develop and evaluate a pharmacophore model previously proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) for ligands binding to the benzodiazepine site of the GABA(A) receptor, 40 new flavone derivatives have been synthesized and their affinities for the benzodiazepine site have been determined. Two new regions of steric repulsive interactions between ligand and receptor have been
Rh(III)-catalyzed C–H activation of salicylaldehyde followed by an insertion reaction with sulfoxonium ylides and cyclization is applied to the synthesis of flavonoids. This one-pot strategy exhibits good functional group tolerance and gives flavones in moderate-to-good yields.
The palladium-catalyzedintramolecular acylation of alkenyl bromides and aldehydes was developed for an efficient synthesis of 4H-chromen-4-ones. With Pd(PPh3)4/Xphos as the catalyst and K2CO3 as the base, this protocol was applied to synthesize a small library of diversely functionalized flavonoids in moderate to good yields in 1,4-dioxane.
开发了钯催化的烯基溴和醛的分子内酰化反应,以有效合成4 H -chromen-4-ones。以Pd(PPh 3)4 / Xphos为催化剂,以K 2 CO 3为碱,该方案被用于合成少量的,功能多样的黄酮类化合物,在1,4-二恶烷中的产率为中等。
Reagent-free intramolecular hydrofunctionalization: a regioselective 6-<i>endo-dig</i> cyclization of <i>o</i>-alkynoylphenols
Solvent-directed intramolecular hydrofunctionalization of readily available o-alkynoylphenols 1 was successfully achieved under reagent-free conditions. The hydrofunctionalization of 1 occurred by nucleophilic attack on the phenolic oxygen followed by consecutive migration of the phenolic H atom to the alkyne center, eventually affording γ-benzopyranones 2. The phenol O–H group forms intramolecular H-bonds
在无试剂条件下成功实现了容易获得的邻炔基酚1的溶剂导向分子内氢官能化。1的氢官能化通过对酚氧的亲核攻击随后酚氢原子连续迁移到炔烃中心而发生,最终得到 γ-苯并吡喃酮2。酚 O-H 基团与羰基形成分子内 H 键,我们预测这些 H 键在极性溶剂存在下可以扭曲成它们最优选的构象。区域选择性 6 -endo-dig环化似乎在热力学上优于 5 -exo-dig循环化,由 DFT 计算支持。该策略之所以引人注目,是因为它无试剂、区域选择性、原子经济性高、原子、碳和反应质量效率高。
Catalytic Asymmetric Reductive Azaarylation of Olefins via Enantioselective Radical Coupling
partners are compatible with the dual catalyst system, leading to a wide array of valuable enantioenriched azaarene variants with high yields and ees. Regulating the types of chiralcatalysts represents one of the important manners to success, in which several readily accessible Cinchona alkaloid-derived bifunctional catalysts are introduced in asymmetric photochemical reactions.
可见光驱动的光催化还原氮杂芳基化已被广泛用于构建重要的含亚胺氮杂芳烃衍生物。除了直接使用各种市售的氰基氮杂芳烃作为原料外,合成的优点还包括精确的区域选择性、高效率、温和的反应条件和良好的官能团耐受性。然而,尽管已经建立了许多有效的还原氮杂芳基化方法,但对映选择性方式的例子仍未得到满足,这很可能归因于高反应性自由基偶联是形成立体中心的关键步骤。因此,探索对映控制的可行性是一项有吸引力但极具挑战性的任务。这里,我们证明手性氢键/光敏剂催化是一个可行的平台,因为它能够实现第一个对映选择性歧管。作为反应伙伴的多种无环和环状烯酮与双催化剂体系兼容,从而产生了具有高产率和 ee 的各种有价值的对映体富集的氮杂芳烃变体。调节手性催化剂的类型是成功的重要途径之一,其中几种容易获得金鸡纳生物碱衍生的双功能催化剂被引入不对称光化学反应。