N-Alkylation of N-silylated derivatives
Russ. Chem. Bull., Int. Ed., Vol. 69, No. 2, February, 2020
399
N-Ethylsuccinimide (4f). Yield 86%, the product crystallized
when standing, m.p. 24 °C. (see Ref. 30: b.p. 119—121 °C
(15 Torr), m.p. 26 °C).
Note, TMS-sulfonates 3a—c that form in these reac-
tions probably serve as catalysts for alkylation similar to
what was found for trimethylsilyl triflate and trimethylsilyl
halogenides,10 i.e. these reactions are autocatalytic.
The herein synthesized N-alkyl derivatives of lactams,
amides, and imides were described in the literature repeat-
edly. Their spectral characteristics, for instance their IR
spectra and 1Н NMR spectra, are similar to those reported.
In conclusion, we developed the new method for
N-alkylation of lactams, aliphatic amides, and imides,
comprising reaction of their N-trimethylsilyl derivatives
with alkyl sulfonates at 140—170 °C for several hours in
absence of solvents. The advantage of this method is ob-
taining of N-alkylation products without thermal or cata-
lytic initiation.
N-Ethyl-N-methylacetamide (4g). Yield 87%, b.p. 185—189 °C
20
(750 Torr), nD 1.4280 (see Ref. 31: b.p. 180 °C (750 Torr)).
Trimethylsilylsulfonate 3b was also obtained (yield 45%), b.p.
168—172 °C (25 Torr), nD20 1.4950.
N-Ethylacetanilide (4h). Yield 78%, b.p. 126—130 °C (12 Torr),
m.p. 53—54 °C (see Ref. 32: b.p. 138 °C (20 Torr), m.p. 53—54 °C,
nD20 1.4772). Trimethylsilylsulfonate 3b was also obtained (yield
71%), b.p. 145—146 °C (12 Torr), nD20 1.4950.
This work is financially supported by Ministry of Health
of the Russian Federation as part of a state assignment for
Pirogov Russian National Research Medical University
for 2018—2020 (State registration number АААА-
А18-118051590108-1).
Experimental
References
IR spectra in solid phase were recorded at Bruker Tensor-2
spectrometer with use of incomplete internal reflection
module (IIRM). 1Н NMR spectra were registered at 20 °C with
Bruker Avance II 300 instrument (1H, 300 MHz) in CDCl3;
in pulse mode with consequent Fourier transform and with 2H-stabiliz-
ation of the resonance conditions. Me4Si was used as an internal
standard.
Alkyl sulfonates 1a—c were commercial reagents (Aldrich).
NMR spectroscopy was used as purity control method. Initial
N-silylated lactams, N-TMS-2-pyrrolidone (2a),19 N-TMS-4-
phenyl-2-pyrrolidone (2b),17 N-TMS-azepan-2-one (2c),20
N-TMS-succinimide (2d),21 N-TMS-N-methylacetamide (2e),22
N-TMS-acetanilide (2f)23 were obtained as described; their
constants and yields correspond with literature data.
1. R. E. Benson, Th. L. Cairns, J. Am. Chem. Soc., 1948, 70, 2115.
2. H. Bredereck, F. Effenberger, G. Simehen, Ber., 1963,
96, 1350.
3. H. Bredereck, R. Gompper, H. Rempfer, K. Klem, H. Kuk,
Ber., 1959, 92, 329.
4. M. Matsui, Mem. Coll. Sci. Eng. Kyoto, 1909, 2, 37.
5. A. Buhner. Ann. Chem., 1904, 333, 289.
6. R. Gommper, Chem. Ber., 1960, 93, 187.
7. J.W. Ralls, J. Org. Chem., 1961, 21, 66.
8. H. Bohme, G. Berg, Chem. Ber., 1966, 99, 2127.
9. R. Roger, D.G. Neilson, Chem. Rev., 1961, 61, 179.
10. E. P. Kramarova, A. G. Shipov, N. A. Anisimova, N. A.
Orlova, O. B. Artamkina, I. Yu. Belavin, Yu. I. Baukov,
J. Gen. Chem. USSR (Engl. Transl.), 1988, 58, 970.
11. A. G. Shipov, E. P. Kramarova, N. A. Kalashnikova, E. A.
Besova, Yu. I. Baukov, Russ. J. Gen. Chem. (Engl. Transl.),
1997, 67, 1736.
12. E. A. Zheltonogova, N. A. Orlova, V. P. Kobzareva, A. G.
Shipov, Yu. I. Baukov, J. Gen. Chem. USSR (Engl. Transl.),
1991, 61, 2092.
13. N. A. Anisimova, E. P. Kramarova, I. Yu. Belavin, Yu. I.
Baukov, J. Gen. Chem. USSR (Engl. Transl.), 1986, 56, 1631.
14. N. A. Anisimova, Abstract of Ph.D. Theses, MGPI, Moscow,
1983, 16 p. (in Russian).
15. N. A. Orlova, I. Yu. Belavin, V. N. Sergeev, A. G. Shipov,
Yu. I. Baukov, J. Gen. Chem. USSR (Engl. Transl.), 1984,
54, 635.
16. A. G. Shipov, N. A. Orlova, I. A. Savost´yanov, O. B.
Artamkina, Yu. I. Baukov, J. Gen. Chem. USSR (Engl. Transl.),
1989, 59, 959.
17. A. G. Shipov, E. P. Kramarova, V. V. Negrebetsky, V. I.
Akhapkina, S. A. Pogozhykh, Ui. I. Baukov, Vestnik RGMU,
2006, No 1, 56.
18. A. I. Albanov, M. F. Larin, V. A. Pestunovich, M. G.
Voronkov, E. P. Kramarova, Yu. I. Baukov, Zh. Obshch. Khim.,
1981, 51, 488 (in Russian).
Synthesis of N-alkyl-substituted derivatives 4a—h (general
procedure). A mixture of alkyl sulfonate 1 (0.05—0.1 mol) with
equimolar amount of N-silyl derivative of 2 was heated for 3—5 h
at 140—170 °C, then fractioned.
N-Methyl-2-pyrrolidone (4a). Yield 72%, b.p. 94—97 °C
20
(18 Torr), nD 1.4705 (see Ref. 24: b.p. 94—96 °C (20 Torr),
nD20 1.4700). Trimethylsilyl sulfonate 3a was also obtained (yield
75%), b.p. 115—120 °C (18 Torr), nD20 1.4298 (see Ref. 25: b.p.
72—73 °C (3 Torr), nD20 1.4300).
N-Methyl-4-phenyl-2-pyrrolidone (4b). Yield 66%, b.p.
182—184 °C (15 Torr), nD20 1.5510 (see Ref. 26: b.p. 127—130 °C
(1 Torr), nD20 1.5538). Trimethylsilyl sulfonate 3a was also ob-
tained (yield 72%), b.p. 117—120 °C (15 Torr), nD20 1.4320.
N-Ethyl-2-pyrrolidone (4c). Yield 59%, b.p. 102—105 °C
20
(20 Torr), nD 1.4660 (see Ref. 27: b.p. 93—97 °C (16 Torr),
nD20 1.4650). Trimethylsilyl sulfonate 3b was also obtained (yield
72%), b.p. 160—163 °C (20 Torr), nD20 1.4935.
N-Penthyl-2-pyrrolidone (4d). Yield 58%, b.p. 117—120 °C
20
(18 Torr), nD 1.4620 (see Ref. 28: b.p. 87—88 °C (1 Torr),
nD20 1.4619). Trimethylsilyl sulfonate 3c was also obtained (yield
51%), b.p. 100—102 °C (18 Torr), nD20 1.4240 (comp. Ref. 26:
b.p. 80—82 °C (8 Torr), nD20 1.4235).
N-Ethylazepan-2-one (4e). Yield 78%, b.p. 125—128 °C
20
(16 Torr), nD 1.4790 (see Ref. 29: b.p. 97 °C (5.5 Torr),
19. K. A. Andrianov, A. I. Nogaydeli, D. Sh. Akhobadze, L. M.
Khananashvili, L. Sh. Tkeshelashvili, Bull. Acad. Sci. USSR,
Div. Chem. Sci. (Engl. Transl.), 1972, 41, 1100.
nD20 1.4772). Trimethylsilyl sulfonate 3b was also obtained (yield
86%), b.p. 155—157 °C (16 Torr), nD20 1.4940.