit in the complex. (C) 2011 Elsevier Inc. All rights reserved.