Sulfonic acid anchored on silica, SiO2@SO3H: A superior solid acid catalyst for quick and solvent-free reductive-deoxygenation of ketones with NaBH3CN

NaBH3CN as a modified hydroborate agent and due to a strong withdrawing CN
group does not show any reducing ability to reduce functional groups in the
absence of acidic media (pH ~ 3–4). In this study, the immobilized sulfonic acid
on silica, SiO2@SO3H, was prepared and applied as a new solid acid catalyst for
extremely enhancing the reducing ability of NaBH3CN. The influence of SiO2@-
SO3H was highlighted by performing the quick and green reduction of structurally
diverse carbonyl compounds involving aldehydes, ketones, α,β-unsaturated enals
and enones, α-diketones, and acyloins to the corresponding alcohols or alkanes
with NaBH3CN. By the NaBH3CN/SiO2@SO3H system, aldehydes were reduced
to the corresponding alcohols and ketonic compounds to alkanes as reductivedeoxygenation
products. All reduction reactions were carried out within 3 min at
room temperature and under solvent-free conditions to afford the products in high
to excellent yields (90–98%).