A novel method for (Z)-stereoselective preparation of CF3-substituted enediynes and their coupling reactions
作者:Hyang Hwa Jeon、Jang Bae Son、Ji Hoon Choi、In Howa Jeong
DOI:10.1016/j.tetlet.2006.11.111
日期:2007.1
Trifluoromethylated enynyl sulfones 3 were reacted with 2-4 equiv of phenyl, n-hexyl, trimethylsilyl, or triisopropylsilyl substituted ethynyllithium reagents in THF or ether at 0 degrees C to give trifluoromethylated enediynes 6 (Z)-stereoselectively in 41-96% yields. The reactions of beta-fluoro-beta-trifluoromethylvinyl sulfone 5 with same ethynyllithium reagents (4 equiv) afforded the corresponding enediynes 6 in 41-90% yields. The cross-coupling reactions of 6 bearing TMS group with aryl iodides in the presence of Pd(PPh3)(2)Cl-2, Ag2CO3, and n-BU4NBr provided the corresponding enediynes 6 in 20-71% yields. Dimerization of (Z)-6 bearing TMS group in the presence of CuBr2 and K2CO3 yielded dimer (Z,Z)-7 in good yield. (c) 2006 Elsevier Ltd. All rights reserved.