Decarboxylative Generation of 2‑Azaallyl Anions: 2‑Iminoalcohols via a Decarboxylative Erlenmeyer Reaction

Condensation
between the tetrabutylammonium salt of 2,2-diphenylglycine
and aldehydes results in a decarboxylative Erlenmeyer reaction, affording
1,2-diaryl-2-iminoalcohols as a mixture of diastereomers in good yields.
The diastereomeric ratio shifts over time, with the anti diastereomer and the syn oxazolidine tautomer serving
as the kinetic and thermodynamic products, respectively. Addition
of Lewis acids can catalyze the rates of reaction and product equilibration.
The results highlight the stereochemical promiscuity of 1,2-diaryl-2-iminoalcohols
in the presence of Lewis acids and Brønsted bases.