A simple synthetic approach to unsymmetrically substituted (γ-oxoalkyl)phosphine oxides

Full text of DOI:10.1134/S1070428010070298

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 7, pp. 1105–1107. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © D.A. Tatarinov, V.F. Mironov, T.A. Baronova, A.A. Kostin, B.I. Buzykin, 2010, published in Zhurnal Organicheskoi Khimii, 2010,
Vol. 46, No. 7, pp. 1103–1104.
SHORT
COMMUNICATIONS
A Simple Synthetic Approach to Unsymmetrically Substituted
(γ-Oxoalkyl)phosphine Oxides
D. A. Tatarinov, V. F. Mironov, T. A. Baronova, A. A. Kostin, and B. I. Buzykin
Arbuzov Institute of Organic and Physical Chemistry, Kazan Research Center, Russian Academy of Sciences,
ul. Arbuzova 8, Kazan, 420088 Tatarstan, Russia
e-mail: mironov@iopc.knc.ru
Received June 25, 2009
DOI: 10.1134/S1070428010070298
Phosphine oxides and phosphines having a chiral
phosphorus atom, including optically active com-
pounds, are successfully used as ligands for metal-
complex catalysts in organic and asymmetric synthesis
[1–3]; some derivatives are known as pesticides and
biologically active substances [4]. However, more
extensive application of these compounds is seriously
limited due to complexity of methods for the prepara-
tion of phosphine oxides and phosphines with three
different substituents, especially with those containing
additional functional groups. Taking into account con-
tinuously growing demands for such compounds,
development of accessible procedures for their syn-
thesis remains to be important (see, e.g., [3–7]). Most
known procedures require the use of expensive
reagents and are complex and laborious; isolation of
intermediate and final products is often difficult. Either
racemates are obtained with subsequent optical resolu-
tion or stereoselective syntheses are necessary.
sible phosphorus-containing heterocycles having two
P–C bonds, in particular 2-alkyl(aryl)-3,3,5-trimethyl-
2,3-dihydro-1,2λ5-oxaphosphole 2-oxides like I
[8–11], with Grignard compounds. Hydrolysis of the
reaction mixture gives targeted (1-methyl-4-oxopent-2-
yl)phosphine oxides II in more than 95% yield. Due to
specific structure of the initial dihydrophosphole
oxides (they possess one exo- and one endocyclic P–C
bond and reactive endocyclic P–O bond), the third P–C
bond is formed with high chemoselectivity with no any
side process. As a result, the products are formed in
high yields and with high purity. The structure of
phosphine oxides II thus obtained was confirmed by
IR, 1H, 31P, and 13C NMR, and mass spectra.
4-[Ethyl(methyl)phosphoryl]-4-methylpentan-2-
one (IIa). Compound Ia, 5.7 g (35.6 mmol), was
added dropwise to the Grignard compound prepared
according to standard procedure from 1.3 g
(54.2 mmol) of magnesium and 4.1 ml (5.9 g,
54.2 mmol) of ethyl bromide in 100 ml of diethyl
ether. When the addition was complete, the mixture
was heated to the boiling point under vigorous stirring
over a period of 1 h, cooled to 20°C, and neutralized
under vigorous stirring at the boiling point by adding
in succession 30 ml of water and 5 ml of hydrochloric
acid. The organic phase was separated, the aqueous
phase was extracted with methylene chloride (2×
100 ml), the extracts were combined with the organic
phase, the solvent was distilled off, and the residue
was dried under reduced pressure (12 mm) at 100°C.
Yield 6.6 g (98%), light brown oily substance. IR spec-
trum, cm–1: 3416, 2972, 2940, 2920, 2881, 2351, 2303,
1713, 1555, 1466, 1420, 1383, 1363, 1298, 1267,
We proposed a new and simple synthetic approach
to unsymmetrically substituted phosphine oxides con-
taining an oxo group as additional functional substit-
uent in the γ-position with respect to the phosphorus
atom. This approach is based on the reaction of acces-
Me
(1) R2MgX
(2) HCl, H2O
O
P
O
O
3
P
O
R1
R2
4
2
R1
–MgClX
6
Me
5
1Me
Me
Me
Me
Ia, Ib
IIa–IIc
I, R1 = Me (a), Ph (b); II, R1 = Me, R2 = Et (a), Pr (b);
R1 = Ph, R2 = PhCH2 (c).
1105

TATARINOV et al.
1106
1240, 1172, 1144, 1032, 1014, 944, 878, 780, 718,
700, 658, 626, 585, 564, 526, 482, 460. 1H NMR spec-
trum, δ, ppm: 1.17 d (3H, CH3, 3JPH = 16.0 Hz), 1.22 d
1154, 1137, 1109, 1073, 1032, 942, 824, 770, 747, 698,
1
675, 600, 557, 505, 486, 460. H NMR spectrum, δ,
3
ppm: 1.23 d (3H, CH3, JPH = 15.8 Hz), 1.40 d (3H,
3
3
(3H, CH3, JPH = 15.9 Hz), 1.54 d (3H, CH3, JPH
=
CH3, 3JPH = 15.6 Hz), 2.08 s (3H, CH3,), 2.51 d.d (1H,
2
2
11.4 Hz), 1.7–2.0 m (2H, PCH2, AB part of ABM3X
spin system), 2.12 s (3H, CH3), 2.78 d (2H, CH2,
3JPH = 10.2 Hz). 13C NMR spectrum, δC, ppm (herein-
after the multiplicity of signal in the proton-decoupled
spectrum is given in parentheses: 5.90 q.d (d),
(CH3CH2, 1JCH = 129.1–129.7, 2JCP = 5.4 Hz), 8.95 q.d
PCH2, part A of ABX spin system, JAB = 16.0, JPH =
8.9 Hz), 2.7 d.d (1H, PCH2, part B of ABX spin system,
2
2JAB = 16.0, JPH = 7.9 Hz), 3.43 d.d (1H, CH2, part A
2
3
of ABX spin system, JAB = 14.9, JPH = 9.2 Hz),
2
3.57 d.d (1H, CH2, part B of ABX spin system, JAB
=
3
3
14.9, JPH = 14.9 Hz), 7.12 m (1H, 3-H, JHH = 7.5–
7.3 Hz), 7.17 m (2H, 2-H, 3JHH = 7.5–7.8, 7.3–7.5 Hz),
7.25 m (2H, 1-H, 3JHH = 7.5–7.8 Hz), 7.42 m (2H, 5-H,
1
1
(d) (PCH3, JCP = 63.7, JCH = 129.2 Hz), 17.75 t.d.m
1
1
(d), (PCH2, JCP = 65.5, JCH = 128.0 Hz), 21.08 q.m
(d), (C1, C6, JCP = 10.2, JCH = 129.0–129.5 Hz),
5JPH = 2.5, 3JHH = 8.5, 7.4 Hz), 7.47 m (1H, 6-H, 3JHH
=
=
2
1
32.46 q (s) (C5, JCH = 128.0 Hz), 34.07 d.m (d) (C2,
7.4, J = 1.2 Hz), 7.71 m (2H, 4-H, JPH = 9.8, JHH
1
4
3
3
1JCP = 67.2 Hz), 47.79 br.t (s) (C3, JCH = 125.0 Hz),
8.5, JHH = 1.3 Hz). 31P–{1H} NMR spectrum:
δP 51.3 ppm. Mass spectrum: m/z 314 [M]+·. Found, %:
C 72.59; H 7.37; P 9.85. C19H23O2P. Calculated, %:
C 72.59; H 7.37; P 9.85.
1
4
206.99 d.m (d) (C4, JCP = 12.01 Hz). 31P–{1H} NMR
3
spectrum: δP 56.3 ppm. Mass spectrum: m/z 191 [M +
H]+·. Found, %: C 56.75; H 10.15; P 16.28. C9H19O2P.
Calculated, %: C 56.83; H 10.07; P 16.28.
The IR spectra were measured on a Bruker Vector-
22 instrument from samples dispersed in mineral oil or
from films between KBr plates. The NMR spectra
were recorded on Bruker Avance-600 (600 MHz for
1H and 150.9 MHz for 13C; internal reference HMDS or
solvent signal) and Bruker CXP-100 (31P, 36.48 MHz;
external reference H3PO4) using CDCl3 as solvent.
The mass spectra (electron impact, 70 eV) were ob-
tained on a TRACE MS Finnigan MAT mass spec-
trometer (ion source temperature 200°C; batch inlet
probe temperature programming from 35 to 150°C at
a rate of 35 deg/min); the data were processed using
Xcalibur program.
Compounds IIb and IIc were synthesized in a sim-
ilar way.
4-Methyl-4-[methyl(propyl)phosphoryl]pentan-
2-one (IIb) was synthesized from compound Ia and
propylmagnesium bromide. Yield 95%, light yellow
thick oily substance. IR spectrum, cm–1: 3040, 2966,
2936, 2876, 1713, 1466, 1421, 1383, 1363, 1298,
1170, 1144, 1076, 946, 907, 875, 833, 769, 730, 626,
565, 526, 463, 445. 1H NMR spectrum, δ, ppm: 1.17 d
3
3
(3H, CH3, JPH = 16.0 Hz), 1.22 d (3H, CH3, JPH
=
3
15.9 Hz), 1.50 d (3H, CH3, JPH = 11.8 Hz), 1.7–1.8 m
(2H, PCH2, AB part of ABM2X spin system), 2.01 s
(3H, CH3), 2.64 d (2H, CH2, JPH = 8.5 Hz). 13C NMR
3
This study was performed under financial support
by the Russian Foundation for Basic Research and
ANT (project no. 09-03-97007-r_povolzh’e_a).
spectrum, δC, ppm: 8.39 br.q.d (d) (PCH3, 1JCH = 130.6,
1JCP = 62.1 Hz), 14.78 br.t.m (br.s) (CH3CH2, JCH
=
1
1
128.0 Hz), 15.05 br.q.m (d) (CH3CH2, JCH = 125.1,
3JCP = 12.0 Hz), 20.41 br.q.m (s) (C1, C6, JCH
=
1
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1
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