Starting from（5S）-（L-menthyloxy）-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[（2S）-4-bromo-2-（L-menthyloxy）-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5（C20H32BrNO5,Mr = 446.37） was obtained in o...Starting from（5S）-（L-menthyloxy）-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[（2S）-4-bromo-2-（L-menthyloxy）-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5（C20H32BrNO5,Mr = 446.37） was obtained in one-pot process via the tandem Michael addition-elimination reaction in the presence of potassium hydroxide.The chemical structure and absolute configuration of the title compound were confirmed via rotation,UV-Vis,FT-IR,1H NMR,13C NMR,MS and elemental analysis,especially by the X-ray single-crystal diffraction.The crystal crystallizes in an orthorhombic system,space group P212121 with a = 12.5249（16）,b = 19.005（3）,c = 19.719（3） ,V = 4693.7（10） 3,Z = 8,Dc = 1.263 g/m3,μ = 1.778 mm-1,F（000） = 1872,the final R = 0.0617 and wR = 0.1576 for 3967 observed reflections（I 2σ（I））.X-ray analysis reveals that the title compound has two independent molecules in the asymmetric part of the unit cell with the two five-membered furanones being almost planar.The essential part of the electron delocalization is concentrated in the N（1）,C（3）,C（1）,C（37） and O（7） region and N（2）,C（28）,C（27）,C（30） and O（4） region in the other molecule respectively,but does not take place at the expense of delocalization within the ester function.展开更多
A new poly brominated dibenzylphenol named as rhodomevoidin was isolated from Rhodomela confervoides. Its structrue was elucidated as 3-bromo-4, 5-bis (2, 3-dibromo-4, 5- dihydroxybenzyl)pyrocatechol by spectroscopic...A new poly brominated dibenzylphenol named as rhodomevoidin was isolated from Rhodomela confervoides. Its structrue was elucidated as 3-bromo-4, 5-bis (2, 3-dibromo-4, 5- dihydroxybenzyl)pyrocatechol by spectroscopic methods including IR, HRFABMS, 1D and 2D NMR techniques.展开更多
A new halogenated biindole and a new apo-carotenone have been isolated from the ethanolic extract of the green alga Chaetomorpha basiretorsa Sethcell. On the basis of chemical and spectroscopic methods including 2D NM...A new halogenated biindole and a new apo-carotenone have been isolated from the ethanolic extract of the green alga Chaetomorpha basiretorsa Sethcell. On the basis of chemical and spectroscopic methods including 2D NMR technique, their structures have been elucidated as 4,4′-dichloro-5,5′-dibromo-7,7′-dimethoxy-2,2′-bi-1H-indole and 1′S*,4′R*-8-(4′-hydroxy-2′,6′,6′- trimethylcyclohex-2-enyl)-6-methyloct-3E,5E,7E-trien-2-one, respectively.展开更多
This paper reports the use of trifluoroacetic acid as a catalyst in the Dakin–Westreaction for the synthesis of b-acetamido ketones. The method has several advantages such asrequiring only mild conditions and a low c...This paper reports the use of trifluoroacetic acid as a catalyst in the Dakin–Westreaction for the synthesis of b-acetamido ketones. The method has several advantages such asrequiring only mild conditions and a low concentration of catalyst. Screening of 19 b-acetamidoketones for antidiabetic activity in vitro showed that their activity as peroxisome proliferatoractivated receptor (PPAR) agonists and as dipeptidyl peptidase 4 (DPP-IV) inhibitors wasfairly weak.展开更多
基金Supported by the National Natural Science Foundation of China (No. 20772035)the Natural Science Foundation of Guangdong Province (No. 5300082)
文摘Starting from（5S）-（L-menthyloxy）-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[（2S）-4-bromo-2-（L-menthyloxy）-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5（C20H32BrNO5,Mr = 446.37） was obtained in one-pot process via the tandem Michael addition-elimination reaction in the presence of potassium hydroxide.The chemical structure and absolute configuration of the title compound were confirmed via rotation,UV-Vis,FT-IR,1H NMR,13C NMR,MS and elemental analysis,especially by the X-ray single-crystal diffraction.The crystal crystallizes in an orthorhombic system,space group P212121 with a = 12.5249（16）,b = 19.005（3）,c = 19.719（3） ,V = 4693.7（10） 3,Z = 8,Dc = 1.263 g/m3,μ = 1.778 mm-1,F（000） = 1872,the final R = 0.0617 and wR = 0.1576 for 3967 observed reflections（I 2σ（I））.X-ray analysis reveals that the title compound has two independent molecules in the asymmetric part of the unit cell with the two five-membered furanones being almost planar.The essential part of the electron delocalization is concentrated in the N（1）,C（3）,C（1）,C（37） and O（7） region and N（2）,C（28）,C（27）,C（30） and O（4） region in the other molecule respectively,but does not take place at the expense of delocalization within the ester function.
基金The authors are grateful to professor Ablez zeper for mass spectra measurements,and financial support from the NSF(Grant No.99-929-01-26)national“863”program(Grant No.2001AA620403).
文摘A new poly brominated dibenzylphenol named as rhodomevoidin was isolated from Rhodomela confervoides. Its structrue was elucidated as 3-bromo-4, 5-bis (2, 3-dibromo-4, 5- dihydroxybenzyl)pyrocatechol by spectroscopic methods including IR, HRFABMS, 1D and 2D NMR techniques.
基金supported by national 863 project(Grant No.2004AA625030,2001AA620503)NNSFC(Grant No.20432030)Key Innovative Project of the Academy(Grant No.KZCX3-SW-215).
文摘A new halogenated biindole and a new apo-carotenone have been isolated from the ethanolic extract of the green alga Chaetomorpha basiretorsa Sethcell. On the basis of chemical and spectroscopic methods including 2D NMR technique, their structures have been elucidated as 4,4′-dichloro-5,5′-dibromo-7,7′-dimethoxy-2,2′-bi-1H-indole and 1′S*,4′R*-8-(4′-hydroxy-2′,6′,6′- trimethylcyclohex-2-enyl)-6-methyloct-3E,5E,7E-trien-2-one, respectively.
基金This project is supported by "The Fundamental Research Funds for the Central Universities"(XDJK2010C067).
文摘This paper reports the use of trifluoroacetic acid as a catalyst in the Dakin–Westreaction for the synthesis of b-acetamido ketones. The method has several advantages such asrequiring only mild conditions and a low concentration of catalyst. Screening of 19 b-acetamidoketones for antidiabetic activity in vitro showed that their activity as peroxisome proliferatoractivated receptor (PPAR) agonists and as dipeptidyl peptidase 4 (DPP-IV) inhibitors wasfairly weak.
