Lewis Base Catalyzed Addition of Trimethylsilyl Cyanide to Aldehydes

Abstract

A variety of achiral Lewis bases were found to catalyze the addition of TMSCN to the aldehydes. Among them, phosphines and amines were the most efficient catalysts. In addition, several chiral amines and phosphines were examined in a catalytic, asymmetric addition of TMSCN to benzaldehyde albeit with low enantioselectivity. A mechanistic study revealed that the reaction was first order in aldehyde, first order in Lewis base, and zeroth order in TMSCN, suggesting the complex formation of TMSCN and Lewis base formation of complex i. However, there are at least two possible scenarios for this catalytic process, and in view of the low selectivities observed, it is not clear which mechanism is operative.

Lewis Base Catalysis in Organic Synthesis

“…[275] Of all the Lewis bases surveyed, the following trend is seen: nBu 3 P > DMAP > Et 3 N > NMI > HMPA (DMF, DMSO, pyridine-Noxide, Ph 3 P=O, tetramethylurea were much less effective). Among the phosphorus derivates, the order of reactivity is nBu 3 P % HMPT > Ph 3 P % (MeO) 3 P. With Et 3 N as the catalyst, the reactions were fastest in acetonitrile by a wide margin over dichloromethane and other solvents.…”

Lewis‐Base‐Katalyse in der organischen Synthese

“…[275] Dabei wurde folgende Tendenz erhalten: nBu 3 P > DMAP > Et 3 N > NMI > HMPA. (DMF, DMSO, Pyridin-N-oxid, Ph 3 P=O und Tetramethylharnstoff waren weit weniger effektiv.)…”

Organocatalytic synthesis of cyanohydrin trimethylsilyl ethers by potassium 4‐benzylpiperidinedithiocarbamate under solvent‐free conditions

“…Accordingly, 2 mol% catalyst loading under solvent-free conditions at room temperature was found to be the optimal All products are known and were well-characterized by IR and NMR spectral data as compared with those obtained from authentic samples or reported in the literature. [9,12,17,18,20,21,35,50,54,70] c Determined by GC analysis.…”