(−)‐Sparteine‐Mediated Directed <i>ortho‐</i>Metalation of <i>N</i>‐Cumyl‐<i>N</i>‐ethylferrocenecarboxamide. Versatile Routes to Functionalized Planar Chiral Ferrocenecarboxamides, Amines, Esters and Phosphines

Abstract

Abstract N ‐Cumyl‐ N ‐ethylferrocenecarboxamide 5 provides planar chiral carboxamides 6 in high yield and % ee via (−)‐sparteine‐mediated directed ortho ‐metalation. Mild decumylation affords secondary amides 7 , which serve as intermediates for a convenient and general route to the venerable Ugi planar chiral ferrocenylamines 13 and as versatile precursors for the preparation of novel chiral ferrocenes 15 and 20 . The chiral TMS‐ferrocenyl derivative 7c is used to prepare the enantiomeric ( S )‐ 7f , circumventing the lack of availability of (+)‐sparteine.