Chiral Isocyanides, Carboxylic Acids and Carbonyl Compounds

Chiral Isocyanides, Carboxylic Acids and Carbonyl Compounds 

As already mentioned in Section 1.4.1, chiral isocyanides usually give no induction at all in Ugi reactions. For example, when using chiral a-substituted or a,a-disubstituted isocyanoacetates [7, 27, 44], the two resulting diastereoisomers are 

At present no chiral carboxylic acid capable of significantly controlling the stereochemistry of the new stereogenic center has been reported [42, 46]. 

Protected a-aminoaldehydes follow the same trend, although a notable exception is represented by the reaction of compound 43 with a bulky isonitrile, affording 44 in a 3 1 ratio (the relative configuration of the major product was not determined) 

Although various chiral glycosyl aldehydes with a direct attachment of the carbonyl group to the anomeric center showed low diastereoselectivity [52], a moderate stereoselectivity was observed in the condensation of 45 with methyl isocyanoa-cetate, propionic acid and a solid-supported amine [53]. 

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