Electrophilic fluorination of a range of N‐protected 2‐piperideines, followed by Lewis‐acid mediated functionalization affords the corresponding 3‐fluoropiperidines. When X = allyl, these reactions were found to be cis‐selective. This was particularly marked in the case of R = 2‐Ns. 19F NMR spectroscopy and X‐ray crystallography were used to understand the stereochemical outcomes of these processes
一系列N保护的2-哌啶的亲电子氟化,然后路易斯酸介导的官能化,提供了相应的3-氟哌啶。当X =烯丙基时,发现这些反应是顺式选择性的。在R = 2–Ns的情况下尤其明显。19 F NMR光谱和X射线晶体学用于了解这些过程的立体化学结果。
Ring Expansion of Lactones and Lactams via Propiolate 1-Carbon Intercalation
作者:Tina N. Grant、Chantel L. Benson、F. G. West
DOI:10.1021/ol8014682
日期:2008.9.18
available five- and six-membered lactones and N-sulfonyllactams undergo efficient addition of t-butyl propiolate, and the resulting adducts undergo cycloisomerization to six- and seven-membered cyclic ethers or amines in the presence of pyridinium acetate. The ring expansion process occurs in generally good yields and is proposed to involve a nucleophilic catalysis mechanism.
synthesized by bioisosteric replacements of the quinazolone moiety of the pentacyclic system with benzothiadiazine 1,1-dioxide. Syntheses were performed efficiently by formation of phenylhydrazones via active methylene group transformations of pyrrolo- and pyrido[1,2-b]1,2,4-benzothiadiazine 5,5-dioxides, and subsequent Fischer-indolization. Preliminary testing of compound 3 showed cytotoxic activity against
Ring Expansion Strategies for the Synthesis of Medium Sized Ring and Macrocyclic Sulfonamides
作者:Zhongzhen Yang、Illya Zalessky、Ryan G. Epton、Adrian C. Whitwood、Jason M. Lynam、William P. Unsworth
DOI:10.1002/anie.202217178
日期:2023.3.20
Two ringexpansion strategies are reported for the synthesis of medium sized and macrocyclic sulfonamides. Both methods proceed without using classical protecting groups, initiated by nitro reduction and amine conjugate addition respectively, to make diversely functionalised cyclic sulfonamides in a range of ring sizes. The ring size dependency of the synthetic reactions is in good agreement with the