Regiochemistry of the reaction of 3,6-bis(tert-butyl)-1,2-benzoquinone with phosphorus trichloride in the presence of arylacetylene

Full text of DOI:10.1023/A:1015452205712

Doklady Chemistry, Vol. 383, Nos. 4–6, 2002, pp. 102–104. Translated from Doklady Akademii Nauk, Vol. 383, No. 5, 2002, pp. 648–650.
Original Russian Text Copyright © 2002 by Mironov, Cherkasov, Alekseev, Azancheev, Litvinov, Dobrynin, Gubaidullin, Konovalov.
CHEMISTRY
Regiochemistry of the Reaction
of 3,6-Bis(tert-butyl)-1,2-benzoquinone with Phosphorus
Trichloride in the Presence of Arylacetylene
V. F. Mironov*, V. K. Cherkasov**, F. F. Alekseev*, N. M. Azancheev*, I. A. Litvinov*,
A. B. Dobrynin*, A. T. Gubaidullin*, and Academician A. I. Konovalov*
Received December 26, 2001
The reaction of phosphorus pentachloride with aryl- vacuo (120°ë, 0.1 mmHg), these products represent
acetylenes followed by hydrolysis of the initially slightly yellow glasses, which are responsible for a
formed phosphonium products is considered as an doublet with δê 16–18 ppm (2JPCH 26.5–27.5 Hz) in the
important method for the synthesis of derivatives of 31P NMR spectrum. A similar doublet is present in the
unsaturated phosphonium acids which can be used as 1ç NMR spectra (ëDël3, δ 6.33–6.38 ppm, 2JPCH 26.5–
initial compounds to prepare various types of new 27.5 Hz). Taking account of the data of the 1ç and 31P
promising biologically active organophosphorus prod- NMR spectra and the results of a 13C NMR study (see
ucts [1]. The replacement of two chlorine atoms in below), the compounds synthesized were identified as
phosphorus pentachloride by the phenylenedioxy frag- 4-aryl-5,8-bis(tert-butyl)-6-chlorobenzo[e]-1,2-
oxaphosphines (IVa, IVb).
ment results unexpectedly in 2,6-dichloro-2-
oxobenzo[e]-1,2-oxaphosphorines, which are products
of multistep transformations including easy formation
of the P–C bond and the phosphoryl group, ipso-substi-
tution of the oxygen atom, and regioselective chlorina-
tion of the aromatic ring in the para-position relative to
endocyclic oxygen of the phosphorine heterocycle [2–
4]. A similar synthetic outcome can be attained in the
O
O
PCl3
PCl3
,
O
O
(I)
(II)
phenanthrenequinone–phosphorus
trichloride–ary-
lacetylene ternary system, in which isolation of the
X–C6H4C≡CH + I
intermediate êV compound is difficult [5].
(III‡, IIIb)
Herein, we show for the first time that the reaction
of sterically hindered 3,6-bis(tert-butyl)-1,2-benzoqui-
onone (I) with phosphorus trichloride in the presence of
arylacetylenes has a number of specific features. First,
it should be noted that in the absence of arylacetylene,
the reaction of quinone (I) with phosphorus trichloride
results in the formation of a êV derivative, 4,7-bis(tert-
butyl)benzo[d]-1,3,2-dioxaphosphole (II), which is
responsible for a high-field signal with δê –27 ppm in
the 31P NMR spectrum. Upon the addition of phospho-
rus trichloride to a mixture of quinone (I) with arylacet-
ylene (IIIa, IIIb), as well as upon the addition of ary-
lacetylene IIIa or IIIb to benzophosphole II, phospho-
nate products are formed almost quantitatively under
mild conditions (10°ë, ëç2Cl2). After keeping in
8
5
O
O
8a
4a
7
P
Cl
6
3
PCl3
[–HCl]
Cl
II
[–HCl]
4
(IIIa, IIIb),
9
10
11
12
X
(IV‡, IVb)
X = H (II‡), 4-CH3 (IIb).
Scheme 1.
It was shown by high-resolution mass spectrometry
for compound IVa that the process is accompanied by
the introduction of a chlorine atom into the ortho-phe-
nylene substituent; the spectrum contains a molecular
ion peak at 422, which corresponds to the calculated
value. The structure of compounds IV and the position
of the chlorine atom in the aromatic ring were deter-
* Arbuzov Institute of Organic and Physical Chemistry,
Kazan Research Center, Russian Academy of Sciences,
ul. akademika Arbuzova 8, Kazan, 420083 Tatarstan, Russia
** Institute of Organometallic Chemistry,
Russian Academy of Sciences, ul. Tropinina 49,
Nizhni Novgorod, 603600 Russia
13
mined by C NMR spectroscopy. The spectra exhibit
four (for compound IVb) or five (for compound IVa)
0012-5008/02/0004-0102$27.00 © 2002 åÄIä “Nauka /Interperiodica”

REGIOCHEMISTRY OF THE REACTION
103
groups of low-field signals for carbon atoms attached to
protons and eight (for compound IVb) or seven (for
compound IVa) groups of low-field signals for carbon
atoms forming no C–H bonds; this confirms the fact of
chlorine introduction into the phenylene substituent.
The multiplicity of the C-8a and C-4a signals (IVa:
C16
2
3
147.73 (ddd, C-8a, JPOC 11.7 Hz, JHCCC 11.2 Hz,
3
4JHCPOC 1.0 Hz), 125.98 (dd, C-4a, JPCCC 20.2 Hz,
O1
C7
3JHCCC 8.1 Hz, 4JHCCCC 0.8 Hz); IVb: 147.47 (ddd, C-8a,
C7A
C2
C6
2JPOC 11.3 Hz, 3JHCCC 10.2 Hz, 4JHCPOC 1.0 Hz), 126.13
C3A
3
3
4
(ddd, C-4a, JPCCC 20.2 Hz, JHCCC 8.1 Hz, JHCCCC
1.1 Hz)) points to the formation of a cyclic structure
and to the presence of chlorine at C-6. The signal for the
C-3 atom shows itself in the typical high-field region
(δë 113.58–114.39 ppm) as a doublet of doublets with
C3
C5
C14
C4
C9
C15
C10
1
1
rather high JPC (166.2–166.6 Hz) and JHC (171.4–
172.1 Hz) constants; conversely, the signal of C-4
occurs in low fields (δë 159.76–159.87 ppm) as a mul-
tiplet (2JPëC 2.2–2.3 Hz).
C13
C11
C12
Unlike arylacetylenes IIIa and IIIb, para-chlo-
rophenylacetylene IIIc reacts with quinone I and phos-
phorus trichloride less ambiguously than with phosp-
hole II. This gives benzophosphorine IVc as either the
only (with phosphorane II) or the major (~62%) reac-
tion product (after removal of CH2Cl2 and styrenes at
130°ë (0.1 mmHg)). The spectroscopic characteristics
of IVc (δê 17.9 ppm (d, 2JPCH 27.2 Hz), δç 6.36 ppm (d,
2JPCH 27.2 Hz)) are close to those for compounds IVa
and IVb. The reaction carried out in a quinone I–phos-
phorus trichloride–acetylene IIIc ternary system gave
phosphorus oxochloride and a phosphorus-free organic
Cl1
Structure of the molecule of Vc in the crystal.
132.5°) and C(4) (C(3a)C(4)C(15), av. 128.5°) and sub-
stantial elongation of the C(3)–C(3a) bond (av., 1.585 Å).
The steric hindrance of the bulky substituents stipulates
an orthogonal conformation of the para-chlorophenyl
group; the dihedral angles between the substituent
plane and the plane of the benzofuran fragment are
85.4° (mean). Short intramolecular contacts are found
between the protons of the methyl groups of the substit-
uent at C(4) and the atoms of the para-chlorophenyl
substituent in the range of 2.60–2.90 Å. Short contacts
between the tert-butyl-group protons at C(7) and the
O(1) atom conforming to the criterion of the ë–ç···é
hydrogen bond occur in the opposite fragment of the
molecule. The formation of compound Vc along with
the evolution of phosphorus oxochloride is yet another
new pathway in these reactions.
compound,
4,7-bis(tert-butyl)-3-para-chlorophenyl-
benzo[d]furan (Vc), in addition to benzophosphorine IVc.
Cl–C6H4C≡CH + I
(IIIc)
O
O
O
P
PCl3
Cl
+
[–HCl], –POCl3, [–Cl2]Cl
Study of the reaction of para-methylacetylene with
quinone (I) and phosphorus trichloride by dynamic 31P
NMR spectroscopy showed that initially, this gives a
compound responsible for a signal located in a lower
field than the signal of phosphorine (IVb) [δê 30.4 ppm
(d, 2JPCH 31.3 Hz)]. Even on heating to 40°ë, this signal
is gradually transformed into the signal of the final
reaction product, benzophosphorine (IVb) (δê 17.9 ppm).
The structure of this intermediate reaction product was
elucidated using 13C NMR spectroscopy. Unlike the
spectrum of IVb, the spectrum of this compound exhib-
its characteristic signals in low (185.84 ppm, m, 4JPCCCC
1.5 Hz, 3JçCCC 9.6 Hz, 4JçCCCC 1.0 Hz) and high fields
C6H4Cl
C6H4Cl
(IVc)
(Vc)
.
Scheme 2.
The structure of the isolated crystalline benzofuran
(Vc) was established by single crystal X-ray diffrac-
tion. In the monoclinic crystal of Vc, the asymmetric
part of the unit cell contains two molecules with nearly
the same conformation. The figure shows the geometry
of one of the crystallographically independent mole-
cules. The benzofuran fragment is planar to within the
experimental error. The key atoms of the tert-butyl
groups, C(15) and C(16), and of the para-chlorophenyl (51.92 ppm, dd, 1JçC 152.2 Hz, 2JçëC 2.8 Hz). The low-
substituent, C(9), are also located in the heterocycle field signal belongs to the C-8a atom of the C=O group,
plane. The presence of two bulky substituents in the 3- while the high-field signal is due to the C-6 atom of the
and 4-positions induces noticeable distortions of the Cl–C6H(ë=ë)2 fragment of the quinoid type structure
exocyclic bond angles at C(3) (C(3a)C(3)C(9), av. VIb. The C-3 carbon atom of VIb resonates in a lower
DOKLADY CHEMISTRY Vol. 383 Nos. 4–6 2002

104
MIRONOV et al.
1
1
field (120.18 ppm, dd, JêC 153.5 Hz, Jçë 164.9 Hz) oxybenzene structure fused to a phosphorine heterocy-
1
than that in heterocycle IVb (114.87 ppm, dd, Jêë cle; cyclization proceeds via intermediate quinoid
166.3 Hr, JHC 172.0 Hz). The acyclic nature of this structures. Regioselective chlorination of the bis(tert-
1
compound and Z configuration of the substituents at the butyl)phenyl substituent in the para-position relative to
ë3=ë4 bond is confirmed by the multiplicity and the the endocyclic oxygen atom of the phosphorine ring
magnitudes of the 3JPCCC and 3JHCCC constants of the C- also takes place during the reaction.
5 and C-9 signals for cis- and trans-orientation of the
The NMR spectra were recorded on Bruker MSL-
400 (162.0 MHz for 31ê, 100.6 MHz for 13ë) and
Bruker WM-250 (1H, 250 MHz) spectrometers in
CDCl3 with respect to internal HMDS or external
H3PO4.
phosphorus substituent: C-5, 139.15 ppm, ddd,
3
3
3Jêëëë(cis) 7.4 Hz, Jçëëë(cis) 4.8 Hz, Jçëëë(trans)
3
7.4 Hz; C-9, 135.87 ppm, dqd, Jêëëë(trans) 28.2 Hz,
3Jçëëë(cis) 7.1 Hz, 3Jçëëë(trans) 7.3 Hz. The Z config-
uration of substituents at the exocyclic multiple bond is
also confirmed by the ease of cyclization of vinylphos-
phonate VIb into the benzophosphorine system (IVc).
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research, project nos. 00–03–32835 and 01–
03–06140.
I + IIIb + PCl3
O
Cl
Cl
O
8a
5
P
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6
3
H
Cl
4
9
.
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IVb
[–HCl]
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CH3
(VIb)
Scheme 3.
The fact of formation of compound VIb appears
rather unusual; in all probability, this is related to the
stabilizing steric effect of tert-butyl substituents.
Thus, despite the presence of bulky tert-butyl
groups in ortho-benzoquinone (I), unusual reactions
with phosphorus trichloride and arylacetylenes take
place under rather mild conditions and result in the con-
version of the ortho-benzoquinone structure into an
DOKLADY CHEMISTRY Vol. 383 Nos. 4–6 2002