ABSTRACT
A novel Pd(OAc)2-NFSI-TFA system was developed for the highly selective ortho-monofluorination directed by diverse aryl-N-heterocyclic directing groups e.g., quinoxaline, pyrazole, benzo[d]oxazole, and pyrazine derivatives. A Pd(II/IV) catalytic cycle was proposed based on the ESI-MS/MS studies.
ABSTRACT
An iron-catalyzed benzylic vinylation was developed to transfer the carbon atom in the N,N-dimethyl moiety of N,N-dimethylacetamide (or N,N-dimethylformamide) to 2-methyl azaarenes to generate 2-vinyl azaarenes.
Subject(s)
Iron/chemistry , Phenazines/chemical synthesis , Acetamides/chemistry , Catalysis , Dimethylformamide/chemistry , Hydrogenation , Molecular Structure , Phenazines/chemistryABSTRACT
Both 1,5-benzodiazepine and quinoxaline derivatives are important heterocycles in pharmaceuticals. We describe an efficient and clean method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones catalyzed by sodium tetrachloroaurate(III) dihydrate under mild conditions. The catalyst was shown to be equally effective for the synthesis of quinoxalines from o-phenylenediamine and alpha-bromo ketones under the similar reaction conditions. This method produced good yields.
ABSTRACT
In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl(4).4H(2)O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant.
Subject(s)
Aldehydes/chemistry , Aminophenols/chemistry , Chlorides/chemistry , Gold Compounds/chemistry , Oxazoles/chemical synthesis , Oxygen/chemistry , CatalysisABSTRACT
A simple and convenient procedure for stereoselective synthesis of (Z)-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCl system to form selenide anions, which then undergo S(N)2' substitution of Baylis-Hillman adducts to produce the (Z)-allyl selenides.
Subject(s)
Organoselenium Compounds/chemistry , Selenium Compounds/chemistry , Selenium Compounds/chemical synthesis , Magnetic Resonance Spectroscopy , Molecular Structure , StereoisomerismABSTRACT
Stereoselective transformation of Baylis-Hillman acetates 1 into corresponding (Z)-allyl iodides 2 has been achieved by treatment of 1 with samarium triiodide in THF. Remarkable rate acceleration of samarium triiodide-mediated iodination of 1 was found when ionic liquid 1-n-butyl-3-methyl-imidazolium tetrafluroborate ([bmim]BF(4)) was used as reaction media in stead of THF. This novel approach proceeds readily at 50 degrees C within a few minutes to afford (Z)-allyl iodides 2 in excellent yields. A mechanism involving stereoselective iodination of the acetates of Baylis-Hillman adducts by samarium triiodide is described, in which a six-membered ring transition state played a key role in the stereoselective formation of 2.