Home About us Contact
|
Home About us Contact | ||
|
|
||
Triethyl Phosphite (triethyl + phosphite)
Selected AbstractsPhosphonylation of 2-Amino- and 2-Amido-3-bromopyridines and 2-Amino-3-chloroquinoxalines with Triethyl PhosphiteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2009M. Shaker S. Adam Abstract The Tavs reaction of 2-amino- and 2-acylamido-3-bromopyridines 1 and 2 with triethyl phosphite in the presence of palladium acetate or chloride allows the synthesis of 2-amino- and 2-acylamidopyridine-3-phosphonates 3 and 4. A second ring nitrogen atom causes strong activation and leads to excellent yields in the phosphonylation of 2-amino-3-chloroquinoxalines. 2,3-Dichloroquinoxaline does not need a catalyst and undergoes double phosphonylation with sodium diethyl phosphite under Michaelis,Becker conditions. The results show an activating influence of pyridine nitrogen (,M) and deactivating influence of the amino group (+M). The reactivity of 1 and 2 in the Tavs coupling is compared with that of the 3-NH-2-bromopyridine position isomers and 2-bromoanilines and discussed in terms of the opposite effects of pyridine and amino(amido) nitrogen and different position of the N atoms towards the reaction site. The advantage of the Tavs reaction is the easy optimization because neither auxiliary ligands are required nor a base to trap the halide or a solvent. Triethyl phosphite itself acts as ligand and forms Pd0{P(OEt)3}n in the initial phase of the reaction. The structures of the products and the expected intramolecular N,H···O=P hydrogen bridging bonds were proven by solution NMR and by X-ray crystal structure analysis of single crystalline 3c.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] ChemInform Abstract: Reactions of ,-Alkoxyvinyl Trihalogenomethyl Ketones with Triethyl Phosphite.CHEMINFORM, Issue 6 2008Karen V. Tarasenko Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: One-Pot Synthesis of Stable Phosphite Ylides by Three-Component Reaction Between Acetylenic Esters, Aldehyde Semicarbazones and Tributyl or Triethyl Phosphite.CHEMINFORM, Issue 6 2008Mohammad Anary-Abbasinejad Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Stereospecific Deoxygenation of Phosphine Oxides with Retention of Configuration Using Triphenylphosphine or Triethyl Phosphite as an Oxygen Acceptor.CHEMINFORM, Issue 12 2005Hai-Chen Wu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Phosphonylation of 2-Amino- and 2-Amido-3-bromopyridines and 2-Amino-3-chloroquinoxalines with Triethyl PhosphiteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2009M. Shaker S. Adam Abstract The Tavs reaction of 2-amino- and 2-acylamido-3-bromopyridines 1 and 2 with triethyl phosphite in the presence of palladium acetate or chloride allows the synthesis of 2-amino- and 2-acylamidopyridine-3-phosphonates 3 and 4. A second ring nitrogen atom causes strong activation and leads to excellent yields in the phosphonylation of 2-amino-3-chloroquinoxalines. 2,3-Dichloroquinoxaline does not need a catalyst and undergoes double phosphonylation with sodium diethyl phosphite under Michaelis,Becker conditions. The results show an activating influence of pyridine nitrogen (,M) and deactivating influence of the amino group (+M). The reactivity of 1 and 2 in the Tavs coupling is compared with that of the 3-NH-2-bromopyridine position isomers and 2-bromoanilines and discussed in terms of the opposite effects of pyridine and amino(amido) nitrogen and different position of the N atoms towards the reaction site. The advantage of the Tavs reaction is the easy optimization because neither auxiliary ligands are required nor a base to trap the halide or a solvent. Triethyl phosphite itself acts as ligand and forms Pd0{P(OEt)3}n in the initial phase of the reaction. The structures of the products and the expected intramolecular N,H···O=P hydrogen bridging bonds were proven by solution NMR and by X-ray crystal structure analysis of single crystalline 3c.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis and chemical transformation of fused tetrazoles derived from 2-bromomethyl- and 2-iodomethyl-3,5,6,7-tetrahydro-4(2H)-benzofuranonesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2006Malose J. Mphahlele The 2-bromomethyl-3,5,6,7-tetrahydrobenzofuranones 1a-d were subjected to triazidochlorosilanesodium azide-mediated Schmidt rearrangement to afford the corresponding tetrazolofuroazepine derivatives 2a-dvia methylene shift. Under similar reaction conditions, the 2-iodomethyl-3,5,6,7-tetrahydrobenzofuranones 1e-h afford mixtures of the corresponding tetrazolofuroazepines 2e-h and the 4-azido-2-iodomethyl-2,3-dihydrobenzofuran derivatives 3a-c. A mechanism is proposed to account for the divergence in the reactivity of these 2-halogenomethyltetrahydrobenzofuranones (X = Br versus I). In turn, the 2-halogenomethyltetrazolofuroazepines 2a,b,d-h and the 4-azido-2-iodomethyl-2,3-dihydrobenzofurans 3a,b underwent nucleophilic substitution with triethyl phosphite and dehydrohalogenation using DBU in refluxing toluene to give the corresponding tetrazolofuroazepines 4a-d and 5a-c and benzofurans 6a,b. [source] | ||||||||||