The Profound Effect of the Ring Size in the Electrocyclic Opening of Cyclobutene-Fused Bicyclic Systems
作者:Michael J. Ralph、David C. Harrowven、Steven Gaulier、Sean Ng、Kevin I. Booker-Milburn
DOI:10.1002/anie.201410115
日期:2015.1.26
Fused cyclobutenes, prepared by the photocycloaddition of propargyl alcohols to cyclic anhydride chromophores, undergo facile thermochemical ringopening to fused γ‐lactones. The size of the fused ring profoundly influences the temperature that is required to facilitate the ringopening (from 50 °C to 180 °C) and the nature of the product that is formed. Our studies provide new insights into the mechanistic
Here we present a comprehensive study on the [3+2]-cycloaddition of thiocarbonyl ylides with a wide variety of alkenes and alkynes. The obtained dihydro- and tetrahydrothiophenes products serve as exceptionally versatile intermediates providing access to thiophenes, dienes, dendralenes, and vic-quarternary carbon centers. The use of high-pressure conditions enables thermally unstable, sterically encumbered
The preparation and spectral studies of a series of cyclic β-ketoesters
作者:Sara Jane Rhoads、J.C. Gilbert、A.W. Decora、T.R. Garland、R.J. Spangler、Mary Jane Urbigkit
DOI:10.1016/s0040-4020(01)99237-3
日期:1963.1
their C-methyl derivatives have been prepared and studied in the U.V. and I.R. spectral regions. The enolizable β-ketoesters show a high intensity K band in the 255–263 mμ region associated with the chelated enolic species and two pairs of bands in the 6 μ double bond stretching region which correspond to the structural features of the keto and enol tautomers. The non-enolizable β-ketoesters show only a
Total Synthesis, Molecular Editing and Evaluation of a Tripyrrolic Natural Product: The Case of “Butylcycloheptylprodigiosin”
作者:Alois Fürstner、Karin Radkowski、Hartwig Peters、Günter Seidel、Conny Wirtz、Richard Mynott、Christian W. Lehmann
DOI:10.1002/chem.200601639
日期:2007.2.23
Diversification in the latter step leads to a set of analogues that differ from the natural product in the terminal (hetero)arene ring. This structural modification results in complete loss of the very pronounced ability of the parent compound 6 to induce oxidative cleavage in double stranded DNA in the presence of Cu(II). Several cyclononane-, cyclononene- and cyclononadiene derivatives prepared en
Synthesis of a Mexican bean beetle azamacrolide allomone via a novel lactam to lactone ring expansion
作者:Gordon W. Gribble、Richard A. Silva
DOI:10.1016/0040-4039(96)00234-1
日期:1996.3
The Mixican bean beetle (Epilachna varivestis) defensive secretion azamacrolide 1 has been synthesized via the novelringexpansion of N-hydroxyethyl lactam 12, which was prepared in seven steps from cyclooctanone (6).