Iminium ion formation between primary or secondary amines and carbonyl compounds containing the moiety OC–CX results in a facile and stereospecific generation of azomethine yields which can be trapped in 1,3-dipolarcycloaddition reactions.
X=Y-ZH compounds as potential 13-dipoles. Part 29. The iminium ion route to azomethine ylides. Reaction of cyclic secondary amines with mono- and bI- functional aldehydes
give azomethine ylides. The anti-dipole is formed stereospecifically or, in the case of benzaldehyde and 2-methylbenzaldehyde, stereoselectively. The effect of the structure of the aldehyde on the stereochemistry of the derived azomethine ylide is rationalised in terms of steric and electronic effects. Inter- and intra-molecular trapping of the azomethine ylides gives cycloadducts in good yield.
The reaction of secondary α-amino acids with carbonyl compounds. Properties of the intermediate azomethine ylides. Oxazolidine formation versus 1.4-prototropy.
作者:Moustafa F. Aly、Harriet Ardill、Ronald Grigg、Stephanie Leong-Ling、Shuleewan Rajviroongit、Sivagnanasundram Surendrakumar
DOI:10.1016/s0040-4039(00)96868-0
日期:1987.1
Cyclic secondary α-amino acids react regiospecifically, via antidipole formation, with aldehydes bearing electron withdrawing substituents to give oxazolidines in good yield. In certain cases structural features in the α-amino acid promote a 1,4-prototropic process in the intermediate azomethine ylide and divert the reaction to give 2-pyrrolines, whilst use of ninhydrin as the carbonyl component results