Abstract An extremely convenient, environmentally benign spirocyclization under either aqueous or solventless conditions, developed for the preparation of spiro [cyclohexane-1, 2′-(1′ H)-quinazolin]-4′(3′ H)-one (3), has been utilized to convert α-and β- aminocarboxamides 5a, 5b, 6a–c and 9 and cycloalkanones 2–2b and alkanones 2c–e into 1, 4-diazaspiro [4.5] decan-2-one (10) and cis-, diexo-or diendo-2, 2′-disubstituted ...