Reaction of N-Vinylic Phosphazenes Derived from β-Amino Acids with Aldehydes. Azadiene-Mediated Synthesis of Dihydropyridines, Pyridines, and Polycyclic Nitrogen Derivatives
摘要:
Enamino phosphonium salts 2 are obtained by 1,2-addition of hydrogen chloride to N-vinylic phosphazenes 1 derived from triphenylphosphine. Aza-Wittig reaction of phosphazenes 1 derived from triphenylphosphine and 6 derived from diphenylmethylphosphine with aldehydes 3 leads to the formation of 2-azadienes 7. Reaction of azadienes 7 with enamines affords dihydropyridines 9 and 11, pyridines 12, and bicyclic nitrogen heterocycles 15-18 in a regioselective fashion, while heterodiene 20 reacts in the same way with pyrrolidinocyclohexanone giving 1-azaphenanthrene compound 21. Reaction of enamino phosphonium salts 2 with aldehydes 3 gives symmetrical dihydropyridines 5.
Synthesis and Reactivity of Electron-Poor 2-Azadienes. [4 + 2] Cycloaddition Reactions with Alkenes and Enamines
摘要:
Electron deficient 2-azadienes derived from beta-amino acids 3 are obtained by aza-Wittig reaction of N-vinylic phosphazenes 4 with carbonyl compounds. Inverse electron demand Diels-Alder reaction of azadienes 3 with trans-cyclooctene 7 and cis,trans-cyclooctadiene 8 leads to the formation of trans-cycloalkanotetrahydropyridines 10. Heterodienes 3 also react with enamines 13, 14, and 18 affording pyridine derivatives 16, 17, and 20 in a regioselective fashion. Norbornadiene 11, a less strained olefin than cycloalkenes 7 and 8, requires the presence of lithium perchlorate as catalyst in a nonaqueous solvent like ether, to give cycloadducts 12.
Regioselective synthesis of pyridines and dihydropyridines derived from β-amino acids and aminophosphonates by reaction of N-vinylic phosphazenes with α,β-unsaturated ketones
作者:Francisco Palacios、Esther Herrán、Gloria Rubiales、Concepción Alonso
DOI:10.1016/j.tet.2007.03.146
日期:2007.6
Reaction of N-vinylic phosphazenes with α,β-unsaturated ketones leads to the formation of pyridines derivedfrom β-amino acids in a regioselective fashion. The use of functionalized enones derivedfrom α-acylstyryl-carboxylates or -phosphonates affords biologically active asymmetrical and symmetrical dihydropyridines substituted with carboxylate or phosphonate groups including nitrendipine, felodipine
Aza-Wittig reaction of N-vinylic phosphazenes with carbonyl compounds. Azadiene-mediated synthesis of dihydropyridines and pyridines
作者:Francisco Palacios、Gloria Rubiales
DOI:10.1016/0040-4039(96)01352-4
日期:1996.8
diphenylmethylphosphine 4 with carbonylcompounds leads to the formation of 2-azadienes derived from β-aminoacids 5. Dimerization of 2-azadienes 5c,d and reaction of compounds 5 with phosphazene 4 or enemine 6 affords substituted dihydropyridines 7 and 8. Aza-Wittig reaction of phosphazenes 4 with α,β-unsaturated aldehydes gives 3-azatrienes 12, which are easily converted into pyridines 13.
Preparation and reactivity of electron-poor 2-azadienes. Diels-Alder reaction with trans-cyclooctene.
作者:Francisco Palacios、Itziar Perez de Heredia、Gloria Rubiales
DOI:10.1016/s0040-4039(00)79357-9
日期:1993.7
Di-, tri- and tetra- substituted 2-azadienes 3 underbar with electron withdrawing groups have been obtained by Aza-Wittig reaction of N-vinylic phosphazenes with carbonyl compounds. The Diels-Alder reaction of 3 underbar with trans-cyclooctene has also been explored.
Synthesis of N-Functionalized Carbodiimides, Hydantoins, 1,3-Diazetidines, and Imidazolidine Derivatives from N-Vinylic Phosphazenes Derived from b-Amino Acids
作者:Francisco Palacios、Marta Legido、Itziar Pérez de Heredia、José María Ezpeleta、Gloria Rubiales
DOI:10.3987/com-01-9264
日期:——
Synthesis of N-vinylic carbodiimides through Aza-Wittig reaction of N-vinylic phosphazenes with isocyanates is reported. These heterocumulenes are used for the preparation of unsymmetrical ureas and nitrogen heterocycles such as hydantoins, 1,3-diazetidines, imidazolidinones, and bis-imidazolidinone azines.
Regioselective cycloaddition of 3-azatrienes with enamines. Synthesis of pyridines derived from β-aminoacids
Aza-Wittig reaction of N-vinylic phosphazenes with alpha,beta-unsaturated aldehydes leads to the formation of 3-azatrienes through a [2+2]-cycloaddition-cycloreversion process. Subsequent, regioselective [4+2]-cycloaddition of 3-azatrienes with pyrrolidinocycloalkanone affords bicyclic dihydropyridines and pyridines in a regioselective fashion. 2-Heterodiene moiety of azatriene is involved in the formation of the six-membered ring skeleton of pyridine derivatives. (c) 2006 Elsevier Ltd. All rights reserved.