High threo diastereoselectivity via europium(III)-catalyzed cyclocondensation of a silyloxy diene with .alpha.-alkoxy aldehydes. Synthesis of (-)pestalotin
been achieved by condensation of methylmalonyl dichloride with ethyl trans-4-methyl-3-oxo-4-hexenoate followed by hydrolysis, decarboxylation, and methylation of the resulting 3-methyl-4-hydroxy-5-carbethoxy-6-(trans-1-methyl-1-propenyl)-2-pyrone. Exploration of an alternate scheme involving the dehydrogenation of 6-substituted-4-methoxy-5,6-dihydro-2-pyrones, prepared by Reformatsky reaction of ethyl
Efficient Enantioselective Hetero-Diels−Alder Reaction of Brassard's Diene with Aliphatic Aldehydes: A One-Step Synthesis of (<i>R</i>)-(+)-Kavain and (<i>S</i>)-(+)-Dihydrokavain
An efficient catalytic asymmetrichetero-Diels-Alderreaction of Brassard'sdiene with aliphatic aldehydes was reported. The catalyst, which was generated from (R)-BINOL, Ti(i-PrO)4, and 4-picolyl chloride hydrochloride, promoted the reaction smoothly to afford the corresponding alpha,beta-unsaturated delta-lactone derivatives in moderate-to-good yields (46-79%) with high enantioselectivities (up to
Synthesis and application of azolium ionic liquid tagged TADDOL catalysts
作者:Zekarias Yacob、Jürgen Liebscher
DOI:10.3998/ark.5550190.0013.322
日期:——
Ionicliquid (IL) tagged organocatalysts based on TADDOL (α,α,α’,α’-tetraaryl-2,2-dimethyl1,3-dioxolane-4,5-dimethanol) comprising various aryl substituents tethered with triazolium and imidazolium based ionicliquids are synthesised in good yields. Investigation of these IL-tagged catalysts on hydrogen-bonding catalyzed hetero-Diels-Alder (HDA) reactions between activated dienes (such as Rawal’s diene
基于 TADDOL(α,α,α',α'-四芳基-2,2-二甲基1,3-二氧戊环-4,5-二甲醇)的离子液体 (IL) 标记的有机催化剂,包含各种芳基取代基与三唑鎓和咪唑鎓基离子液体以良好的产率合成。对这些带 IL 标记的催化剂对活化二烯(如拉瓦尔二烯和布拉萨德二烯)和苯甲醛之间的氢键催化异狄尔斯-阿尔德 (HDA) 反应的研究表明它们在有机催化中的应用潜力和局限性。
Synthesis of β-Methoxyacrylate Natural Products Based on Box-PdII-Catalyzed Intermolecular Methoxycarbonylation of Alkynoles
5‐membered lactones 3p, 3q, 16 were obtained in moderate yields. The one‐pot synthesis of kawa lactones 3a, 3r, 3s and formal synthesis of dihydroxycystothiazole A and dihydroxycystothiazole C are presented. To elucidate the stereochemistry of (+)‐annularin G and (−)‐annularin H, the first asymmetric syntheses of these naturalproducts were achieved.
作者:William C. Groutas、Tien L. Huang、Michael A. Stanga、Michael J. Brubaker、Min K. Moi
DOI:10.1002/jhet.5570220243
日期:1985.3
A series of substituted 2-pyrones and 5,6-dihydropyrones have been synthesized and investigated for their inhibitory activity toward human leukocyte elastase, procine pancreatic elastase and chymotrypsin.