A series of functionalized 2,3-dihydro-1,4-benzoxazines were obtained in moderate to excellent yields via domino [5 + 1] annulations of 2-halo-1,3-dicarbonyl compounds 2 with imines 1 under mild conditions and the application of this method in the synthesis of bioactive analogues, such as functionalized tetracyclic-1,4-benzoxazines which contain two new heterocyclic rings and one quaternary carbon
Abnormal effect of hydroxyl on the longest wavelength maximum in ultraviolet absorption spectra for bis-aryl Schiff bases
作者:Chao-Tun Cao、Wei Zhou、Chenzhong Cao
DOI:10.1002/poc.3672
日期:2017.10
4‐HOArCH=NArY and XArCH=NArOH‐4′, and the second set consists of 2‐HOArCH=NArY and XArCH=NArOH‐2′. Their ultravioletabsorptionspectra were measured and investigated. A very interesting phenomenon was observed by analyzing their wave number νmax (cm−1) of longest wavelength maximum λmax (nm) of ultraviolet. Compared with the change regularity of the νmax of XArCH=NArY (where the X and Y excluded OH), the
The asymmetric Povarov reaction with α‐alkyl styrenes as dienophiles was catalyzed by an N,N′‐dioxide L4–Sc(OTf)3 complex. Enantiopure tetrahydroquinoline derivatives with a quaternary stereocenter at the C4 position were synthesized for the first time. A wide variety of α‐alkyl styrenes and N‐aryl aldimines were tolerated in the reaction, to give excellent diastereo‐ (up to 99:1 d.r.) and enantioselectivities
Rhodium(II) catalyzed multi-component reactions of aryldiazoacetates with titanium(IV) isopropoxide and imines
作者:Xu Zhang、Na Zhang、Xin Guo、Liping Yang、Wenhao Hu
DOI:10.1016/j.tet.2009.07.049
日期:2009.9
Rh2(OAc)4 catalyzed diazo decomposition of aryldiazoacetates in the presence of titanium(IV) isopropoxide generated oxonium ylide intermediates. Trapping of the oxonium ylide intermediates with imines occurred subsequently via a nucleophilic addition. The three-component reaction of aryldiazoacetates, titanium(IV) isopropoxide, and imines gave α-alkoxyl-β-amino acid derivatives with C–N/C–C bond formation