Cyano-Schmittel Cyclization through Base-Induced Propargyl-Allenyl Isomerization: Highly Modular Synthesis of Pyridine-Fused Aromatic Derivatives
作者:Xu You、Xin Xie、Haoyi Chen、Yuxue Li、Yuanhong Liu
DOI:10.1002/chem.201503374
日期:2015.12.14
cyano‐Schmittel cyclization of in situ‐generated cyano‐allenes has been carried out. The DFT calculation results suggest that the diradical pathway plays a major role in this cyclization. The reactions can be conveniently performed in a one‐pot manner through cascade Sonogashira coupling of terminal cyano‐ynes with organic halides, followed by base‐promoted propargyl‐allenyl isomerization/cyclization, leading
Competitive 1,2- and 1,5-Hydrogen Shifts Following 2-Vinylbiphenyl Photocyclization
作者:Frederick D. Lewis、Meledathu C. Sajimon、Xiaobing Zuo、Michael Rubin、Vladimir Gevorgyan
DOI:10.1021/jo051730y
日期:2005.12.1
occur via a two-step mechanism: photocyclization to form an unstable 8a,9-dihydro-phenanthrene intermediate, followed by exothermic unimolecular isomerization to a 9,10-dihydrophenanthrene. The mechanism of the hydrogen shift process has been investigated using deuterated derivatives of 2-isopropenylbiphenyl and 2,6-diphenylstyrene. 1H NMR analysis of the photoproducts indicates that the thermally allowed
已经提出2-乙烯基联苯及其衍生物的光环化通过两步机理发生:光环化以形成不稳定的8a,9-二氢菲中间体,然后放热单分子异构化为9,10-二氢菲。已经使用2-异丙烯基联苯和2,6-二苯基苯乙烯的氘代衍生物研究了氢转移过程的机理。1个光产物的1 H NMR分析表明,热允许的1,5-氢或氘转移是次要的产物形成途径,而异常的双1,2氢或氘转移是主要的产物形成途径。已经通过计算探索了光环化和氢转移过程的势能面。预测的1,5-班次的势垒将大大低于1,2-班次的势垒。提出了发生1,2-氢或氘迁移的替代机制。
Visible-Light-Mediated Deacylated Alkynylation of Unstrained Ketone
Deconstructive alkynylation of an unstrained ketone catalyzed by an organic photocatalyst under blue light irradiation is reported for the first time. A broad substrate scope with up to 63 examples, excellent functional group tolerance, and gram scale reaction demonstrated the practicality of this novel alkynylation method. The dihydroquinazolinone derivative of trifluoroacetophenone had been proved