Pyrano[2,3-d]thiazoline-7-spiro-3
-(1
-substitutedindoline-2
-ones) 5a,b has been synthesized and reacted with some nucleophile reagents to afford new spirothiazolino[4,5:2
,3
]pyrano[6
,5
-d]pyrimidine derivatives 6a,b–13a,b, which are analogues of some reported biologically active spiroheterocyclic compounds