16665-90-0Relevant academic research and scientific papers
Photoinduced rearrangement of aromatic N-chloroamides to chloroaromatic amides in the solid state: Inverted Πn-ΣN occupational stability of amidyl radicals
Naumov, Pan?e,Topcu, Yildiray,Eckert-Maksi?, Mirjana,Glasovac, Zoran,Pavo?evi?, Fabijan,Kochunnoonny, Manoj,Hara, Hideyuki
body text, p. 7834 - 7848 (2011/08/09)
We report a solid-state photochemical rearrangement reaction by which aromatic N-chloroamides exposed to UV light or sunlight are rapidly and efficiently converted to chloroaromatic amides. The course, the intermediate (nascent chlorine vs dichlorine) and the outcome of the reaction depend on the excitation (exposure time, wavelength, and intensity) and on inherent structural factors (the directing role of the substituents and, as demonstrated by the different reactivity of two polymorphs of N-chlorobenzanilide, the supramolecular structure). The photolysis of the chloroamides provides facile photochemical access to arylamidyl radicals as intermediates, which in the absence of strong hydrogen bond donors are stabilized in the reactant crystals by C-H/N-Cl?π interactions, thus, providing insight into their structure and chemistry. Thorough theoretical modeling of the factors determinant to the stability and the nature of the spin-hosting orbital evidenced that although the trans-Π|| state (Np spin) of the amidyls is normally preferred over the trans-Σ⊥ configuration (Nsp2 spin), stabilization by aromatic conjugation, steric and geometry factors, as well as by electronic effects from the substituents can decrease the Π-Σ gap in these intermediates significantly, resulting in similar and, in the case of the orthogonal amide-phenyl disposition, even reversed population of the unpaired electron in the two orbitals. Quantitative correlation established that the inverted occupational spin stability and the ΠN-ΣN crossover are collectively facilitated by the conformation, valence angle, and disposition of the amide group relative to the aromatic system. The stabilization and detection of a trans-Σ⊥ radical was experimentally accomplished by steric locking of the orthogonal trans-amide conformation with double ortho-tert-butyl substitution at the phenyl ring. The effects of the single para-phenyl substituents on the relative occupational stability of the arylamidyl radical states point out to non-Hammett behavior. By including cumulative electronic effects from multiple substitutions, four distinct families of the aromatic amidyl radicals were identified. The Π∥ state is the most stable structure of the N-phenylacetamidyl radical and of most of the substituted arylamidyls, although the Σ⊥ and Π⊥ states can also be stabilized by introducing tert-butyl and nitro groups, respectively.
Highly selective stereodivergent synthesis of separable amide rotamers, by using Pd chemistry, and their thermodynamic behavior
Ototake, Nobutaka,Nakamura, Masashi,Dobashi, Yasuo,Fukaya, Haruhiko,Kitagawa, Osamu
supporting information; experimental part, p. 5090 - 5095 (2009/12/26)
By using Pd chemistry, a highly selective stereodivergent synthesis of separable amide rotamers was achieved. Allylation of 2,4,6-tri-tert-bu- tylanilides using a π-allyl-Pd catalyst gave N-allylated anilides with moderate-to-excellent Z-rotamer selectivi
Stereoselective synthesis of separable amide rotamers using π-allyl-Pd catalyst and their thermodynamic behavior
Ototake, Nobutaka,Taguchi, Takeo,Kitagawa, Osamu
, p. 5458 - 5460 (2008/12/21)
Separable amide rotamers were prepared with moderate to excellent Z-selectivities by N-allylation of 2,4,6-tri-tert-butyl-NH-anilides using a π-allyl-Pd catalyst. The present allylation proceeded through a unique mechanism involving O-allylation and the subsequent O,N-allylic rearrangement. The prepared amide rotamers of Z-major changed to equilibrium mixtures of E-major when heated in toluene.
Sterically hindered aromatic compounds. XI. Spectral and product studies of the decomposition of N-nitrosoacetanilides
Barclay, L. Ross C.,Dust, Julian M.
, p. 607 - 615 (2007/10/02)
Decomposition of N-nitroso-2,4,6-tri-tert-butylacetanilide (1) in benzene forms products 2,4,6-tri-tert-butylphenyl acetate (3), 3-(3,5-di-tert-butylphenyl)-2-acetoxy-2-methylpropane (4), and hydrocarbons 3-(3,5-di-tert-butylphenyl)-and 1-(3,5-di-tert-butylphenyl)-2-methylpropene (5 and 6) explained by a reactive aryl cation (2), the rearranged products (4, 5, 6) originating from a 1,5-hydride shift from an ortho tert-butyl group in 2.In contrast, decomposition of 1 in triethylamine forms products 1,3,5-tri-tert-butylbenzene (10), 2,4,6-tri-tert-butylacetanilide (15), and 2-(3,5-di-tert-butylphenyl)-2-methylpropanal oxime (13), expected of a free radical pathway.Electron spin resonance evidence is given for intermediates formed by rearrangement of the 2,4,6-tri-tert-butylphenyl radical and spin trapped by the nitroso group of 1.CIDNP and esr studies on the dediazoniation of N-nitrosoacetanilide and aniline in the presence of tertiary amines support the proposed electron transfer mechanism.The results are briefly discussed in terms of the role of steric effects and electron transfer in the dediazoniation of nitrosoacetanilides and diazonium salts.
