Noncatalytic regio- and stereoselective addition of secondary phosphines to cyanoacetylenic alcohols

Article abstract of DOI:10.1007/s11176-005-0263-5

Secondary phosphines regio- and stereoselectively add to 4-hydroxy-4-methyl-2-pentynenitrile, a typical and available representative of cyanoacetylenic alcohols, without catalyst at room temperature (THF, 3 h) to form (Z)-3-[dialkyl(aryl) phosphino]-4-hydroxy-4-methyl-2-pentenenitriles in 80-85% yields. These compounds relate to a new class of functionalyzed phosphines, promising ligands for the design of metal-complex catalysts. 2005 Pleiades Publishing, Inc.

Full text of DOI:10.1007/s11176-005-0263-5

Russian Journal of General Chemistry, Vol. 75, No. 4, 2005, pp. 514 517. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005,
pp. 552 555.
Original Russian Text Copyright
2005 by Arbuzova, Shaikhutdinova, Gusarov, Nikitin, Mal’kina, Sukhov, Bogdanova, Trofimov.
Noncatalytic Regio- and Stereoselective Addition
of Secondary Phosphines to Cyanoacetylenic Alcohols
S. N. Arbuzova, S. I. Shaikhutdinova, N. K. Gusarov, M. V. Nikitin,
A. G. Mal’kina, B. G. Sukhov, M. V. Bogdanova, and B. A. Trofimov
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Received October 30, 2003
Abstract Secondary phosphines regio- and stereoselectively add to 4-hydroxy-4-methyl-2-pentynenitrile, a
typical and available representative of cyanoacetylenic alcohols, without catalyst at room temperature (THF,
3 h) to form (Z)-3-[dialkyl(aryl)phosphino]-4-hydroxy-4-methyl-2-pentenenitriles in 80 85% yields. These
compounds relate to a new class of functionalyzed phosphines, promising ligands for the design of metal-
complex catalysts.
Addition of phosphines to acetylene and its deriva-
tives is a convenient approach to formation of a C P
bond and synthesis of unsaturated phosphines that are
promising building blocks for preparing chiral phos-
phorus-containing ligands [1, 2]. Special place among
such reactions is occupied by addition of secondary
phosphines to cyanoacetylenes, permitting to prepare
amphiphilic tertiary phosphines with hydrophobic
substituents and polar acrylonitrile function (easily
transformed to amide or carboxy groups). Such com-
pounds are promising ligands for metal complexes
that combine properties of phase-transfer and micellar
catalysts. At the same time, the information on phos-
phorylation of cyanoacetylenes is scarce. It is known
that diisopropyl- and di-tert-butylphosphines stereo-
selectively react with cyanoacetylene to form the Z
isomers of corresponding phosphinoacrylonitriles in
28 33% yields [3]. In the case of the less sterically
congested dimethylphosphine, a mixture of (Z)- and
reactions of a typical and available [6] representative
of cyanoacetylenic alcohols, 4-hydroxy-4-methyl-2-
pentynenitrile with dialkyl- and bis[aryl(hetaryl)-
ethyl]phosphines. The latter are nowadays easily
prepared from red phosphorus and alkyl halides [7] or
aryl(hetaryl)ethenes [8, 9].
Dibutyl, bis(2-phenylethyl)- and bis[2-(2-pyridyl)-
ethyl]phosphines regio- and stereoselectively add to
4-hydroxy)4-methyl-2-pentynenitrile in THF at room
temperature to form (Z)-[dialkyl(aryl)phosphino]-4-
hydroxy-4-methyl-2-pentenenitriles IIa IIc in 80
85% yields.
R
Me
OH
CN
R
P
R2PH + Me
Ia Ic
CNTHF
Me
OH
IIa IIc
Me
(E)-3-(dimethylphosphino)acrylonitriles
(1:2)
is
formed in 50% yield [3]. The chemo-, regio-, and
stereoselective addition of primary [4] and secondary
[5] phosphines to phenylcyanoacetylene has been
reported, leading to corresponding secondary and
tertiary cyanoethenylphosphines of Z configuration
in an almost quantitative yield. Furthermore, a short
communication on the reaction of 4-hydroxy-4-methyl-
2-pentynenitrile with secondary phosphines has been
published [4].
R = p-Bu (a), PhCH2CH2 (b), 2-PyCH2CH2 (c).
The structure and configuration of compounds IIa
IIc were confirmed by their chemical transformations
and NMR spectra.
The doublet ethenyl proton signals in the range
6.2 6.5 ppm (3JHP 5.4 and 6.6 Hz), observed in the
1H NMR spectra of phosphines IIb and IIc, should,
according to published data [3, 5, 10, 11], correspond
to cis location of hydrogen and phosphorus.
In the present work with the purpose of synthesiz-
ing new functionalyzed tertiary phosphines and their
derivatives, as well as gaining additional information
on the regularities of phosphorylation of acetylenes
with secondary phosphines, we have investigated the
1
1
However, the presence in the two-dimensional H H
NOESY NMR spectra of these phosphines of cross
peaks corresponding to interaction of protons of the
ethenyl and methyl groups, that is only possible if
1070-3632/05/7504-0514 2005 Pleiades Publishing, Inc.

NONCATALYTIC REGIO- AND STEREOSELECTIVE ADDITION
515
these groups are cis to each other, provides un-
ambiguous evidence for Z configuration of com-
pounds IIb and IIc.
IVa and 32.2 Hz for compounds IVb and IVc, which
is characteristic of Z isomers [10, 11].
Contrary to the majority of tertiary phosphines,
phosphines IIa IIc are oxidized slowly, probably
because the electron density on phosphorus in them is
decreased by conjugation of its lone electron pair with
the double carbon carbon bond.
1
In the H NMR spectrum of phosphine IIa, the
doublet signal of the ethenyl proton (6.40 ppm), too,
3
has a low JHP coupling constant (4.8 Hz), which is
more characteristic of the E isomers of such com-
1
pounds [3, 5, 10, 11]. The 1H H NOESY NMR spec-
Knowing that tertiary phosphines mildly reduce
cyanoacetylenic alcohols to allenes [12], we made an
attempt to effect an analogous redox reaction between
phosphine IIa and 4-hydroxy-4-methyl-2-pentynenit-
rile. In this case, the reaction proceeds with heat evo-
lution (the reaction mixture warmes up to 50 55 C)
and gives a mixture of products, in which we iden-
trum of phosphine IIa does not give such an un-
ambiguous picture as the spectra of compounds IIb
and IIc, because the signal of the methyl group is
overlapped by the multiplet of methylene protons of
the butyl substituent. However, treatment of 3-(dibutyl-
phosphino)-4-hydroxy-4-methyl-2-pentenenitrile (IIa)
with methyl iodide in THF at room temperature gave
1
tified oxide IVa (by 31P and H NMR spectroscopy)
phosphonium salt III of Z configuration (3JHP
35.9 Hz) [10] in quantitative yield.
and the expected reduction product of the starting
hydroxyacetylene, 4-methylpenta-2,3-dienenitrile [ ,
1
cm : 1969.4 (C=C=C);
,
ppm: 4.99 heptet
+
Bu-n
(=CHCN)] (these data agree with those reported in
[12]).
Me
CN
n-Bu P
MeI
I
IIa
Me
Me
Me
Me
Me
.
IIa + Me
CN
IVa +
OH
III
CN
OH
Hence, the reaction of cyanoacetylenic alcohols
with secondary phosphines, that proceeds regio- and
stereoselectively under mild conditions as trans addi-
tion of nucleophiles (specifically, P-nucleophiles [3,
13]) to activated acetylenes [14], opens up a con-
venient and effective synthetic route to new functio-
nalyzed tertiary phosphines, promising polydentate
amphiphilic ligands for the design of catalysts of new
generation [15, 16], as well as highly reactive inter-
mediates for fine organic synthesis.
In view of this result, we assigned to 3-(dibutyl-
phosphino)-4-hydroxy-4-methylpentenenitrile (IIa),
like to compounds IIb and IIc, Z configuration.
When exposed to air, phosphines IIb and IIc are
slowly (for about 2 months) oxidized to phosphine
oxides
IVb
and
IVc
(isolable
with
51 61%); phosphorus-containing polymers are formed
under these conditions as by-products.
O
R
EXPERIMENTAL
CN
R
P
The H and 31P NMR spectra were recorded on a
O2
1
IIa IIc
Me
Me
IVa IVc
Bruker DPX-400 spectrometer (400.13 and 161.98
MHz, respectively) in CDCl3 against internal HMDS
and external 85% phosphoric acid. The IR spectra
were obtained on a Bruker IFS-25 spectrometer in thin
layer or in KBr. All experiments were carried out
under argon.
OH
R = n-Bu (a), PhCH2CH2 (b), 2-PyCH2CH2 (c).
Under analogous conditions, phosphine IIa gives
a mixture of several organophosphorus compounds,
among which 3-(butylphosphinoyl)-4-hydroxy-4-
methyl-2-pentenenitrile (IVa). The latter product was
(Z)-3-(Dibutylphosphino)-4-hydroxy-4-methyl-2-
pentenenitrile (IIa). To a solution of 0.28 g of di-
butylphosphine in 4 ml of THF, a solution of 0.21 g
of 4-hydroxy-4-methyl-2-pentenenitrile in 4 ml of
THF was added dropwise with stirring at room tem-
perature in 10 min. The reaction mixture was stirred
at room temperature for 3 h and then passed through
a bed of Al2O3 (1 cm). The solvent was removed at
reduced pressure, and the residue was distilled in a
identified by means of NMR spectroscopy (
P
50.8 ppm; 6.03 ppm, doublet). The Z configuration
of phosphine oxides IVa IVc was confirmed by their
3
1H NMR spectra. The JHP coupling constants of the
ethenyl proton doublets are 31.8 Hz for compound
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

516
ARBUZOVA et al.
vacuum to give 0.41 g (81%) of phosphine IIa as a
Found, %: C 45.63; H 7.65; I 31.60; N 3.60; P 7.58.
C15H29INOP. Calculated, %: C 45.35; H 7.36; I
31.94; N 3.53; P 7.80.
1
light yellow oil. IR spectrum, , cm : 2215 (C N),
1
3300 (OH). H NMR spectrum, , ppm: 0.93 t (6H,
3
MeCH2, JHH 6.8 Hz), 1.39 1.54 m (14H, MeCOH,
(Z)-3-[Bis(2-phenylethyl)phosphinoyl]-4-hydr-
oxy-4-methyl-2-pentenenitrile (IVb). Phosphine IIb,
0.3 g, was allowed to stand in air for 2 months. The
resulting viscous product was dissolved in 3 ml of
THF, and the solution was passed through a bed
of Al2O3 (1 cm) the solvent was removed at reduced
pressure, and the residue was dried in a vacuum to
give 0.19 g (61%) of phosphine oxide IVb, white
powder, mp 100 102 C (from ether). IR spectrum, ,
CH2), 1.85 1.94 m and 2.08 2.17 m (4H, CH2P),
3
6.40 d (1H, =CH, JHP 4.8 Hz). 31P NMR spectrum:
28.7 ppm. Found, %: C 65.57; H 10.56; N 5.74; P
1P1.85. C14H26NOP. Calculated, %: C 65.85; H 10.26;
N 5.49; P 12.13.
(Z)-3-[Bis(2-phenylethyl)phosphino]-4-hyd-
roxy-4-methyl-2-pentenenitrile (IIb) was prepared
similarly to phosphine IIa from 0.36 g of phosphine
Ib and 0.15 g of 4-hydroxy-4-methyl-2-pentenenitrile.
The resulting product was dissolved in diethyl ether,
insoluble substances were filtered off, the ether was
removed at reduced pressure, and the residue was
dried in a vacuum to give 0.42 g (80%) of phosphine
1
1
cm : 2210 (C N), 3300 (OH), 1160 (P=O). H NMR
spectrum, , ppm: 1.55 s (6H. Me), 2.30 2.45 m and
2.52 2.65 m (4H, CH2P), 2.85 2.98 m and 3.00
3.10 m (4H, CH2Ph), 5.25 s (1H, OH), 6.02 d (1H,
=CH, JHP 32.3 Hz), 7.18 7.31 m (10H, Ph). 31P
3
1
NMR spectrum:
46.9 ppm. Found, %: C 71.65; H
IIb as a yellow oil. IR spectrum, , cm : 2210 (C N),
P
1
7.43; N 3.72; P 8.63. C22H26NO2P. Calculated, %: C
71.92; H 7.13; N 3.81; P 8.43.
3300 (OH). H NMR spectrum , ppm: 1.41 s (6H,
Me), 1.81 1.95 m (4H, CH2P), 2.60-2.75 m (4H,
3
CH2Ph), 6.45 d (1H, =CH, JHP 5.4 Hz), 7.15 7.27 m
(Z)-3-[Bis[2-(2-pyridyl)ethyl]phosphinoyl]-4-
hydroxy-4-methyl-2-pentenenitrile (IVc) was pre-
pared similarly to phosphine oxide IVb from 0.3 g of
phosphine IIc. Yield 0.16 g (51%), yellow oil. IR
(10H, Ph). 31P NMR spectrum:
28.9 ppm. Found,
P
%: C 74.98; H 7.55; N 3.76; P 9.05. C22H26NOP.
Calculated, %: C 75.19; H 7.46; N 3.99; P 8.81.
1
spectrum, , cm : 2215 (C N), 3270 (OH), 1152
(Z)-3-{Bis[2-(2-pyridyl)ethyl]phosphino}-4-hyd-
roxy-4-methyl-2-pentenenitrile (IIc) was prepared
similarly to compound IIa from 0.37 g of phosphine
Ic and 0.16 g of 4-hydroxy-4-methyl-2-pentenenitrile.
1
(P=O). H NMR spectrum, , ppm: 1.53 s (6H, Me),
2.78 2.90 m and 3.03 3.31 m (8H, CH2), 6.04 d (1H,
3
3
=CH, JHP 32.2 Hz), 7.18 d.d (2H, pyridine, JHH
3
3
1
7.8 Hz, JHH 12.5 Hz), 7.24 d (2H, pyridine, JHH
Yield 0.45 g (85%), yellow oil. IR spectrum, , cm :
1
3
2215 (C N), 3276 (OH). H NMR spectrum, , ppm:
7.8 Hz), 8.50 d (2H, CH=N, pyridine, JHH 12.6 Hz).
31P NMR spectrum: P 49.1 ppm. Found, %: C 64.81;
H 6.80; N 11.32; P 8.61. C20H24N3O2P. Calculated,
%: C 65.03; H 6.55; N 11.38; P 8.38.
1.43 s (6H, Me), 2.30 2.41 m and 2.58 2.69 m (4H,
CH2P), 2.91 3.01 m (4H, CH2), 6.25 d (1H, =CH,
3
3JHP 6.6 Hz), 7.18 d.d (2H, pyridine, JHH 7.8 Hz,
3
3JHH 12.5 Hz), 7.24 d (2H, pyridine, JHH 7.8 Hz),
3
3
ACKNOWLEDGMENTS
7.64 d.d (2H, pyridine, JHH 7.8 Hz, JHH 7.8 Hz),
8.50 d (2H, CH=N, pyridine, 3JHH 12.5 Hz). 31P NMR
The work was financially supported by the Program
of the President of the Russian Federation for Support
of Leading Scientific Schools (project no. NSh-2241.
2003.3) and Russian Foundation for Basic Research
(project no. 02-03-32648).
spectrum:
25.1 ppm. Found, %: C 67.68; H 7.02;
P
N 11.60; P 8.97. C20H24N3OP. Calculated, %: C
67.97; H 6.85; N 11.89; P 8.76.
Dibutyl[(Z)-2-cyano-1-(1-hydroxy-1-methyl-
ethyl)vinyl]methylphosphonium iodide (III). To
a solution of 0.11 g of phosphine IIa, a solution of
0.4 g of methyl iodide in 3 ml of THF was added. The
reaction mixture was stirred at room temperature for
8 h, the solvent and and unreacted methyl iodide were
removed at reduced pressure, and the residue was
dried in a vacuum to give 0.17 g (100%) of phos-
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