Can protection group be used in a Wolff–Kishner reaction?
@Halake: The protection of adipaldehyde as the monoacetal was solved by Schreiber and Claus some years ago [Also see, Schreiber, S.L.; Claus, R.E.; Reagan, J. Tetrahedron Letters, 1982, 23, 3867.] Ozonolysis of cyclohexene (1) in the presence of methanol leads to the molozonide 2, that opens to the zwitterion 3 which is trapped as the methoxy hydroperoxide 4. Addition of p-toluenesulfonic acid catalyzes the formation of the acetal 5. After neutralization with sodium bicarbonate, reduction of the hydroperoxide with dimethyl sulfide affords the monodimethyl acetal of adipaldehyde 6. Since acetals are base stable, Wolff-Kishner reduction of the aldehyde can be accomplished followed by aqueous acid hydrolysis of the acetal.