The first successful example of the direct synthesis of Weinreb amides using catalytic hydroxy-directed dehydrative amidation of carboxylicacids using the diboronic acid anhydride catalyst is described. The methodology is applicable to the concise syntheses of eight α-hydroxyketone natural products, namely, sattabacin, 4-hydroxy sattabacin, kurasoins A and B, soraphinols A and B, and circumcins B
Natural L‐α‐amino acids and L‐norleucine were transformed to the corresponding α‐hydroxy acids by formal biocatalytic inversion or retention of absolute configuration. The one‐pot transformation was achieved by a concurrent oxidation reduction cascade in aqueous media. A representative panel of enantiopure (R)‐ and (S)‐2‐hydroxy acids possessing aliphatic, aromatic and heteroaromatic moieties were
Stepwise O-Atom Transfer in Heme-Based Tryptophan Dioxygenase: Role of Substrate Ammonium in Epoxide Ring Opening
作者:Inchul Shin、Brett R. Ambler、Daniel Wherritt、Wendell P. Griffith、Amanda C. Maldonado、Ryan A. Altman、Aimin Liu
DOI:10.1021/jacs.8b00262
日期:2018.3.28
produced from probe 2 in a significant quantity. Analysis of this new product by HPLC coupled UV-vis spectroscopy, high-resolution massspectrometry, 1H NMR, 13C NMR, HSQC, HMBC, and infrared (IR) spectroscopies concluded that this monooxygenated product is a furoindoline compound derived from an unstable epoxyindole intermediate. These results prove that small molecules can manipulate the stepwise O atom
基于血红素的色氨酸双加氧酶是具有重要生物医学意义的已建立的免疫抑制金属蛋白。在这里,我们合成了两种机械探针,专门测试底物的 α-氨基是否直接参与人色氨酸 2,3-双加氧酶 (TDO) 催化过程中 O 原子转移的关键步骤。将底物的氮原子替换为碳(探针 1)或氧(探针 2)会减慢第一个 O 原子转移后的催化步骤,从而使第二个 O 原子的转移不太可能发生,尽管观察到双氧化产物两个探头。探针 2 也产生了大量的单氧化产物。通过 HPLC 耦合紫外-可见光谱、高分辨质谱、1H NMR、13C NMR、HSQC、HMBC、红外 (IR) 光谱得出结论,这种单氧化产物是一种呋喃二氢吲哚化合物,源自不稳定的环氧吲哚中间体。这些结果证明小分子可以操纵 TDO 的逐步 O 原子转移反应,并为合成化合物的可调机制提供了展示。产物分析结果证实了催化过程中底物基环氧吲哚中间体的存在,并为底物α-氨基参与催化过程中的
Structure and enantioselective synthesis of polyamine toxin MG30 from the venom of the spider Macrothele gigas
A novelpolyamine toxin, named MG30, was isolated from the venom of the spider, Macrothele gigas, and its structure was elucidated by two-dimensional NMR and mass analysis. In addition, the enantioselective synthesis of MG30 was achieved to assign its absolute stereochemistry.
There is provided amino acid derivatives of formula I,
1
wherein p, q, R
1
, R
2
, R
3
, R
4
, Y, n and B have meanings given in the description which are useful as competitive inhibitors of trypsin-like proteases, such as thrombin, and in particular in the treatment of conditions where inhibition of thrombin is required (e.g. thrombosis) or as anticoagulants.