Catalytic Enantioselective Synthesis of Cyclobutenes from Alkynes and Alkenyl Derivatives
作者:Mahesh M. Parsutkar、Vinayak Vishnu Pagar、T. V. RajanBabu
DOI:10.1021/jacs.9b07885
日期:2019.9.25
compounds from readily available precursors, using scalable and environmentally benign chemistry, can greatly impact their design, synthesis and eventually manufacture on scale. Functionalized cyclobutanes and cyclobutenes are important structural motifs seen in many bioactive natural products and pharmaceutically relevant small molecules. They are also useful precursors for other classes of organic compounds
使用可扩展且环境友好的化学方法,发现用于从容易获得的前体制备手性化合物的对映选择性催化反应,可以极大地影响它们的设计、合成和最终的规模制造。功能化环丁烷和环丁烯是许多生物活性天然产物和药学相关小分子中的重要结构基序。它们也是其他类别有机化合物的有用前体,例如其他环烷烃衍生物、杂环化合物、立体定义的 1,3-二烯和催化不对称合成的配体。制造环丁烯的最简单方法是通过炔烃和烯基衍生物之间的对映选择性 [2+2]-环加成反应,这种反应历史悠久。然而,给出可接受的对映选择性的此类已知反应的范围非常窄,并且严格限于活化的炔烃和高反应性烯烃。在这里,我们公开了一种广泛适用的对映选择性 [2+2]-环加成反应,在各种炔烃和烯基衍生物(两种最丰富的有机前体类别)之间进行。关键的环加成反应使用衍生自易于合成的配体和地球上丰富的金属钴的催化剂。记录了 50 多种对映选择性在 86-97% ee 范围内的不同
Remote ether groups-directed regioselective and chemoselective cycloaddition of azides and alkynes
作者:Xuelun Duan、Nan Zheng、Ming Li、Xinhao Sun、Zhuye Lin、Pan Qiu、Wangze Song
DOI:10.1016/j.cclet.2021.05.037
日期:2021.12
5-regioselectivities and excellent chemoselectivities. Ether group could coordinate with iridium catalyst by lone-pair electron at a distance (up to four σ bonds) away from alkyne to control the regioselectivity by weak coordination effect. The cycloaddition reaction chemoselectively occurred at the propargyl ether moiety of diyne to give unique fully substituted 4-alkynyl-triazole.
Hydrophosphination of Propargylic Ethers with Diphenylphosphine in the Presence of LiHMDS,<i>N</i>-Heterocyclic Carbene, and Ti(NMe<sub>2</sub>)<sub>4</sub>
Regio- and stereoselective hydrophosphination of propargylic ethers with diphenylphosphine has been achieved using three-component catalyst, LiN(SiMe3)2/1,3-dimethylimidazol-2-ylidene/Ti(NMe2)4 (10 mol % of each).
Treatment of propargylic ethers with sodium dispersion in the presence of lithium iodide results in the generation of the corresponding carbanion species via cleavage of the propargylic C–O bond. The anionic species react with trimethoxyborane to yield the allenylboronates including highly substituted ones that are difficult to synthesize.
Diastereoselective Synthesis of Eight-Membered-Ring Allenes from Propargylic Epoxides and Aldehydes by Silylene Insertion into Carbon-Oxygen Bonds
作者:Christina Z. Rotsides、Chunhua Hu、K. A. Woerpel
DOI:10.1002/anie.201306093
日期:2013.12.2
Bent out of shape: Silver‐catalyzed insertions of silylenes into propargylic CO bonds of epoxides regioselectively form 1,2‐silaoxetanes, which add to aldehydes to give the title allenes as single diastereomers (see scheme; Ts=4‐toluenesulfonyl). An X‐ray crystal structure confirmed the stereochemistry of the allene, which is bent significantly from linearity (164°).