Table 3.

Results of the synthesis of vicinal tricarbonyl compounds 11 and the nitrogen heterocycles 12 and 13 arising from them.

Entry	Compound	R1	ZR2	Yield, %
1	11a	2-ClC6H4	n-BuNH	67
2	11b	(2,5-MeO)2C6H3	n-BuNH	64a
3	12a	2-ClC6H4	n-BuNH	64
4	12b	(2,5-MeO)2C6H3	n-BuNH	67
5	13a	2-ClC6H4	n-BuNH	61
6	13b	(2,5-MeO)2C6H3	n-BuNH	74
7	13c	2-ClC6H4	OMe	74

^aTwo equivalents of perchloric acid were required in this case. The normal reaction conditions (1 equiv HClO₄) led to 13% yield of 11b and 52% of compound 14b (see below the mechanistic discussion associated to Scheme 7).