Brønsted acid assisted regio- and enantioselective direct O-nitroso aldol reaction catalysed by alpha,alpha-diphenylprolinol trimethylsilyl ether.
In the presence of p-nitrobenzoic acid, the O-nitroso aldol reaction of nitrosobenzene with enolisable aldehydes may be promoted by commercially available alpha,alpha-diphenylprolinol trimethylsilyl ether. The reaction proceeds with good yields and essentially complete enantioselectivity, with catalyst loadings in the 5-10 mol % range. The resulting alpha-oxyaldehyde adducts may be transformed in situ into alpha-oxyimines, which provide 1,2-amino alcohols upon treatment with Grignard reagents, in good overall yield (45-59%) and with typical diastereomeric ratios > or = 95:5.
Mielgo
Antonia
A
Departamento de Química Orgánica I, Universidad del País Vasco, Manuel Lardizabal 3, 20018 San Sebastián, Spain.
Velilla
Irene
I
Gómez-Bengoa
Enrique
E
Palomo
Claudio
C