A Mild and Green Method for the N-BOC Protection
Letters in Organic Chemistry, 2013, Vol. 10, No. 2
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BOC derivatives in moderate to excellent isolated yields.
This new method offers the following competitive advan-
tages: (i) it is mild and operationally simple; (ii) high activity
and good chemoselectivity; (iii) no side reaction; (iv) wide
substrate scope and generality in the presence of various
other functions; (v) catalyst and solvent-free, making the
protocol environmentally benign.
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General Procedure for the Boc Protection of Amines
To (Boc)2O (1.0 mmol), was added an amine (1.0 mmol)
and the mixture was stirred at room temperature for the time
indicated in Table 1. The progress of the reaction was moni-
tored by TLC. In most cases, the BOC protected product was
found to be sufficiently pure and did not require any further
purification. In some cases the product was purified by silica
gel column chromatography (1:2; EtOAc/ Petrolium ether).
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1
All products were characterized by IR, H NMR and their
physical properties.
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Representative Examples
tert-butyl pyrrolidine-1-carboxylate (C9H17NO2)
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IR (KBr): ꢀ = 3457, 2973, 2876, 1694, 1478, 1366 cm-1;
1H NMR (500 MHz, CDCl3): ꢁ = 1.2 (s, 9H, J = 4 Hz), 1.7
(m, 4H, J = 3.5 Hz), 3.2 (t, 4H, J = 6.5 Hz).
tert-butyl phenylcarbamate (C11H15NO2)
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IR (KBr): ꢀ = 3420, 2969, 2925, 1700, 1502, 1308, 1165
cm-1; 1H NMR (500 MHz, CDCl3): ꢁ = 1.5 (s, 9H, J = 4 Hz),
6.5 (s, NH), 7.1 (t, 2H, J = 5 Hz), 7.3 (d, 2H, J = 5 Hz), 7.4
(d, 1H, J = 5.0 Hz).
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Tert-butyl2,3dimethylphenyl-carbamate (C13H19NO2)
IR (KBr): ꢀ = 3355, 2930, 1697, 1504, 1300, 1168 cm-1;
1H NMR (500 MHz, CDCl3): ꢁ = 1.5 (s, 9H, J = 4 Hz), 2.2
(d, 6H, J = 5 Hz), 6.3 (s, NH), 6.9 (d, 1H, J = 5 Hz), 7.1 (t,
2H, J = 5 Hz). 13C NMR (500 MHz, CDCl3): ꢁ = 13.9, 21.0,
28.8, 77.2, 77.4, 77.74, 80.6, 120.7, 126.2, 126.5, 136.3,
137.5, 153.9 ppm; Mass: 221 (M+ 79%), 163, 147, 131, 118,
103, 91, 77.
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CONFLICT OF INTEREST
The author(s) confirm that this article content has no con-
flict of interest.
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ACKNOWLEDGEMENTS
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Declared none.
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