Regiochemistry of the reaction of 3,4,6-triisopropyl-1,2-benzoquinone with phenylacetylene in the presence of phosphorus trichloride

Article abstract of DOI:10.1134/S107042801207010X

The reaction of 3,4,6-triisopropyl-1,2-benzoquinone with phenylacetylene and phosphorus trichloride gave 2,6-dichloro-5,7,8-triisopropyl-4-phenyl-1, 2λ⁵-benzoxaphosphinine 2-oxide whose structure was determined by X-ray analysis.

Full text of DOI:10.1134/S107042801207010X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 7, pp. 948–952. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.F. Mironov, A.V. Bogdanov, A.B. Dobrynin, N.N. Vavilina, V.K. Cherkasov, I.A. Litvinov, 2012, published in Zhurnal
Organicheskoi Khimii, 2012, Vol. 48, No. 7, pp. 953–957.
Regiochemistry of the Reaction
of 3,4,6-Triisopropyl-1,2-benzoquinone with Phenylacetylene
in the Presence of Phosphorus Trichloride
V. F. Mironova, A. V. Bogdanova, A. B. Dobrynina, N. N. Vavilinab,
V. K. Cherkasovb, and I. A. Litvinova
a 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.ru
b Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
Nizhnii Novgorod, Russia
Received November 30, 2011
Abstract—The reaction of 3,4,6-triisopropyl-1,2-benzoquinone with phenylacetylene and phosphorus tri-
chloride gave 2,6-dichloro-5,7,8-triisopropyl-4-phenyl-1,2λ5-benzoxaphosphinine 2-oxide whose structure was
determined by X-ray analysis.
DOI: 10.1134/S107042801207010X
Development of new efficient procedures for the
synthesis of organophosphorus compounds containing
a phosphorus–carbon bond is an important problem
due to significance of such compounds from the
practical viewpoint [1–4]. During past years we have
developed an approach based on reactions of 2,2,2-tri-
halo-1,3,2λ5-benzodioxaphospholes with arylacety-
lenes, which produced heterocyclic compounds with
a P–C bond, 1,2-benzoxaphosphinines [5, 6]. Some
1,2-benzoxaphosphinine derivatives were found to
exhibit diverse biological activity [7, 8]. Analogous
results may be obtained using a three-component
system consisting of a disubstituted ortho-quinone,
phosphorus trihalide, and monosubstituted acetylene;
however, in this case, greater diversity of synthetic
pathways is observed. For example, 9,10-phenan-
threnequinone reacted with arylacetylenes in the pres-
ence of phosphorus trichloride to give new phos-
phorus-containing heterocycles with a P–C bond,
1,2-oxaphosphatriphenylenes I and 4-aryl-2-chloro-
spiro[[1,2λ5]oxaphosphole-5,9′-phenanthren]-10′-one
2-oxides II [9, 10]. The reaction in the system chry-
senequinone–phenylacetylene–phosphorus trichloride
afforded benzo[o][1,2λ5]oxaphosphatriphenylene III
[11] (Scheme 1). Unsymmetrical 3,5-di-tert-butyl-1,2-
benzoquinone reacted with arylacetylenes and PCl3 to
produce 1,2- benzoxaphosphinine (IV) as a result of
ipso-substitution of one tert-butyl group by chlorine
atom [12]. Sterically more crowded disubstituted
3,6-di-tert-butyl-1,2-benzoquinone under analogous
conditions was converted into 6-chloro-1,2λ5-benzoxa-
phosphinine derivative V [13–15]. Tetrasubstituted
quinones, such as tetrachloro-1,2-benzoquinone [16]
and 3,6-di-tert-butyl-4,5-dichloro-1,2-benzoquinone
[17], turned out to form open-chain products in reac-
tions with phenylacetylene and phosphorus trichloride;
the products, quinoid vinylphosphonate derivatives VI
and VII (Scheme 1), may be considered to be inter-
mediates on the paths leading to 1,2λ5-benzoxaphos-
phinines.
We were the first to study the regiochemistry of the
reaction of sterically crowded 3,4,6-triisopropyl-1,2-
benzoquinone (VIII) with phenylacetylene in the pres-
ence of phosphorus trichloride. The reaction turned out
to occur under mild conditions (20°C, CH2Cl2, 24 h)
and produce almost quantitatively a compound which
displayed in the 31P NMR spectrum a signal at
δP 17.8 ppm (2JPH = 27.7 Hz). According to the MS
data, the molecular ion with m/z 436 corresponds to
C23H2735Cl2O2P. The isotope peak ratio in the molec-
ular ion cluster was consistent with the presence of two
1
chlorine atoms. Taking into account the H, 13C, and
13C–{1H} NMR spectra, the product was assigned the
structure of 2,6-dichloro-5,7,8-triisopropyl-4-phenyl-
948

REGIOCHEMISTRY OF THE REACTION OF 3,4,6-TRIISOPROPYL-1,2-BENZOQUINONE
949
Scheme 1.
Cl
+
+
Ar
PCl3
+
HC
O
O
P
O
Ar
O
O
O
Ar
P
O
Cl
Cl
I
II
Cl
+
+ PCl3
HC
Ph
Ph
O
O
O
P
P
Cl
III
O
Bu-t
Bu-t
O
O
O
O
Cl
+
+ PCl3
HC
Ar
t-Bu
Cl
Ar
IV
Bu-t
Bu-t
O
O
O
P
Cl
+
+ PCl3
HC
Ar
O
Cl
Bu-t
Bu-t Ar
V
R
R
Cl
O
Cl
O
P(O)Cl2
+
+ PCl3
HC
Ph
Cl
Cl
Cl
O
R
R
Ph
VI, VII
VI, R = Cl; VII, R = t-Bu.
1,2-benzoxaphosphinine 2-oxide (IX). The 13C NMR
spectrum of IX contained the following signals typical
whose reactions with phenylacetylene and PCl3 were
accompanied by almost complete or partial replace-
ment of one tert-butyl group by chlorine [12–15], in
the reaction with compound VIII all three isopropyl
groups remained intact. Insofar as the process was ac-
companied by liberation of hydrogen chloride, excess
phenylacetylene was taken to bind liberated HCl. The
reaction is likely to involve intermediate formation of
2,2,2-trichloro-3,4,6-triisopropyl-1,3,2λ5-benzodioxa-
1
of P(O)CH=C fragment, δC, ppm: 118.28 d.d (C3, JPC
= 163.2 , 1JCH = 172.0 Hz), 158.12 m (C4).
Thus introduction of three fairly bulky isopropyl
groups does not hinder substitution of one oxygen
atom, closure of 1,2-oxaphosphinine ring, and chlori-
nation of the pentasubstituted aromatic fragment.
Unlike 3,5- and 3,6-di-tert-butyl-1,2-benzoquinones
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 7 2012

MIRONOV et al.
950
Scheme 2.
Pr-i
Pr-i
Pr-i
Pr-i
O
8
i-Pr
O
O
i-Pr
i-Pr
O
8a
7
O
PCl3
HC
Ph
P
Cl
PCl3
6
–HCl
3
O
4a
Cl
5
4
Pr-i
X
Pr-i
IX
Ph
VIII
determined by X-ray analysis of its single crystal ob-
tained from a solution in methylene chloride (Fig. 1). It
was found that the chlorine atom is attached to C6 and
that oxygen atom in the para position with respect to
isopropyl group was replaced. Molecule IX is steri-
cally strained; it contains hexasubstituted benzene
rings with bulky substituents and oxaphosphinine
heteroring having two planar fragments connected by
a single bond. Steric strains induce appreciable twist-
ing of multiple bonds: the torsion angles O1C8aC4aC4
and P2C3C4C4a are –14.6(2) and –9.2(1)°, respectively.
Assuming that these four-atom fragments are approxi-
mately planar, the C3 and P2 atoms deviate from the
plane of the first fragment (O1C8aC4aC4), and the O1
and C8a atoms, from the plane of the second fragment
(P2C3C4C4a), toward one side but by different dis-
tances. Such geometry of the six-membered heteroring
corresponds to distorted (unsymmetrical) boat con-
formation. The O2 atom at the phosphorus occupies
equatorial position, and Cl2, axial (Fig. 2a). The
benzene ring is also appreciable twisted (Fig. 2b): the
torsion angles are as follows: C8aC4aC5C6 12.8(2),
C4aC5C6C7 –2.2(3), C5C6C7C8 –8.1(3), C6C7C8C8a
7.3(2), C7C8C8aC4a 3.6(3), C8C8aC4aC5 –14.1(3)°; the
maximal twisting is observed for the fusion bond: the
torsion angle C7C8C8aC4a is 3.6(3)°.
phosphole (X) which then reacts with phenylacetylene
according to the path described in [14, 15], leading to
compound IX as final product (Scheme 2).
With a view to elucidate the regiochemistry of ipso-
substitution of oxygen and chlorination of the aromatic
fragment the structure of IX was unambiguously
C12
C16
C13
C11
C10
C14
C17
C15
C9
Cl6
C5
C4
C4a
C3
C6
C7
Cl2
P2
C8a
C18
C8
O1
O2
C20
C19
C21
C22
C23
Thus the regiochemistry of the reaction of 3,4,6-tri-
isopropyl-1,2-benzoquinone (VIII) with phosphorus
trichloride and phenylacetylene, leading to the forma-
tion of 2,6-dichloro-5,7,8-triisopropyl-4-phenyl-1,2λ5-
benzoxaphosphinine 2-oxide (IX), includes selective
substitution of the oxygen atom in the para-position
with respect to one isopropyl group by carbon. Despite
the presence of three bulky isopropyl groups in initial
benzoquinone, the benzene fragment undergoes chlori-
nation with formation of hexasubstituted structure.
Fig. 1. Structure of the molecule of 2,6-dichloro-5,7,8-triiso-
propyl-4-phenyl-1,2λ5-benzoxaphosphinine 2-oxide (IX)
according to the X-ray diffraction data; non-hydrogen atoms
are shown as thermal vibration ellipsoids with a probability
of 30%. Selected bond lengths (Å) and bond and torsion
angles (deg): Cl2–P2 2.017(1), Cl6–C6 1.759(2), P2–O1
1.591(2), P2–O2 1.456(2), P2–C3 1.746(2), O1–C8a 1.399(2),
C3–C4 1.340(3), C4–C4a 1.488(2), C4–C9 1.486(3), C4a–C5
1.413(2), C4a–C8a 1.394(2), C5–C6 1.392(2), C6–C7 1.406(3),
C7–C8 1.404(3), C8–C8a 1.393(2), C5–C15 1.530(3), Cl2P2O1
102.90(5), Cl2P2O2 111.88(8), Cl2P2C3 108.73(7), O1P2O2
112.45(8), O1P2C3 102.06(8), O2P2C3 117.47(9), P2O1C8a
120.2(1), P2C3C4 118.2(1), O2P2O1C8a 173.2(1), O2P2C3C4
–150.1(2), P2O1C8aC4a –29.0(2), P2O1C8aC8 152.9(1),
P2C3C4C4a –9.1(2), P2C3C4C9 161.5(1), C9C4C4aC5 40.5(2),
C3C4C9C10 –133.1(2), C3C4C9C14 42.6(3), C9C4C4aC8a
–136.7(2), C3C4C4aC5 –148.7(2), C3C4C4aC8a 34.1(2).
EXPERIMENTAL
1
The H, 31P, 31P–{1H}, 13C, and 13C–{1H} NMR
spectra were recorded on a Bruker Avance 400 spec-
trometer at 400 (1H), 161.9 (31P), and 100.6 MHz (13C)
1
at 20°C using the solvent signals (CDCl3, H, 13C) or
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 7 2012

REGIOCHEMISTRY OF THE REACTION OF 3,4,6-TRIISOPROPYL-1,2-BENZOQUINONE
(a)
951
(b)
Cl2
–2.7926(8) (pl1)
–1.8185(8) (pl2)
–0.779(2) (pl1)
–0.582(2) (pl2)
–0.920(8) (pl1)
O2
–0.175(1)
P2
O1
C21
–0.077(2)
0.532(2) (pl2)
O1
C8
C8a
C8a
0.846(1) (pl2)
C3
C4a
0.422(2)
C4
C4a
–0.430(2) (pl1)
C7
Cl6
C18
C4
C9
C6
C5
C15
0.270(2)
–0.379(2)
–0.1510(6)
Fig. 2. (a) Boat conformation of the oxaphosphinine heteroring in IX; deviations of the C3, P1, Cl2, and O2 atoms from the
O1C8aC4aC4 plane [pl1; planar within 0.065(2) Å] and of the O1, C8a, O2, and Cl2 atoms from the P2C3C4C4a [plane [pl2; planar within
0.044(2) Å] are given. (b) Steric structure of the benzene ring C4aC5C6C7C8C8a [planar within 0.086(2) Å] and deviations of the O1,
C4, C15, Cl6, C18, and C21 atoms. The phenyl substituent on C4 and hydrogen atoms are not shown for the sake of simplicity.
2
H3PO4 (31P, external) as reference. The mass spectrum
(electron impact, 70 eV) was obtained on a Trace MS
Finnigan MAT mass spectrometer with direct sample
admission into the ion source; ion source temperature
200°C, batch inlet probe temperature programming
from 35 to 150°C at a rate of 35 deg/min. The mass
spectral data were processed using Xcalibur program.
The synthesis of quinone VIII was described in [18].
136.36 br.t (br.s) (C8), 149.33 br.s (br.d) (C8a, JPC
=
6.0 Hz), 141.54 d.d.t (d) (C9, JPC = 20.5, J11-H = 7.7,
3
3
3J3-H = 6.2 Hz), 126.80 br.d (s) (C10, JCH = 161.8 Hz),
1
128.95 br.d (s) (C11, JCH = 160.3 Hz), 129.55 d.t (s)
1
(C12, JCH = 161.7, JCH = 7.3 Hz), 35.10 d.sept (s)
1
3
(C18, JCH = 126.2, JCH = 3.7 Hz), 30.89 br.d (s) (C21,
1
3
1JCH = 127.6), 29.06 br.d (br.s) (C15, JCH = 127.3 Hz),
1
21.52 br.q.m (br.s) (C19, C20, JCH = 126.7 Hz),
1
20.85 br.q.m and 20.54 br.q.m (br.s each) (C22, C23,
2,6-Dichloro-5,7,8-triisopropyl-4-phenyl-1,2λ5-
benzoxaphosphinine 2-oxide (IX). Phenylacetylene,
0.70 ml (6.48 mmol), was added at room temperature
to a solution of 0.48 g (2.05 mmol) of quinone VIII in
10 ml of methylene chloride, and 0.28 ml (3.24 mmol)
of phosphorus trichloride was added dropwise while
bubbling dry argon through the mixture. The mixture
was kept for 24 h, and evaporated at a residual pressure
of 18 mm (40°C) under argon. After cooling, a dark
yellow viscous material was obtained, which solidified
in 2 h to give colorless crystals. Yield 0.85 g (95%),
1
1JCH = 126.7– 127.0 Hz), 20.64 q.q.d (s) (C16, JCH
=
127.3, JCH = 5.4, JCH = 5.4 Hz), 19.18 q.m (s) (C17,
3
2
1JCH = 126.9, JCH = 5.0, JCH = 5.0 Hz). 31P NMR
spectrum: δP 17.8 ppm, d (2JPH = 27.7 Hz). Mass spec-
trum, m/z: 436 [M]+·, 421 [M – Me], 401 [M – Cl], 394
[M – MeCH=CH2], 393 [M – CHMe2], 358 [M –
CHMe2 – Cl], 351 [M – MeCH=CH2 – CHMe2].
3
2
The X-ray diffraction study of compound (IX) was
performed at the X-Ray Department, Collective Use
Center, Spectral–Analytical Center, Laboratory of
Diffraction Methods, Arbuzov Institute of Organic and
Physical Chemistry, Kazan Research Center, Russian
Academy of Sciences. Triclinic crystals, C23H27Cl2O2P,
M 437.32, with the following unit cell parameters
(296 K): = a 8.461(4), b = 9.371(5), c = 16.172(8) Å;
α = 74.184(5), β = 77.713(5), γ = 68.556(5)°; V =
1139(1) Å3; Z = 2; space group P-1; dcalc = 1.275 g×
cm–3; μ = 0.371 mm–1; F(000) = 460. The data were
acquired on a Bruker Smart APEX II CCD automatic
diffractometer [graphite monochromator, λ(MoKα) =
0.71073 Å, ω-scanning, 2θ < 54°]. Total of 15555 re-
flections were measured, 4945 of which were inde-
pendent (Rint = 0.0180, and 4150 reflections were
characterized by I > 2σ(I); final divergence factors:
1
mp 186°C. H NMR spectrum, δ, ppm (for atom num-
2
bering, see Fig. 1): 6.43 d (1H, 3-H, JPCH = 27.7 Hz),
7.05 br.m (2H, 10-H), 7.38–7.40 m (3H, 11-H, 12-H),
4.11 br.s (1H, 21-H), 3.65 br.s (1H, 18-H), 2.97 m (1H,
15-H, 3J = 6.8–7.2 Hz); 1.48 br.d, 1.47 d, and 1.46 br.d
3
(12H, 19-H, 20-H, 22-H, 23-H, J = 6.8–7.1 Hz),
1.08 d (3H, 16-H, 3J = 7.2 Hz), 0.88 d (3H, 17-H, 3J =
6.8 Hz). 13C NMR spectrum, δC, ppm (in parentheses is
given the multiplicity of the corresponding signal in
the proton-decoupled spectrum): 118.28 d.d (d) (C3,
1
1JPC = 163.2, JHC = 172.0 Hz), 158.12 br.s (s) (C4),
3
3
3
123.46 d.d.d (d) (C4a, JPC = 18.3, J3-H = 8.4, J15-H
=
4.0 Hz), 143.47 br.m (br.s) (C5), 132.51 br.d.d (br.s)
(C6, J = 7.5–7.7, 4.8–5.0 Hz), 149.01 br.m (br.s) (C7),
3
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 7 2012

MIRONOV et al.
952
Dobrynin, A.B., Alekseev, F.F., Litvinov, I.A., and
Konovalov, A.I., Dokl. Ross. Akad. Nauk, 2002,
vol. 385, p. 196.
R = 0.0407, wR2 = 0.1236; goodness of fit 1.045; num-
ber of refined parameters 259. Absorption by the crys-
tal was taken into account using SADABS program
[19]. The structure was refined by the direct method
using SIR program [20] and was refined first in
isotropic and then in anisotropic approximation using
SHELXL-97 software package [21]. All hydrogen
atoms were placed into calculated positions which
were refined according to the riding model. All cal-
culations were performed with the aid of WinGX [22]
and APEX2 [23]. The structures were plotted, and
intermolecular contacts were analyzed using PLATON
[24] and ORTEP [25]. The set of crystallographic data
for compound IX was deposited to the Cambridge
Crystallographic Data Centre (http://www.ccdc.cam.
ac.uk; entry no. CCDC 877458).
11. Bogdanov, A.V., Mironov, V.F., Krivolapov, D.B.,
Litvinov, I.A., Musin, R.Z., Latypov, Sh.K., and Kono-
valov, A.I., Mendeleev Commun., 2005, vol. 15, p. 101.
12. Mironov, V.F., Bogdanov, A.V., Nemtarev, A.V., Shtyr-
lina, A.A., Varaksina, E.N., Cherkasov, V.K., Dobry-
nin, A.B., Krivolapov, D.B., Musin, R.Z., Litvinov, I.A.,
and Konovalov, A.I., Izv. Ross. Akad. Nauk, Ser. Khim.,
2007, p. 1836.
13. Alekseev, F.F., Mironov, V.F., Cherkasov, V.K., Azan-
cheev, N.M., and Konovalov, A.I., Russ. J. Gen. Chem.,
2002, vol. 72, p. 1311.
14. Mironov, V.F., Cherkasov, V.K., Alekseev, F.F., Azan-
cheev, N.M., Litvinov, I.A., Dobrynin, A.B., Gubaidul-
lin, A.T., and Konovalov, A.I., Dokl. Ross. Akad. Nauk,
2002, vol. 383, p. 648.
15. Nemtarev, A.V., Mironov, V.F., Bogdanov, A.V., Cher-
kasov, V.K., Druzhkov, N.O., Gubaidullin, A.T., Litvi-
nov, I.A., and Musin, R.Z., Izv. Ross. Akad. Nauk, Ser.
Khim., 2009, p. 182.
16. Mironov, V.F., Baronova, T.A., Konovalov, A.I., Azan-
cheev, N.M., Alekseev, F.F., Zyablikova, T.A., and Mu-
sin, R.Z., Russ. J. Org. Chem., 2002, vol. 38, p. 1183.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 10-03-00525a).
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