1569-08-0Relevant articles and documents
Reactions of 2-(Tributylstannyl)-4,4-dimethyl-2-oxazoline with Organic Halides. Unusual Product from Aroyl Halide
Kosugi, Masanori,Fukiage, Akio,Takayanagi, Mitsuhiro,Sano, Hiroshi,Migita, Toshihiko,Satoh, Mitsuo
, p. 1351 - 1354 (1988)
2-(Tributylstannyl)-4,4-dimethyl-2-oxazoline (1) reacted with aroyl chloride smoothly without any palladium catalyst to give the unusual product, bis(N-aroyl-4,4-dimethyl-2-oxazolinylidene) in good yields.The reaction of 1 with other types of halide neede
Additive-free pd-catalyzed α-allylation of imine-containing heterocycles
Kljajic, Marko,Puschnig, Johannes G.,Weber, Hansj?rg,Breinbauer, Rolf
supporting information, p. 126 - 129 (2017/11/27)
An additive-free Pd-catalyzed α-allylation of different imino-group-ontaining heterocycles is reported. The activation of α-CH pronucleophiles (pKa (DMSO) > 25) occurs without the addition of strong bases or Lewis acids using only the Pd/Xantphos catalyst system. The reaction scope has been studied for various 5- and 6-membered nitrogen-containing heterocycles (yields up to 96%). Mechanistic investigations suggest an initial allylation of the imine-N followed by a Pd-catalyzed formal aza-Claisen rearrangement.
Hexaalkylguanidinium salts as ionic liquids - Applications in titanium and aluminium alcoholate assisted synthesis
Arkhipova, Maria,Eichel, Svetlana,Maas, Gerhard
, p. 56506 - 56517 (2015/02/05)
The solubility of titanium and aluminium alcoholates and of titanium tetrakis(trimethylsilanolate) in several hexaalkylguanidinium-based room temperature ionic liquids was screened. The solvent/solute combinations which displayed the highest alcoholate solubility and stability were applied as Lewis-acidic catalytic media for several dehydrating cyclocondensations: lactamisation of ω-aminocarboxylic acids, direct amidation of carboxylic acids, synthesis of oxazolines from carboxylic acids and 2-aminoethanol, lactonisation of 6-hydroxyhexanoic acid, and Paal-Knorr synthesis of pyrroles.
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.
Aryl-oxazoline chelates of first-row transition metals: Structures of {Κ-C,N-(o-C6H4)CMe2(COCH 2CMe2N)}FeCl(py) and [(Κ-C,N-(o-C6H 4)CMe2(COCH2CMe2N)}Cr(μ-Cl)] 2
Volpe, Emily C.,Manke, David R.,Bartholomew, Erika R.,Wolczanski, Peter T.,Lobkovsky, Emil B.
scheme or table, p. 6642 - 6652 (2011/02/27)
Aryl-oxazoline synthons have been explored for the preparation of strong-field first-row transition metal chelate species. With 4,4-dimethyl-2-phenyloxazoline (HPhOx), no CH bond activations afforded complexation, and aside from Zn(Κ-C,N-4,4-Me2-2-(o-C 6H4)oxazoline)2 (Zn(PhOx)2), aryl-coupling reactions were noted with 4,4-dimethyl-2-(2-lithiophenyl)oxazoline (LiPhOx) and MX2; [Κ-N,N-{4,4-Me2-(2-o-C 6H4)-2-oxazoline}2]CoCl2 (1-Co) was structurally characterized. Metalations with 4,4-dimethyl-2-benzyloxazoline (PhCH2Ox) were prone to deprotonation, as exemplified by (Me 2N)3Ti(η-N-(4,4-dimethyl-(2-CHPh)oxazoline)) (2) and bis-N,N′-(4,4-dimethyl-(2-pyridylmethylyl)oxazoline)Fe (3). Oxidative addition of 4,4-dimethyl-2-(2-bromophenylpropan-2-yl)oxazoline (BrPhCMe 2Ox) to Ni(COD)2 provided [{Κ-C,N-(o-C 6H4)CMe2(COCH2CMe 2N)}Ni]2(μ-Br)2 (42). With 4,4-dimethyl-2-(2-lithiophenylpropan-2-yl)oxazoline (LiPhCMe2Ox), salt (FeBr2) metathesis proved uncompetitive with oxazoline ring-opening, as exhibited by [{Κ-N,O-C6H4CMe 2C=NCMe2CH2(μ-O)-}BrFe{Κ-N,O-C 6H4CMe2C=NCMe2CH2(μ-O) -}FeBr]Li {Κ-N,O-C6H4CMe2-C=NCMe 2CH2(μ-O)-}(DME) (5-Fe2Li). Metatheses utilizing (PhCMe2Ox)2Zn, prepared from LiPhCMe 2Ox and ZnCl2, gave structurally characterized dichromium, i.e., [{Κ-C,N-(o-C6H4)CMe2 (COCH 2CMe2N)}Cr]2(μ-Cl)2 (6 2), and iron, i.e., {Κ-C,N-{(o-C6H 4)CMe2(COCH2CMe2N)}Fe(py)Cl (7) products. Bis-aryloxazoline metal complexes proved difficult to prepare, with {Κ-C,N-(o-C6H4)CMe2(COCH 2CMe2N)}2M (M = Ni, 9) the only clear example, although NMR evidence exists for M = Fe (8).
Effect of chain length on radical to carbanion cyclo-coupling of bromoaryl alkyl-linked oxazolines: 1,3-Areneotropic migration of oxazolines
Marshall, Laura J.,Roydhouse, Mark D.,Slawin, Alexandra M. Z.,Walton, John C.
, p. 898 - 911 (2007/10/03)
(Chemical Equation Presented) 2-Halophenylalkyl-2-oxazolines with alkyl chain spacers of two to six C atoms (n = 0-4) were prepared and their S RN1-type reactions with several base systems examined. The best conditions to promote cyclocoupling to the corresponding benzocycloalkane derivatives involved use of LDA in THF. The precursors with 3-C-atom and 4-C-atom spacers gave good yields of 2-(1′-phenylindan-1′-yl)-2- oxazolines and 2-(1-phenyl-1,2,3,4-tetrahydronaphthalen-1-yl)-2-oxazoline, respectively. The major products from the precursor with a 5-C-atom spacer were derivatives of benzocycloheptane in which the oxazoline group had undergone a novel areneotropic migration from the end of the spacer to the benzo ring. The product from reaction of the corresponding 2-C-atom precursor was a 9-oxazolinophenanthrene derivative. EPR spectroscopy showed the intermediates of the LDA-promoted reactions to be radical anions of the product benzocycloalkanes. This supported an SRN1-type chain mechanism involving initial production of aryl radicals connected to azaenolate ions via the spacer groups. Intramolecular radical to carbanion coupling then generated ring-closed benzocycloalkane radical anions that transferred an electron to more precursor. Diastereoselective radical to carbanion cyclo-coupling reactions were carried out with 2-bromophenylpropyl precursors containing chiral 2-oxazolines. The diastereoselectivity achievable was modest, but the product diastereoisomeric Indane derivatives were easily separable by chromatography.
Direct synthesis of 2-oxazolines from carboxylic acids using 2-chloro-4,6-dimethoxy-1,3,5-triazine under mild conditions
Bandgar,Pandit
, p. 2331 - 2333 (2007/10/03)
2-Acyloxy-4,6-dimethoxy-1,3,5-triazines obtained from carboxylic acids and 2-chloro-4,6-dimethoxy-1,3,5-triazine were subsequently treated with 2-amino-2-methyl-1-propanol to afford the corresponding 2-oxazolines in excellent yield at room temperature.
The direct synthesis of 2-Oxazolines from carboxylic esters using lanthanide chloride as catalyst
Zhou, Peiwen,Blubaum, Jason E.,Burns, Christopher T.,Natale, Nicholas R.
, p. 7019 - 7020 (2007/10/03)
Using catalytic amounts of lanthanide III (Ln = La, Sm) chlorides and amino alkoxides as reagents, an one-pot direct synthesis for 2-oxazolines, in good yield, from carboxylic esters has been developed.
Compatibility of Various Carbanion Nucleophiles with Heteroaromatic Nucleophilic Substitution by the SRN1 Mechanism
Wong, Jim-Wah,Natalie Jr., Kenneth J.,Nwokogu, Godson C.,Pisipati, Jyothi S.,Flaherty, Patrick T.,Greenwood, Thomas D.,Wolfe, James F.
, p. 6152 - 6159 (2007/10/03)
Carbanions generated from 2,4,4-trimethyl-2-oxazoline (1a), 2-benzyl-4,4-dimethyl-2-oxazoline (1b), 2,4-dimethylthiazole (13a), 2-benzyl-4-methylthiazole (13b), N,N-dimethylacetamide (17a), tert-butyl acetate (17b), ethyl phenylacetate (17c), N-methyl-N-phenyl-2-butenamide (22), tert-butyl 3-butenoate (25), and dimethyl methylphosphonate (29a) by means of KNH2 in liquid NH3 all reacted with 2-bromopyridine (2) via photoassisted reactions that exhibited characteristics of the SRN1 mechanism. Similar results were obtained in reactions of these carbanions with other substrates, including 2-chloroquinoline (6), iodobenzene (9), bromobenzene (10), and bromomesitylene (11).
SYNTHESIS OF ISOTHIOCYANATES FROM NON-AROMATIC NITROGEN-CONTAINING HETEROCYCLES
Gonda, Jozef,Kristian, Pavol,Mikler, Lubomir
, p. 112 - 117 (2007/10/02)
Investigation of the reaction of thiophosgene with Δ2-oxazolines I, Δ3-thiazolines II, 4H-benzothiazines III, 2-methoxypentahydro-Δ1-azepine IV, theophylline and caffeine showed that only compounds I and IV reacted to give 2-acyloxyethyl isothiocyanates and methyl 6-isothiocyanatohexanoate.The structure of these products was corroborated by IR, 1H NMR, 13C NMR and mass spectral methods.The suitability of the above-mentioned compounds to react is discussed.
