通过2-乙炔基-N-三苯基磷酰亚苯胺苯胺和α-二氮酮通过酮亚胺中间体的串联反应,以中等至良好的产率制备了5 H-苯并[ b ]咔唑。通过使用这种方法,苯并[ b ]苯并[5,6]吲哚并[3,2- h ]咔唑,芴[9,1- ab ]咔唑和芴[9,1- ab ]氟[1',9 ′:5,6,7] indolo [3,2- h ]咔唑是在一个锅中制成的。而且,最终产物发出的光在410-521 nm范围内,量子产率高达62%。
Efficient Regioselective Synthesis of Indole <i>N</i>-Carboximidamides and <i>N</i>-Carboximidoates by a Sequential Aza-Wittig/Ag(I)-Catalyzed Cyclization
作者:Nian-Yu Huang、Ming-Guo Liu、Ming-Wu Ding
DOI:10.1021/jo901362c
日期:2009.9.4
An efficient Ag(I)-catalyzed regioselectivecyclization of (2-alkynylphenyl)guanidine or (2-alkynylphenyl)isourea to indole N-carboximidamides or N-carboximidoates has been developed. The approach has the advantages of high regioselectivity, mild reaction conditions, easily accessible starting materials, and good yields.
Thermal C<sup>2</sup>−C<sup>6</sup> Cyclization of Enyne−Carbodiimides: Experimental Evidence Contradicts a Diradical and Suggests a Carbene Intermediate
Mechanistic details of the thermal C(2)-C(6) cyclization of enyne-carbodiimides are investigated. A variety of product and kinetic studies on solvent and substituent effects open the way for a deeper mechanistic understanding. Nonlinear Hammett correlations suggest that a change of mechanism takes place: the thermal C(2)-C(6) cyclization of enyne-carbodiimides with electron-withdrawing substituents may be best described as a coarctate cyclization to a carbene and with electron-donating substituents as a polar cyclization to a carbene with strong zwitterionic character. Theoretical investigations had originally suggested a diradical intermediate. DFT computations and NBO analysis for the parent diazafulvenediyl are in agreement with a carbene intermediate. While any intermolecular trapping of the intermediate failed, the formation of the C-H insertion product 19 strongly supports the carbene hypothesis.