An easy and high yielding transformation of epoxyketones and phenyl substituted epoxides to trans olefins in a convergent diastereoselective process is reported. The method was applied to the selective C-25 hydroxy-functionalisation of 3-keto-Delta(4)-cholestan-3-one, a key intermediate for the synthesis of C-25 hydroxy vitamin D-3. (C) 2000 Elsevier Science Ltd. All rights reserved.
Identification of a Fossil Sterane Biomarker in Crude Oil - an Androstane with a Modified Carbon Skeleton
作者:Matthias Bender、Marc Schmidtmann、Jürgen Rullkötter、Roger E. Summons、Jens Christoffers
DOI:10.1002/ejoc.201300788
日期:2013.9
of four stereoisomers of 3-methyl-A-nor-androstane (4 % overall yield) was prepared by ionic hydrogenation of the olefin after A-ring recyclization in three steps. 17-Methyl-18-nor-androstane was synthesized in four steps as a mixture of isomers (58 % overall yield) from dihydrotestosterone with a Wagner–Meerwein shift of the 13β-methyl group to C-17 as the key step. Pure 17β- and 17α-methyl-18-nor-13α-androstane
Unambiguous assignment of 13C NMR signals in epimeric 4,5-epoxy-3-oxo-steroids assisted by X-ray diffraction and gauge invariant atomic orbitals calculation of absolute isotropic shieldings
作者:Pablo Labra-Vázquez、Annia Galano、Margarita Romero-Ávila、Marcos Flores-Álamo、Martín A. Iglesias-Arteaga
DOI:10.3998/ark.5550190.p008.237
日期:——
Complete assignments of the 13 C signals of diastereomeric 4,5-epoxy-3-oxosteroids based on a combination of 1D and 2D NMR techniques are described The assignments were corroborated or corrected by calculation of the absolute isotropic 13 C NMR shieldings using the Gauge Invariant
描述了基于 1D 和 2D NMR 技术组合的非对映体 4,5-epoxy-3-oxo 类固醇的 13 C 信号的完整分配 通过使用 Gauge 计算绝对各向同性 13 C NMR 屏蔽来证实或校正分配不变量
Reaktionen von Steroid-Hypojoditen IV. �ber den Verlauf intramolekularer Substitutionsreaktionen, insbesondere bei 2?- und 4?-Hydroxysteroiden. �ber Steroide, 192. Mitteilung
From 4β- as well as from 2β-hydroxy-steroids 19-hemiacetal derivatives are formed in the «hypoiodite reaction», especially with lead tetraacetate and iodine, whereas 6β-hydroxy-steroids give 6β,19-ethers exclusively(1). This behaviour is explained on the basis of the differences in the relative orientation of the hydroxyl groups towards the conformationally fixed 19-CH2I group in the iodohydrin intermediates
The invention provides a method for detecting a hapten in a sample comprising the steps of: a) providing a sample potentially containing the hapten; b) providing a pre-determined amount of a first moiety, said first moiety being bound to a signaller and separated therefrom by a first linker, which first moiety is either: i) a binding partner that specifically binds to the hapten of interest, or ii) the hapten of interest or an analogue thereof; wherein said signaller is a macromolecule or a nanoparticle providing high mass signal; c) providing a flow of a) and b) separately or together to an immobilised second moiety, said second moiety being bound to the surface of a sensor and separated therefrom by a second linker, which second moiety is either: i) a binding partner that specifically binds to the hapten of interest, or ii) is the hapten of interest or an analogue thereof, providing that when the first moiety is a binding partner, the second moiety is a hapten or hapten analogue and when the first moiety is a hapten or hapten analogue, the second moiety is a binding partner; and d) detecting the amount of first moiety bound to second moiety.
A concise and divergent synthesis of the polychlorinated marine steroids clionastatin A and B from inexpensive testosterone has been achieved through a unique two-stage chlorination–oxidation strategy. Key features of the two-stage synthesis include (1) conformationally controlled, highly stereoselective dichlorination at C1 and C2 and C4–OH-directed C19 oxygenation followed by a challenging neopentyl
通过独特的两阶段氯化 - 氧化策略,从廉价的睾酮中实现了多氯海洋类固醇 clionastatin A 和 B 的简明和不同的合成。两阶段合成的主要特点包括(1)在 C1 和 C2 的构象控制、高度立体选择性的二氯化和 C4-OH 定向的 C19 氧化,然后是具有挑战性的新戊基氯化以安装三个氯原子;(2) 通过光氧化还原-金属双催化一锅光化学二溴化-还原脱溴和抗马尔科夫尼科夫烯烃氧化去饱和,提高主链的氧化水平;(3) Wharton 换位以提供 D 环烯酮。,通过独特的两阶段氯化 - 氧化策略,从廉价的睾酮中实现了多氯海洋类固醇 clionastatin A 和 B 的简明和不同的合成。两阶段合成的主要特点包括(1)在 C1 和 C2 的构象控制、高度立体选择性的二氯化和 C4-OH 定向的 C19 氧化,然后是具有挑战性的新戊基氯化以安装三个氯原子;(2) 通过光氧化还原-金属双催化一锅光