Sclareolide was developed as an efficientC-nucleophilic reagent for an asymmetric Mannich addition reaction with a series ofN-tert-butylsulfinyl aldimines. The Mannich reaction was carried out under mild conditions, affording the corresponding aminoalkyl sclareolide derivatives with up to 98% yield and 98:2:0:0 diastereoselectivity. Furthermore, the reaction could be performed on a gram scale without any reduction in yield and diastereoselectivity. Additionally, deprotection of the obtained Mannich addition products to give the target sclareolide derivatives bearing a free N-H group was demonstrated. In addition, target compounds4–6were subjected to an antifungal assay in vitro, which showed considerable antifungal activity against forest pathogenic fungi.