Reactivity of Planar‐Chiral α‐Ferrocenyl Carbocations towards Electron‐Rich Aromatics

Abstract

The reaction of the enantiopure, planar‐chiral α‐ferrocenyl carbocation (Sp)‐2‐(P(=S)Ph2)FcCH2+ (Fc = Fe(η5‐C5H5)(η5‐C5H3)) towards electron‐rich arenes C6H5E (E = NH2, NMe2, NiPr2, NPh2, PPh2, P(=S)Ph2, OH, SH, SMe) regarding either a nucleophilic attack of the group E or an electrophilic aromatic substitution reaction of the arene at the CH2+ unit is reported. It was found that the amino, oxo or thio functionalities gave the respective ferrocenes in various product distributions, while the P‐based species didn't. Appropriate thiophosphine derivatives could be reduced to their PIII species that were applied as supporting ligands in atropselective C,C cross‐coupling reactions for the synthesis of sterically hindered biaryls, where sandwich compound (Sp)‐1‐(PPh2)‐2‐(o‐NMe2‐C6H4)CH2‐Fc gave an ee of 69 % (1 mol‐% [Pd]), which is up to date the highest observed value for planar‐chiral ferrocenes. The absolute configuration of the chiral ferrocenes was confirmed by single‐crystal X‐ray diffraction analysis. For seleno phosphane 1‐(P(=Se)Ph2)‐2‐(CH2OH)‐Fc a unique Se single‐atom transfer occurred within its reaction with Sanger's reagent. The presence of two chemically different Se atoms in 1‐(P(=Se)Ph2)‐2‐(((2,4‐(NO2)2‐C6H3)Se)CH2)‐Fc was confirmed by 77Se{1H} NMR spectroscopy and single‐crystal X‐ray diffraction analysis, respectively.

Bis(2-nitrophenyl) selenide, bis(2-aminophenyl) selenide and bis(2-aminophenyl) telluride: structural and theoretical analysis

“…Table 2 Selected geometric parameters (Å , ) for 2. -Se1-O2 72.21 (7) C7-Se1-O3 68.23 (7) C7-Se1-O2 167.00 (8) O2-Se1-O3 124.39 (6) examples of bis(2-nitrophenyl) selenides gave 21 hits [CSD refcodes GISKAX (Korb et al, 2019), BEYCOY (Rodilla et al, 2004), FEGSAL (Gicquel-Mayer et al, 1987, HEPPIE and HEPPIE01 (Wang et al, 2018), IUSJUC and ISUKAJ (Singh et al, 2011a), IVEKIE, IVEKUQ and IVELEB (Singh et al, 2011a), MILCUF (Bragg et al, 2001), NBZSES, NBZSES01 (Eriksen, 1975), NBZSET (Eriksen & Hauge, 1972), QOZPAX and QOZPEB (Stuhr-Hansen et al, 2009), QQQHCS and QQQHCV (Eriksen, 1972), REFYEG (Brantley et al, 1997), XEPQAM (Singh et al, 2011b), and YUFNOC (Meyers et al 1995) , of which the shortest involve the chloromethyl groups of adjoining molecules. These contacts seem to be the major factor in influencing the differences in conformation.…”

Rearrangements and Migrations along the Ferrocene Periphery: On the Way to Planar‐Chiral and (Multi)Substitution Patterns

“… Chalcogene exchange and formation of thio and seleno 185 ethers from alcohols 182 under basic conditions [28,6b] …”

“…However, an unexpected rearrangement was recently observed for ortho ‐P(X)Ph 2 ‐functionalized ferrocene compounds 182 (X=S, Se) depending on the reaction conditions (Scheme 48). [28,6b] Acid mediated dehydration gave the respective α‐ferrocenyl carbocations that underwent S E Ar reactions with aromatic solvents. However, in the absence of additional arenes, chalcogene ethers of type 183 were formed, in which the P‐bonded chalcogene seemed to have migrated towards the α position.…”

Widening the Scope of “Inherently Chiral” Electrodes: Enantiodiscrimination of Chiral Electroactive Probes with Planar Stereogenicity

“…All compounds were synthesized according to previously reported procedures, [81][82][83][84][85] starting from ferrocenyl aldehydes, which were (stereo-)selectively lithiated in ortho-position followed by reaction with the appropriate phosphorus electrophile. The various vinyl functionalities were introduced using Horner-Wadsworth-Emmons (HWE) reactions of ferrocenyl aldehydes with phosphonates.…”

“…The parent P III phosphines of compounds 1, [75] 2-6,12-13,15,16, [74] 7-9,14,16 [82] and 10,11 [83][84][85] were synthesized according to published procedures. The herein applied P V -sulfides were obtained by stirring of the parent P III phosphines with an excess of elemental sulfur in dichloromethane or tetrahydrofuran according to literature.…”