Butenolide Synthesis by Molybdenum-Mediated Hetero-Pauson−Khand Reaction of Alkynyl Aldehydes
摘要:
The highly reactive complex Mo(CO)(3)(DMF)(3) promotes the CO gas-free cyclocarbonylation of 1,5- and 1,6-alkynyl aldehydes under very mild reaction conditions to provide fused butenolides in good yields. This novel Mo-mediated hetero-Pauson-Khand reaction is very general with regard to the substitution at the alkyne terminus and tether (18 tested cases). Using readily available chiral alkynyl aldehydes, this procedure has been applied to the enantio- and stereoselective synthesis of highly substituted bicyclic butenolides, including an intermediate in natural product synthesis.
ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neatwater. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π
Biocatalytic racemization of α-hydroxycarboxylic acids using a stereo-complementary pair of α-hydroxycarboxylic acid dehydrogenases
作者:Anne Bodlenner、Silvia M. Glueck、Bettina M. Nestl、Christian C. Gruber、Nina Baudendistel、Bernhard Hauer、Wolfgang Kroutil、Kurt Faber
DOI:10.1016/j.tet.2009.06.051
日期:2009.9
Biocatalyticracemization of aliphatic, (aryl)aliphatic and aromatic α-hydroxycarboxylicacids was achieved via a reversible oxidation-reductionsequence using a pair of stereo-complementary Prelog- and anti-Prelog d- and l-α-hydroxyisocaproate dehydrogenases from Lactobacillus confusus DSM 20196 and Lactobacillus paracasei DSM 20008, resp., overexpressed in Escherichia coli. The mild reaction conditions
Highly diastereoselective titanium tetrachloride-mediated aldol condensation of the bistrimethylsilyl enol ether of acetoacetic ester with 2-benzyloxyhexanal. A synthesis of (–)-pestalotin
作者:Hisahiro Hagiwara、Katsuhiko Kimura、Hisashi Uda
DOI:10.1039/c39860000860
日期:——
Titaniumtetrachloride-mediated aldol condensation of the bistrimethylsilyl enol ether of methyl acetoacetate (1) with 2-benzyloxyhexanal (3) gives highly selectively (99 : 1) the syn aldol adduct (5); the stereocontrolled synthesis of (–)-pestalotin (9) has been accomplished.
Asymmetric transfer hydrogenation of α-azido acrylates
作者:Yang Ji、Ping Xue、Dan-Dan Ma、Xue-Qiang Li、Peiming Gu、Rui Li
DOI:10.1016/j.tetlet.2014.11.072
日期:2015.1
The asymmetric transfer hydrogenation of alpha-azido acrylates has been explored, a range of alpha-hydroxy esters are produced with good enantioselectivities (80-90% ee). The reaction was conducted in the wet HCO2H/NEt3 with Ru-TsDPEN A. (C) 2014 Elsevier Ltd. All rights reserved.
High diastereoselection in the aldol reaction of the bistrimethylsilyl enol ether of methyl acetoacetate with 2-benzyloxyhexanal: synthesis of (–)-pestalotin
作者:Hisahiro Hagiwara、Katsuhiko Kimura、Hisashi Uda
DOI:10.1039/p19920000693
日期:——
Aldol condensation of the bistrimethylsilyl enol ether of methyl acetoacetate, compound 2, with 2-benzyloxyhexanal 3c affords highly selectively (99:1) the syn-aldol adduct 4c in the presence of titanium tetrachloride. The stereocontrolled synthesis of (-)-pestalotin 7 has been achieved.