Enzyme mediated kinetic resolution of δ-hydroxy-α,β-unsaturated esters as a route to optically active δ-lactones
摘要:
A novel synthetic route to optically active saturated and unsaturated delta-lactones based on enzymatic kinetic resolution and ring-closing metathesis reactions has been proposed. The influence of temperature, co-solvent, organic additives and the substrate structure on the catalytic behavior of selected hydrolases was studied. The substantial impact of the organic co-solvent and surfactant type on the enzymatic activity and enantioselectivity was observed providing enantiomerically pure delta-hydroxy-alpha,beta-unsaturated esters. The established protocol combining enzymatic kinetic resolution with ring closing metathesis was successfully applied in the synthesis of the enantiomerically pure (6R)-phenyl-5,6-dihydro-2H-pyran-2-one which plays crucial role in the synthesis of the number of bioactive compounds. (C) 2017 Elsevier Ltd. All rights reserved.
Concise Total Syntheses of (±)-Strychnine and (±)-Akuammicine
作者:Gopal Sirasani、Tapas Paul、William Dougherty、Scott Kassel、Rodrigo B. Andrade
DOI:10.1021/jo100516g
日期:2010.5.21
Concise total syntheses of Strychnos alkaloids strychnine (1) and akuammicine (2) have been realized in 13 and 6 operations, respectively. Key steps include (1) the vinylogous Mannich reaction; (2) a novel, sequential one-pot spirocyclization/intramolecular aza-Baylis−Hillman reaction; and (3) a Heck cyclization. The synthesis of 1 proceeds via the Wieland−Gumlich aldehyde (26).
respective amino and hydroxy acids. A new synthetic route to unit A allows the selective generation of all four stereogenic centres in a short, efficient and reliable synthesis and contributes to an easier and faster synthesis of cryptophycins. The first two stereogenic centres are introduced by a catalytic asymmetricdihydroxylation, whereas the remaining two stereogenic centres are introduced with
It was found that the reaction of O-silylated enolates of carboxylicesters and of lactones with aminomethyl ethers proceeds smoothly under a catalytic action of zinc chloride to afford the corresponding α-aminomethylated carboxylicesters or lactones, except only one case using O-silylated enolate of δ-valerolactone, in which the resultant α-aminomethyl-δ-valerolactone is somewhat unstable and undergoes
Coupling reactions of vinylketene silyl acetals promoted by titanium tetrachloride
作者:Kenji Hirai、Iwao Ojima
DOI:10.1016/s0040-4039(00)81527-0
日期:1983.1
Homo- and cross-couplings of vinylketene silyl acetals were found to be effectively promoted by titaniumtetrachloride to give the corresponding unsaturated diesters in good yields. The reactionsbetween two different ketene silyl acetate afforded the corresponding cross-coupling products in unexpectedly good selectivities.
Total Syntheses of Thailanstatins A–C, Spliceostatin D, and Analogues Thereof. Stereodivergent Synthesis of Tetrasubstituted Dihydro- and Tetrahydropyrans and Design, Synthesis, Biological Evaluation, and Discovery of Potent Antitumor Agents
作者:K. C. Nicolaou、Derek Rhoades、S. Mothish Kumar
DOI:10.1021/jacs.8b04634
日期:2018.7.5
hydrogenations of these dihydropyran systems afford their tetrahydropyran counterparts, also in a highly stereoselective manner. The synthesized thailanstatins and related analogues were biologically evaluated for their cytotoxic properties, leading to the identification of a number of compounds with exceptionally potent antitumor activities suitable for further development as potential antibody-drug conjugate
报道了剪接体调节天然产物泰兰他汀 AC 和剪接抑制素 D 的高效和选择性全合成。开发了许多用于构建各种四取代二氢和四氢吡喃的立体选择性方法,作为合成这些天然存在的分子及其变体的先决条件。吡喃形成反应利用 Heck/Saegusa-Ito 级联序列生成羟基 α,β,γ,δ-不饱和醛前体,然后通过催化剂控制的 oxa-Michael 环化提供具有高度立体控制的四取代二氢吡喃。随后对这些二氢吡喃系统进行优化的均相或非均相氢化,也以高度立体选择性的方式提供了它们的四氢吡喃对应物。合成的泰兰他汀和相关类似物对其细胞毒性特性进行了生物学评估,从而鉴定了许多具有异常有效抗肿瘤活性的化合物,适合进一步开发为潜在的抗体药物偶联物有效载荷、单一药物或用于癌症治疗的药物组合。讨论了泰兰他汀家族中重要的构效关系和结构相关的化合物,并有望成为未来研究的方向。