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Reactivity of Planar‐Chiral α‐Ferrocenyl Carbocations towards Electron‐Rich Aromatics
Author(s) -
Korb Marcus,
Mahrholdt Julia,
Liu Xianming,
Lang Heinrich
Publication year - 2019
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201801430
Subject(s) - chemistry , enantiopure drug , reactivity (psychology) , carbocation , medicinal chemistry , steric effects , electrophile , nucleophile , stereochemistry , crystallography , enantioselective synthesis , organic chemistry , catalysis , medicine , alternative medicine , pathology
The reaction of the enantiopure, planar‐chiral α‐ferrocenyl carbocation ( S p )‐2‐(P(=S)Ph 2 )FcCH 2 + (Fc = Fe(η 5 ‐C 5 H 5 )(η 5 ‐C 5 H 3 )) towards electron‐rich arenes C 6 H 5 E (E = NH 2 , NMe 2 , N i Pr 2 , NPh 2 , PPh 2 , P(=S)Ph 2 , OH, SH, SMe) regarding either a nucleophilic attack of the group E or an electrophilic aromatic substitution reaction of the arene at the CH 2 + 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 P III species that were applied as supporting ligands in atropselective C , C cross‐coupling reactions for the synthesis of sterically hindered biaryls, where sandwich compound ( S p )‐1‐(PPh 2 )‐2‐( o ‐NMe 2 ‐C 6 H 4 )CH 2 ‐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)Ph 2 )‐2‐(CH 2 OH)‐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)Ph 2 )‐2‐(((2,4‐(NO 2 ) 2 ‐C 6 H 3 )Se)CH 2 )‐Fc was confirmed by 77 Se{ 1 H} NMR spectroscopy and single‐crystal X‐ray diffraction analysis, respectively.