enaminones was achieved to access naphtho[1,8-bc]pyrans by oxidative annulation to internal alkynes. 1-Naphthols might be formed as the only products, depending on the steric and/or electronic environment around the aroyl moiety of the aryl enaminones or the electronic impact from the alkynes. With propargyl alcohols as the masked terminal alkynes, aryl enaminones underwent rhodium(III)- or rhodium(I)-catalyzed
铑 (III) 催化的芳基烯胺酮的三 C-H 键活化通过氧化环化成内部炔烃来获得萘并[1,8- bc ]吡喃。1-萘酚可能作为唯一的产物形成,这取决于芳基烯胺酮的芳酰基部分周围的空间和/或电子环境或来自炔烃的电子影响。使用炔丙醇作为掩蔽的末端炔烃,芳基烯胺酮经历铑 (III) 或铑 (I) 催化的内部烯基 C-H 键活化以提供官能化的丁-2-烯-1,4-二酮。所得萘并[1,8- bc ]吡喃具有高荧光,可通过氯化、溴化和二氟甲基化进一步转化,证明了合成方案的潜在实用性。
Zinc(II)-Catalyzed [2+2+1] Annulation of Internal Alkenes, Diazooxindoles, and Isocyanates to Access Spirooxindoles
Zinc(II)-catalyzed [2+2+1] annulation of internal alkenes, diazooxindoles, and isocyanates was successfully developed for the construction of multisubstituted spirooxindoles. This multicomponent transformation involves in situ generation of a sulfur-containing spirocyclic intermediate from the [4+1] annulation of diazooxindole to sulfonyl isocyanate, which subsequently reacts as a 1,3-dipole with the
Infrared spectra and theoretical study of the conformations of substituted benzoylketene-S,S-acetals
作者:A. Perjéssy、W. -D. Rudorf、D. Loos、Z. Šusteková
DOI:10.1007/bf00811088
日期:1994.12
The C=O stretching frequencies of substituted benzoylketene-S,S-dimethylacetals (1a-1o) and benzoylketene-S,S-ethyleneacetals (2a-2m) were measured in CHCl3 and CCl4 and correlated with the Hammett substituent constants. The correlations were split into two different and well separated lines for compounds containing electron donor and electron acceptor substituents, which were assigned to s-trans and s-cis quasiplanar conformations. The correlations of carbonyl stretching frequencies with C=O bond orders and oxygen atom charge densities calculated using the semiempirical AM1 method reveal similar results consistent with assignments of structures 1 and 2 to two quasiplanar conformations. The preparation of some new benzoylketene-S,S-acetals is reported as well.
Hydroxyl-Directed Rh(III)-Catalyzed C–H Functionalization: Access to Benzo[<i>de</i>]chromenes
作者:Xing-Mei Hu、Rong Huang、Qiu-Lin Wen、Ying-Gang Duan、Xin-Ling Cao、Sheng-Jiao Yan