Recent developments in the synthesis and applications of chiral ferrocene ligands and organocatalysts in asymmetric catalysis

Abstract

With the ever-present need for novel asymmetric methodologies in organic synthesis to allow chemists to access enantiopure compounds, so too is there a need for new chiral ligands and organocatalysts...

Unravelling functions of halogen substituents in the enantioseparation of halogenated planar chiral ferrocenes on polysaccharide-based chiral stationary phases: experimental and electrostatic potential analyses

“…The latter are derivatized with chloro-or/and methyl-substituted phenylcarbamate pendant groups determining the distinctive stereoelectronic properties of each selector (Table S1, Supplementary data,) [40]. The amylose-based columns provided baseline enantioseparation for eight compounds (1-6, 10, 11), whereas 10 only two compounds (3,8) were baseline enantioseparated with cellulose-based selectors. The column performances, in terms of number of baseline enantioseparations, decreased following the order A-1 (7)…”

“…The serendipitous discovery of ferrocene in 1951 [1,2], and its structural determination a year later [3][4][5], have initiated an ever-increasing number of researches, which have led to the synthesis of numerous substituted ferrocenyl derivatives for various applications, from fuel additive and electrochemistry to catalysis, medicinal chemistry, optoelectronics, and material sciences [6][7][8].…”

“…Monosubstituted ferrocenes are prochiral compounds, while different disubstitution on one ferrocene ring leads to planar chirality. Such phenomenon has led to the huge development of ferrocenyl derivatives as chiral ligands in asymmetric synthesis and catalysis [8,16]. However, only a few enantiomerically enriched haloferrocenes are known [17][18][19][20].…”

Bimetallic complexes that merge metallocene and pincer-metal building blocks: synthesis, stereochemistry and catalytic reactivity

“…[12][13][14][15] Nevertheless, in terms of produced volume, the most important role of metallocenes is in the realm of catalysis. [16][17][18][19][20][21][22][23][24] Notably, in polymerization catalysis rather than a genuine metallocene, so-called half-sandwich metallocenes, i.e., metallocenes in which one of the two Cp rings is replaced by other neutral/anionic ligands, have found extensive application. [25][26][27][28][29][30] The exploration of complexes with a pincer-metal platform is a more recent development although the isolation of the first pincer complexes by Shaw et al already dates back to the mid 1970′s.…”

Planar Chiral 1,3-Disubstituted Ferrocenyl Phosphine Gold(I) Catalysts

“…Since the pioneering work of Ugi, 2 followed by those of Kagan, 3 Richard, 4 Uemura, 5 and Sammakia, 6 C 2 -functionalization of enantiopure ferrocenes by a chiral directing metalation group allowed the access of a variety of chiral 1,2-disubstituted ferrocene ligands such as PPFA, 1 Josiphos, 7 Fcphox, 4 and Fesulphos, 8 among others. 9 Ferrocenyl phosphine ligands are mainly bidentate and display central chirality in addition to planar chirality, which plays a crucial role on the enantioinduction. 10 The pioneering examples in enantioselective gold(I) catalysis 11 referred to the use of a chiral ferrocenyl phosphine-gold(I) catalysts in the asymmetric aldol reaction between aldehydes and isocyanoacetates.…”