ortho-DIQUATERNARY AROMATIC COMPOUNDS: I. THE SYNTHESIS OF ortho-DITERTIARYBUTYLBENZENE. SOME REACTIONS OF SIDE CHAIN SUBSTITUTED DERIVATIVES

1962 ◽  
Vol 40 (8) ◽  
pp. 1664-1671 ◽  
Author(s):  
L. R. C. Barclay ◽  
C. E. Milligan ◽  
N. D. Hall
Keyword(s):  
Benzene Ring ◽  
Aromatic Compounds ◽  
Dimethyl Ester ◽  
Lead Tetraacetate ◽  
Spectral Studies ◽  
Side Chain ◽  
Side Reactions ◽  
Hydride Reduction ◽  
Spectral Evidence

1,1,4,4-Tetramethyltetralone (I) was converted by oxidative procedures into o-phenylene-diisobutyric acid (III). Hydride reduction of the dimethyl ester of III yielded β,β′-dihydroxy-o-di-t-butylbenzene (IV). The ditosylate of IV was converted by hydride reduction into o-di-t-butylbenzene (VI) (44%) together with rearrangement products. Ultraviolet spectral evidence indicated a slight distortion of the benzene ring in VI and its various side chain derivatives. Side reactions were encountered in the synthesis of III, which involved the conversion of this acid by periodate or lead tetraacetate oxidation into a lactone (X) and the anhydride (XI). A mechanism is postulated to account for the formation of X. The structures postulated for the various compounds were confirmed by n. m. r. spectral studies.

ortho-Diquaternary aromatic compounds. II. Synthesis and spectral properties of β,β′-dihydroxy-2,3-di-t-butylnaphthalene and related crowded aromatics

1969 ◽  
Vol 47 (23) ◽  
pp. 4313-4318 ◽  
Author(s):  
L. R. C. Barclay ◽  
G. R. Nixon ◽  
H. M. Foote ◽  
S. L. Barclay
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Compounds ◽  
Spectral Properties ◽  
Bond Angle ◽  
Chemical Shifts ◽  
Dimethyl Ester ◽  
Selenium Dioxide ◽  
Hydride Reduction ◽  
Cyclic Compounds ◽  
Compression Effects

Cyclialkylation of naphthalene with 2,2,5,5-tetramethyltetrahydrofuranone yielded 2-keto-1,1,4,4-tetramethyl-1,2,3,4-tetrahydroanthracene (1). Selenium dioxide oxidation of 1 yielded the corresponding diketone (3) and periodate cleavage of 3 yielded 2,3-naphthalene-diisobutyric acid (4). Hydride reduction of the dimethyl ester (6) of 4 yielded the diol, β,β′-dihydroxy-2,3-di-t-butylnaphthalene (7). The relative chemical shifts of aromatic protons of 1,2,4,5-tetraalkylbenzenes containing gem dimethyls are rationalized in terms of compression effects exerted by the bulky ortho groups. Nuclear magnetic resonance and ultraviolet spectral results for the ortho di-t-butyl aromatic derivatives 4, 6, and 7 are compared to the model cyclic compounds 1 and anhydride (5) of 4 in terms of the strain caused by bond angle deformations in the side chains.

1H and 13C NMR Spectral Studies on N-(Aryl)-Substituted Acetamides, C6H5NHCOCH3-iXi and 2/4-XC6H4NHCOCH3-iXi (where X = Cl or CH3 and i = 0, 1, 2 or 3)

2003 ◽  
Vol 58 (12) ◽  
pp. 801-806 ◽  
Author(s):  
B. Thimme Gowda ◽  
K. M. Usha ◽  
K. L. Jayalakshmi
Keyword(s):  
Chemical Shift ◽  
Benzene Ring ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectral Studies ◽  
Side Chain ◽  
1H And 13C Nmr ◽  
Methyl Group ◽  
Solution State

35 N-(Phenyl)-, N-(2/4-chlorophenyl)- and N-(2/4-methylphenyl)-substituted acetamides are prepared, characterised and their NMR spectra studied in solution state. The variation of the chemical shifts of the aromatic protons in these compounds follow more or less the same trend with changes in the side chain. The chemical shifts remain almost the same on introduction of Cl substituent to the benzene ring, while that of methyl group lowers the chemical shifts of the aromatic protons. But only 13C-1 and 13C-4 chemical shifts in these compounds are sensitive to variations of the side chain. The incremental shifts in the chemical shifts of the aromatic protons and carbons due to -COCH3−iXi or NHCOCH3−iXi groups in all the N-(phenyl)-substituted acetamides, C6H5NHCOCH3−iXi (where X = Cl or CH3 and i = 0, 1, 2 or 3) are calculated. These incremental chemical shifts are used to calculate the chemical shifts of the aromatic protons and carbons in all the N-(2/4-chlorophenyl)- and N-(2/4-methylphenyl)-substituted acetamides, in two ways. In the first way, the chemical shifts of aromatic protons or carbons are computed by adding the incremental shifts due to -COCH3−iXi groups and the substituents at the 2nd or 4th position in the benzene ring to the chemical shifts of the corresponding aromatic protons or carbons of the parent aniline. In the second way, the chemical shifts are calculated by adding the incremental shifts due to -NHCOCH3−iXi groups and the substituents at the 2nd or 4th position in the benzene ring to the chemical shift of a benzene proton or carbon, respectively. Comparison of the two sets of calculated chemical shifts of the aromatic protons or carbons of all the compounds revealed that the two procedures of calculation lead to almost the same values in most cases and agree well with the experimental chemical shifts.

Infrared, 1H and 13C NMR Spectral Studies on Di- and Tri-substituted N-Aryl Amides, 2,6-X2C6H3NHCOCH3 – IXi and 2,4,6-X3C6H2NHCOCH3 – IXi (X = Cl or CH3 and I = 0, 1, 2 or 3)

2004 ◽  
Vol 59 (1-2) ◽  
pp. 69-76 ◽  
Author(s):  
B. Thimme Gowda ◽  
K. M. Usha ◽  
K. Jyothi
Keyword(s):  
General Formula ◽  
Benzene Ring ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Spectral Studies ◽  
Side Chain ◽  
1H And 13C Nmr ◽  
Stretching Vibrations ◽  
Absorption Frequencies ◽  
C Nmr

Several di- and tri-substituted amides of the general formula, 2,6-X2C6H3NHCOCH3−iXi and 2,4,6-X3C6H2NHCOCH3−iXi (X = Cl or CH3 and i = 0, 1, 2, or 3) are prepared, characterised, and their infrared spectra in the solid state and 1H and 13C NMR spectra in solution are studied. The C=O stretching vibrations of N-(2,6-dichlorophenyl)- and N-(2,6-dimethylphenyl)-amides appear as strong absorptions in the ranges 1707 - 1658 cm−1 and 1700 - 1647 cm−1, respectively, while the N-H stretching vibrations of N-(2,6-dichlorophenyl)- and N-(2,6-dimethylphenyl)-amides appear as strong vibrations in the ranges 3271 - 3209 cm−1 and 3285 - 3214 cm−1, respectively. The N-H stretching vibrations of N-(2,4,6-trichlorophenyl)- and N-(2,4,6-trimethylphenyl)- amides also appear as strong absorptions in the ranges 3370 - 3212 and 3283 - 3225 cm−1, respectively, while those of the C=O vibrations appear in the ranges 1688 - 1617 and 1704 - 1647 cm−1. The analysis of the C=O and N-H absorption frequencies of all amides of the general formula XiC6H5−iNHCOCH3−iXi (where X = Cl or CH3, and i = 0, 1, 2 or 3) indicates that their variations do not show regular trends with substitution either in the phenyl ring or in the side chain. The chemical shifts of both the aromatic protons and the aromatic carbons of all the amides are calculated in two ways, either by adding the incremental shifts due to -COCH3−iXi groups and the substituents in the benzene ring to the chemical shifts of the corresponding aromatic protons or carbons of the parent aniline, or by adding the incremental shifts due to -NHCOCH3−iXi groups and the substituents in the benzene ring to the chemical shift of the benzene proton or carbon. The calculated chemical shifts of the aromatic protons and carbons of all the substituted amides by both methods lead to almost the same values in most cases and agree well with the observed chemical shifts, indicating that the principle of additivity of the substituent effects is valid in these compounds.

scholarly journals Enabling microbial syringol conversion through structure-guided protein engineering

2019 ◽  
Vol 116 (28) ◽  
pp. 13970-13976 ◽  
Author(s):  
Melodie M. Machovina ◽  
Sam J. B. Mallinson ◽  
Brandon C. Knott ◽  
Alexander W. Meyers ◽  
Marc Garcia-Borràs ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Protein Engineering ◽  
Aromatic Compounds ◽  
Side Chain ◽  
Microbial Conversion ◽  
Sinapyl Alcohol ◽  
Analogous Compound ◽  
Dynamics Simulations ◽  
Rate Limiting

Microbial conversion of aromatic compounds is an emerging and promising strategy for valorization of the plant biopolymer lignin. A critical and often rate-limiting reaction in aromatic catabolism isO-aryl-demethylation of the abundant aromatic methoxy groups in lignin to form diols, which enables subsequent oxidative aromatic ring-opening. Recently, a cytochrome P450 system, GcoAB, was discovered to demethylate guaiacol (2-methoxyphenol), which can be produced from coniferyl alcohol-derived lignin, to form catechol. However, native GcoAB has minimal ability to demethylate syringol (2,6-dimethoxyphenol), the analogous compound that can be produced from sinapyl alcohol-derived lignin. Despite the abundance of sinapyl alcohol-based lignin in plants, no pathway for syringol catabolism has been reported to date. Here we used structure-guided protein engineering to enable microbial syringol utilization with GcoAB. Specifically, a phenylalanine residue (GcoA-F169) interferes with the binding of syringol in the active site, and on mutation to smaller amino acids, efficient syringolO-demethylation is achieved. Crystallography indicates that syringol adopts a productive binding pose in the variant, which molecular dynamics simulations trace to the elimination of steric clash between the highly flexible side chain of GcoA-F169 and the additional methoxy group of syringol. Finally, we demonstrate in vivo syringol turnover inPseudomonas putidaKT2440 with the GcoA-F169A variant. Taken together, our findings highlight the significant potential and plasticity of cytochrome P450 aromaticO-demethylases in the biological conversion of lignin-derived aromatic compounds.

scholarly journals 3-Acetyl-1-(3-methylphenyl)thiourea

2012 ◽  
Vol 68 (8) ◽  
pp. o2574-o2574 ◽  
Author(s):  
B. Thimme Gowda ◽  
Sabine Foro ◽  
Sharatha Kumar
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Side Chain ◽  
Maximum Deviation ◽  
Methyl Groups ◽  
Compound C ◽  
Ring Motif

In the crystal structure of the title compound, C10H12N2OS, the conformation of the two N—H bonds areantito each other. The amide C=O and the C=S are are alsoantito each other. The N—H bond adjacent to the benzene ring issynto them-methyl groups. The dihedral angle between the benzene ring and the side chain [mean plane of atoms C—C(O)N—C—N; maximum deviation 0.029 (2) Å] is 14.30 (7)°. There is an intramolecular N—H...O hydrogen bond generating anS(6) ring motif. In the crystal, the molecules are linkedviaN—H...) hydrogen bonds, forming chains propagating along [001]. The S atom is disordered and was refined using a split model [occupancy ratio 0.56 (4):0.44 (4)].

Degradation of bile acid side chain with lead tetraacetate

1968 ◽  
Vol 9 (50) ◽  
pp. 5173-5174 ◽  
Author(s):  
A.S. Vaidya ◽  
S.M. Dixit ◽  
A.S. Rao
Keyword(s):  
Bile Acid ◽  
Lead Tetraacetate ◽  
Side Chain
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