Download PDF
Synlett 2004(12): 2180-2184  
DOI: 10.1055/s-2004-830896
LETTER
© Georg Thieme Verlag Stuttgart · New York

An Insight of the Reactions of Amines with Trichloroisocyanuric Acid

Lidia De Luca*, Giampaolo Giacomelli*
Dipartimento di Chimica, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy
Fax: +39(079)229559; e-Mail: ggp@uniss.it;
Further Information

Publication History

Received 30 April 2004
Publication Date:
05 August 2004 (online)

    Permissions and Reprints All articles of this category

Abstract

The reaction between amines or α-aminoacids with trichloroisocyanuric acid is studied under various conditions: N,N-dichloroamines, nitriles and ketones can be obtained from primary amines, while free aminoacids undergo oxidative decarboxylation to the corresponding nitrile of one less carbon atom.

Key words

dichloroamines - trichloroisocyanuric acid - nitriles - aminoacids

10

These results are obviously inconsistent with those published (ref.9). We have repeated the experiments with other substrates, such as those reported in Table 1, following the reported procedure and always no traces of nitriles were detected. We have no explanation for this disagreement: in our opinion, this might perhaps depend on the distillation procedure adopted from the above-cited authors that should have caused hydrochloride elimination from the substrate.

12

The reaction is not chemoselective: a mixture of primary and secondary amines yielded a mixture of chloroamines when reacted with 1 equiv of TCCA.

15

Probably owing to the formation of insoluble salts formed by TEA and the formed trihydroxytriazine.

16

The presence of the compounds in the reaction mixture was evidenced by 1H NMR analysis.

21

All solvents and reagents were used as obtained from commercial source. Standard 1H NMR and 13C NMR were recorded from CDCl3 solutions at 300 MHz and 75.4 MHz. Mass spectra were recorded at 70 eV with a direct probe for sample introduction. When possible, compounds were identified by comparison with authentic samples. All runs were conducted at least in duplicate. General Preparation of N , N -Dichloroamines. The procedure for the chlorination of benzylamine (Table 1, run 3) is representative for all cases. Benzylamine (2.00 g, 19 mmol) was dissolved in CH2Cl2 (80 mL) and treated with TCCA (4.64 g, 19 mmol) at 0 °C. After the addition, the mixture was warmed to r.t. and stirred for the required time until completion. After 1 h, TLC analysis showed the complete absence of the amine, the reaction mixture was filtered on Celite and the solvent evaporated to yield N,N-dichlorobenzylamine(3) that was isolated without further purification (oil, 3.2 g, 98%). 1H NMR: δ = 7.39 (s, 5 H), 4.68 (s, 2 H). 13C NMR: δ = 135.1, 130.3, 129.5, 128.8, 79.1. MS: m/e (relative intensity): 179 (1), 177 (3), 176 (1), 175 (4), 112 (2), 106 (3), 105 (14), 104 (23), 103 (4), 92 (91), 91 (100), 79 (1), 78 (4), 77 (15), 76 (3), 65 (9), 63 (2), 51 (9). General Procedure for the Preparation of Nitriles and N -Chloroimines from N , N -Dichloroamine. The reported procedure is representative: N,N-dichlorocyclohexanamine (2, 1.00 g, 6 mmol) was dissolved in CH2Cl2 (20 mL) and treated with TEA (2.56 mL, 18 mmol) at 25 °C. After 2 h, TLC analysis showed the complete absence of the N,N-dichloroamine. Then the reaction mixture was washed with H2O (15 mL), with HCl 0.5 N (10 mL), dried on Na2SO4, filtered on Celite and concentrated in vacuo to yield N-chlorocyclohexanimine (18, oil, 0.61 g, 77%). 1H NMR: δ = 2.60-0.95 (br m, 10 H). 13C NMR: δ = 182.8, 36.9, 32.7, 26.9, 25.9, 25.1.
General One-Pot Procedure. The reported procedure is representative: Benzylamine (1.00 g, 9.5 mmol) was dissolved in DMF (10 mL) and treated with TEA (4 mL, 28.5 mmol), and with TCCA (2.32 g, 9.5 mmol) at 25 °C. After 4 h, the reaction mixture was quenched with H2O (20 mL), and then it was extracted twice with Et2O (15 mL). The organic layers were washed with H2O (10 mL), then with HCl 0.5 N (10 mL), were dried (Na2SO4), and the solvent was evaporated to yield benzonitrile (19, 1.1 g, 95%). General One-Pot Procedure for the Preparation of Nitriles from α-Aminoacids. The reported procedure is representative: l-Phenylalanine (1.20 g, 7.6 mmol) was dissolved in an aq solution of 2 N NaOH (3.8 mL) and treated with TCCA (1.17 g, 5.1 mmol) at 25 °C. After 10 min, when TLC analysis showed the complete absence of the l-phenylalanine, the reaction mixture was treated with HCl (15 mL), followed by an aq solution of 3 N HCl (2.5 mL). After 10 min the mixture was extracted twice with Et2O (15 mL). The organic layers were washed with H2O (10 mL), dried on Na2SO4, filtered and concentrated in vacuo to yield 2-phenylacetonitrile (20, 0.87 g, 98%). 1H NMR: δ = 7.38 (m, 5 H), 3.75 (s, 2 H). 13C NMR: δ = 142.1, 129.1, 127.9, 127.8, 117.8, 23.5.
Some other examples: N -Chlorodiphenylmethanimine (23): 1H NMR: δ = 7.76 (m, 4 H), 7.39 (m, 6 H). 13C NMR: δ = 165.6, 132.9, 131.5, 129.2, 127.8. Anal. Calcd for C13H10ClN (215.68): C, 72.39; H, 4.67; Cl, 16.44; N, 6.49. Found: C, 72.40; H, 4.66; Cl, 16.44; N, 6.50. The compound was dissolved in THF (10 mL) and treated with 10 mL of aq HCl (1 N) to yield 1.0 g of benzophenone, identified by comparison with an authentic sample.
Methyl-2-chloroimino-3-phenylpropanoate (24): 1H NMR: δ = 7.30 (m, 5 H), 4.26 (s, 2 H), 3.83 (s, 2 H). 13C NMR: δ = 172.3, 172.1, 137.5, 130.3, 129.1, 128.9, 128.7, 53.5, 38.5. Anal. Calcd for C10H10ClNO2 (211.64): C, 56.75; H, 4.76; Cl, 16.75; N, 6.62. Found: C, 56.74; H, 4.76; Cl, 16.75; N, 6.60. The compound was then dissolved in THF (10 mL) and treated with 10 mL of aq HCl (1 N) to yield 1.0 g of methyl phenylpyruvate. 1H NMR: δ = 8.15 (br s, 1 H), 7.30-7.14 (m, 5 H), 6.53 (s, 1 H), 3.93 (s, 3 H). 13C NMR:
δ = 162.4, 152.3, 137.5, 129.1, 128.9, 128.7, 104.5, 53.5.
( S )-2-Methylbutanenitrile (28): [α]D 25 +39 (c 1.5, CHCl3). 1H NMR: δ = 2.56 (d, J = 7 Hz, 1 H), 1.62 (m, 2 H), 1.31 (d, J = 7 Hz, 3 H), 1.08 (t, J = 7 Hz, 3 H). 13C NMR: δ = 124.8, 27.1, 26.9, 17.4, 11.1.