Ferrocenyl-QUINAP: a planar chiral P,N-ligand for palladium-catalyzed allylic substitution reactions

Synthesis of chiral ferrocenylazines. Negishi cross-coupling or S N H reactions?

“…This approach has a number of advantages: It permits avoiding the use of quinoline haloderivatives, does not require the application of palladium salts and of the accompanying ligands, reduces the number of stages. The overall yield with respect to compound I along our protocol reached 50.4% (28.5% [18]). …”

“…Quite a number [12][13][14][15][16][17] of compounds is known containing chiral groups, among them sulfoxide I (Scheme 1) [18]. The presence in the ferrocene structure of directing the 1,2-lithiation chiral moieties plays a decisive role in attaining both regio-and diastereoselectivity owing to the formation of cyclic structures in the intermediate metal derivatives (Complex Induced Proximity Effect, CIPE) [19,20] due to the coordination of the lithium atom by the lone electron pair in the directing group, and to the spatial orientation of the substituent at the asymmetric center of the side chain of the ferrocene scaffold (compound B, Scheme 2).…”

“…In [18] (Scheme 1) a fi ve-stage synthesis was described of a ligand (S Fc ,S)-[2-(quinolin-8-yl)ferrocene-1-yl]-p-tolylsulfoxide (III) using as the initial reagent sulfoxide I [26] that was subjected to lithiation (i), then to transmetallation into Zn-derivative А (ii), and to palladium-catalyzed cross-coupling with 8-bromoquinoline by Negishi reaction to obtain fi nally compound III, whose p-tolyl sulfoxide group was replaced by a diphenylphosphine residue.…”

“…In the study were used commercial reagents quinoline, (S)-(-)-menthyl p-tolylsulfi nate, BuLi, LDA, PhLi, THF purchased from Sigma-Aldrich, all other reagents and solvents were obtained from Khimreaktivsnab. Bromoferrocene [28], Ph 2 PCl·BH 3 [18] were synthesized by published methods. The properties of compounds coincide with the published data [18,28].…”

“…Bromoferrocene [28], Ph 2 PCl·BH 3 [18] were synthesized by published methods. The properties of compounds coincide with the published data [18,28].…”