115492-23-4Relevant academic research and scientific papers
An alternative approach to differentially substituted 2-oxazoline chalcogen derivatives
De Mello, Murilo B.M.,Clososki, Giuliano C.,Piovan, Leandro,De Oliveira, Alfredo R.M.
supporting information, p. 11 - 16 (2015/07/02)
In this study we present an alternative method to obtain several substituted mono or bis-2-oxazolines containing a chalcogen atom as a tether element. Alkylation of 2-tosyloximethylene-2-oxazoline with an appropriate sodium, lithium or potassium alkoxide yielded the corresponding ether. Introduction of sulfur or selenium was easily accomplished using the corresponding sodium salts. The 77Se NMR for alkyl or aryl 2-methylene-2-oxazoline selenides shows good correlation with the electronegativity pattern of substituents. Most products containing oxazolinyl-chalcogen were stable under the usual experimental conditions. However, the tellurium derivatives showed unusual sensitivity to light and oxygen, decomposing through a very complex mechanistic pathway. As a result of this oxidative process, 4,4-dimethyl-2-oxazoline-2-carbaldehyde could be isolated and fully characterized for the first time, in 17% yield.
Gas-phase reactivity of protonated 2-oxazoline derivatives: Mass spectrometry and computational studies
Vessecchi, Ricardo,Tomaz, Jose Carlos,Santos, Guilherme Purcote Dos,De Oliveira, Alfredo R. Marques,Lopes, Norberto Peporine,Clososki, Giuliano Cesar
experimental part, p. 1061 - 1069 (2012/08/08)
RATIONALE Oxazolines have attracted the attention of researchers worldwide due to their versatility as carboxylic acid protecting groups, chiral auxiliaries, and ligands for asymmetric catalysis. Electrospray ionization tandem mass spectrometric (ESI-MS/MS) analysis of five 2-oxazoline derivatives has been conducted, in order to understand the influence of the side chain on the gas-phase dissociation of these protonated compounds under collision-induced dissociation (CID) conditions. METHODS Mass spectrometric analyses were conducted in a quadrupole time-of-flight (Q-TOF) spectrometer fitted with electrospray ionization source. Protonation sites have been proposed on the basis of the gas-phase basicity, proton affinity, atomic charges, and a molecular electrostatic potential map obtained on the basis of the quantum chemistry calculations at the B3LYP/6-31 + G(d,p) and G2(MP2) levels. RESULTS Analysis of the atomic charges, gas-phase basicity and proton affinities values indicates that the nitrogen atom is a possible proton acceptor site. On the basis of these results, two main fragmentation processes have been suggested: one taking place via neutral elimination of the oxazoline moiety (99 u) and another occurring by sequential elimination of neutral fragments with 72 u and 27 u. These processes should lead to formation of R+. CONCLUSIONS The ESI-MS/MS experiments have shown that the side chain could affect the dissociation mechanism of protonated 2-oxazoline derivatives. For the compound that exhibits a hydroxyl at the lateral chain, water loss has been suggested to happen through an E2-type elimination, in an exothermic step.
A NOVEL PREPARATIVE METHOD FOR α,β-UNSATURATED OXAZOLINES VIA α-PHENYLTHIOOXAZOLINES
Clinet, J. C.,Balavoine, G.
, p. 5509 - 5512 (2007/10/02)
α,β-Unsaturated oxazolines are prepared in excellent yield and with high stereoselectivity, via α-phenylthiooxazolines by the sequence of alkylation-oxidation-dehydrosulfenylation.
