4028-66-4Relevant articles and documents
Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum
Rinkel, Jan,Babczyk, Alexander,Wang, Tao,Stadler, Marc,Dickschat, Jeroen S.
, p. 2974 - 2990 (2019/01/05)
The volatiles emitted by the ascomycetes Hypoxylon griseobrunneum and Hypoxylon macrocarpum (Hypoxylaceae, Xylariales) were collected by use of a closed-loop stripping apparatus (CLSA) and analysed by GC-MS. The main compound class of both species were polysubstituted benzene derivatives. Their structures could only be unambiguously determined by comparison to all isomers with different substitution patterns. The substitution pattern of the main compound from H. griseobrunneum, the new natural product 2,4,5-trimethylanisole, was explainable by a polyketide biosynthesis mechanism that was supported by a feeding experiment with (methyl-2H3)methionine.
Molecular Dynamics Simulations of the Initial-State Predict Product Distributions of Dediazoniation of Aryldiazonium in Binary Solvents
Cruz, Gustavo N.,Lima, Filipe S.,Dias, Luís G.,El Seoud, Omar A.,Horinek, Dominik,Chaimovich, Hernan,Cuccovia, Iolanda M.
, p. 8637 - 8642 (2015/09/15)
The dediazoniation of aryldiazonium salts in mixed solvents proceeds by a borderline SN1 and SN2 pathway, and product distribution should be proportional to the composition of the solvation shell of the carbon attached to the -N2 group (ipso carbon). The rates of dediazoniation of 2,4,6-trimethylbenzenediazonium in water, methanol, ethanol, propanol, and acetonitrile were similar, but measured product distributions were noticeably dependent on the nature of the water/cosolvent mixture. Here we demonstrated that solvent distribution in the first solvation shell of the ipso carbon, calculated from classical molecular dynamics simulations, is equal to the measured product distribution. Furthermore, we showed that regardless of the charge distribution of the initial state, i.e., whether the positive charge is smeared over the molecule or localized on phenyl moiety, the solvent distribution around the reaction center is nearly the same.
Mimicking the reaction of phenylalanine ammonia lyase by a synthetic model
Rettig, Martin,Sigrist, Andreas,Retey, Janos
, p. 2246 - 2265 (2007/10/03)
Phenylalanine and histidine ammonia lyases (PAL and HAL) catalyze the reversible conversion of α-amino acids to the corresponding acrylic acids by elimination of ammonia. The prosthetic group 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) at the active site of both enzymes supposedly undergoes an electrophilic attack at the aromatic nucleus in the first step of the mechanism of action. Since no chemical analogy existed for such an electrophile-assisted elimination, we synthesized model compounds, some portion of which mimicked the essentials of the substrate phenylalanine and another portion the electrophilic Michael acceptor in a sterically appropriate distance. The first model, (±)-rel-(1R,2S,3S)-3-[1-methylidene-2-oxo-2-(pyrrolidin-1-yl)ethyl]-2-phenyl cyclohexanamine (7) did not react under Friedel-Crafts conditions in the expected way (Scheme 2). The second model compound (±)-2-rel-(1R,2S,3S)-3-(dimethylamino)-2-(3-methoxyphenyl)cyclohexyl]prop-2- enal (12) with a more nucleophilic methoxyphenyl and a more electrophilic α,β-unsaturated carbonyl moiety, underwent an intramolecular Friedel-Crafts-type substitution, but no elimination of the dimethylamino group (Scheme 4). The third model compound, (±)-γ-[(dimethylamino)methyl]-3-methoxy-2,4,6-trimethyl-α-methylidenebenze nebutanal (25) eliminated dimethylamine upon treatment with Lewis acids and subsequent hydrolysis of the intermediate (Scheme 6). When the 3-methoxy-2,4,6-trimethylphenyl moiety of 25 was replaced by the 2,4,6-trimethyl-3-nitrophenyl group, no elimination product could be observed (Scheme 7).
