N,N-Bis(silyloxy)aminocyclopropanes
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 12, December, 2001 2439
diluted with anhydrous Et2O (25 mL). The precipitate was
filtered off in an inert atmosphere. The mother liquor was
concentrated in vacuo and the crude product was purified by
column chromatography (a 1 : 3 EtOAclight petroleum
mixture as the eluent, 20 g of silica gel Silica Woelm 32-63).
Nitrone 11a, the yield was 0.47 g (67%), white crystals,
m.p. 132133 °C, Rf = 0.16 (EtOAclight petroleum, 1 : 3,
Merck 60 F254). Found (%): C, 67.30; H, 5.34; N, 4.31.
C20H19NO5. Calculated (%): C, 67.98; H, 5.42; N, 3.96.
Nitrone 11f, the yield was 0.35 ã (44%), yellow crystals, m.p.
158161 °C, Rf = 0.16 (EtOAclight petroleum, 1 : 3, Merck
60 F254). Found (%): C, 60.43; H, 4.60; N, 7.24. C20H18N2O7.
Experimental
The NMR spectra were recorded on a Bruker AM-300
instrument in CDCl3. The chemical shifts were measured
relative to the residual signal of the solvent (1H, δ 7.26; 13C,
δ 77.16),26 Me4Si (29Si, δ 0) as the internal standard, and
MeNO2 (14N and 15N, δ 0) as the external standard. The 29Si
and 15N signals were observed using the INEPT pulse se-
quence.27
All operations were carried out under an atmosphere of dry
argon using freshly distilled CH2Cl2. The starting ANC
1àd,fh,28 1e,29 1i,30 1j,31 and 1k
32
were synthesized
Calculated (%): C, 60.30; H, 4.55; N, 7.03.
according to known procedures.
Enoxime 5. Distilled compound 4 (0.12 ã, 0.46 mmol,
syn-4 : anti-4 = 1 : 2.7) was dissolved in MeOH (5 mL). Then
40% HF (0.03 mL) was added. The mixture was kept at ∼20 °C
for 2 h and then concentrated in vacuo. The residue was
recrystallized from a 7 : 1 light petroleum (b.p. 64 °C)CH2Cl2
mixture to give 0.053 g (62%) of compound 5, syn-5 : anti-5 =
1 : 21, white crystals, m.p. 8385 °C (cf. lit. data24: m.p. 71 °C).
Found (%): C, 44.87; H, 4.83; N, 7.45. C7H9NO5. Calcu-
lated (%): C, 44.92; H, 4.85; N, 7.48.
Methanolysis of cyclopropane 2à. Compound 2à (0.08 g,
0.19 mmol) was dissolved in CH2Cl2 (1 mL). Then MeOH
(0.5 mL) was added at 0 °C. The reaction mixture was kept at
∼20 °C for 1 h and concentrated in vacuo. The crystalline
residue was pure ANC 1à obtained in a yield of 0.05 g (97%).
Synthesis of cyclopropanes 2 (general procedure). Triethyl-
amine (0.27 mL, 1.92 mmol) was added to a solution of ANC
1 (0.60 mmol) in CH2Cl2 (3 mL) at 30 °C and then a
solution of Me3SiBr (0.24 mL, 1.80 mmol) in CH2Cl2 (1 mL)
was added dropwise during 5 min. The reaction mixture was
kept with intermittent stirring for 18 days (see Table 1),
diluted with light petroleum (10 mL), and poured with stirring
into a mixture of water (10 mL) and light petroleum (15 mL).
The organic layer was separated, washed with water (10 mL)
and brine (5 mL), and dried with Na2SO4. The solvents were
evaporated in vacuo. The yields of the reaction products were
determined by NMR spectroscopy using ClCH2CH2Cl as the
internal standard.
Compound 2a, the yield was 0.25 g, yellowish crystals,
m.p. 5457 °C (light petroleum). Found (%): C, 52.89;
H, 7.20; N, 3.27; Si, 13.44. C19H31NO6Si2. Calculated (%):
C, 53.62; H, 7.34; N, 3.29; Si, 13.20. Compound 2b, the yield
was 0.24 g, yellowish oil. Compound 2ñ, the yield was 0.25 g,
yellowish oil. Compound 2d, the yield was 0.23 g, yellowish oil.
Compound 2e, the yield was 0.27 g, greenish oil. Compound 2f,
the yield was 0.27 g, yellowish crystals, m.p. 129133 °C
(light petroleum). Found (%): C, 48.55; H, 6.40; N, 6.03;
Si, 12.04. C19H30N2O8Si2. Calculated (%): C, 48.49; H, 6.43;
N, 5.95; Si, 11.94. Compound 2g, the yield was 0.22 g,
yellowish crystals, m.p. 121124 °C (light petroleum).
Found (%): C, 49.82; H, 6.67; Cl, 7.86; N, 3.12; Si, 12.54.
C19H30ClNO6Si2. Calculated (%): C, 49.60; H, 6.57; Cl, 7.71;
N, 3.04; Si, 12.21. Compound 2h, the yield was 0.25 g,
yellowish crystals, m.p. 7275 °C (light petroleum). Found (%):
C, 54.53; H, 7.43; N, 3.10; Si, 12.90. C20H33NO6Si2. Calcu-
lated (%): C, 54.64; H, 7.57; N, 3.19; Si, 12.78. Compound 2i,
the yield was 0.17 g, greenish oil.
This study was carried out at the Scientific and
Educational Center of the N. D. Zelinsky Institute of
Organic Chemistry of the Russian Academy of Sciences
and the Moscow Chemical Lyceum and was financially
supported by the Russian Foundation for Basic Research
(Project Nos. 98-03-33002 and 00-15-97455) and by the
Federal Program "Integration" (Project No. A0082).
References
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Analogously, derivative 4 was obtained from compound
1k; the ratio of the syn and anti isomers was 1 : 2.7, the yield
was 0.14 g, colorless oil, b.p. 110115 °C (0.07 Torr).
Found (%): C, 46.25; H, 6.57; N, 5.35; Si, 10.90.
C10H17NO5Si. Calculated (%): C, 46.31; H, 6.61; N, 5.40;
Si, 10.83.
Silyl nitronates 3f,j. Silylation of compounds 1f,j was
carried out according to the above-described procedure under
conditions indicated in Table 1. The reaction mixture was
diluted with dry toluene and the precipitate of [Et3NH]+Br
was filtered off in an inert atmosphere. The mother liquor was
concentrated in vacuo and the residue was analyzed by 1H NMR
spectroscopy using ClCH2CH2Cl as the internal standard.
Nitrones 11a,f. 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)
(0.30 mL, 2 mmol) was added to a solution of PhCH2NO2
(0.276 g, 2 mmol) in CH2Cl2 (9 mL) at 30 °C and the
reaction mixture was kept for 5 min. Then a solution of
cyclopropane 2 (2 mmol) in CH2Cl2 (6 mL) was added
dropwise at the same temperature over 10 min. The reaction
mixture was kept with stirring at 30 °C for 1.5 h and then
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Yu. A. Strelenko, and V. A. Tartakovsky, Tetrahedron,
1997, 53, 13085.