Rhodium(III)-Catalyzed<i>ortho</i>Alkenylation of<i>N</i>-Phenoxyacetamides with<i>N</i>-Tosylhydrazones or Diazoesters through CH Activation
作者:Fangdong Hu、Ying Xia、Fei Ye、Zhenxing Liu、Chen Ma、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201309650
日期:2014.1.27
A coupling reaction of N‐phenoxyacetamides with N‐tosylhydrazones or diazoestersthrough RhIII‐catalyzed CHactivation is reported. In this reaction, ortho‐alkenyl phenols were obtained in good yields and with excellent regio‐ and stereoselectivity. Rh–carbene migratory insertion is proposed as the key step in the reaction mechanism.
OH-Directed Alkynylation of 2-Vinylphenols with Ethynyl Benziodoxolones: A Fast Access to Terminal 1,3-Enynes
作者:Peter Finkbeiner、Ulrich Kloeckner、Boris J. Nachtsheim
DOI:10.1002/anie.201412148
日期:2015.4.13
The first direct alkynylation of 2‐vinylphenols was developed. The rationally optimized hypervalent iodine reagent TIPS‐EBX* in combination with [(Cp*RhCl2)2] as a CH‐activating transition metal catalyst enables the construction of a variety of highly substituted 1,3‐enynes in high yields of up to 98 %. This novel CH activation method shows excellent chemoselectivity and exclusive (Z)‐stereoselectivity
An efficient asymmetric hydroesterfication of diarylmethyl carbinols is developed for the first time with a Pd‐WingPhos catalyst, resulting in a series of chiral 4‐aryl‐3,4‐dihydrocoumarins in excellent enantioselectivities and good yields. The method features mild reaction conditions, a broad substrate scope, use of easily accessible starting materials, and low palladium loadings. A plausible stereochemical
Cp*Co(III)-Catalyzed Annulations of 2-Alkenylphenols with CO: Mild Access to Coumarin Derivatives
作者:Xu-Ge Liu、Shang-Shi Zhang、Chun-Yong Jiang、Jia-Qiang Wu、Qingjiang Li、Honggen Wang
DOI:10.1021/acs.orglett.5b02728
日期:2015.11.6
Cp*Co(III)-catalyzed annulations of 2-alkenylphenols with CO for the synthesis of coumarin derivatives have been developed. The reaction features mild reaction conditions, broad substrate scope, and good functional group tolerance. Preliminary mechanistic studies were conducted, suggesting that C-H activation is the turnover limiting step. Furthermore, the efficiency of this reaction was demonstrated by the rapid total synthesis of three natural products herniarin, xanthyletin, and seselin.