Organic Chemistry International

Research Article

Organic Solid Acid/NaNO₂: An Efficient System for the Oxidation of Urazoles and Bis-Urazoles under Mild and Heterogeneous Conditions

Table 1

Oxidation of urazoles (1) and bis-urazoles (3) to their corresponding triazolinediones (2, 4) with either one of the Polymer-supported sulfonic acid (I), sulfamic acid (II) or isocyanuric acid (III) in the presence of NaNO₂ in dichloromethane at room temperature.


Entry	Urazole	Product	Reagent/substrate (mmol)			Time (h)			Yields^a (%)
Entry	Urazole	Product	I	II	III ^b	I	II	III	I	II	III

1	1a	2a	2	0.2	0.75	1	2	0.0	100^c	100^c	100^c
2	1b	2b	2	0.2	0.75	1	2	0.0	100^c	100^c	100^c
3	1c	2c	2	0.2	0.75	1	2	0.0	90	72	91
4	1d	2d	2	0.2	0.75	1	2	0.0	99	99	90
5	1e	2e	2	0.2	0.75	1	2	0.5	90	85	90
6	1f	2f	2	0.2	1	1	2	0.5	91	80	95
7	1g	2g	2	0.2	1	1	2	0.5	94	83	89
8	1h	2h	2	0.2	1.25	1	2	0.5	90	92	80
9	1i	2i	2	0.2	1	1	2	0.5	89	81	100^c,d
10	1j	2j	2	0.2	1	1	2	0.5	93	75	70
11	1k	2k	2	0.2	1	1	2.5	0.5	98	94	96
12	1l	2l	2	0.2	1.25	1	2.5	0.5	87	80	84
13	3a	4a	4	0.4	2	2	4	0.5	85	82	94
14	3b	4b	4	0.4	2	2.5	5	0.5	90	99	93

^aIsolated yields. ^bIn the presence of a few drops of water. ^cConversion. ^d4-Nitrophenyl triazolinedione is very labile. Therefore, it was destructed in the course of passing through a pad of silica gel.

Organic Chemistry International

Organic Solid Acid/NaNO2: An Efficient System for the Oxidation of Urazoles and Bis-Urazoles under Mild and Heterogeneous Conditions

Table 1

Organic Solid Acid/NaNO₂: An Efficient System for the Oxidation of Urazoles and Bis-Urazoles under Mild and Heterogeneous Conditions