An efficient, sustainable organocatalyst, glycine betaine, was developed for the reductive functionalization of CO₂ with amines and diphenylsilane by Prof. Liangnian He' group . Methylamines and formamides were obtained in high yield by tuning the CO₂ pressure and reaction temperature. Based on identification of the key intermediate, that is, the aminal, an alternative mechanism for methylation involving the C⁰ silyl acetal and aminal is proposed. Furthermore, reducing the CO₂ amount afforded aminals with high yield and selectivity. Therefore, betaine catalysis affords products with a diversified energy content that is, formamides, aminals and methylamines, by hierarchical two-, four- and six-electron reduction, respectively, of CO₂ coupled with C−N bond formation.

Link: http://onlinelibrary.wiley.com/doi/10.1002/anie.201702734/full