Iron-catalysed, general and operationally simple formal hydrogenation using Fe(OTf)3 and NaBH4

Area of Science:

• Green Chemistry
• Organic Synthesis
• Catalysis

Background:

• Traditional hydrogenation often requires expensive precious metal catalysts or harsh reaction conditions.
• Developing sustainable and cost-effective reduction methods is crucial for industrial applications.

Purpose of the Study:

• To develop an operationally simple and environmentally benign formal hydrogenation protocol.
• To demonstrate the utility of iron(III) salts and sodium borohydride (NaBH4) as a catalytic system for reduction reactions.

Main Methods:

• Utilized iron(III) salts as a catalyst precursor with sodium borohydride (NaBH4) as the stoichiometric reductant.
• Conducted reactions in ethanol under ambient temperature and pressure.
• Investigated the reduction of terminal alkenes and nitro-groups.
• Performed deuterium labeling studies to elucidate the reaction mechanism.

Main Results:

• Successfully reduced 22 examples of terminal alkenes with yields up to 95%.
• Successfully reduced 26 examples of nitro-groups with yields up to 95%.
• Deuterium labeling studies indicated an ionic mechanism, distinguishing it from radical pathways.

Conclusions:

• The developed protocol offers a simple, cost-effective, and environmentally friendly alternative for hydrogenation.
• Iron(III) salts in combination with NaBH4 provide a versatile system for the reduction of various functional groups.
• Understanding the ionic mechanism opens avenues for further optimization and application of this methodology.