Synthesis of 2-phenyl-2-cycloalkenones via palladium-catalyzed tandem epoxide isomerization-intramolecular aldol condensation
作者:Ji-Hyun Kim、Robert J. Kulawiec
DOI:10.1016/s0040-4039(98)00513-9
日期:1998.5
We have extended the scope of our palladium-catalyzed tandem epoxide isomerization/aldol condensation reaction to encompass intramolecular condensations, which provide facile access to conjugated cycloalkenones from epoxy aldehydes or diepoxides. For example, reaction of 5,6-epoxy-6-phenylhexanal with Pd(OAc)2-PBu3 catalyst in the presence of NaHCO3 and 3Å molecular sieves forms 2-phenyl-2-cyclopentenone
我们已经扩展了钯催化的串联环氧化物异构化/羟醛缩合反应的范围,使其涵盖分子内缩合,从而使环氧醛或二环氧化物易于连接到共轭环烯酮。例如,在NaHCO 3和3Å分子筛的存在下,5,6-环氧-6-苯基己醛与Pd(OAc)2 -PBu 3催化剂的反应形成2-苯基-2-环戊烯酮(80%)。类似地,1,2; 5,6-二乙氧基-1-苯基己烷得到3-甲基-2-苯基-2-环戊烯酮(72%)。对二羰基中间体(例如,在后一种情况下为1-苯基-2,5-己二酮)的观察表明,该反应是通过Pd催化的二环氧化物异构化为二酮,然后进行碱催化的羟醛缩合而进行的。