Direct Reductive Amination of Camphor Using Iron Pentacarbonyl as Stoichiometric Reducing Agent: Features and Limitations

Abstract

The method of direct reductive amination of camphor and fenchone was proposed. The most effective reducing agent is iron carbonyl. No ligands or solvents are needed. The stereochemistry of the corresponding products was determined by HMBC, HSQC, and NOESY spectra. The limitations of the method were shown. The reaction of camphor with primary amines led to exclusively exo product, while the reaction of fenchone led to exclusively endo product. The reaction of camphor with cyclic secondary amines led to the mixture of endo and exo isomers.

Sodium Hypophosphite as a Bulk and Environmentally Friendly Reducing Agent in the Reductive Amination

“…Nevertheless, all gas reductants require high pressure and utilization of special equipment in comparison with NaH 2 PO 2 . Application of liquid Fe­(CO) 5 as an alternative to CO allows us to avoid the use of high pressure and successfully put very inert ketones into reductive amination, but Fe­(CO) 5 is toxic, unlike sodium hypophosphite. − Considering all these factors, the developed protocol with NaH 2 PO 2 as a reducing agent is distinguished by higher safety for the environment and operational simplicity compared to other presented methods. Further investigation of this reducing agent is in process.…”