Stereoselective Ring Expansion of Vinyl Oxiranes: Mechanistic Insights and Natural Product Total Synthesis
作者:Matthew Brichacek、Lindsay A. Batory、Jon T. Njardarson
DOI:10.1002/anie.200906830
日期:2010.2.22
applicable, catalytic, and stereoselective vinyl oxirane ringexpansion is described (see scheme; hfacac=hexafluoroacetylacetonate). The stereoselectivity was influenced by several reaction parameters, and kinetic studies support a mechanistic proposal involving the in situ formation of a more reactive catalytic species. This ring‐expansion reaction has been employed in the asymmetric total synthesis
Gold Catalysis: Efficient 1,3-Induction with Diastereotopic Homopropargyl Alcohols in the Phenol Synthesis
作者:A. Stephen K. Hashmi、Melissa Hamzić、Matthias Rudolph、Martin Ackermann、Frank Rominger
DOI:10.1002/adsc.200900402
日期:2009.10
Furans with diastereotopic alkynyl groups were prepared and then converted to anellated phenols in gold-catalyzed reactions. In all cases a highly diastereoselective reaction was observed. The stereochemical outcome of the 1,3-induction could be assigned by two independent crystal structure analyses, showing a cis-arrangement of the two alkyl substituents on the benzoanellated cyclohexene ring.
Tandem Transformations via Friedel–Crafts Acylation Followed by a Ring-Expansion, Ring-Opening, and Cycloisomerization Sequence
作者:Hun Young Kim、Kyungsoo Oh
DOI:10.1021/acs.orglett.8b03881
日期:2019.2.1
A tandem synthetic route to a diverse array of cyclic compounds has been developed from Friedel–Craftsacylation of alkynes followed by the microwave irradiation of β-chlorovinyl ketone intermediates. The stereoisomeric β-chlorovinyl ketone intermediates smoothly underwent a thermal α-vinyl enolization and ring expansion to vinyl and carbocyclic furans as well as cyclopetene derivatives in good to
Studies on Elimination Pathways of β-Halovinyl Ketones Leading to Allenyl and Propargyl Ketones and Furans under the Action of Mild Bases
作者:Hun Young Kim、Jian-Yuan Li、Kyungsoo Oh
DOI:10.1021/jo302253c
日期:2012.12.21
stereochemically defined β-halovinyl ketones has been investigated using a mild base, NEt3, leading to the formation of allenyl ketones and propargyl ketones. A preferential α-vinyl enolization of (E)-β-chlorovinyl ketones has been observed where a nonplanar s-cis conformation is proposed as a dominant conformation as opposed to a planar s-cis conformation of (Z)-β-chlorovinyl ketones. Other eliminative pathways
作者:A. Stephen K. Hashmi、Melissa Hamzić、Frank Rominger、Jan W. Bats
DOI:10.1002/chem.200901695
日期:2009.12.14
Selecting one out of two enantiotopic alkynes: A furan–diyne substrate with enantiotopic alkynyl groups was prepared and the gold‐catalyzed cycloisomerization by a series of different chiral cationic gold(I) complexes was investigated (see scheme).