Three-component reaction of an alpha -(isocyano)acetamide, a homoallyl amine and an aldehyde in methanol at room temp. provides an oxa-bridged tricyclic compd. in good to excellent yield as a mixt. of two separable diastereoisomers. In this one-pot multicomponent process, one C-N, one C-O and three C-C bonds are formed with concomitant creation of five asym. centers and three rings. Fragmentation of (epoxy)tetrahydro naphthyridine affords differentially substituted 5,6,7,8-tetrahydro-1,7-naphthyridine derivs., depending on the reaction conditions, providing thus addnl. structural diversity. A one-pot three-component synthesis of 5,6,7,8-tetrahydro-1,7-naphthyridine derivs. is also documented. [on SciFinder (R)]