Reductive Cross-Coupling of 3-Substituted Δ<sup>3</sup>-Cephems with Alkenyl Halides in an Al/PbBr<sub>2</sub>/NiBr<sub>2</sub>(bpy) Triplemetal Redox System. Synthesis of 3-Alkenyl-Δ<sup>3</sup>-cephems
作者:Hideo Tanaka、Jinfeng Zhao、Hiroshi Kumase
DOI:10.1021/jo001429b
日期:2001.1.1
successfully by cross-coupling 3-(trifluoromethylsulfonyloxy or chloro)-delta 3-cephem with alkenyl halides, e.g., vinyl bromide, trans-1-bromo-1-propene, and trans-beta-bromostyrene in an Al/cat.PbBr2/cat.NiBr2(bpy)/NMP (or DMF) system. Reduction of 3-(trifluoromethylsulfonyloxy)-delta 3-cephem into norcephalosporin was also achieved by a similar reaction in the presence of 5 molar equiv of water. Scope
通过将3-(三氟甲基磺酰氧基或氯代)-δ3-头孢与烯基卤化物,例如溴化乙烯基酯,反式-1-溴-1-丙烯和反式烯基进行交叉偶联,可以成功地完成3-烯基-δ3-乙烯的合成。 Al / cat.PbBr2 / cat.NiBr2(bpy)/ NMP(或DMF)系统中的-β-溴苯乙烯。在存在5摩尔当量的水的情况下,通过类似的反应也可以实现将3-(三氟甲基磺酰氧基)-δ3-cephem还原成正头孢菌素。讨论了Al / Pb / Ni三元金属-氧化还原促进反应的范围和可能的机理。