Ferrocenes: Difunctional Ferrocenes from 1,1´-Ferrocenedicarboxylic Acid.

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

“… Double Curtius rearrangements at 1,1’‐dicaylazido ferrocene 203 towards diisocyanate 225 and peptides 227 [68,69] …”

“…The rearrangement of two almost simultaneous Curtius rearrangements of C(O)N 3 groups at 1,1’‐substituted ferrocenes are commonly used for the synthesis of 1,1’‐diamino ferrocene (Scheme 60). [68,69] Heating the respective carbonyl azide 203 in anhydrous toluene at 80 °C for 40 min gives the respective diisocyanate 225 as a rather stable solid on a 70 gram scale. Reaction with t BuOH produced in a very clean way the bis‐Boc‐protected derivative, serving as a synthon for the preparation of 1,1’‐diamino‐ferrocenes.…”

“…Reaction with t BuOH produced in a very clean way the bis‐Boc‐protected derivative, serving as a synthon for the preparation of 1,1’‐diamino‐ferrocenes. Further applications as amino acid conjugates of L‐ and D‐alanine have been reported [68,69] . A variety of procedures for the synthesis of 203 , 225 and its reaction products have since then been reported that slightly differ in their reaction protocol.…”

“…The rearrangement of two almost simultaneous Curtius rearrangements of C(O)N 3 groups at 1,1'-substituted ferrocenes are commonly used for the synthesis of 1,1'-diamino ferrocene (Scheme 60). [68,69] Heating the respective carbonyl azide 203 in anhydrous toluene at 80 °C for 40 min gives the respective Scheme 56. Remote Curtius rearrangement.…”

“…Further applications as amino acid conjugates of L-and D-alanine have been reported. [68,69] A variety of procedures for the synthesis of 203, 225 and its reaction products have since then been reported that slightly differ in their reaction protocol. However, since the overall reaction profile is similar they are not mentioned in detail.…”