PdI2-Catalyzed Coupling–Cyclization Reactions Involving Two Different 2,3-Allenols: An Efficient Synthesis of 4-(1′,3′-Dien-2′-yl)-2,5-dihydrofuran Derivatives
作者:Youqian Deng、Jing Li、Shengming Ma
DOI:10.1002/chem.200800167
日期:2008.5.9
Transition-metal-catalyzed dimeric coupling-cyclizationreactions of twodifferent2,3-allenols afforded 4-(1',3'-dien-2'-yl)-2,5-dihydrofuranderivatives3. 2-Substituted 2,3-allenols1 cyclized to form the 2,5-dihydrofuran ring, whereas the 2-unsubstituted 2,3-allenols 2 provided the 1,3-diene unit at the 4-position. The reaction is proposed to proceed through an oxypalladation, insertion, and beta-hydroxide
PdCl<sub>2</sub>/NaI-Catalyzed Homodimeric Coupling-Cyclization Reaction of 2,3-Allenols: An Efficient Synthesis of 4-(1‘,3‘-Dien-2‘-yl)-2,5-dihydrofuran Derivatives
作者:Youqian Deng、Yihua Yu、Shengming Ma
DOI:10.1021/jo702332m
日期:2008.1.1
A PdCl2/NaI-catalyzed homodimeric coupling-cyclizationreaction of 2,3-allenols was observed to provide an efficient route to 4-(1‘,3‘-dien-2‘-yl)-2,5-dihydrofuranderivatives. By using the easily available optically active starting materials, 2,5-dihydrofurans with high enantiopurity may be prepared. A Pd(II)-catalyzed mechanism was also discussed.
Efficient Highly Selective Synthesis of Methyl 2-(Ethynyl)alk-2(<i>E</i>)-enoates and 2-(1′-Chlorovinyl)alk-2(<i>Z</i>)-enoates from 2-(Methoxycarbonyl)-2,3-allenols
作者:Youqian Deng、Xin Jin、Chunling Fu、Shengming Ma
DOI:10.1021/ol9004273
日期:2009.5.21
Highly regio- and stereoselective reactions of readily available 2-(methoxycarbonyl)-2,3-allenols 1 with oxalylchloride in the presence of Et3N or DMSO afforded methyl 2-(ethynyl)alk-2(E)-enoates (E)-2 and 2-(1′-chlorovinyl)alk-2(Z)-enoates (Z)-3, respectively, in moderate to good yields.