scholarly journals Biosynthetic studies on aromatic carotenoids. Biosynthesis of chlorobactene

1973 ◽  
Vol 136 (2) ◽  
pp. 395-404 ◽  
Author(s):  
S. E. Moshier ◽  
D. J. Chapman
Keyword(s):  
Benzene Ring ◽  
Specific Radioactivity ◽  
Oxidative Degradation ◽  
Mevalonic Acid ◽  
Methyl Group ◽  
Biosynthetic Studies ◽  
Benzenecarboxylic Acids

1. The incorporation of [2-14C]mevalonic acid by Chloropseudomonas ethylica strain 2K into chlorobactene was studied. 2. Oxidative degradation of chlorobactene of constant specific radioactivity produced labelled benzenecarboxylic acids and indicated that the benzene ring originates from mevalonic acid. 3. Decarboxylation studies demonstrated a stereospecific methyl migration in the formation of the 1,2,5-trimethylphenyl group of chlorobactene. The migrating methyl group was derived from the C-3′ position of mevalonic acid.

XXI.—The Synthesis of Some Methyl- and Dimethylfluoranthenes

1972 ◽  
Vol 69 (4) ◽  
pp. 281-286
Author(s):  
H. F. Andrew ◽  
Neil Campbell ◽  
E. M. Swan ◽  
N. H. Wilson
Keyword(s):  
Benzene Ring ◽  
Propionic Acid ◽  
Hydrofluoric Acid ◽  
Phenyl Ring ◽  
Ring Closure ◽  
Methyl Group ◽  
Image Position

3-Methylfluorene-9-propionic acid (1) with hydrofluoric acid undergoes ring-closure on the substituted ring to give 1,2,3,10b-tetrahydro-5-methylfluoranthen-3-one (II).Wolff-Kishner reduction of the ketone yielded l,2,3,10b-tetrahydro-5-methylfluoranthene which on dehydrogenation gave 2-methylfluoranthene (III, R=H) identical with a sample prepared according to the method of Tucker (1952) and differing from 8-methylfluoranthene. This proved that ring-closure of (I) had occurred as expected on the methyl-bearing benzene ring. In this instance ring-closure occurs in the position meta to the methyl group and is reminiscent of the similar ring-closure of 2-phenyl-2-p-tolylpropionic acid to give 6-methyl-3-phenylindanone (Pfeiffer and Roos 1941). It thus provided a further example of the limitations of von Braun's statement that Friedel-Crafts ring-closure occurs much less readily at the position meta to a methyl group than on a phenyl ring (von Braun, Manz and Reinsch 1928).

scholarly journals Benzazole derivatives, IV: Reaction of 1,2,3-trimethylbenzimidazolium salts with aromatic aldehydes

2005 ◽  
Vol 70 (12) ◽  
pp. 1381-1388 ◽  
Author(s):  
Cernatescu Corina ◽  
Comanita Eugenia
Keyword(s):  
Ir Spectroscopy ◽  
Benzene Ring ◽  
Absorption Spectroscopy ◽  
Electronic Absorption ◽  
Aromatic Aldehydes ◽  
Electronic Absorption Spectroscopy ◽  
Methyl Group ◽  
Practical Applications ◽  
Hemicyanine Dyes

1,2,3-Trimethylbenzimidazolium iodide and its analogue salts with one or two substituents on benzene ring (X=NO2,Br,Cl,CH3) are, due to the reactivity of the 2-methyl group, able to react with para-substituted aromatic aldehydes (X=OH,OCH3,CH3,NMe2,NO2) using piperidine as a catalyst. 1-Methyl-2-styrylbenzimidazole iodomethylates were obtained and their structure elucidated by means of NMR and IR spectroscopy. The compounds are interesting as hemicyanine dyes. They lend themselves to studies based on electronic absorption spectroscopy and they have potential practical applications linked to their photosensitive properties.

Competitive fluorination on methyl-group and benzene-ring during the anodic fluorination of fluorotoluenes in Et4NF · mHF

1998 ◽  
Vol 87 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Kunitaka Momota ◽  
Tetsuo Yonezawa ◽  
Katsuji Mukai ◽  
Masayuki Morita
Keyword(s):  
Benzene Ring ◽  
Methyl Group

scholarly journals 2,5-Dimethoxy-3,4,6-trimethylbenzaldehyde

IUCrData ◽  
2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Ravindra Wickramasinhage ◽  
C. John McAdam ◽  
Jim Simpson
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Methyl Group ◽  
Compound C

In the molecule of the title compound, C12H16O3, the methyl and aldehyde substituents are disordered over four inversion-related C atoms on the benzene ring with an occupancy ratio of 0.75:0.25. The crystal structure features weak C—H...O hydrogen bonds and C—H...π contacts between a methoxy/methyl group and the benzene ring.

scholarly journals 5,8-Dimethoxy-3,9-dimethyl-3a,4,9,9a-tetrahydro-4,9-epoxynaphtho[2,3-d]isoxazole

2014 ◽  
Vol 70 (5) ◽  
pp. o544-o544 ◽  
Author(s):  
Alan J. Lough ◽  
Jaipal R. Nagireddy ◽  
William Tam
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Title Compound ◽  
Three Dimensional ◽  
Methyl Group ◽  
Isoxazole Ring ◽  
Compound C ◽  
Dimensional Network ◽  
Weak Hydrogen Bonds

The title compound, C15H17NO4, is theexoisomer with asynarrangement of the O atom in the isoxazole ring to the methyl group of the bicyclic alkene. The dihedral angle between the isoxazole ring and the benzene ring is 7.42 (9)°. In the crystal, weak C—H...O hydrogen bonds link molecules, forming a three-dimensional network. The isoxazole O atom is an acceptor for both weak hydrogen bonds.

Nonenzymatic Transformation of Riboflavin into 5,6-Dimethylbenzimidazole

1977 ◽  
Vol 32 (7-8) ◽  
pp. 523-527 ◽  
Author(s):  
Paul Renz ◽  
Rainer Wurm ◽  
Joachim Hörig
Keyword(s):  
Carboxylic Acid ◽  
Specific Radioactivity ◽  
Oxidative Degradation ◽  
Side Chain ◽  
Vitamin B ◽  
Enzymatic Process ◽  
Biosynthetic Precursor ◽  
Alkaline Conditions ◽  
Imidazoline Derivative

Riboflavin, the biosynthetic precursor of the 5,6-dimethylbenzimidazole moiety of vitamin B12, is transformed non-enzymatically into 5,6-dimethylbenzimidazole in small yield on treatment with 1 ɴ or 5 ɴ NaOH at 100 °C. Besides 5,6-dimethylbenzimidazole 1,2-diamino-4,5-dimethylbenzene, 1.2- dihydro-6,7-dimethyl-2-keto-1-ᴅ-ribityl-3-quinoxaline carboxylic acid and N-1-ᴅ-ribitylamino-2- amino-4,5-dimethylbenzene can be detected. When [1′-14C] riboflavin is used the 5,6-dimethyl­benzimidazole contains about 75 per cent of the specific radioactivity of riboflavin. N-1-ᴅ-ribityl- amino-2-amino-4,5-dimethylbenzene is transformed into 5,6-dimethylbenzimidazole more efficiently than riboflavin. Oxygen enhances the yield of 5,6-dimethylbenzimidazole and 1,2-diamino-4,5-di- methylbenzene from riboflavin as well as from N-1-ᴅ-ribitylamino-2-amino-4,5-dimethylbenzene. 1.2- diamino-4,5-dimethylbenzene reacts together with formaldehyde but not with formate to form 5,6-dimethylbenzimidazole under alkaline conditions at 100 °C. It is therefore suggested that the nonenzymatic reaction of riboflavin proceeds via N-1-ᴅ-ribityl- amino-2-amino-4,5-dimethylbenzene and 1,2-diamino-4,5-dimethylbenzene, and that the latter reacts with formaldehyde preferably formed by oxidative degradation of C-1′ of the ribityl side chain to form 5,6-dimethylbenzimidazole via its unstable imidazoline derivative. The possible relevance of these results for the enzymatic process is discussed.

scholarly journals Synthesis of tritium-labelled isopenicillin N, penicillin N and 6-aminopenicillanic acid

1975 ◽  
Vol 151 (3) ◽  
pp. 729-739 ◽  
Author(s):  
J J Usher ◽  
B Loder ◽  
E P Abraham
Keyword(s):  
Specific Radioactivity ◽  
Side Chain ◽  
Subsequent Removal ◽  
Methyl Group ◽  
Protective Groups ◽  
Isopenicillin N

1. Phenoxymethylpenicillin sulphoxide 4-methoxybenzyl ester was labelled with 3H in its 2-β-methyl group. Its specific radioactivity was 362 mCi/mmol. 2. Removal of the side chain of this compound yielded the corresponding ester of 6-aminopenicillanic acid sulphoxide and coupling of the latter with the appropriate protected α-aminoadipic acid gave 4-methoxybenzyloxycarbonylisopenicillin N sulphoxide di-4-methoxybenzyl ester or the corresponding derivative of penicillin N. 3. Removal of the protective groups by hydrogenolysis and reduction of the sulphoxide group yielded 3H-labelled isopenicillin N or penicillin N. 4. 3H-labelled phenoxymethylpenicillin sulphoxide was obtained by hydrogenolysis from its 4-methoxybenzyl ester. Reduction of its sulphoxide group and subsequent removal of the side chain gave 3H-labelled 6-aminopenicillanic acid.

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.

Metal hydride mediated reduction of 3-(alkylthio)oxindoles containing other potentially reducible groups

1997 ◽  
Vol 75 (5) ◽  
pp. 536-541 ◽  
Author(s):  
Terrence J. Connolly ◽  
Tony Durst
Keyword(s):  
Benzene Ring ◽  
Metal Hydride ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Ester Group ◽  
Methyl Group ◽  
Mediated Reduction

The reduction of several 3-(methylthio)oxindoles bearing ester groups on the benzene ring has been studied. The reaction is very dependent on the substitution of the oxindole, and the position of the ester group. Deprotonation of the C3 center by the metal hydride is the major initial pathway. This deprotonation plays a role in the reduction of the pendant ester group. Ester groups ortho, and presumably para, to C3 are very difficult to reduce, reaction only occurring with excess LiAlH4 at elevated temperatures. Once reduction starts, it is very difficult to stop, with reduction of the ester to a methyl group being observed. When deprotonation at this center is blocked, ester reduction becomes straightforward and can be accomplished at room temperature with LiEt3BH. Keywords: oxindole, reduction, anion.

scholarly journals Benzazole derivatives, VI: Synthesis of some 2-styrylbenzimidazoles and their quaternization

2005 ◽  
Vol 11 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Corina Cernatescu ◽  
Eugenia Comanita
Keyword(s):  
High Temperature ◽  
Benzene Ring ◽  
Methyl Iodide ◽  
1H Nmr ◽  
Aromatic Aldehydes ◽  
Spectral Measurements ◽  
Methyl Group ◽  
Alternative Method ◽  
Ethylene Bond

In this paper an alternative method for obtaining styrylbenzimidazolium iodides was described. Thus, some 1-methyl-2-styrylbenzimidazoles were synthesized by the condensation of 1,2-dimethylbenzimidazoles containing a mono- or di-substituted benzene ring (X = NO2, Br), at their reactive 2-methyl group with aromatic aldehydes by heating at high temperature. Some of the 2-styrylbenzimidazoles were proved to be able to convert into benzimidazolium quaternary iodides by treating them with methyl iodide in an autoclave. The structures of the 2-styrylbenzimidazoles and corresponding iodomethyl derivatives were investigated by IR and 1H-NMR spectral measurements. The obtained compounds are valuable due to their structures of polyenic dyes, with a photoexcitable ethylene bond.

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