Metal-Free Transfer Hydroiodination of C–C Multiple Bonds
作者:Weiqiang Chen、Johannes C. L. Walker、Martin Oestreich
DOI:10.1021/jacs.8b12318
日期:2019.1.16
The design and a gram-scalesynthesis of a bench-stable cyclohexa-1,4-diene-based surrogate of gaseous hydrogen iodide are described. By initiation with a moderately strong Brønsted acid, hydrogen iodide is transferred from the surrogate onto C-C multiple bonds such as alkynes and allenes without the involvement of free hydrogen iodide. The surrogate fragments into toluene and ethylene, easy-to-remove
描述了基于环己-1,4-二烯的气态碘化氢替代品的设计和克级合成。通过用中等强度的布朗斯台德酸引发,碘化氢从替代物转移到 CC 多重键上,例如炔烃和丙二烯,而没有游离碘化氢的参与。代用品碎片化为甲苯和乙烯,易挥发废物。这种氢碘化反应避免了对碘化氢或氢碘酸的不稳定处理。通过这种方式,可以以立体控制的方式访问范围广泛的以前未知或难以制备的乙烯基碘。
The Cyclohexa‐2,5‐dienyl Group as a Placeholder for Hydrogen: Organocatalytic Michael Addition of an Acetaldehyde Surrogate
An aldehyde with a cyclohexa‐2,5‐dienyl group in the α‐position is introduced as a storable surrogate of highly reactive acetaldehyde. The cyclohexa‐2,5‐dienyl unit is compatible with an enantioselective Michael addition to nitroalkenes promoted by a Hayashi–Jørgensen catalyst and can be removed by a boron Lewis acid mediated C−C bond cleavage. The robust two‐step sequence does not require a large
(S)-4-Trimethylsilyl-3-butyn-2-ol as an auxiliary for stereocontrolled synthesis of salinosporamide analogs with modifications at positions C2 and C5
作者:Landy K. Blasdel、DongEun Lee、Binyuan Sun、Andrew G. Myers
DOI:10.1016/j.bmcl.2013.09.066
日期:2013.12
steps using as the first and key transformation a diastereoselective Mukaiyama aldol reaction between the chiral 5-tert-butyldimethylsiloxy-3-methyl-1H-pyrrole-2-carboxylic ester depicted and various aldehyde substrates, promoted by tert-butyldimethylsilyl triflate. In this transformation, the 4-trimethylsilyl-3-butyn-2-ol ester functions to direct the formation of predominantly one of four possible diastereomeric
具有 C2 和 C5 取代基变化的盐孢菌酰胺 A 类似物通过 8-10 个步骤制备,使用手性 5-叔丁基二甲基甲硅烷氧基-3-甲基-1 H -吡咯-2 之间的非对映选择性 Mukaiyama 羟醛反应作为第一个也是关键的转化所示的β-羧酸酯和各种醛底物,由叔丁基二甲基甲硅烷基三氟甲磺酸酯促进。在此转化中,4-三甲基甲硅烷基-3-丁炔-2-醇酯的作用是引导主要形成四种可能的非对映异构羟醛产物之一。通过后期立体控制烷基化反应引入 C2 附属物允许在该位置构建类似物变体。报告了蛋白酶体抑制的体外和基于细胞的测定的结果。质谱研究提供了盐孢菌酰胺 A 及其类似物对蛋白酶体修饰的机制细节。