A Protected 5-Hydroxypentanal Synthon

Abstract

In connection with other work, we needed a synthon which corresponded to 5-hydroxypentanal (2) separately protected at each end. To some extent this requirement is met by dihydropyran (1), but in the reactions of this compound both of the masked functional groups are released at the same time. Obviously, it would be an advantage to use this readily available compound as our starting material for the preparation of a

protected derivative of the hydroxyaldehyde (2). We now report that a simple solution to the problem is the one-pot preparation of the crystalline acetal tosylate (3), and we illustrate one way in which such a derivative can be used in synthesis.