The light sensitivity and unstable nature of 11-cis-retinoids makes them ideal visual chromophores in nature. The synthesis of 11-cis-retinal analogues is of paramount importance in bioorganic studies of rhodopsin, the photoreceptor of the visual transduction pathway, but the instability of 11-cis-retinoids complicates their synthesis and there is no general synthetic route. Common strategies to the cis geometry have failed in the case of 11-cis-retinoids, and most often low yields and complex isomeric mixtures are obtained. Herein we report an efficient, general, and mild preparation of 11-cis-retinoids by semi-hydrogenation of 11-yne-retinoid precursors with Cu/Ag-activated zinc dust.
does not cohere with the conventional logic of metathesis, according to which macrocycles are best closed at a disubstituted olefinic site; rather, the trisubstituted C11−C12 alkene flanked by an allylic ‐OH group served as the pivot point for synthesis. This motif was attained in good yield and excellent selectivity by a sequence of alkyne metathesis, trans‐hydrostannation and cross coupling. Because
total of twelve different calyculins (A–J) and calyculinamides (A, B and F) have been described, the most abundant (in D. calyx) being calyculins A and C. Herein, we demonstrate a concise route to access the C1–C12 tetraene fragment of calyculin C using transition-metal-catalyzed coupling reactions (Suzuki–Miyaura, Stille, Negishi and Heck) for the key connections. The synthesis starts from propionaldehyde
Yessotoxin was isolated from the digestive glands of the scallop, Patinopecten yessoensis, and would be of use as a promising therapeutic tool. We attained the stereoselective construction of KJ ring system of yessotoxin by the intramolecular cyclization of the trisubstituted allylic alcohol using Pd(II) catalyst.
Exploration of GGTase-I substrate requirements. Part 2: Synthesis and biochemical analysis of novel saturated geranylgeranyl diphosphate analogs
作者:Kayla J. Temple、Elia N. Wright、Carol A. Fierke、Richard A. Gibbs
DOI:10.1016/j.bmcl.2016.06.035
日期:2016.8
Protein prenylation is a type of post-translational modification that aids certain proteins in localizing to the plasma member where they activate cell signaling. To better understand the isoprenoid requirements and differences of FTase and GGTase-I, a series of saturated geranylgeranyl diphosphate analogs were synthesized and screened against both mammalian FTase and GGTase-I. Of our library of compounds
Synthesis of Chiral Chromans by the Pd-Catalyzed Asymmetric Allylic Alkylation (AAA): Scope, Mechanism, and Applications
作者:Barry M. Trost、Hong C. Shen、Li Dong、Jean-Philippe Surivet、Catherine Sylvain
DOI:10.1021/ja048078t
日期:2004.9.1
influence of olefin geometry, as well as substitution pattern on the ee and the absolute configuration of the chiral chromans were explored in detail. These observations suggest a mechanism involving the cyclization of the more reactive pi-allyl palladium diastereomeric intermediate as the enantiodiscriminating step (Curtin-Hammett conditions). This methodology led to the enantioselective synthesis of the
Pd 催化的苯酚烯丙基碳酸酯的不对称烯丙基烷基化 (AAA) 是构建烯丙基 CO 键的有效策略,允许获得高达 98% ee 的手性色满。详细探讨了 pH 值的影响和烯烃几何结构的影响,以及取代模式对 ee 和手性色满的绝对构型的影响。这些观察结果表明一种机制涉及反应性更强的 pi-烯丙基钯非对映体中间体的环化作为对映体区分步骤(Curtin-Hammett 条件)。这种方法导致了维生素 E 核心的对映选择性合成,首次对 (+)-clusifoliol 和 (-)-siccanin 进行了对映选择性全合成,以及合成了 (+)-红花紫杉酸 A 的高级中间体。