Regioselective Synthesis of 3-Alkynyl-5-bromo-2-pyrones via Pd-Catalyzed Couplings on 3,5-Dibromo-2-pyrone
摘要:
[GRAPHICS]3,5-Dibromo-2-pyrone underwent facile Pd(0)-catalyzed coupling reactions with various alkynes to give rise to the corresponding 3-alkynyl-5-bromo-2-pyrones with good to excellent chemical yields and regioselectivity.
Regioselective Synthesis of 3-Alkynyl-5-bromo-2-pyrones via Pd-Catalyzed Couplings on 3,5-Dibromo-2-pyrone
摘要:
[GRAPHICS]3,5-Dibromo-2-pyrone underwent facile Pd(0)-catalyzed coupling reactions with various alkynes to give rise to the corresponding 3-alkynyl-5-bromo-2-pyrones with good to excellent chemical yields and regioselectivity.
Divergent Asymmetric Total Synthesis of (+)-Vincadifformine, (−)-Quebrachamine, (+)-Aspidospermidine, (−)-Aspidospermine, (−)-Pyrifolidine, and Related Natural Products
作者:Nengzhong Wang、Shuo Du、Dong Li、Xuefeng Jiang
DOI:10.1021/acs.orglett.7b01292
日期:2017.6.16
uniformly strategic total synthesis of Aspidosperma alkaloids (+)-vincadifformine, (−)-quebrachamine, (+)-aspidospermidine, (−)-aspidospermine, (−)-pyrifolidine, and nine others from efficiently constructed tricyclic ketone 13 is reported. Highlights of these divergent and practical syntheses include (i) stereoselective intermolecular [4 + 2] cycloaddition to establish a C–E ring with one all-carbon quaternary
Regioselectivity in the Stille Coupling Reactions of 3,5-Dibromo-2-pyrone
作者:Won-Suk Kim、Hyung-Jin Kim、Cheon-Gyu Cho
DOI:10.1021/ja037043a
日期:2003.11.1
C3, lower in electron density than C5, thus oxidative addition proceeds faster . When the reactions are carried out with Cu(I) in DMF or other polar aprotic solvent, however, the couplings occur predominantly at C5. The observed regiochemical reversal is attributed to the preferred formation of 5-pallado-2-pyrone intermediate which, in addition, turned out to be more reactive than 3-pallado-2-pyrone
Imidazole-Selective Alkyne Hydroamination under Physiological Conditions
作者:Hyung-Joon Kang、Joon-Ho Lee、Dong-Hyun Kim、Cheon-Gyu Cho
DOI:10.1021/acs.orglett.0c02785
日期:2020.10.2
Imidazole-selective intermolecular hydroamination reaction has been discovered. This unprecedented additive-free addition reaction proceeds in an exclusively regioselective and stereoselective manner with high atom economy under extremely mild reaction conditions.