New Insights into Cyclobutenone Rearrangements: A Total Synthesis of the Natural ROS-Generating Anti-Cancer Agent Cribrostatin 6
作者:Mubina Mohamed、Théo P. Gonçalves、Richard J. Whitby、Helen F. Sneddon、David C. Harrowven
DOI:10.1002/chem.201102263
日期:2011.12.2
Aryl‐ and heteroarylcyclobutenone rearrangements proceed in excellent yield under continuous‐flow conditions. The former shows a Hammett correlation with σI providing strong evidence that electrocyclisation is the rate‐determining step and has a late transition state. The reaction has been modelled by using DFT and CCSD(T) methods, with the latter giving excellent correlation with the experimental
An Efficient Flow-Photochemical Synthesis of 5<i>H</i>-Furanones Leads to an Understanding of Torquoselectivity in Cyclobutenone Rearrangements
作者:David C. Harrowven、Mubina Mohamed、Théo P. Gonçalves、Richard J. Whitby、David Bolien、Helen F. Sneddon
DOI:10.1002/anie.201200281
日期:2012.4.27
with the flow: 4‐Hydroxycyclobutenones were efficiently transformed into 5H‐furanones using an inexpensive flow‐photochemical setup. The results challenge the notion that this and the related thermochemical rearrangement display torquoselectivity in their electrocyclic opening to a vinylketene intermediate. Selectivity in the photochemicalrearrangement is due a dichotomous reactivity of the (E)‐ and