102,194 research outputs found
I classici dell'estetica
No full textLa storia dell’estetica rappresenta un capitolo assolutamente decisivo all’interno delle complesse vicende del pensiero occidentale, dalle sue origini fino agli ultimi sviluppi contemporanei. Il rinvenimento dello statuto epistemologico della disciplina, che la manualistica riconduce correttamente alla metà del XVIII secolo, e più precisamente alla definizione che ne darà Baumgarten nel 1750 come “gnoseologia inferior”, costituisce infatti il punto di arrivo di una riflessione sul “non so che” estetico che affonda le radici nei grandi dibattiti filosofici della più pura tradizione filosofica antica e moderna, ma anche il punto di partenza di una ricerca che oggi pare non essersi ancora esaurita.
Nella molteplicità di personaggi e problematiche che hanno caratterizzato tale dibattito, in questo volume si è optato per identificare quelle figure, da Platone a Nietzsche, che ne hanno costituito i capisaldi riconosciuti e che possono per questo essere ricondotti alla categoria di “classico”
Synthesis of enantiopure highly functionalized pyrrolizines and indolizines from natural alpha-amino acids : an experimental and theoretical investigation
No full textVariously substituted enantiopure 2-benzylamino-1-hydroxymethyl-2,3- dihydro-1H-pyrrolizines and 6-benzylamino-5,6,7,8-tetrahydroindolizin-8-ols have been prepared. The reaction sequence starts from L-α-amino acids and involves an intramolecular cycloaddition of pyrrole-based nitrone intermediates. A theoretical investigation at the HCTH/6-311+G(d,p)//HCTH/6-31+G(d) level of theory was performed with the aim of rationalizing the effects of substituents on the regiochemistry of the cycloaddition reaction
A facile synthesis of 2-methyl-1,4-benzodiazepin-5-ones via intramolecular azide cycloaddition
No full textIt is well known that a large array of pharmaceuticals contain the 1,4-benzodiazepine skeleton. A number of them are 1,4-benzodiazepin-5-ones, e.g. the antibiotic neothramycin, the antidepressant flumazenil, and the antihistaminic clobenzepam(1-5). The literature on this subject, although very copious, is mainly constituted by patents. Therefore, both new synthetic methods and new representatives of this class of compounds are valuable targets. This paper describes a facile and general synthesis of 2-methyl-1,4-benzodiazepin-5-ones based on an intramolecular azide cycloaddition
THE INTRAMOLECULAR AZIDE CYCLOADDITION ROUTE TO TRIAZOLAM ANALOGS
No full textA facile synthesis of [1,2,3]triazolo[1,5-a][1,4]benzodiazepines starting from isatoic anhydrides and involving an intramolecular azide cycloaddition as the key step is reported
SITE SELECTIVITY AND REGIOSELECTIVITY OF NITRILE OXIDE CYCLOADDITIONS TO N,N-DIARYLAMINOALLENES
No full textIntramolecular nitrile imide cycloadditions onto the furan ring: synthesis of the new 3a,4-dihydro-6H-difuro[3,2-c;3,4-d]pyrazole skeleton
No full textIntramolecular nitrile imide cycloadditions onto the furan ring have been exploited in the construction of the hitherto unknown 3a,4-dihydro-6H-difuro[3,2-c;3,4-d]pyrazole skeleton
The intramolecular azide cycloaddition route to triazolam analogues
No full textA facile synthesis of [1,2,3]triazolo[1,5-a][1,4]benzodiazepines starting from isatoic anhydrides and involving an intramolecular azide cycloaddition as the key step is reported
Intramolecular reactions of nitrilimines as a fruitful source of heterocycles
No full textThe multiform intramolecular reactivity of nitrilimines is presented in a systematic way, giving emphasis to its versatile potential in heterocyclic synthesis
NOVEL-APPROACH TO 1-ARYL-1H-4,1,2-BENZOXADIAZINES INVOLVING A SMILES REARRANGEMENT
No full textSome representatives of the title ring system have been obtained from ortho-(aryloxy)phenylhydrazonyl chlorides through a pathway involving (i) nitrile imide formation, (ii) Smiles rearrangement and (iii) intramolecular nucleophilic addition
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