Anderson James C, Osborne James D, Woltering Thomas J
School of Chemistry, University of Nottingham, Nottingham, UKNG7 2RD.
Org Biomol Chem. 2008 Jan 21;6(2):330-9. doi: 10.1039/b715323f. Epub 2007 Nov 29.
The s-BuLi-sparteine base combination deprotonated the C-2' position of 1,2,3,4,5-pentamethylazaferrocene and subsequent reaction with a range of electrophiles gave C-2 substituted products in 76-93% yield and approximately 80% ee. The products could be recrystallised to enrich ee's to >90%. Resubjection of the initial addition products ( approximately 80% ee) to the deprotonation conditions led to a kinetic resolution to give products with >90% ee and superior overall yields compared to recrystallisation for the cases where the electrophiles were Ph2CO, MeI and Ph2S2. Transmetallation of the 2-lithiopentamethylazaferrocene ( approximately 80% ee) with ZnCl2 allowed palladium catalysed cross coupling with a variety of C-2 haloaryl, heteroaryl and vinyl groups to give some novel C-2' substituted pentamethylazaferrocene derivatives in 61-77% yield in 80% ee. Potential N,N-chelate ligands were recrystallised to >95% ee. A novel C2-symmetric bis-pentamethylazaferrocene could be synthesised by an iron catalysed oxidative coupling of the enatioenriched C-2 lithio derivative and in the presence of a PhMe-Et2O solvent mixture proceeded in 97% ee.
仲丁基锂-鹰爪豆碱碱组合使1,2,3,4,5-五甲基氮杂二茂铁的C-2'位去质子化，随后与一系列亲电试剂反应，得到产率为76 - 93%且对映体过量率约为80%的C-2取代产物。这些产物可通过重结晶使对映体过量率富集至>90%。将初始加成产物（对映体过量率约为80%）重新置于去质子化条件下会导致动力学拆分，从而得到对映体过量率>90%且与重结晶相比总体产率更高的产物，其中亲电试剂为二苯甲酮、碘甲烷和二硫化二苯。2-锂代五甲基氮杂二茂铁（对映体过量率约为80%）与氯化锌进行金属转移反应后，可实现钯催化与多种C-2卤代芳基、杂芳基和乙烯基的交叉偶联，以61 - 77%的产率和80%的对映体过量率得到一些新型的C-2'取代五甲基氮杂二茂铁衍生物。潜在的N,N-螯合配体经重结晶后对映体过量率>95%。一种新型的C2对称双五甲基氮杂二茂铁可通过对映体富集的C-2锂代衍生物的铁催化氧化偶联反应合成，在甲苯-乙醚溶剂混合物存在下反应的对映体过量率为97%。
