Novel reaction of arylmalonate carbanions
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 8, August, 2007
1673
2
3
CH3CHaHbN, JH,H = 7.6 Hz, JH,H = 7.1 Hz); 4.18 (dq, 1 Н,
the methinic protons: δCH 5.82 (8a) and 5.98 (8b)). Thus,
as we assumed, the introduction of electron acceptors
into the benzene ring of phenylmalonate inhibits the forꢀ
mation of carbamates in the reactions of anions of the
corresponding CH acids with phenyl isocyanate, most
likely, due to a decrease in the rate of the first step of the
reaction (see Scheme 2).
CH3CHaHbN, JH,H = 7.6 Hz, JH,H = 7.1 Hz); 4.22 (dq, 1 Н,
2
3
2
3
CH3CHaHbCC, JH,H = 8.4 Hz, JH,H = 7.2 Hz); 4.26 (dq, 1 Н,
3
CH3CHaHb
,
2JH,H = 8.4 Hz, JH,H = 7.2 Hz); 5.98 (s, 1 Н,
Ph
4
СН); 7.10 (dq, 2 Н, Но
7.34—7.43 (m, 3 Н, НPh); 7.55 (dq, 2 Н, НоAr, 3JH,H = 8.8 Hz,
4JH,H = 2.2 Hz); 8.55 (dt, 2 Н, Но
,
3JH,H = 6.7 Hz, JH,H = 1.9 Hz):
, =
3JH,H = 8.8 Hz, JH,H
Ar
4
2.2 Hz). IR, ν/cm–1: 2932 (CH), 1739 (CCOOEt), 1714
(NCOOEt), 1708 (C(O)N), 1597 (С=СPh), 1527, 1374 (NO2).
Competitive reaction of the carbanions obtained from CH
acids 5a and 5b with phenyl isocyanate. Sodium hydride (28 mg,
7.0 mmol) was added to a solution of a mixture of 5a (0.2 g,
3.5 mmol) and 5b (0.16 g, 3.5 mmol) in THF (3 mL). Phenyl
isocyanate (47 mg, 4.0 mmol) was added to the resulting mixꢀ
ture. After 1 h, the mixture was poured into diethyl ether (30 mL),
and the precipitate was filtered off and treated with a solution of
hydrochloric acid (1 : 10) in the presence of diethyl ether. After
drying the solvent was distilled off in vacuo. The 1H NMR specꢀ
trum contains, along with the signals from the starting CH acids
5a,b, the signals δH = 5.82 (8a) and 5.98 (8b).
Experimental
1
H NMR spectra were obtained on a Bruker АМХꢀ400 specꢀ
trometer in CDCl3. IR spectra were recorded on a Magnaꢀ
IRꢀ750 FTꢀIR spectrometer (Nicolet) in Nujol. Diethyl phenylꢀ
malonate and phenyl isocyanate were purchased from ACROS
Organics. Diethyl 4ꢀnitrophenylmalonate was synthesized by
the reaction of malonic ester, NaH, and 4ꢀnitrofluorobenzene
in THF. The yield was 23%, m.p. 58—59 °С (cf. Ref. 6: m.p.
56—57 °C).
Phenyl(ethoxycarbonyl)acetic acid (NꢀethoxycarbonylꢀNꢀ
phenyl)amide (8a). Diethyl phenylmalonate (4.72 g, 20.0 mmol)
was added dropwise to a suspension of sodium hydride (0.80 g,
20.0 mmol) in THF (30 mL), The reaction mixture was stirred
for 10 min, and phenyl isocyanate (4.3 mL, 40.0 mmol) was
added dropwise to the transparent reaction solution. After 4 h,
the solvent was distilled off in vacuo, and the residue was washed
with diethyl ether and treated in benzene with dilute (1 : 10)
hydrochloric acid. The organic layer was separated and dried
over sodium sulfate for 12 h. Benzene was removed in vacuo,
and the residue was twice crystallized from a petroleum
ether—diethyl ether (1 : 1) mixture. The white precipitate was
obtained in a yield of 1.21 g (20%), m.p. 68—69 °C. Found (%):
Xꢀray diffraction study of the 1 : 1 adduct of compound 8a
with the phenyl isocyanate trimer. The crystals of zwitterion
8a•C21H15N3O3 (C41H36N4O8, M = 712.74) are triclinic, space
–
group P1, at T = 100 K a = 9.6517(12), b = 11.0568(13), c =
18.281(3) Å, α = 100.044(5), β = 97.607(5), γ = 108.732(5)°,
V = 1781.7(4) Å3, Z = 2, F(000) = 748, dcalc = 1.329 g/cm3,
µ = 0.093 mm–1. The unit cell parameters and intensities of
15 607 reflections were measured on a Bruker SMART Apex II
CCD automated diffractometer (T = 100 K, λMoꢀKα radiation,
graphite monochromator, ϕ and ω scan modes, θ
= 26.2°).
max
Xꢀray absorption correction was applied to the obtained data by
the SADABS program.7 The structure was determined by a diꢀ
rect method and refined by the fullꢀmatrix leastꢀsquares method
in the anisotropic approximation for nonꢀhydrogen atoms. In
the crystal, one of the ethyl groups is disordered over two posiꢀ
tions with site occupancies of 0.7 : 0.3. The positions of the
hydrogen atoms were geometrically calculated and refined in
the isotropic approximation with the fixed positional (riding
model) and thermal parameters (Uiso(H) = 1.5Ueq(C) for the
CH3 groups and Uiso(H) = 1.2Ueq(C) for all other groups). The
final R factors are R1 = 0.0543 for 3817 independent reflections
with I > 2σ(I ) and wR2 = 0.0870 for all 7058 independent reꢀ
flections. All calculations were performed using the SHELXTL
PLUS (Version 5.10) program package.8 The tables of the coorꢀ
dinates of atoms, bond lengths, bond angles, and anisotropic
temperature parameters for compound 1 were deposited with
the Cambridge Structure Database.
С, 67.58; H, 5.81; N, 4.36. C20H21NO5. Calculated (%):
N
С, 67.60; H, 5.91; N, 3.94. 1H NMR, δ: 1.14 (t, 3 Н, CH3CH2
,
3JH,H = 7.1 Hz); 1.27 (t, 3 Н, CH3CH2C, 3JH,H = 7.2 Hz); 4.15
(dq, 1 Н, CH3CHaHbN, JH,H = 8.0 Hz, JH,H = 7.1 Hz); 4.18
2
3
(dq, 1 Н, CH3CHaHbN, JH,H = 8.0 Hz, JH,H = 7.1 Hz); 4.23
2
3
(dq, 1 Н, CH3CHaHbC, JH,H = 8.4 Hz, JH,H = 7.2 Hz); 4.26
2
3
(dq, 1 Н, CH3CHaHbC, JH,H = 8.4 Hz, JH,H = 7.2 Hz); 5.86
2
3
(s, 1 Н, СН); 7.11—7.12 (m, 1 Н, НоС); 7.30—7.42 (m, 8 Н,
H
Рh). IR, ν/cm–1: 2980 (CH), 1748 (CCOOEt), 1728 (NCOOEt),
1708 (C(O)N).
4ꢀNitrophenyl(ethoxycarbonyl)acetic acid (Nꢀethoxycarboꢀ
nylꢀNꢀphenyl)amide (8b). Diethyl 4ꢀnitrophenylmalonate (1.41 g,
5.0 mmol) in THF (10 mL) was added dropwise to a suspension
of sodium hydride (0.20 g, 5.0 mmol) in THF (10 mL). The
reaction mixture was stirred for 30 min, and a solution of phenyl
isocyanate (1.1 mL, 10.0 mmol) in THF (10 mL) was added
dropwise to the transparent reaction solution. After 5 h, the
solvent was distilled off in vacuo, and the residue was washed
with a mixture of petroleum ether, diethyl ether, and benzene.
The filteredꢀoff powder was treated in benzene with dilute (1 : 10)
hydrochloric acid. The organic layer was separated and dried over
sodium sulfate for 12 h. The solvent was removed in vacuo, and
the residue was twice crystallized from a petroleum ether—diethyl
ether (1 : 1) mixture. The white precipitate was obtained in a
yield of 0.60 g (30%), m.p. 111—114 °C. Found (%): C, 60.28;
H, 4.81; N, 6.91. C20H20N2O7. Calculated (%): С, 60.00;
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 04ꢀ03ꢀ
32489).
References
1. Yu. G. Gololobov, N. A. Kardanov, V. N. Khroustalyov, and
P. V. Petrovskii, Tetrahedron Lett., 1997, 38, 7437.
2. Yu. G. Gololobov, N. G. Senchenya, O. A. Linchenko, P. V.
Petrovskii, and I. A. Garbuzova, Zh. Obshch. Khim., 2006, 76,
1154 [Russ. J. Gen. Chem., 2006, 76 (Engl. Transl.)].
H, 5.00; N, 7.00. 1H NMR, δ: 1.40 (t, 3 Н, CH3CH2N, 3JH,H
7.1 Hz); 1.26 (t, 3 Н, CH3CH2C, 3JH,H = 7.1 Hz); 4.15 (dq, 1 Н,
=