巴豆醛(1)是一种诱变剂和致癌物,但其与DNA的反应仅得到部分表征。在先前的研究中,我们发现释放了大量的2-(2-羟丙基)-4-羟基-6-甲基-1,3-二恶烷(paraldol,7),即3-羟基丁醛的二聚体(8)。经酶促或中性热水解后已与巴豆醛反应的DNA。现在,我们已经在此DNA中表征了两个paraldol-deoxyguanosine加合物:N(2)-[2-(2-羟丙基)-6-甲基-1,3-二恶烷-4-基] deoxyguanosine(N(2)-paraldol- dG,13)和N(2)-[2-(2-羟丙基)-6-甲基-1,3-二氧六环-4-基]脱氧胍基-(5'-3')-胸苷[N(2)-帕拉多尔-dG-(5'-3')-胸苷,14]。观察到N(2)-paraldol-dG(13)的四个非对映异构体。它们的整体结构由(1)H NMR,MS,以及帕拉尔多与脱氧鸟苷和DNA的反应。(1)1 H
motif and a novel set of homochiral linkers has been synthesized. Starting from amino acids available from the chiral pool a synthesis procedure was established that allows a straightforward, multigram scale synthesis of homochiral linkers in 4–5 steps. These linkers carry substituents that have been proven useful in stereoselective organic chemistry, such as the Evans auxiliary or chiral amino alcohols
基于铜桨轮基序和一组新的同手性连接基,已经合成了一个新的等网状金属-有机骨架系列,称为UHM-25(UHM:汉堡材料大学)。从手性库中可用的氨基酸开始,建立了合成程序,该程序允许在4-5个步骤中直接,数克规模的同手性连接体合成。这些接头带有已被证明可用于立体选择性有机化学的取代基,例如伊文思助剂或手性氨基醇。所得的MOF仅在氨基酸原料提供的手性部分上有所不同。UHM-25的结构由Cu 2的立方八面体笼组成通过连接子的间苯二甲酸酯部分连接的桨轮图案。这些笼通过连接子的弯曲骨架连接在一起,从而形成原始的立方排列,从而产生了稀有的下层(3,4)-c双齿净ucp。UHM-25系列的MOF的表面积高达S BET = 1900 m 2 / g。具有优良转化率的合成后修饰反应证实了手性基团的可及性。此外,带有丙醇功能的UHM-25-Pro被用于乙醛的自定向对映选择性醇醛加成中,证明了UHM-25系列在多相,立体选择性催化方面的潜力。
Biocatalytic Aldol Addition of Simple Aliphatic Nucleophiles to Hydroxyaldehydes
Asymmetric aldol addition of simple aldehydes and ketones to electrophiles is a cornerstone reaction for the synthesis of unusual sugars and chiral buildingblocks. We investigated d-fructose-6-phosphate aldolase from E. coli (FSA) D6X variants as catalysts for the aldol additions of ethanal and nonfunctionalized linear and cyclic aliphatic ketones as nucleophiles to nonphosphorylated hydroxyaldehydes
A Schiff Base Is a Major DNA Adduct of Crotonaldehyde
作者:Mingyao Wang、Edward J. McIntee、Guang Cheng、Yongli Shi、Peter W. Villalta、Stephen S. Hecht
DOI:10.1021/tx000234w
日期:2001.4.1
LC-APCI-MS, and MS/MS. Four isomers of N(2)-(3-hydroxybutylidene)dG were observed. The (R)- and (S)-isomers were identified by reactions of chiral paraldol with dG; each existed as a pair of interconverting (E)- and (Z)-isomers. These data indicate that the structure of the major Schiff base DNA adduct in crotonaldehyde-treated DNA is N(2)-(3-hydroxybutylidene)dG (7). This adduct is unstable at the nucleoside
of the cascade, the aldol product is selectively oxidised to the lactone. A commercially available ADH was identified to selectively catalyse this oxidation using NADP+ as electron acceptor. NADP+ regeneration was achieved using O2 as substrate in two different ways: using either photo-activated flavin or NADPH oxidase (NOX). The lactone was successfully purified from the enzymatic cascades from a preparative
本研究提出了用于合成 δ-内酯的三步一锅酶级联。利用乙醛,将 2-脱氧核糖-5-磷酸醛缩酶 (DERA) 与乙醇脱氢酶 (ADH) 和辅因子再生系统相结合,合成出具有与他汀类药物侧链前体相同的立体化学的 δ-内酯。该级联的初始阶段涉及双羟醛反应,由 DERA 催化,从非手性底物乙醛产生手性内酯前体。此阶段的主要挑战是 DERA 在高乙醛浓度存在下的不稳定性。因此,对具有高天然乙醛耐受性的短乳杆菌DERA进行了基因改造,以进一步改善这一特性。与野生型(20% 活性损失)相比,Lb DERA C42M E78K 表现出改善的活性和稳定性(2 小时内无活性损失)。在级联的第二阶段,羟醛产物被选择性氧化成内酯。市售的 ADH 被鉴定为使用 NADP +作为电子受体选择性催化这种氧化。 NADP +再生是使用O 2作为底物以两种不同的方式实现的:使用光激活黄素或NADPH氧化酶(NOX)。内酯从制备规模反应的酶级联中成功纯化,纯度为
Total synthesis of (-)-colletol
作者:Gary E. Keck、Jerry A. Murry
DOI:10.1021/jo00023a029
日期:1991.11
The first total synthesis of the unsymmetrical bis-macrolide (-)-colletol is described. The synthesis involves a Lewis acid mediated addition of triphenylallylstannane to aldehyde 14 to set the C12 stereochemistry. The penultimate step utilized macrolactonization to assemble the 14-membered ring. The natural product was prepared in 12 linear steps and 12% overall yield.