New Chiral Benzothiazine Ligand and Its Use in the Synthesis of a Chiral Receptor
摘要:
The development of chiral ligands to direct the course and stereoselectivity of many catalytic asymmetric reactions is an important area of interest for many research groups. As part of a program examining the chemistry of 2,1-benzothiazines, we have prepared a new chiral benzothiazine ligand. This ligand can be made in as few as three steps from commercially available starting materials. Presented herein is the synthesis of the ligand along with the synthesis of a chiral molecular receptor that potentially presages a new class of chiral molecular tweezers.
This invention provides, among other things, novel compounds useful for treating bacterial infections, pharmaceutical compositions containing such compounds, as well as combinations of these compounds with at least one additional therapeutically effective agent.
Atropisomeric Phosphine Ligands Bearing C–N Axial Chirality: Applications in Enantioselective Suzuki–Miyaura Cross-Coupling Towards the Assembly of Tetra-<i>ortho</i>-Substituted Biaryls
of chiral phosphines featuring a C–N axial chirality and their applications in enantioselective Suzuki–Miyaura cross-coupling for accessing highly steric hindered tetra-ortho-substitutedbiaryls (26 examples up to 98:2 er). It is worth noting that the embodied carbazolyl framework is crucial to succeed the reaction, by the fruitful steric relief of bulky substrate coordination and transmetalation via
带有 C (Ar) -C (Ar)轴向手性的联芳基膦是众所周知的,并已成功应用于许多不对称催化剂中。然而,开发具有轴向手性 C (Ar)的手性配体-N 骨架由于其不受欢迎的较少限制的旋转屏障而仍然难以捉摸。事实上,克服配体开发中的这一挑战非常有吸引力,因为在手性轴上掺入 N 供体组分更有利于瞬态金属配位,因此,预计接近的底物会有更好的立体通信结果. 在此,我们提出了一种新的具有 C-N 轴向手性的手性膦的合理设计及其在对映选择性 Suzuki-Miyaura 交叉偶联中的应用,以获得高位阻四邻-取代的联芳基(26 个实例,最高 98:2 er)。值得注意的是,通过短暂的 Pd-N 跃迁到 Pd-π 方式,大量的底物配位和金属转移有效地释放空间位阻,体现的咔唑基框架对于反应的成功至关重要。DFT 计算揭示了一个有趣的 Pd-芳烃在咔唑平面上的行走特性,用于在催化循环中获得较低能量的首选路
Studies towards the total synthesis of mumbaistatin: synthesis of highly substituted benzophenone and anthraquinone building blocks
Model compounds and building blocks for a planned total synthesis of the highly potent glucose-6-phosphate (G6P) translocase inhibitor mumbaistatin (1) and structural analogs were elaborated: compound 1 represents a lead structure in the development of potential new antidiabetic drugs. With the model substrate 20 it was demonstrated that highly functionalized, tetra-ortho-substituted benzophenones can be prepared by nucleophilic addition of an aryllithium-building block to a benzaldehyde followed by oxidation. For compound 37, a potential precursor of the anthraquinone part of mumbaistatin, various approaches via aryne/phthalide annulations were developed and evaluated. The required functionalized arenes were prepared exploiting, among others, regioselective bromination and ortho-lithiation reactions. Coupling reactions of the anthracene-carbaldehyde 44 derived from 37 with various metalated arenes proved to be unexpectedly difficult and failed so far. (C) 2003 Elsevier Science Ltd. All rights reserved.