Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines

In the presence of 3-5 mol% Crabtree's catalyst or the corresponding tetrakis[3,5-bis(trifluoromethyl)phenyl]borate salt (Cy3P)Ir+(pyridine)(1,5-cyclooctadiene)·X- {X = PF6, [3,5-(F3C)2C6H3]4B}, aryl 1,1-disubstituted epoxides such as α-methylstyrene oxide underwent chemoselective isomerization to aldehydes; treatment with benzhydrylamine and pyrrolidine and redn. with NaBH4 yielded 2,2-disubstituted amines such as PhCHMeCH2NHR [R = Ph2CH, 4-MeOC6H4, PhCH2, (R)-PhCHMe] in one pot. DFT calcns. were performed to rationalize the obsd. selectivity.