Dearomative (3 + 2) Cycloadditions of Unprotected Indoles
作者:Bram Ryckaert、Jan Hullaert、Kristof Van Hecke、Johan M. Winne
DOI:10.1021/acs.orglett.2c01214
日期:2022.6.17
The (3 + 2) cycloaddition of various indoles with a dithioallyl cation affords dearomatized cyclopentannulated adducts, with complete control of regioselectivity and excellent chemo- and diastereoselectivity. The success of the reaction critically relies on the use of an excess of very strong Brønsted acid, which paradoxically prevents carbocationic side reactions. The reaction tolerates sensitive
Construction of cyclopenta[<i>b</i>]dihydronaphthofurans <i>via</i> TsOH-catalyzed consecutive biscyclization of dithioallylic alcohols and 1-styrylnaphthols
作者:He-Ping Li、Xiao-Ling Wu、Gu Zhan、Xue-Ju Fu、Jian-Hua Chen、Xiang-Hong He、Bo Han
DOI:10.1039/d2cc06324g
日期:——
An efficient TsOH-catalyzed consecutive biscyclization cascadereaction of dithioallylic alcohols with 1-styrylnaphthols is demonstrated for the concise construction of pharmaceutically important cyclopenta[b]dihydrobenzofuran scaffolds. This process involved an acid-catalyzed (3+2) cycloaddition followed by an intramolecular nucleophilic addition, providing cyclopenta[b]dihydronaphthofurans bearing
证明了二硫代烯丙醇与 1-苯乙烯基萘酚的有效 TsOH 催化的连续双环化级联反应可用于简明构建药学上重要的环戊[ b ]二氢苯并呋喃支架。该过程涉及酸催化的 (3+2) 环加成,然后是分子内亲核加成,以良好的产率提供带有四取代或完全取代的环戊烷核心的环戊[ b ] 二氢萘并呋喃,并具有独特的非对映选择性 (>20 : 1 dr)。
Dithioallyl cation (3 + 2) cycloadditions under aprotic reaction conditions: rapid access to spiro-fused cyclopentane scaffolds
作者:Frederick Degroote、Bram Denoo、Bram Ryckaert、Brenda Callebaut、Kristof Van Hecke、Jan Hullaert、Johan M. Winne
DOI:10.1039/d3ob01273e
日期:——
We report a general method to effect all-carbon (3 + 2) cycloadditions that can elaborate cyclopentenes from a range of olefins. The required dithioallyl cation reagents can be generated in a newly developed mild protocol starting from 2-allyloxypyridine precursors, thus avoiding the use of strong Brønsted acids. The novelmethod significantly expands the substrate scope, which now also includes acid-sensitive
Dithioallyl Cations in Stereoselective Dearomative (3 + 2) Cycloadditions of Benzofurans: Mechanism and Synthetic Applications
作者:Bram Ryckaert、Jan Hullaert、Kristof Van Hecke、Johan M. Winne
DOI:10.1021/acs.joc.3c01546
日期:2023.10.20
govern the stereoselectivity of the intriguing dearomative transformations using dithioallyl cations and demonstrate how the stereoselectivity depends on electronic factors of the starting materials. The stereoselective methodology is also applied in a straightforward dearomative synthesis of the tricyclic sesquiterpenoid natural product aplysin and its analogues, starting from a simple benzofuran
2-[[O-(p-Methoxybenzyl)-oxy]methyl]-5,6-dihydro-1,4-dithiin 1 is a versatile three carbon homologation reagent which has been conveniently used in the synthesis of enantiomerically pure modified nucleosides.