Formal Insertion of o-Carborynes into Ferrocenyl C–H Bonds: A Simple Access to o-Carboranylferrocenes

Abstract

Insertion of o-carborynes (1,2-dehydro-ocarboranes) into ferrocenyl C−H bonds has been described, providing a convenient methodology for the preparation of functionalized ferrocenyl o-carboranes. Reaction of the

Functionalization of Carborane via Carboryne Intermediates

“…This methodology provides a simple access to ferrocenyl (Fc)-substituted o-carboranes [75]. It is noted that no C-H bond insertion is observed between benzyne and ferrocene.…”

“…This is supported by the fact that the treatment of 1,2-dilithioo-carborane with ferrocenium hexafluorophosphate also generates monoferrocenylo-carboranes. A plausible mechanism is proposed in Scheme 1.23 [75] attack of the carboryne radical anion on the cyclopentadienyl ring produces adduct VII. Direct radical-induced hydrogen shift of VII or intramolecular single-electron transfer followed by an intramolecular protonation gives final C-H bond insertion product.…”

Recent advances in the chemistry of carborynes

“…This is supported by the fact that treatment of 1,2-dilithio-o-carborane with ferrocenium hexafluorophosphate also generates monoferrocenyl-o-carborane. A plausible mechanism is proposed in Scheme 20 [46]. Nucleophilic attack of the carboryne radical anion on the cyclopentadienyl ring produces adduct VII.…”

Regioselective Insertion of o‐Carborynes into the α‐CH Bond of Tertiary Amines: Synthesis of α‐Carboranylated Amines

“…Two diastereoisomers were formed in a 1:1 ratio for 3-substitued carboranes (5 ba and 5 ca). [13,17] A significant electronic effect was observed (5 da-fa). For example, the 9,12-dimethyl carboranylated amine 5 da [18] was obtained in 76 % yield, whereas no reaction was observed for either 9,12-diiodo-o-carborane (1 e) [19] or 4,5,7,8,9,10,11,12-octamethyl-o-carborane (1 f).…”