A Metal-Free Amination of Benzoxazoles – The First Example of an Iodide-Catalyzed Oxidative Amination of Heteroarenes
作者:Tanja Froehr、Christian P. Sindlinger、Ulrich Kloeckner、Peter Finkbeiner、Boris J. Nachtsheim
DOI:10.1021/ol201439t
日期:2011.7.15
An efficient transition-metal-free amination of benzoxazoles has been developed. With catalytic amounts of tetrabutylammoniumiodide (TBAI), aqueous solutions of H2O2 or TBHP as co-oxidant and undermild reaction conditions, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 93%. First mechanistic experiments indicate the in situ iodination of the secondary amine as the
已经开发出有效的无过渡金属苯并恶唑胺化的方法。用催化量的四丁基碘化铵(TBAI),H 2 O 2或TBHP水溶液作为助氧化剂,并在温和的反应条件下,以高达93%的优异收率分离出了非常理想的2-氨基苯并恶唑。最初的机械实验表明,仲胺的原位碘化是假定的活化方式。
Synthesis of Naphthoxazoles by Photocyclization of 4-/5-(Phenylethenyl)oxazoles
The biological activity of naphtho[1,2‐d]oxazoles and heterobenz[1,2‐d]oxazoles prompted us to investigate the photochemical synthesis of substituted naphtho[1,2‐d/2,1‐d]oxazoles. The required p‐ and o‐phenyl‐substituted 5‐arylethenyloxazoles were prepared by the Van Leusen reaction. The substituted 4‐(aryl/heteroarylethenyl)oxazoles were prepared by the Wittig reaction.
萘并[1,2- d ]恶唑和杂苯并[1,2- d ]恶唑的生物活性促使我们研究取代的萘并[1,2- d / 2,1- d ]恶唑的光化学合成。所需的对-和邻-苯基取代的5-芳基乙烯基恶唑是通过Van Leusen反应制备的。取代的4-(芳基/杂芳基乙烯基)恶唑是通过Wittig反应制备的。
A Metal-Free Oxidative Amination of Benzoxazoles with Primary Amines and Ammonia
An efficient synthesis of 2-aminobenzoxazoles is described by a direct oxidative amination of unfunctionalized benzoxazoles with primary amines. The reaction could be performed in the absence of transition metals by using catalytic amounts of a quaternary ammonium iodide and tert-butylhydroperoxide as a cheap and easy-to-handle co-oxidant. In addition to primary amines, aqueous solutions of NH3 were used to introduce a primary amine group into the heterocyclic core.
A symmetric cyanine of the formula:
wherein:
X is selected from the group consisting of O, S and C(CH3)2;
W represents non-metal atoms required to form a benzo-condensed or a naphto-condensed ring;
R1 is selected from the group consisting of (CH2)nCH3, (CH2)nSO3- and (CH2)nSO3H, wherein n is an integer selected from 0 to 6 when R1 is (CH2)nCH3, and n is an integer selected from 3 to 6 when R1 is (CH2)nSO3- or (CH2)nSO3H;
R2 and R3 are independently selected from the group consisting of H, a sulphonic moiety and a sulphonate moiety;
Q is selected from the group consisting of:
wherein q is 0 or 1 and D is selected from the group consisting of:
-C≡C-G;
and
wherein A is O or S and G is, or contains a N, O or S nucleophile moiety or is, or contains a moiety capable of reacting with N, O or S nucleophiles.
The present invention provides a polymerizable compound having high storage stability without causing crystal precipitation when added to a polymerizable composition. The present invention also provides a polymerizable composition containing the compound. When the filmy polymer produced through polymerization of the polymerizable composition is irradiated with UV light, it hardly discolors or peels from substrate. Further, the present invention provides a polymer produced through polymerization of the polymerizable composition and an optically anisotropic body using the polymer.