ABSTRACT
Tonsil Actisil FF, which is a commercial bentonitic clay, promotes the formation of cycloveratrylene macrocycles and benzyl oligomers from the corresponding benzyl alcohols in good yields under microwave heating and infrared irradiation in the absence of solvent in both cases. The catalytic reaction is sensitive to the type of substituent on the aromatic ring. Thus, when benzyl alcohol was substituted with a methylenedioxy, two methoxy or three methoxy groups, a cyclooligomerisation process was induced. Unsubstituted, methyl and methoxy benzyl alcohols yielded linear oligomers. In addition, computational chemistry calculations were performed to establish a validated mechanistic pathway to explain the growth of the obtained linear oligomers.
Subject(s)
Bentonite/chemistry , Macrocyclic Compounds/chemical synthesis , Alkenes/chemical synthesis , Benzyl Compounds/chemical synthesis , Catalysis , Computer Simulation , Macrocyclic Compounds/chemistry , Microwaves , Models, Chemical , Models, Molecular , Molecular Conformation , Polymers/chemical synthesis , Quantum Theory , Solvents , ThermodynamicsABSTRACT
Three new diarylbutane lignans, named 9-acetyl-9'-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of (1)H and (13)C NMR spectra.
Subject(s)
Bursera/chemistry , Butanes/chemistry , Lignans/chemistry , Resins, Plant/chemistry , Lignans/isolation & purification , Magnetic Resonance Spectroscopy , Medicine, Traditional , Molecular Structure , Plants, Medicinal/chemistry , Resins, Plant/analysisABSTRACT
From the aerial parts of Salvia occidentalis (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This new compound was named salvioccidentalin and its structure was established by spectroscopic means. A probable biogenetic relationship with salvigenolide from S. fulgens and salvileucalin A and spiroleucantholide from Salvia leucantha is proposed.
Subject(s)
Diterpenes, Clerodane/chemistry , Diterpenes/chemistry , Salvia/chemistry , Humans , Medicine, Traditional , Molecular Structure , Nuclear Magnetic Resonance, BiomolecularABSTRACT
From the aerial parts of Salvia mexicana var. mexicana, two C-10 epimers (α and ß) of salvimexicanolide were isolated. Our interpretation of the data, especially the 13C NMR, led us to conclude that the previously described 13C-NMR spectrum of the α-epimer was not accurately assigned and it actually corresponds to the ß-epimer. The structures proposed for the salvimexicanolides were verified by means of NOESY experiments. Dugesin B, arbutin, naringenin and the mixture of oleanolic and ursolic acids were also isolated from this Salvia spp.
Subject(s)
Diterpenes/chemistry , Diterpenes/isolation & purification , Plant Extracts/chemistry , Salvia/chemistry , Arbutin/isolation & purification , Flavanones/isolation & purification , Lamiaceae , Magnetic Resonance Spectroscopy , Oleanolic Acid/isolation & purification , Plant Components, Aerial , Triterpenes/isolation & purification , Ursolic AcidABSTRACT
Tonsil Actisil FF, a commercial bentonitic clay, promotes the formation of a series of electrophilic-aromatic-substitution products from para-methoxybenzyl acetate in carbon disulfide. The molecules obtained correspond to linear isomeric dimers, trimers, tetramers and a pentamer, according to their spectroscopic data. A clear indication of the title mechanistic pathway for the oligomerization growth was obtained from the analysis of a set of computational-chemistry calculations using the density-functional-theory level B3LYP/6-311++G(d,p). The corresponding conclusions were based on the computed dipole moments, the HOMO/LUMO distributions, and a natural-populations analysis of the studied molecules.
Subject(s)
Acetates/chemistry , Bentonite/chemistry , Models, Theoretical , Computer Simulation , Molecular StructureABSTRACT
Linear oligomerization of 3,5-dimethyl benzyl alcohol is induced by a montmorillonite clay (Tonsil Optimum Extra), producing 1,3,5,7-tetramethyl-9,10-dihydro-anthracene, which, by loss of protons results in the product 1,3,5,7-tetramethylanthracene. It was also found that the compounds 4-(3´,5´-dimethylbenzyl)-1,3,5,7-tetramethyl-9,10-dihydroanthracece and 4-(3´,5´-dimethylbenzyl)-1,3,5,7-tetra-methylanthracene were formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene. 1,3,5,7-Tetramethylanthryl radical cation was formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene; it was characterized by Electronic Paramagnetic Resonance (EPR). On the other hand, a theoretical analysis was performed, allowing the rationalization of the observed products and some of the key reaction steps.
Subject(s)
Bentonite/chemistry , Benzyl Alcohol/chemistry , Electron Spin Resonance Spectroscopy , Molecular Structure , PolymerizationABSTRACT
Three homoisoflavanones were isolated from the "piña" and leaves of Agave tequilana Weber. The compounds were identified as: 5,7-dihydroxy-3-(4-methoxybenzyl)-chroman-4-one (1), 7-hydroxy-3-(4-hydroxybenzyl)-chroman-4-one (2) and 4'-demethyl-3,9-dihydro-punctatin (3). This is the first phytochemical study carried out to Agave tequilana Weber.
Subject(s)
Agave/chemistry , Flavanones/isolation & purification , Photochemical Processes , Plants, Medicinal/chemistryABSTRACT
4-Piperidone and 4-alkyl piperidones react selectively with aromatic hydrocarbons in a mixture of trifluoromethanesulfonic acid (TFSA) and CH(2)Cl(2) to give linear polymers, while N-(2-phenethyl)piperidone undergoes self-polymerization to yield virtually 100%-hyperbranched polymer.
