ABSTRACT
The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining α,ß-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(ii) complex formed in situ has been found to be a selective catalyst for the syntheses of building blocks from the corresponding aryl halides and allylic alcohols, with yields ranging from 50% to 90%. The lack of toxic effects of the ligand precursor (1,2,3-triazolium salt) of the palladium(ii) complex for the harpacticoid copepod Amphiascoides atopus allowed us to contrast the efficiency of the catalytic system with the potential impact of the principal waste chemical in global aquatic ecosystems, which has not been previously addressed.
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
A facile and mild macrolactonization reaction of ω-hydroxy acids was developed based on the transesterification of benzotriazole esters. Treatment of ω-hydroxy acids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1-hydroxy benzotriazole (HOBT) in chloroform provided macrolactones in excellent yields. The reactions were performed under basic, neutral and acidic conditions using N,N-dimethylaminopyridine (DMAP), tetrabutylammonium tetrafluoroborate (TBABF(4)) and BF(3)·Et(2)O, respectively. A calcined hydrotalcite was also used instead of DMAP. Finally, to test the scope of the protocol in the synthesis of biologically relevant macrolactones, the total synthesis of Sansalvamide A was carried out.
