Combinations of Alkyllithiums and Lithium Aminoalkoxides for Generation of Functional Pyridine Organometallics and Derivatives

Abstract

This account covers the current status of pyridine metallation with alkyllithium/lithium aminoalkoxide reagents and follows a previous review focusing on pioneering works on the nBuLi/LiDMAE reagent. An updated overview of the scope of metallation with this superbase is presented, together with the development of new reagents and synthetic applications based on selective lithiation methodology.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Lithium Cadmate-Mediated Deprotonative Metalation of Anisole: Experimental and Computational Study

“…Well-known examples of powerful RR'MLi mixtures of organolithiums and M alkali metal alkoxides are LIC-KOR (LIC = (common) BuLi, KOR = potassium tert-butoxide) first described by Schlosser 2 and Lochmann, 3 and BuLi-LiDMAE (DMAE = 2-dimethylaminoethoxide) developed in the pyridine series by Gros and Fort. 4 (R) n (R') n' MLi type bases with M different from an alkali metal have also been described since by different groups. 5 Among them, examples are the mixed Li-Zn bases R 2 Zn(TMP)Li-(·TMEDA) (R = t Bu, Bu) described by the groups of Kondo, Uchiyama, Mulvey and Hevia, 6 and (TMP) 2 Zn·2MgCl 2 ·2LiCl 7 and TMPZnCl·LiCl 8 developed by the group of Knochel.…”

Sodium Diisopropylamide in N,N-Dimethylethylamine: Reactivity, Selectivity, and Synthetic Utility

“…The facile haloarene metalations in entries 9 and 10 again underscore a surprising reluctance of the arylsodium to form benzyne at temperatures below −30 °C. Compared with the ~1:1 mixture observed for LDA, the regioselectivity in entry 10 that favors metalation at the 6-position rather than at the doubly activated 2-position is higher, 22 but facile equilibration 22,23 even at −78 °C affords the 2-sodiated intermediate as the exclusive form, as shown via quenching and 19 F NMR spectroscopy.…”

Transition‐Metal‐Free Heterobiaryl Synthesis via Aryne Coupling

“…This unfavorable influence of TMEDA on the aryne coupling is consistent with the reported results in the biphenyl series. [39] In contrast, use of its aminoalkoxide analog, DMAE [58][59][60][61] (LC1) afforded the expected heterobiaryl in a slightly better -but still modest -20 % yield. Although one could have expected a favorable influence of the alkoxide moiety, the reaction failed to occur when using the corresponding dialkoxide ligand LB1.…”