The multicomponent Petasis borono‐Mannich reaction proceeds via an imine with the boronic acid acting as the nucleophile for the preparation of amines and their derivatives, including amino acids. In view of the expansion of the poorly‐exploited carbohydrate chemistry using this reaction, a new α‐hydroxy aldehyde moiety from the terminal diol of d‐glucose diacetonide was synthesized and applied to this multicomponent reaction, demonstrating the scope of this method and the applicability to the convenient preparation of a protected polyfunctional δ‐amino acid in only three synthetic steps from the Petasis reaction intermediate.