2-Acylidene-3,5-diaryl-2,3-dihydro-1,3,4-thiadiazoles and related compounds: a question of hypervalent S … O interactions

1993 ◽  
Vol 71 (4) ◽  
pp. 561-571 ◽  
Author(s):  
Naresh Pandya ◽  
Anthony J. Basile ◽  
Ajay K. Gupta ◽  
Patrick Hand ◽  
Cindy L. MacLaurin ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Carbonyl Oxygen ◽  
Side Chain ◽  
Molecular Mechanics Calculations ◽  
New Synthesis ◽  
Cell Dimensions ◽  
Thiadiazole Ring ◽  
Hypervalent Interaction ◽  
Related Compounds ◽  
Selective Deacetylation

A new synthesis of 1 by selective deacetylation of 2 is reported. The acylation step implied in earlier syntheses of 1 and related compounds is exemplified by direct acylations of 3 to give 4a and 4b. Several new 2-acylidene-3-(2,4-dibromophenyl)-5-phenyl-2,3-dihydro-1,3,4-thiadiazoles (11) and thioacylidene analogues (12) are described. The crystal structures of 11a, 11b, 11c, and 11d reveal a hypervalent interaction, ca. 2.45–2.7 Å long, between the sulfur and carbonyl oxygen atoms. The dibromophenyl ring is nearly perpendicular to the thiadiazole ring plane in the crystal structures, and NMR data suggest that this conformation is maintained in solution. Molecular mechanics calculations show that the S … O interaction need only be a few kilocalories in order to stabilize the observed acylidene side chain configuration over other possible isomers. Crystals of 11a are triclinic, [Formula: see text] with cell dimensions a = 12.937(2), b = 13.429(2), c = 13.489(2) Å, α = 60.14(1)°, β = 74.59(1)°, γ = 58.70(1)°, Z = 4, and R = 0.044 for 3287 observed reflections. Crystals of 11b are monoclinic, P21/c, with cell dimensions a = 10.512(1), b = 12.084(2), c = 16.268(4) Å, β = 96.91(1)°, Z = 4, R = 0.050 for 1938 observed reflections. Crystals of 11c are monoclinic, P21/c, with cell dimensions a = 17.492(4), b = 16.979(1), c = 14.962(1) Å, β = 106.46(1)°, Z = 8, R = 0.057 for 3112 observed reflections. Crystals of 11d are monoclinic, P21/c, with cell dimensions a = 11.749(1), b = 8.533(1), c = 22.670(4) Å, β = 100.17(1)°, Z = 4, and R = 0.059 for 2265 observed reflections.

35Cl NQR and Structural Studies on Substituted Amides, XyC6H5–yNHCOR (X = H or Cl; y = 0, 1 or 2 and R = C(CH3)3, CHClCH3, C6H5 or 2-ClC6H4)

2003 ◽  
Vol 58 (4) ◽  
pp. 225-230 ◽  
Author(s):  
B. Thimme Gowda ◽  
K. Jyothi ◽  
Helmut Paulus ◽  
Hartmut Fuess
Keyword(s):  
Bond Length ◽  
Crystal Structures ◽  
The Other ◽  
Side Chain ◽  
Structural Studies ◽  
Lattice Constants ◽  
Alkyl Groups ◽  
The Family ◽  
35Cl Nqr ◽  
Related Compounds

35Cl NQR frequencies of some N-(substitutedphenyl)-amides represented by the general formula, XyC6H5−yNHCOR (where X = H or Cl; y = 0, 1 or 2 and R = H, CH3, CH2CH3, CH(CH3)2, C(CH3)3, CH2Cl, CHCl2 or CCl3) have been measured and compared with those of other compounds in the family to analyse the effect of substitution in the side chain on the frequencies. Comparison of 35Cl NQR frequencies of all the N-(2-chlorophenyl)- and N-(2,6-dichlorophenyl)-amides reveals that the presence of alkyl groups in the side chain lowers the frequency, while that of aryl or chlorosubstituted alkyl groups enhance the frequencies to some extent, when compared to the frequencies of either N-(2-chlorophenyl)-acetamide or N-(2,6-dichlorophenyl)-acetamide. In addition, the crystal structures of N-(phenyl)-2-chloro-2-methylacetamide (C6H5NHCOCHClCH3) and N-(phenyl)-2- chloro-benzamide (C6H5NHCO-(2-ClC6H4)) have been determined and the data analysed along with the crystal structures of related compounds. The data (lattice constants in Å) of the new structures are: C6H5NHCO- CHClCH3: monoclinic, P21/c, Z = 4, a = 10.879(2), b = 9.561(2), c = 10.067(2), β = 116.080(10)°; C6H5NHCO-(2-ClC6H4): tetragonal, P4(3), Z = 4, a = 8.795(4), b = 8.795(4), c = 15.115(6), β = 90.0°. It is evident from a comparison, that the side chain substitution influences the C(S)-C(O) bond length, while the effect on the other bond lengths is not significant except for benzanilide. Similarly, only the side chain angles are affected to some extent. The variations do not show definite trends, probably due to the differences in the crystallisations.

scholarly journals Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Ilya V. Kornyakov ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Complexity ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Complexity Measures ◽  
X Ray ◽  
The Family ◽  
Similarities And Differences ◽  
Related Compounds

Single crystals of two novel shchurovskyite-related compounds, K2Cu[Cu3O]2(PO4)4 (1) and K2.35Cu0.825[Cu3O]2(PO4)4 (2), were synthesized by crystallization from gaseous phase and structurally characterized using single-crystal X-ray diffraction analysis. The crystal structures of both compounds are based upon similar Cu-based layers, formed by rods of the [O2Cu6] dimers of oxocentered (OCu4) tetrahedra. The topologies of the layers show both similarities and differences from the shchurovskyite-type layers. The layers are connected in different fashions via additional Cu atoms located in the interlayer, in contrast to shchurovskyite, where the layers are linked by Ca2+ cations. The structures of the shchurovskyite family are characterized using information-based structural complexity measures, which demonstrate that the crystal structure of 1 is the simplest one, whereas that of 2 is the most complex in the family.

ChemInform Abstract: New Synthesis of Cyproheptadine and Related Compounds Using Low Valent Titanium.

ChemInform ◽  
1989 ◽  
Vol 20 (9) ◽  
Author(s):  
M. M. CID ◽  
J. A. SEIJAS ◽  
M. C. VILLAVERDE ◽  
L. CASTEDO
Keyword(s):  
New Synthesis ◽  
Low Valent ◽  
Related Compounds

Structural Studies on N-(2,4,6-Trimethylphenyl)-methyl/ chloro-acetamides, 2,4,6-(CH3)3C6H2NH-CO-CH3–yXy (X = CH3 or Cl and y = 0, 1, 2)

2006 ◽  
Vol 61 (10-11) ◽  
pp. 588-594 ◽  
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Jozef Kožíšek ◽  
Hartmut Fuess
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Data ◽  
The Other ◽  
Side Chain ◽  
Structural Studies ◽  
Asymmetric Unit ◽  
Lattice Constants ◽  
Peptide Linkage ◽  
The Mean

TMPAThe effect of substitutions in the ring and in the side chain on the crystal structure of N- (2,4,6-trimethylphenyl)-methyl/chloro-acetamides of the configuration 2,4,6-(CH3)3C6H2NH-COCH3− yXy (X = CH3 or Cl and y = 0,1, 2) has been studied by determining the crystal structures of N-(2,4,6-trimethylphenyl)-acetamide, 2,4,6-(CH3)3C6H2NH-CO-CH3 (); N-(2,4,6- trimethylphenyl)-2-methylacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH2-CH3 (TMPMA); N-(2,4,6- trimethylphenyl)-2,2-dimethylacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH(CH3)2 (TMPDMA) and N-(2,4,6-trimethylphenyl)-2,2-dichloroacetamide, 2,4,6-(CH3)3C6H2NH-CO-CHCl2 (TMPDCA). The crystallographic system, space group, formula units and lattice constants in Å are: TMPA: monoclinic, Pn, Z = 2, a = 8.142(3), b = 8.469(3), c = 8.223(3), β = 113.61(2)◦; TMPMA: monoclinic, P21/n, Z = 8, a = 9.103(1), b = 15.812(2), c = 16.4787(19), α = 89.974(10)◦, β = 96.951(10)◦, γ =89.967(10)◦; TMPDMA: monoclinic, P21/c, Z = 4, a =4.757(1), b= 24.644(4), c =10.785(2), β = 99.647(17)◦; TMPDCA: triclinic, P¯1, Z = 2, a = 4.652(1), b = 11.006(1), c = 12.369(1), α = 82.521(7)◦, β = 83.09(1)◦, γ = 79.84(1)◦. The results are analyzed along with the structural data of N-phenylacetamide, C6H5NH-CO-CH3; N-(2,4,6-trimethylphenyl)-2-chloroacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH2Cl; N-(2,4,6-trichlorophenyl)-acetamide, 2,4,6-Cl3C6H2NH-COCH3; N-(2,4,6-trichlorophenyl)-2-chloroacetamide, 2,4,6-Cl3C6H2NH-CO-CH2Cl; N-(2,4,6-trichlorophenyl)- 2,2-dichloroacetamide, 2,4,6-Cl3C6H2NH-CO-CHCl2 and N-(2,4,6-trichlorophenyl)- 2,2,2-trichloroacetamide, 2,4,6-Cl3C6H2NH-CO-CCl3. TMPA, TMPMA and TMPDCA have one molecule each in their asymmetric units, while TMPDMA has two molecules in its asymmetric unit. Changes in the mean ring distances are smaller on substitution as the effect has to be transmitted through the peptide linkage. The comparison of the other bond parameters reveal that there are significant changes in them on substitution.

Crystal Structures of Intermediates in a New Synthesis of Antitumor Drug Cabozantinib

Heterocycles ◽  
2016 ◽  
Vol 93 (1) ◽  
pp. 323
Author(s):  
Sven Nerdinger ◽  
Gerhard Laus ◽  
Erwin Schreiner ◽  
Volker Kahlenberg ◽  
Klaus Wurst ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Antitumor Drug ◽  
New Synthesis

Direct side-chain acylamination of 4-picoline 1-oxides and related compounds

1979 ◽  
pp. 956 ◽  
Author(s):  
Rudolph A. Abramovitch ◽  
Dorota A. Abramovitch ◽  
Piotr Tomasik
Keyword(s):  
Side Chain ◽  
Related Compounds

ChemInform Abstract: DIRECT SIDE-CHAIN ACYLAMINATION OF 4-PICOLINE 1-OXIDES AND RELATED COMPOUNDS

1980 ◽  
Vol 11 (9) ◽  
Author(s):  
R. A. ABRAMOVITCH ◽  
D. A. ABRAMOVITCH ◽  
P. TOMASIK
Keyword(s):  
Side Chain ◽  
Related Compounds

scholarly journals Insights into the substrate discrimination mechanisms of methyl-CpG-binding domain 4

2021 ◽  
Author(s):  
Hala Ouzon-Shubeita ◽  
Lillian Feigang Schmaltz ◽  
Seongmin Lee
Keyword(s):  
Carbonyl Oxygen ◽  
Binding Domain ◽  
Dna Glycosylase ◽  
Side Chain ◽  
Dna Glycosylases ◽  
Base Pairs ◽  
Thymine Dna Glycosylase ◽  
Mismatched Dna ◽  
Domain 4

G:T mismatches, the major mispairs generated during DNA metabolism, are repaired in part by mismatch-specific DNA glycosylases such as methyl-CpG-binding domain 4 (MBD4) and thymine DNA glycosylase (TDG). Mismatch-specific DNA glycosylases must discriminate the mismatches against million-fold excess correct base pairs. MBD4 efficiently removes thymine opposite guanine but not opposite adenine. Previous studies have revealed that the substrate thymine is flipped out and enters the catalytic site of the enzyme, while the estranged guanine is stabilized by Arg468 of MBD4. To gain further insights into mismatch discrimination mechanism of MBD4, we assessed the glycosylase activity of MBD4 toward various base pairs. In addition, we determined a crystal structure of MBD4 bound to T:O6-methylguanine-containing DNA, which suggests the O6 and N2 of purine and the O4 of pyrimidine are required to be a substrate for MBD4. To understand the role of the Arg468 finger in catalysis, we evaluated the glycosylase activity of MBD4 mutants, which revealed the guanidinium moiety of Arg468 may play an important role in catalysis. D560N/R468K MBD4 bound to T:G mismatched DNA shows that the side chain amine moiety of the Lys stabilizes the flipped-out thymine by a water-mediated phosphate pinching, while the backbone carbonyl oxygen of the Lys engages in hydrogen bonds with N2 of the estranged guanine. Comparison of various DNA glycosylase structures implies the guanidinium and amine moieties of Arg and Lys, respectively, may involve in discriminating between substrate mismatches and nonsubstrate base pairs.

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