Direct Carbocyclization of Aldehydes with Alkynes: Combining Gold Catalysis with Aminocatalysis
摘要:
A combination of gold(l) complexes and amine bases catalyzes the 5-exo-dig cyclization of formyl alkynes. This direct alpha-functionalization of aldehydes with unactivated alkynes does not involve the use of preformed enol equivalents.
Combination iminium, enamine and copper(i) cascade catalysis: a carboannulation for the synthesis of cyclopentenes
作者:Ting Yang、Alessandro Ferrali、Leonie Campbell、Darren J. Dixon
DOI:10.1039/b802416b
日期:——
A one-pot, multistep reaction cascade to cyclopentenes from alpha,beta-unsaturated ketones and propargylated carbon acids through a combination of organocatalysis and transition metal ion catalysis is reported; the reaction cascade is simple to perform, occurs under mild conditions and is broad in scope.
A Conia‐Ene‐Type Cyclization under Basic Conditions Enables an Efficient Synthesis of (−)‐Lycoposerramine R
作者:Felix W. W. Hartrampf、Takayuki Furukawa、Dirk Trauner
DOI:10.1002/anie.201610021
日期:2017.1.16
An enantioselective total synthesis of the Lycopodium alkaloid lycoposerramine R is presented. It relies on a base‐mediated cyclization that resembles the Conia‐ene reaction of ynones and gold‐catalyzed variants thereof. Thus, hydrindanones and other functionalized ring systems bearing an exocyclic alkene can be rapidly accessed at room temperature without noble metal catalysis or substrate preactivation
method for cyclization of alkynes is described. The reaction cascade involves the intermolecular addition of a phenylthiyl radical to a terminal triple bond generating an alkenylradical, followed by a 1,5-hydrogen atom transfer and a 5-exo-trig radicalcyclization. This very efficient tin-free procedure allows one to prepare highly functionalized cyclopentane derivatives as well as fused bicyclic and
Gold-Catalyzed 5- and 6-exo-dig Selective Cyclizations of Alkynyl Silyl Enol Ethers: Efficient Method for [3+2] and [4+2] Annulations onto α,β-Enones
作者:Kooyeon Lee、Phil Ho Lee
DOI:10.1002/adsc.200700304
日期:2007.9.3
An efficient method for the annulation of five- and six-membered rings onto α,β-enones is described via gold-catalyzed 5- and 6-exo-dig selective cyclizations of alkynyl silyl enolethers.