Stereospecific preparation of symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes from 1-bromo-1-fluoroalkenes
作者:Jianjun Xu、Donald J. Burton
DOI:10.1016/j.jfluchem.2006.10.002
日期:2007.1
A straightforward method to prepare symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes is described. High E/Z ratio 1-bromo-l-fluoroalkenes, prepared by isomerization from the E/Z approximate to 1:1 isomeric mixtures, reacted with Bu3SnSnBu3 and Pd(PPh3)(4) to afford (1Z, 3Z)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes in good yield. (Z)-1-Bromo-1-fluoroalkenes, which were prepared by kinetic reduction from 1-bromo-1-fluoroalkenes (E/Z approximate to 1:1), can undergo similar reaction with Bu3SnSnBu3 and Pd(PPh3)(4)/Cul to prepare (lE, 3E)-2,3difluoro-1,4-disubstituted-buta-1,3-dienes. (c) 2006 Elsevier B.V. All rights reserved.