Dry and Wet Green Synthesis of 2,2′-Disubstituted Quinazolinones

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 alpha- and beta-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 quinazolinones 5a, 5b, 7a-f and 8. diexo-Methylene-bridged carboxamides 6a and 6b were treated on water with N-benzylpiperidinone (11) to afford spiropiperidine-quinazolinones 12a and 12b. All these reactions were performed at room temperature, without any catalyst or co-solvent, and gave yields of up to 99%.