Electrocyclization of phosphahexatrienes: An approach to λ5-phosphinines

Article abstract of DOI:10.1021/jo200847r

We experimentally verified an assumption that the substitution of a carbon atom with a pentavalent phosphorus atom in 1-alkoxy (dialkylamino) hexatrienes will not hamper its ability to electrocyclize. A series of 1-, 3-, and 5-phosphahexatrienes were synt

Full text of DOI:10.1021/jo200847r

ARTICLE
pubs.acs.org/joc
Electrocyclization of Phosphahexatrienes: An Approach to
λ5-Phosphinines
Yurii V. Svyaschenko, Bogdan B. Barnych, Dmitriy M. Volochnyuk, Nadiya V. Shevchuk, and
Aleksandr N. Kostyuk*
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska 5, Kyiv-94, 02094, Ukraine
S Supporting Information
b
ABSTRACT: We experimentally verified an assumption that the substitution of a
carbon atom with a pentavalent phosphorus atom in 1-alkoxy (dialkylamino)
hexatrienes will not hamper its ability to electrocyclize. A series of 1-, 3-, and
5-phosphahexatrienes were synthesized. It was shown that parent λ5-phosphi-
nines could be synthesized by electrocyclization of the 3- and 5-phosphahexa-
trienes. The resultant electrocyclization is a convenient method for the synthesis
of parent λ5-phosphinines bearing different substituents on the phosphorus atom.
’ INTRODUCTION
electron-withdrawing group at the second and fourth positions.8
In previous work, we have already used this approach in the
synthesis of λ5-phosphinines and have shown that such cyclization
ispossiblefor1-dialkylamino-3(and5)-phosphahexa-1,3,5-trienes9a
and 1-hydroxy-3-phosphahexa-1,3,5-trienes.9b Moreover, we
have also demonstrated that cyclization of 1-dialkyl amino-3
(or 5)-phosphazahexa-1,3,5-trienes is possible.9c
Electrocyclization of 1,3,5-hexatrienes into cyclohexadienes
has been thoroughly studied and widely used in organic chem-
istry because the oxidation or elimination of leaving groups from
the intermediate cyclohexadienes affords benzene derivatives. The
method has mainly been used for the synthesis of complex natural
compounds. Detailed theoretical studies of these reactions allow
one to promote a slower reaction by placing proper substituents
at the 1,3,5-hexatrienes.1 Its synthetic utility has been further
enhanced by finding a catalytic version of the reaction that allows
the synthesis of complicated molecules under mild conditions.2 It
is also well-known that a carbon atom in hexatrienes can be replaced
by a nitrogen atom, and the resulting aza-homologues undergo
cyclization as well.3 This method appears to be quite practical and
has been used in many syntheses of natural compounds.4
In this paper we studied and analyzed whether carbon in
hexatriene can be replaced by heavier atoms and still allow the
molecule to keep its ability to electrocyclize. For a long time,
phosphorus has been thought to mimic a carbon in many respects.
Indeed, there are many examples of analogous behavior.5 The
analogy can be demonstrated on the parent λ3-phosphinine,
which possesses aromaticity comparable to that of benzene.6
Experimentally, the parent λ3-phosphinine was prepared by flash
vacuum pyrolysis of vinyldiallylphosphine at 700 °C. Researchers
claimed that it formed via electrocyclization, and the most
plausible pathway was proposed based on DFT calculations.7
Our attention was focused on the cyclization of 1-dialkylami-
no-1,3,5-hexatrienes, where it was shown that the introduction of
an oxygen- or nitrogen-containing substituent at C-1 has a small
effect versus the parent 1,3,5-hexatriene. Also, the neutral and
anionic 2-hydroxy-1,3,5-hexatrienes have been shown to have
activation energies for these processes of 29.9 and 29.6 kcal/mol,
respectively. The activation energy for electrocyclization is strongly
dependent upon substituents in the 1-amino-1,3,5-hexatriene.
The process can be made more facile by introducing a strong
Literature analysis of λ5-phosphinines reveals that no gene-
ral methods for their synthesis have been proposed, with
λ3-phosphinines10 remaining as the main starting materials for
the synthesis of most λ5-phosphinines.11 It is worth mentioning
that a few known parent phosphinines are difficult to access.
Summarizing these facts, we assume that electrocyclization of
phosphahexa-1,3,5-trienes might be a convenient approach to
synthesize parent λ5-phosphinines. Moreover, taking into account
the fact that the methods for synthesizing parent λ3-phosphinine
and λ5-phosphinines are quite scarce, we decided to system-
atically study phosphahexatrienes that bear an electron-donating
group such as dialkyl amino or alkoxy groups at the first position
and then move the phosphorus atom from the first to sixth
position as presented in Figure 1.
It was our objective to use this approach for the synthesis of
previously little studied, hardly accessible parent λ5-phosphi-
nines VII. As the starting hexatrienes IꢀVI are unstabilized ylids,
the proposed synthetic approach envisages their formation from
the corresponding phosphonium salts at the final stage. In this
work we have designed and tested synthetic schemes for I, III,
and V phosphahexatrienes.
Synthesis of parent λ5-phosphinines VII by electrocyclization
would be of great importance because convenient approaches to
these rather scarce compounds would make their further study
possible.
Received: April 26, 2011
Published: June 21, 2011
r
2011 American Chemical Society
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Scheme 2. Reagents and Conditionsa
a i, Ph2PCl, Et3N, CH2Cl2, 3 days; ii, CH2dCHCH2Br, benzene, reflux,
7 h; iii, THF, n-BuLi, ꢀ78 °C, 1 h, rt, 1 day.
Scheme 3. Reagents and Conditionsa
Figure 1. Types of hexatrienes studied in the cyclization.
Scheme 1. Reagents and Conditionsa
a i, PCl3, Et3N, CH2Cl2, 2 days; ii, hexane, HNAlk2, for a: HN(C2H4)2O
and Et3N; iii, CH2dCHCH2Br, CH2Cl2; iv, THF, n-BuLi, ꢀ78 °C, 1 h.
8. It was treated with n-butyl lithium in THF that led directly to
phosphinine 10 (Scheme 2). The reaction proceeded quickly and
our attempts to register intermediate phosphahexatriene 9 by 31P
NMR spectroscopy of the reaction mixture failed.
a i, for 11a: toluene, 40 °C, 3 h, for 11b: hexane, 3 h; ii, THF, n-BuLi.
’ RESULTS AND DISCUSSION
Unfortunately, the phosphorylation of enamine 6 with other
phosphorylating agents, such as PCl3, PhPCl2, is quite compli-
cated and does not lead to individual phosphorylated enamines.
Thus, we were unable to extend this approach to other derivatives.
As the main object of our study is parent λ5-phosphinines, it
was logical to use N,N-dialkylvinylamines as the most suitable
starting materials. Despite their relative availability,14 these com-
pounds areunstable andprone to polymerization. These enamines
are generated in situ, and for a short period of time (<24 h) they
can be stored at low temperature. Moreover, phosphorylation
of enamines of this type has not been studied extensively, and
C-phosphorylated derivatives are shown to have quite labile CꢀP
bonds. Thus, it was impossible to usethemasthestartingmaterials.
At the same time, there are well documented procedures in the
literature for the synthesis of dichlorophosphine 12 from ethyl
vinyl ether, which is a stable, easily available compound,15 so it was
used for further transformations (Scheme 3).
In our investigation we started by synthesizing 1-phospha-
1,3,5-hexatrienes. It should be noted that compounds of this
type are described in the literature as extended ylides for Wittig
reactions.12 Nevertheless, no examples of cyclization are men-
tioned. All these compounds have only aryl (alkyl) substituents
on the phosphorus atom, so our aim was to introduce dialkyla-
mino groups on the phosphorus atom and study their cyclization.
We synthesized ylids 4 by the reaction of hexaalkylphosphorus
triamides 1 with penta-2,4-dienyl bromide 2,13 followed by treat-
ment with a base. Formation of ylid 4 was confirmed by 31P NMR
spectra of the reaction mixture, but isolation of 4 in pure state
failed. Nevertheless, even on prolonged standing and heating the
reaction mixture cyclization failed (Scheme 1).
Our experience with phosphorylated enamines was applied to
the synthesis of hexatrienes III. For further investigation we
selected the stable pushꢀpull enamine 6 bearing a nitrile group.
It easily reacted with diphenyl chlorophosphine giving phosphine
7, which is a crystalline, stable compound. Treatment of phosphine
7 with allyl bromide in boiling benzene afforded phosphonium salt
Thus, dichlorophosphine 12 easily reacted with 2-fold excess
of dialkylamines, affording diamides 13, which are stable distill-
able compounds. They readily reacted with allyl bromide, giving
phosphonium salts 14, precursors to 3-phosphahexatrienes.
Further treatment of phosphonium salts 14 with n-BuLi in THF
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Scheme 4. Reagents and Conditionsa
Scheme 5. Reagents and Conditionsa
a i, 1 eqiv of 13c neat; ii, RLi or RMgX, THF; iii, CH2dCHCH2Br,
CH2Cl2; iv, THF, n-BuLi, ꢀ78 °C, 1 h.
at ꢀ78 °C led directly to the targeted phosphinines 16. The
reaction proceeded spontaneously at this low temperature, but we
were unable to register signals of intermediary ylids 15 by 31P
spectroscopy.
a i, for 20a: benzene, rt, 1 day, for 20b: hexane, rt, 1 day; ii, pyridine,
Et3N, reflux, 4 h; iii, i-PrOH, DMFDMA, reflux, for 26a: 16 h, for 26b: 9
days; iv, THF, n-BuLi, ꢀ78 °C, 1 h, rt, 1 day.
This approach proved to be very convenient for the synthesis
of parent λ5-phosphinines with various substituents on the phos-
phorus atom. Thus, dichlorophosphine 12 readily reactedwith aryl
and alkyl C-nucleophiles, affording phosphines 17, with both
Grignard reagents and organo lithium compounds being highly
efficient. Phosphonium salts 18 were prepared in good yields
with allyl bromide. Previously known phosphinines 19a,b were
prepared by treatment of salts 18 with a strong base (Scheme 4).
It should be noted that previously these phosphinines were
prepared by other methods. Thus, 1,1-dimethyl-λ5-phosphinine
was synthesized by Ashe et al. by interaction of λ3-phosphinine
with MeLi and water, followed by quaternization with methyl
iodide and deprotonation with dimsyl anion.16a,b The synthetic
approach to 1,1-diphenyl-λ5-phosphinine by M€arkl was double
alkylation of potassium phosphide with 1,5-bis halogen deriva-
tives followed by oxidation.16c
also be synthesized via 5-phosphahexatrienes by the route pro-
posed in Scheme 5. Starting phosphonites 24 were alkylated with
allyl bromide, affording phosphonium salts 25. Further, it was
necessary to elongate the carbon chain to access phosphahexa-
trienes. Salt 25a was isomerized into salt 26a that reacted with
DMFDMA to give 27a. The insertion of a dimethyl amino meth-
ylene group proceeded exclusively at the terminal methyl group
of the propenyl substituent, leaving the methyl group on the
phosphorus atom intact. Monitoring the reaction by 31P NMR
spectroscopy indicated the presence of only one product that was
proved to be salt 27a. We have also shown that salts 27 can be
prepared directly from salts 25. Thus, refluxing salt 25b with
DMFDMA in isopropanol led directly to salt 27b in almost
quantitative yield. Again we did not observe any products resulting
from insertion of the dimethyl amino methylene group, either at
the methyl group on the phosphorus atom or on the methylene
group. Nevertheless, this method has the disadvantage of requir-
ing a reaction time 10 times longer than the analogous reaction of
salts 26.
Salts 27 are precursors to 5-phosphahexatrienes. Indeed, treat-
ment of salts 27 with n-BuLi led to formation of 5-phosphahex-
atrienes 28 that spontaneously cyclized to λ5-phosphinines 16.
5-Phosphahexatrienes 28 can be registered spectroscopically
by 31P NMR, contrary to 3-phosphahexatrienes 15. Thus, the
addition of n-BuLi to phosphonium salts 27 at ꢀ70 °C for 30 min
results in a 31P NMR spectra, which exhibits three signals that
correspond to the starting salts 27 (δP = 57.5 ppm), the final
phosphinine 16 (poorly resolved triplet at δP = 46.3 ppm), and
the ylid 28 (broadened multiplet at 73.5ꢀ75.5 ppm) (Figure 2).
Keeping the reaction mixtures at room temperature for an addi-
tional 12 h leads to disappearance of all signals, with the exception
of the final phosphinines 16. Heating the reaction mixture facilitates
the reaction so that phosphinines form almost immediately.
This approach is also very convenient for the synthesis of λ5-
phosphinines bearing different substituents at the phosphorus
atom. Thus, dichlorophosphine 12 and diamide 13c reacted neat,
giving dimethyl amido chlorophosphine 20. Unfortunately, further
reaction of compound 20 with Grignard’s reagents led to a mixture
of 17, 13c, and 21 in equal ratio, so for the preparation of amides
21, only organo lithium compounds were used as C-nucleophiles.
Phosphonium salts 22 were readily prepared by alkylation with
allyl bromide. As in previous cases, phosphonium salts 22 were
directly transformed into the corresponding 1-R-1-N,N-dimethyl-
amino-λ5-phosphinines 23a,b upon treatment with a strong base
(Scheme 4). Thus, we have developed a new approach to parent
λ5-phosphinines allowing varying substituents at the phosphorus
atom. It should be noted that parent phosphinines that bear
different substituents at the phosphorus atom were described by
Quinetal. These compounds werecharacterizedbut notseparated
as individual compounds.17
Previously we have reported on the cyclization of 5- and
3-phosphahexatrienes, which affords phosphinines.9a On the basis
of these results, we assume that parent λ5-phosphinines 16 can
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Figure 2. 31P NMR studies of transformation of salt 27 into phosphinine 16 via ylid 28.
Table 1. Chemical Shifts 1H and 13C NMR Spectra for Core
of Phosphinines 16, 19, 23
1H NMR chemical shifts
13C NMR chemical shifts
R0, R00
2H
3H
4H
2C
3C
4C
N(CH2CH2)2O 4.28
7.35
7.46
7.45
7.14
7.11
7.39
7.44
5.66
5.71
5.70
5.24
5.05
5.64
5.70
72.3
75.6
71.1
66.4
65.9
72.4
70.7
140.4
138.9
140.2
140.3
139.4
139.6
139.8
99.3
97.7
99.1
96.2
96.0
98.6
99.3
(CDCl3)
NEt2
NMe2
Me
4.54
4.48
3.9
Ph (CDCl )
Me, NMe2
Ph, NMe2
4.36
4.41
4.61
3
going from dialkylamino substituents to alkyl and aryl ones,
spinꢀspin coupling constants increase 2ꢀ2.5 times (Figure 3);
meta and para spinꢀspin coupling constants in all cases remain
roughly the same.
Figure 3
Despite a plethora of literature data on λ5-phosphinines, there
The reverse tendency is observed for 13C NMR spectra. Thus,
the direct spinꢀspin coupling constants between the phosphorus
and C2 and C6 atoms is ∼125 Hz for dialkylamino derivatives,
which is 25ꢀ30 Hz more than for methyl and phenyl derivatives
and 15 Hz more for unsymmetrical derivatives having a dialky-
lamino group and alkyl (aryl) group.
are only a few examples of parent λ5-phosphinines. These are the
above-mentioned 1,1-dimethyl-λ5-phosphinine and 1,1-diphen-
yl-λ5-phosphinine, as well as three unsymmetrical λ5-phosphi-
nines prepared by silylation of 1,6-dihydrophosphinine-l-oxides.
Parent λ5-phosphinines are relatively stable compounds and
can be exposed to air for a short time, but on longer exposure they
visibly darken and decompose. Thus, they should be stored in a
freezer under inert atmosphere.
Chemical shifts of ortho protons at the phosphinines and
chemical shifts of carbon atoms directly bound to the phosphorus
atom are quite sensitive to substituents at the phosphorus atom,
with dialkylamino substituents shifting them downfield (Table 1).
Besides NMR investigation, the structure of phosphinine 16a
was unambiguously proved by X-ray diffraction study. It is the
first X-ray study of parent λ5-phosphinines. The phosphinines
16a have an almost symmetrical and planar structure of the core
(the mean deviation from the plane is 0.0225 Å; Figure 4).
Geometric parameters of the central core are close to the parameters
of previously investigated related 1,1-(bis)dimethylamino-2,4,6-
triphenylphosphinine.18 The phosphorusꢀnitrogen bond lengths
1H NMR spectra of parent λ5-phosphinines (in C6D6)
exhibited three multiplets of the heterocyclic core. Their complex
multiplicity is due to spinꢀspin interactions of all protons with the
phosphorus atom. Mean values of spinꢀspin coupling constants
and their characteristic appearances are given in Figure 3. It is
worth mentioning that substituents at the phosphorus atom
markedly influence spinꢀspin coupling constants between the
phosphorus atom and ortho protons of the phosphinine. When
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Synthesis of Phosphonous Diamides 13. To a stirred solution of
(2-ethoxyvinyl)phosphonous dichloride 12 (3 g, 16.8 mmol) in hexane
(20 mL) wasadded a solutionof morpholine (33.6 mmol) andEt3N (33.6
mmol) dropwise for 13a or the corresponding amine (67.2 mmol) for
13b,c in hexane (20 mL) at 0ꢀ5 °C. The reaction mixture was stirred for
1 day at rt. The precipitated solid was filtered off and the filtrate was
evaporated in vacuo. For 13b,c the residue was distilled in vacuo (0.03
Torr, bp 76ꢀ81 °C for 13b, 78 °C for 13c).
Synthesis of Phosphines 17. To a stirred solution of (2-ethoxyvinyl)-
phosphonous dichloride 12 (5 g, 28.9 mmol) in Et2O (20 mL) was added
dropwise a solution of CH3MgI for 17a or PhMgBr for 17b (57.8 mmol)
in Et2O (40 mL) at ꢀ50 °C. The reaction mixture was stirred for 3 h and
was allowed to warm to rt, and then the solution of NH4Cl (4.64 g,
86.7 mmol) in deoxygenated water (30 mL) was added. The reaction
mixture was stirred for 1 day at rt. The organic layer was separated, dried
(Na2SO4), and evaporated in vacuo.
Synthesis of Phosphinous Amides 21. To a stirred solution of phos-
phonamidous chloride 20 (1 g, 5.5 mmol) in THF (30 mL) was added a
solution of CH3Li for 21a or PhLi for 21b (5.5 mmol) dropwise. The
reaction mixture was stirred for 1 h, allowed to warm to rt, and evaporated
in vacuo. The residue was extracted with pentane; the residue was distilled
using a short path vacuum distillation apparatus.
Figure 4. The X-ray crystal structure of λ5-phosphinine 16a. H atoms
were omitted for clarity. Selected bond lengths [Å] and angles [deg]:
P(1)ꢀC(1) 1.719, C(1)ꢀC(2) 1.385, C(2)ꢀC(3) 1.390, C(3)ꢀC(4)
1.392, C(4)ꢀC(5) 1.376, C(5)ꢀP(1) 1.718, C(5)ꢀP(1)ꢀC(1) 104.76,
N(1)ꢀP(1)ꢀN(2) 99.11.
Synthesis of Allyl Phosphonium Salts 14, 18, 22. To a stirred
solution of phosphonous diamide 13 for 14, phosphine 17 for 18 or
phosphinous amide 21 for 22 (6.6 mmol) in CH2Cl2 (10 mL), allyl
bromide (0.8 g, 6.6 mmol) was added. The reaction mixture was stirred at
rt for 3 h and evaporated in vacuo. The residue was washed with hexane.
Synthesis of Allyl Phosphonium Salts 8, 25. To a stirred solution of
phosphine 7 or phosphonite 24 (3.3 mmol) in benzene (for 25b hexane)
(10 mL), a solution of allyl bromide (0.4 g, 3.3 mmol) was added. The
reaction mixture was refluxed with stirring for 7 h for 8 or stirred for
1 day for 25. The precipitated solid was collected by filtration and washed
with an appropriate solvent.
are almost equivalent: 1.6785(11) and 1.6865(11). Geometric
parameters of morpholine substituents are usual.
’ CONCLUSIONS
In conclusion we have demonstrated that phosphahexatrienes
that bear phosphorus at the 3- and 5-positions can be cyclized. The
proposed method is very convenient for the synthesis of parent
λ5-phosphinines, especially starting with ethyl vinyl ether. Thus,
these compounds can now be prepared in bulk quantities. It
is worth continuing these synthetic efforts to synthesize other
phosphahexatrienes to check their suitability for the synthesis of
phosphinines.
Synthesis of Phosphonium Salts 27. To a solution of 26a for 27a or
25b for 27b (2.9 mmol) in isopropanol (20 mL), DMADMF (3.5 g,
3.91 mL, 0.029 mol) was added with stirring. The reaction mixture was
refluxed for 16 h for 27a or 9 days for 27b. The solvents were evaporated
and the residue was triturated with heptane. The solid was collected,
washed with heptane, and dried.
’ EXPERIMENTAL SECTION
Synthesis of λ5-Phosphinines 10, 16, 19, 23. To a suspension of allyl
phosphonium salts 8, 14, 18, 22 or salt 27 (2 mmol) in THF (20 mL)
cooled to ꢀ78 °C, a solution of n-BuLi (4 mmol, 2.5 M, 1.62 mL) was
added with stirring. The reaction mixture was stirred 1 h, allowed to
warm to rt, and was kept stirring for 12 h.
General Comments. All procedures with compounds sensitive to
hydrolysis and oxidation were carried out in an atmosphere of dry argon.
All solvents were purified and dried by standard methods. 1H spectra were
recorded at 300 or 500 MHz; C6D6, CDCl3 or DMSO-d6 as solvents with
TMS as an internal standard; 31P NMR spectra were recorded at
81 MHz with 85% H3PO4 as an external standard. For all compounds,
phosphorus spectra were recorded in the same solvent that was used for
taking up 1H NMR spectra.
For 10: The reaction mixture was evaporated and the residue was
extracted with CHCI3 (3 ꢁ 10 mL). The solution was evaporated and
the solid was dried.
For 16: Water (50 mL) was added to the reaction mixture and the
phosphinine was extracted with benzene (3 ꢁ 20 mL). The solution was
evaporated and the residue was dried and crystallized from pentane for
16a or distilled in vacuo (0.03 Torr, bp 90ꢀ95 °C) for 16b,c.
For 19, 23: Water (50 mL) was added to the reaction mixture and the
phosphinine was extracted with Et2O (3 ꢁ 20 mL). The solution was
evaporated and the residue was dried.
The peak assignments in the NMR spectra of the compounds 10 and
16a were confirmed by COSY and HSQC 2D correlations. LC/MS
(APCI MS) spectra for compounds 3b, 7, 8, 10, 18a and 21a were
recorded using a chromatography/mass spectrometric system. Mass
spectra (EI, 70 eV) for compounds 13a, 16aꢀc, 17b, 19b, 20 and 23a,b
were obtained by direct inlet. Compounds 13b,c and 17a were oxidized
to appropriate phosphorus oxides in a mass spectrometer and mass
spectra are shown for their phosphorus oxides. FAB mass spectra for 3a,
b, 14aꢀc, 18b, 22b, 25a,b, 26b, 27a,b substances were recorded.
Microanalyses were obtained using elemental microanalyzers. Melting
points are uncorrected. Yields refer to pure isolated products.
General Procedures. Synthesis of Phosphonium Salts 3. To a
solution of pent-2,4-dien-yl bromide 2(0.87 g, 6 mmol) in hexane (10 mL),
hexa alkylphosphorus triamide 1 (6 mmol) was added with stirring. The
reaction mixture was left for 3 h with stirring. The precipitated solid was
collected by filtration and washed with hexane. (For 1a toluene at 40 °C
was used.)
Experimental Data. Trimorpholin-4-yl(penta-2,4-dien-1-yl)phos-
phonium Bromide (3a). Yield: 29.4%; amorphous solid (hexaneꢀ
toluene); 1H NMR (300 MHz, CDCl3): δ 3.32 (br t, 12H), 3.78 (br t,
12H), 4.46 (dd, 3JHH =7.8 Hz, 2JPH =17.4 Hz, 2H), 5.23(d, 3JHH =9.6Hz,
1H), 5.36 (d, 3JHH = 18 Hz, 1H), 5.43ꢀ5.55(m, 1H), 6.27ꢀ6.39 (m, 1H),
6.68ꢀ6.78 (m, 1H). 13C NMR (125 MHz, CDCl3): δ 28.2 (d, 1JPC = 99.3
3
Hz, CH2ꢀP), 45.7 (NCH2), 66.6 (d, JPC = 5.0 Hz, OCH2), 118.0
(d, J = 13.8 Hz, CH), 120.3 (d, 5JPC = 3.8 Hz, CH2dCH), 135.0 (d, J =
3.8 Hz, CH), 139.9 (d, J = 15.1 Hz, CH); 31P NMR (81 MHz, CDCl3)
δ 49.3; MS-FAB, m/z (%): 356 ([M ꢀ Br]+, 100); Anal. Calcd for
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3
1
C17H31BrN3O3P: C, 46.80; H, 7.16; N, 9.63; P, 7.10. Found C, 46.83; H,
7.17; N, 9.7; P, 7.15.
68.0 (d, JPC = 7.5 Hz, OCH2) 97.9 (d, JPC = 5 Hz, CHꢀP), 155.7
(d, 2JPC = 40.2 Hz, EtOꢀCHdCH); 31P NMR (81 MHz, C6D6): δ 87.3;
MS-EI, m/z (%): 274(M+, 18), 189(11), 188(100), 103(26), 86(19),
85(7), 83(8), 75(12), 56(10), 42(6). Anal. Calcd for C12H23N2O3P: C,
52.55; H, 8.45; N, 10.21; P, 11.29. Found C, 52.49; H, 8.47; N 10.23;
P 11.30.
Tris(dimethylamino)(penta-2,4-dien-1-yl)phosphonium Bromide (3b).
Yield: 96%; amorphous solid (hexane); 1H NMR (300 MHz, CDCl3):
δ 2.85 (d, 3JPH = 10.5 Hz, 18H), 3.86 (dd, 3JHH = 7.5 Hz, 2JPH = 17.7 Hz,
3
3
2H), 5.16 (d, JHH = 9.6 Hz, 1H), 5.28 (d, JHH = 16.8 Hz, 1H),
5.48ꢀ5.62 (m, 1H), 6.29ꢀ6.54 (m, 1H), 6.70ꢀ6.79 (m, 1H); 13C NMR
P-(2-Ethoxyvinyl)-N,N,N0,N0-tetraethylphosphonous Diamide (13b).
1
1
(125 MHz, CDCl3): δ 28.9 (d, JPC = 104.4 Hz, CH2ꢀP), 37.54
Yield: 69%; bp 76ꢀ81 °C (0.03 Torr); H NMR (300 MHz, C6D6):
5
(NCH3), 118.9 (d, JPC = 10.1 Hz, CH), 119.2 (d, JPC = 3.8 Hz,
δ 0.98ꢀ1.03 (m, 15H), 2.96ꢀ3.17 (m, 8H), 3.49 (q, 3JHH = 6.9 Hz, 2H),
5.09 (dd, 3JHH = 13.5 Hz, 2JPH = 13.5 Hz, 1H), 6.68 (dd, 3JHH = 13.5 Hz,
3JPH = 4.5 Hz, 1H); 13C NMR (125 MHz, C6D6): δ 14.5 (OCH2CH3),
CH2dCH), 135.4 (d, JPC = 5.0 Hz, CH), 138.8 (d, JPC = 13.8 Hz, CH);
31P NMR (81 MHz, CDCl3): δ 55.9; APCI MS: [M ꢀ Br]+ = 230; Anal.
Calcd for C11H25BrN3P: C, 42.59; H, 8.12; N, 13.55; P, 9.98. Found C,
42.62; H, 8.11; N, 13.57; P, 10.02.
3
2
14.9 (d, JPC = 3.8 Hz, CH3), 42.4 (d, JPC = 17.6 Hz, NCH2), 64.2
(OCH2CH3), 101.1 (CHꢀP), 154.1 (d, 2JPC = 39 Hz, EtOꢀCHdCH);
31P NMR (81 MHz, C6D6): δ 86.8; MS-EI for PdO, m/z (%): 262(M+,
6), 217(17), 190(77), 136(78),100(24), 73(21), 72(100), 58(78),
44(42), 42(17). Anal. Calcd for C12H27N2OP: C, 58.51; H, 11.05;
N 11.37; P 12.57. Found C, 58.49; H, 11.07; N 11.41; P 12.55.
P-(2-Ethoxyvinyl)-N,N,N0,N0-tetramethylphosphonous Diamide (13c).
2-(Diphenylphosphino)-3-pyrrolidin-1-ylacrylonitrile (7). To a solu-
tion of Ph2PCl (3.6 g, 16.4 mmol, 2.94 mL) in CH2Cl2 (10 mL) a
mixture of 14 (2 g, 16.4 mmol) and Et3N (2.16 g, 21.3 mmol, 2.96 mL)
in CH2CI2 (30 mL) was added with stirring. The reaction mixture was
kept stirring at room temperature for 3 days. Water (50 mL) was added
to the reaction mixture, the reaction mixture was thoroughly shaken, and
the organic layer was separated and dried over Na2SO4. The solvent was
evaporated; the residue was recrystallized from isopropanol. Yield:
31.1%; mp 125ꢀ127 °C (2-propanol); 1H NMR (300 MHz, CDCl3):
δ 1.88 (br m, 2H), 1.98 (br m, 2H), 3.51 (br m, 2H), 3.85 (br m, 2H),
7.25 (d, 3JPH = 11.7 Hz, 1H), 7.35ꢀ7.47 (m, 6H), 7.49ꢀ7.52 (m, 4H)
(this substance exists as a mixture of Z/E isomers; 1H NMR spectra refer
to the major isomer). 13C NMR (125 MHz, CDCl3): δ 24.6 (b, CH2),
25.8 (b, CH2), 47.7 (b, NCH2), 54.1 (b, NCH2), 67.3 (d, 1JPC = 11.3 Hz,
C(2)), 120.7 (d, 2JPC = 5 Hz, CN), 128.3 (d, 3JPC = 7.5 Hz, PPh2), 128.6
(PPh2), 132.5 (d, 2JPC = 20 Hz, PPh2), 137.8 (d, 1JPC = 6.3 Hz, PPh2),
155.3 (d, 2JPC = 74.2 Hz, C(3)); 31P NMR (81 MHz, CDCl3): δ 1.7;
APCI MS: [M+ + 1] = 307; Anal. Calcd for C19H19N2P: C, 74.49; H,
6.25; N, 9.14; P, 10.11. Found C, 74.61; H, 6.13; N, 9.26; P, 10.00.
Allyl(1-cyano-2-pyrrolidin-1-ylvinyl)diphenylphosphonium Bromide
1
Yield: 85%; 70 °C (0.05 Torr); H NMR (300 MHz, C6D6): δ 1.00
(t, 3JHH = 7.2 Hz, 3H), 2.63 (d, 3JPH = 9.3 Hz, 12H), 3.41 (q, 3JHH
=
7.2 Hz, 2H), 5.07 (dd, 3JHH = 13.8 Hz, 2JPH = 10.8 Hz, 1H), 6.64 (dd,
3JHH = 13.8 Hz, 3JPH = 5.4 Hz, 1H); 13C NMR (125 MHz, C6D6): δ 14.4
2
(CH3), 40.5 (d, JP2C = 15.1 Hz, NꢀCH3), 64.3(OꢀCH2), 100.1-
(CHꢀP), 155.3 (d, JPC = 42.8 Hz, EtOꢀCHdCH); 31P NMR (81
MHz, C6D6) 92.1; MS-EI for PdO, m/z (%): 206(M+, 7), 176(1),
161(30), 136(14),119(13), 108(97), 72(40), 58(12), 44(100); Anal.
Calcd for C8H19N2OP: C, 50.51; H 10.07; N, 14.73; P, 16.28. Found C,
50.48; H, 10.06; N, 14.77; P, 16.25.
Allyl(2-ethoxyvinyl)dimorpholin-4-ylphosphonium Bromide (14a).
1
Yield: 88%; amorphous solid; H NMR (300 MHz, CDCl3): δ 1.39
(t, 3JHH = 7.2 Hz, 3H), 3.28ꢀ3.33 (m, 8H), 3.74ꢀ3.77 (m, 8H), 4.08
(dd, 2H, 3JHH = 6.6 Hz, 2JP2H = 16.8 Hz), 4.33 (q, 3JHH = 7.2 Hz, 2H),
3
5.07 (dd, JHH = 13.2 Hz, JPH = 13.2 Hz, 1H), 5.44ꢀ5.47 (m, 1H),
5.59ꢀ5.69 (m, 2H), 7.82 (dd, 3JHH = 13.2 Hz, 3JPH = 10.5 Hz, 1H); 13
C
1
(8). Yield: 24.3%; mp 203ꢀ205 °C (acetone); H NMR (300 MHz,
NMR (125 MHz, CDCl3): δ 14.5 (CH3CH2O), 30.1 (d, 1JPC = 81.7 Hz,
CDCl3): δ 1.88ꢀ2.12 (m, 4H), 3.93 (t, 3JHH = 7.2 Hz, 2H), 4.16 (t, 3JHH
=
2
7.2 Hz, 2H), 4.62 (dd, 3JHH = 5.69 Hz, 2JPH = 20.4 Hz, 2H), 5.31ꢀ5.36
PꢀCH2), 45.4 (NCH2), 67.2 (d, JPC = 5.1, OꢀCH2), 69.6
1
2
(OꢀCH2CH3), 79.5 (d, JPC = 137 Hz, CHꢀP), 124.4 (d, JPC
=
(m, 1H), 5.51ꢀ5.56 (m, 2H), 7.65ꢀ7.83 (m, 6H), 7.85ꢀ7.93 (m, 4H),
3
3
8.65 (d, JPH = 11.7 Hz, 1H); 13C NMR (125 MHz, CDCl3): δ 23.6
7.5 Hz, CH2dCH), 124.5 (d, JPC = 11.3 Hz, CH2dCH), 168.3 (d,
2JPC = 22.6 Hz, EtOꢀCHdCH); 31P NMR (81 MHz, CDCl3) δ 53.7;
MS-FAB, m/z (%): 315([M ꢀ Br]+, 100); Anal. Calcd for C15H28-
N2O3PBr: C, 45.58; H, 7.14; Br, 20.21; N, 7.09; P, 7.84. Found C, 45.54;
H, 7.12; Br, 20.1; N, 7.13; P, 7.87.
(CH2), 25.0 (CH2), 27.4 (d, 1JPC = 51.6 Hz, CH2ꢀP), 48.2 (NCH2),
55.3 (NCH2), 117.4 (d, 2JPC = 7.5 Hz, CN), 119.3 (d, 1JPC = 90.2 Hz,
3
PPh2), 123.3 (d, 2JPC = 10 Hz, CH2dCH), 125.5 (d, JPC = 12.6 Hz,
CH2dCH), 129.9 (d, 3JPC = 12.6 Hz, PPh2), 133.3 (d, 2JPC = 10 Hz,
PPh2), 134.6 (d, 4JPC = 2.8 Hz, PPh2), 156.2 (d, 2JPC = 20 Hz, C(2)), the
C(1) signal is not observed; 31P NMR (81 MHz, CDCl3): δ 25.1; APCI
MS: [M ꢀ Br]+ = 347; Anal. Calcd for C22H24BrN2P: C, 61.84; H,
5.66; N, 6.56; P, 7.25. Found C, 61.98; H, 5.72; N, 6.40; P, 7.14.
1,1-Diphenyl-1-λ5-phosphinine-2-carbonitrile (10). Yield: 78%; mp
Allyl(bis(diethylamino))(2-ethoxyvinyl)phosphonium Bromide (14b).
1
Yield: 100%; amorphous solid; H NMR (300 MHz, CDCl3): δ 1.1
(t, 3JHH = 6.9 Hz, 12H), 1.28 (t, 3JHH = 6.9 Hz, 3H), 3.06ꢀ3.17 (m, 8H),
3.54 (dd, 2H, 3JHH = 6.9 Hz, 2JPH = 16.2 Hz), 4.21 (q, 3JHH = 6.9 Hz,
2H), 4.95 (dd, 3JHH = 13.5 Hz, 2JPH = 13.5 Hz, 1H), 5.31ꢀ42 (m, 1H),
3
1
3
5.48ꢀ5.61 (m, 1H), 5.62ꢀ5.78 (m, 1H), 7.51 (dd, JHH = 13.5 Hz,
132 °C (CHCl3); H NMR (300 MHz, CDCl3) δ 5.00 (dd, JHH
=
3JPH = 11.1 Hz, 1H); 13C NMR (125 MHz, CDCl3): δ 14.1 (d, 3JPC
=
11.4 Hz, 3JPH = 17.4 Hz, 1H), 5.29 (ddd, 3JHH = 7.2 Hz, 3JHH = 8.7 Hz,
4JPH = 1.5 Hz, 1H), 7.08 (dd, 3JHH = 8.7 Hz, 3JPH = 26.1 Hz, 1H), 7.27
(ddd, 3JHH = 7.2 Hz, 3JHH = 11.4 Hz, 3JPH = 36.6 Hz, 1H), 7.45ꢀ7.63
(m, 10H); 13C NMR (125 MHz, CDCl3): δ 44.8 (d, 1JPC = 113.2 Hz,
C(2)), 78.9 (d, 1JPC = 93 Hz, C(6)), 100.7 (d, 3JPC = 17.6 Hz, C(4)),
122.7 (d, 2JPC = 11.3 Hz, CN), 122.7 (d, 3JPC = 13.8 Hz, PPh2), 130.8 (d,
1
2.5 Hz, CH3CH2N), 14.5 (CH3CH2O), 31.5 (d, JPC = 85.5 Hz,
3
PꢀCH2), 40.2 (d, JPC = 3.8 Hz, CH2N), 69.2 (OꢀCH2), 81.6 (d,
1JPC = 137 Hz, CHꢀP), 123.9 (d, 3JPC = 13.8 Hz, CH2dCH), 124.7 (d,
2JPC = 8.8 Hz, CH2dCH), 166.9 (d, 2JPC = 21.4 Hz, EtOꢀCHdCH);
31P NMR (81 MHz, CDCl3) δ 54.8; MS-FAB, m/z (%): 287([M ꢀ
Br]+, 100); Anal. Calcd for C15H32N2OPBr: C, 49.05; H, 8.78; Br,
21.75; N, 7.63; P, 8.43. Found C, 49.00; H, 8.76; Br, 21.69; N, 7.67;
P, 8.45.
1JPC = 90.5 Hz, PPh2), 131.7 (d, 2JPC = 11.3 Hz, PPh2), 132.1 (d, 4JPC
=
3.8 Hz, PPh2), 139.0 (d, 2JPC = 3.8 Hz, C(3)), 143.6 (C(5)); 31P NMR
(81 MHz, CDCl3) δ 8.48. APCI MS: [M+ + 1] = 276; Anal. Calcd for
C18H14NP: C, 78.53; H, 5.13; N, 5.09; P, 11.25. Found C, 78.47; H,
5.05; N, 5.13; P, 11.4.
Allyl(bis(dimethylamino))(2-ethoxyvinyl)phosphonium Bromide (14c).
1
Yield: 100%; amorphous solid; H NMR (300 MHz, CDCl3): δ 1.32
3
3
4,40-((2-Ethoxyvinyl)phosphinediyl)dimorpholine (13a). Yield: 69%;
oil; 1H NMR (300 MHz, C6D6): δ 1.02 (t, 3JHH = 6.9 Hz, 3H), 2.75ꢀ3.20
(m, 8H), 3.42ꢀ3.52 (m, 10H), 4.89 (dd, 3JHH = 13.8 Hz, 2JPH = 12 Hz,
1H), 6.60 (dd, 3JHH = 13.8 Hz, 3JPH = 5.1 Hz, 1H); 13C NMR (125 MHz,
C6D6): δ14.4 (CH3), 49.1(d, 2JPC = 12.6 Hz, NCH2), 64.6 (OCH2CH3),
(t, JHH = 7.2 Hz, 3H), 2.80 (d, JPH = 10.2 Hz, 12H), 3.58 (dd,
3JHH = 7.2 Hz, 2JPH = 16.2 Hz, 2H), 4.25 (q, 3JHH = 7.2 Hz, 2H), 4.97
3
2
(dd, JHH = 13.8 Hz, JPH = 13.8 Hz, 1H), 5.35ꢀ5.43 (m, 1H),
3
5.45ꢀ5.55 (m, 1H), 5.61ꢀ5.80 (m, 1H), 7.59 (dd, JHH = 13.8 Hz,
3JPH = 10.5 Hz, 1H); 13C NMR (125 MHz, CDCl3): δ 14.5 (CH3), 30.9
6130
dx.doi.org/10.1021/jo200847r |J. Org. Chem. 2011, 76, 6125–6133

The Journal of Organic Chemistry
ARTICLE
(d, 1JPC = 84.3 Hz, PꢀCH2), 37.4 (NꢀCH3), 69.2(OꢀCH2), 80.3 (d,
1JPC = 137 Hz, CHꢀP), 123.9 (d, 3JPC = 12.6 Hz, CH2dCH), 124.4 (d,
2JPC = 8.8 Hz, CH2dCH), 167.1 (d, 2JPC = 20.1 Hz, EtOꢀCHdCH);
31P NMR (81 MHz, CDCl3) δ 57.4; MS-FAB, m/z (%): 231([M ꢀ
Br]+, 100); Anal. Calcd for C11H24N2OPBr: C, 42.46; H, 7.77; Br,
25.68; N, 9.00; O, 5.14; P, 9.95. Found C, 42.43; H, 7.75; Br, 25.70; N,
8.98; P, 9.93.
(t, 3JHH = 6.9 Hz, 3H), 2.14 (d, 2JPH = 14.1 Hz, 6H), 3.48 (dd, 3JHH
=
2
3
7.5 Hz, JPH = 16.8 Hz, 2H), 4.07 (q, JHH = 6.9 Hz, 2H), 5.19 (dd,
3JHH = 13.5 Hz, 2JPH = 12.3 Hz, 1H), 5.36ꢀ5.47 (m, 2H), 5.52ꢀ5.69 (m,
3
3
1H), 7.47 (dd, JHH = 13.5 Hz, JPH = 11.7 Hz, 1H); 13C NMR
(125 MHz, CDCl3): δ 9.0 (1JPC = 57.8 Hz, PCH3), 14.3 (CH3), 30.2 (d,
1JPC = 55.3 Hz, PꢀCH2), 68.1 (OꢀCH2), 80.8 (d, JPC = 96.8 Hz,
1
CHꢀP), 124.2 (d, 3JPC = 12.6 Hz, CH2dCH), 124.3 (d, 2JPC = 10 Hz,
1,1-Dimorpholin-4-yl-1λ5-phosphinine (16a). Yield: 46.6%; mp
75ꢀ80 °C (diethyl ether); 1H NMR (300 MHz, C6D6): δ 2.59ꢀ2.65
(m, 8H), 3.33 (t, 3JHH = 4.5 Hz, 8H), 4.28 (dd, 3JHH = 11.1 Hz, 2JPH = 6.9
Hz, 2H), 5.66 (dt, 4JPH = 3 Hz, 3JHH = 7.5 Hz, 1H), 7.35 (ddd, 3JHH = 7.5
Hz, 3JHH = 11.1 Hz, 3JPH = 36.9 Hz, 2H); 13C NMR (125 MHz, C6D6):
δ 44.7 (NCH2), 66.9 (d, 3JPC = 8.0 Hz, OCH2), 72.3 (d, 1JPC = 123 Hz,
C(2), C(6)), 99.3 (d, 3JPC = 21.4 Hz, C(4)), 140.4 (d, 2JPC = 3.8 Hz,
C(3), C(5)); 31P NMR (81 MHz, C6D6) δ 46.3. MS-EI, m/z (%):
268(M+, 67), 211(14), 183(34), 182(100), 134(8), 126(9), 97(23),
87(99), 86(75), 56(22); Anal. Calcd for C13H21N2O2P: C, 58.20; H,
7.89; N, 10.44; P, 11.54. Found C, 58.24; H, 7.87; N, 10.42; P, 11.53.
N1,N1,N1,N1-Tetraethyl-1λ5-phosphinine-1,1-diamine (16b). Yield:
48%; bp 90ꢀ95 °C (0.05 Torr); 1H NMR (500 MHz, CDCl3): δ 0.87
CH2dCH), 164.8 (d, JPC = 16.3 Hz, EtOꢀCHdCH); 31P NMR
2
(81 MHz, CDCl3) δ 20.5; APCI MS: [M ꢀ Br]+ = 173; Anal. Calcd for
C9H18OPBr: C, 42.71; H, 7.17; Br, 31.57; P, 12.24. Found C, 42.69; H,
7.15; Br, 31.52; P, 12.18.
Allyl(2-ethoxyvinyl)diphenylphosphonium Bromide (18b). Yield:
79.1%; amorphous solid (hexane); 1H NMR (300 MHz, CDCl3): δ 1.32
(t, 3JHH = 6.9 Hz, 3H), 4.26 (dd, 3JHH = 7.2 Hz, 2JPH = 15.9 Hz, 2H), 4.36
3
(q, JHH = 6.9 Hz, 2H), 5.34ꢀ5.39 (m, 1H), 5.48ꢀ5.53 (m, 1H),
5.62ꢀ5.68 (m, 1H), 5.91 (dd, 3JHH = 12 Hz, 2JPH = 13.5 Hz, 1H), 7.15
(dd, 3JHH = 12 Hz, 3JPH = 12.6 Hz, 1H), 7.65ꢀ7.88 (m, 10H); 13C NMR
(125 MHz, CDCl3): δ 14.1 (CH3), 30.0 (d, 1JPC = 54.1 Hz, PꢀCH2),
69.3 (OꢀCH2), 78.8 (d, 1JPC = 103 Hz, CHꢀP), 119.4 (d, 1JPC = 89.3
Hz, PPh2), 123.8 (d, 2JPC = 10 Hz, CH2dCH), 125.2 (d, 3JPC = 13.8 Hz,
3
3
CH2dCH), 130.1 (d, JPC = 11.3 Hz, PPh2), 133.3 (d, 2JPC = 10 Hz,
(t, J = 7.2 Hz, 12H), 2.78ꢀ2.89 (m, 8H), 4.54 (dd, JHH = 11.4 Hz,
2JPH = 7.5 Hz, 2H), 5.71 (dt, 4JPH = 2.4 Hz, 3JHH = 7.5 Hz, 1H), 7.46
(ddd, 3JHH = 7.5 Hz, 3JHH = 11.4 Hz, 3JPH = 37 Hz, 2H); 13C NMR (125
MHz, CDCl3): δ 14.1 (CH3), 38.6 (NCH2), 75.6 (d, 1JPC = 124.2 Hz,
C(2), C(6)), 97.7 (d, 3JPC = 21.3 Hz, C(4)), 138.9 (d, 2JPC = 3.8 Hz,
C(3), C(5)); 31P NMR (81 MHz, CDCl3) δ 49.26. MS-EI, m/z (%):
240(M+, 41), 169(37), 168(100), 98(23), 97(27), 72(53), 58(32),
56(18), 44(23), 42(22); Anal. Calcd for C13H25N2P: C, 64.97; H,
10.49; N, 11.66; P, 12.89. Found C, 64.96; H, 10.48; N, 11.64; P, 12.91.
N1,N1,N1,N1-Tetramethyl-1λ5-phosphinine-1,1-diamine (16c). Yield:
44.5%; bp 75ꢀ80 °C (0.05 Torr); 1H NMR (300 MHz, C6D6): δ 2.21
(d, 3JPH = 11.7 Hz, 12H), 4.48 (dd, 3JHH = 11.4 Hz, 2JPH = 6.6 Hz, 2H),
5.70 (dtt, 4JPH = 2.4 Hz, 3JHH = 7.8 Hz, 4JHH = 0.6 Hz 1H), 7.45 (ddd,
3JHH = 7.8 Hz, 3JHH = 11.4 Hz, 3JPH = 36.6 Hz, 2H); 13C NMR (125 MHz,
C6D6): δ 35.9 (d, 2JPC = 2.5 Hz, NCH3), 71.1 (d, 1JPC = 125 Hz, C(2),
C(6)), 99.1 (d, 3JPC = 21.4 Hz, C(4)), 140.2 (d, 2JPC = 4 Hz, C(3), C(5));
31P NMR (81 MHz, C6D6) δ 51.9. MS-EI, m/z (%): 184(M+, 5),
140(12), 57(3), 45(46), 44(100), 43(8), 41(6), 36(5), 30(3); Anal.
Calcd for C9H17N2P: C, 58.68; H, 9.30; N, 15.21; P, 16.18. Found C,
58.67; H, 9.32; N, 15.27; P, 16.22.
4
2
PPh2), 134.6 (d, JPC = 2.5 Hz, PPh2), 167.8 (d, JPC = 17.6 Hz,
EtOꢀCHdCH); 31P NMR (81 MHz, CDCl3): δ 18.1; MS-FAB, m/z
(%): 298([M ꢀ Br]+, 42); Anal. Calcd for C19H22OPBr: C, 60.49; H,
5.88; Br, 21.18; P, 8.21. Found C, 60.52; H, 5.86; Br, 21.02; P, 8.25.
1
1,1-Dimethyl-1λ5-phosphinine (19a). Yield: 44.5%; oil; H NMR
2
3
(300 MHz, C6D6): δ 0.91 (d, JPH = 12.6 Hz, 6H), 3.9 (dd, JHH
=
11.1 Hz, 2JPH = 17.4 Hz, 2H), 5.24 (t, 3JHH = 7.8 Hz, 1H), 7.14 (ddd,
3JHH = 7.8 Hz, 3JHH = 11.1 Hz, 3JPH = 33.9 Hz, 2H); 13C NMR (125
MHz, C6D6): δ 24.6 (d, 2JPC = 56.6 Hz, PCH3), 66.4 (d, 1JPC = 96.8 Hz,
C(2), C(6)), 96.2 (d, 3JPC = 21.4 Hz, C(4)), 140.3 (C(3), C(5)); 31
P
NMR (81 MHz, C6D6) δ ꢀ3.8. Anal. Calcd for C7H11P: C, 66.65; H,
8.79; P, 24.56. Found C, 66.69; H, 8.82; P, 24.51.
1
1,1-Diphenyl-1λ5-phosphinine (19b). Yield: 61.2%; oil; H NMR
(300 MHz, CDCl3): δ 4.36 (dd, 3JHH = 10.8 Hz, 2JPH = 14.4 Hz, 2H),
5.05 (t, 3JHH = 8.1 Hz, 1H), 7.11 (ddd, 3JHH = 8.1 Hz, 3JHH = 10.8 Hz,
3JPH = 34.5 Hz, 2H), 7.43ꢀ7.50 (m, 10H); 13C NMR (125 MHz,
CDCl3): δ 65.9 (d, 1JPC = 99.4 Hz, C(2), C(6)), 96.0 (d, 3JPC = 21.4 Hz,
C(4)), 128.6 (d, 3JPC = 11.3 Hz, PPh2), 130.3 (d, 4JPC = 2.5 Hz, PPh2),
131.0 (d, 2JPC = 11.3 Hz, PPh2), 136.6 (d, 1JPC = 88.0 Hz, PPh2), 139.4
(C(3), C(5)); 31P NMR (81 MHz, C6D6) δ 4.1. MS-EI, m/z (%):
250(M+, 100), 216(35), 215(81), 202(52), 201(73), 183(35), 173(91),
77(86), 51(55), 47(44); Anal. Calcd for C17H15P: C, 81.58; H, 6.04; P,
12.38. Found C, 81.56; H, 6.05; P, 12.39.
(2-Ethoxyvinyl)(dimethyl)phosphine (17a). Yield: 88%; oil; 1H NMR
(300 MHz, C6D6): δ 0.96 (t, 3JHH = 6.9 Hz) 0.98 (d, 2JPH = 3 Hz, 6H),
3.37 (q, 3JHH = 6.9 Hz, 2H), 4.84 (dd, 3JHH = 13.5 Hz, 2JPH = 3.9 Hz, 1H),
3
3
6.82 (dd, JHH = 13,5 Hz, JPH = 9.9 Hz, 1H); 13C NMR (125 MHz,
1
C6D6): δ 14.3 (CH3), 16.1 (d, JPC = 10 Hz, PCH3), 64.4 (OꢀCH2),
P-(2-Ethoxyvinyl)-N,N-dimethylphosphonamidous Chloride (20).
To a stirred phosphonous diamide 13c (13.2 g, 69.4 mmol), (2-ethox-
yvinyl)phosphonous dichloride 12 (12 g, 69.4 mmol) was added at 0 °C.
The reaction mixture was allowed to warm to rt. Yield: ∼100%; oil; bp
1
2
103.6 (d, JPC = 10 Hz, CHꢀP), 155.7 (d, JPC = 60.4 Hz,
EtOꢀCHdCH); 31P NMR (81 MHz, C6D6) ꢀ57.2. MS-EI for PdO,
m/z(%):148(M+, 11), 128(25), 87(89), 86(62), 85(37), 83(51), 72(14),
58(25), 57(100), 56(43). Anal. Calcd for C6H13OP: C, 54.54; H 9.92; P,
23.44. Found C, 54.59; H, 9.94; P, 23.38.
102ꢀ105 °C (7 Torr); 1H NMR (300 MHz, C6D6): δ 0.85 (t, 3JHH
=
6.9 Hz, 3H), 2.45 (d, 3JPH = 13.8 Hz, 6H), 3.19 (q, 3JHH = 6.9 Hz, 2H),
5.48 (dd, 3JHH = 13.8 Hz, 2JPH = 4.2 Hz, 1H), 6.77 (dd, 3JHH = 13.8 Hz,
3JPH = 9.6 Hz, 1H); 13C NMR (125 MHz, C6D6): δ 14.1 (CH3), 39.2 (d,
(2-Ethoxyvinyl)(diphenyl)phosphine (17b). Yield: 74.2%; oil; 1H
3
NMR (300 MHz, C6D6): δ 0.91 (t, JHH = 6.9 Hz, 3H), 3.31 (q,
3JHH = 6.9 Hz, 2H), 5.35 (dd, 3JHH = 13.5 Hz, 2JPH = 4.2 Hz, 1H), 6.92
(dd, 3JHH = 13.5 Hz, 3JPH = 9.9 Hz, 1H), 7.00ꢀ7.15 (m, 6H), 7.48ꢀ7.53
(m,4H); 13C NMR (125 MHz, C6D6): δ 14.3 (CH3), 64.9 (OꢀCH2),
98.3 (d, 1JPC = 3.8 Hz, CHꢀP), 128.1 (PPh2), 128.4 (d, 3JPC = 6.3 Hz,
PPh2), 132.5 (d, 2JPC = 18.9 Hz, PPh2), 141.1 (d, 1JPC = 7.6 Hz, PPh2),
155.7 (d, 2JPC = 69.1 Hz, EtOꢀCHdCH); 31P NMR (81 MHz, C6D6)
δ ꢀ19.5; MS-EI, m/z (%): 256(M+, 100), 241(49), 201(58), 186(25),
183(25), 153(28), 141(31), 108(60), 77(56), 47(24); Anal. Calcd for
C16H17OP: C, 74.99; H 6.69; P, 12.09. Found C, 75.05; H, 6.71;
P, 11.99.
2JPC = 10.0 Hz, NꢀCH3), 65.3 (OꢀCH2), 103.8 (d, JPC = 23.9 Hz,
1
2
CHꢀP), 158.1 (d, JPC = 70.4 Hz, EtOꢀCHdCH); 31P NMR
(81 MHz, C6D6) 142.5; MS-EI, m/z (%): 181(M+, 45), 146(100),
137(12), 118(20), 109(32), 92(22), 83(18), 75(12), 60(10), 44(69),
32(81).
P-(2-Ethoxyvinyl)-N,N,P-trimethylphosphinous Amide (21a). Yield:
91.3%; oil; 1H NMR (300 MHz, C6D6): δ 0.97 (t, 3JHH = 6.9 Hz, 3H),
3
3
1.16 (d, JHH = 5.4 Hz, 3H) 2.45 (d, JPH = 10.5 Hz, 6H) 3.38 (q,
3JHH = 6.9 Hz, 2H), 5.14 (dd, 3JHH = 13.8 Hz, 1H), 6.81 (dd, JHH
=
3
3
13.8 Hz, JPH = 8.7 Hz, 1H); 13C NMR (125 MHz, C6D6): δ 14.0
1
2
Allyl(2-ethoxyvinyl)dimorpholin-4-ylphosphonium Bromide (18a).
Yield: 85.5%; amorphous solid; 1H NMR (300 MHz, CDCl3): δ 1.28
(d, JPC = 10.0 Hz, PCH3), 14.3 (CH3), 39.6 (d, JPC = 12.6 Hz,
NꢀCH3), 64.5 (OꢀCH2), 100.7 (d, JPC = 20.1 Hz, CHꢀP), 156.9
1
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ARTICLE
(d, 2JPC = 60.4 Hz, EtOꢀCHdCH); 31P NMR (81 MHz, C6D6) 38.9;
APCI MS: [M+ + 1] = 161; Anal. Calcd for C7H16NOP: C, 52.16; H
10.01; N, 8.69; P, 19.22. Found C, 52.13; H, 9.98; N, 8.63; P, 19.15.
P-(2-Ethoxyvinyl)-N,N-dimethyl-P-phenylphosphinous Amide (21b).
Yield: 77%; oil; 1H NMR (300 MHz, C6D6): δ 0.97 (t, 3JHH = 7.2 Hz,
3H), 2.53 (d, 3JPH = 10.2 Hz, 6H), 3.40 (q, 3JHH = 7.2 Hz, 2H), 5.36 (dd,
83(9), 77(9), 57(11), 44(11). Anal. Calcd for C13H16NP: C, 71.87; H,
7.42; N, 6.45; P, 14.26. Found C, 71.81; H, 7.43; N, 6.47; P, 14.19.
Allyl(methyl)dimorpholin-4-ylphosphonium Bromide (25a). Yield:
58.6%; mp 180ꢀ185 °C (2-propanol); 1H NMR (300 MHz, CDCl3): δ
2.37 (d, 2JPH = 13 Hz, 3H), 3.26 (br m, 8H), 3.70 (br m, 8H), 3.90 (dd,
3JHH = 6.6 Hz, 2JPH = 17 Hz, 2H), 5.39ꢀ5.47 (m, 1H), 5.60ꢀ5.71 (m,
2H); 13C NMR (125 MHz, CDCl3): δ 8.9 (d, 1JPC = 80.5 Hz, CH3ꢀP),
29.3 (d, 1JPC = 76.7 Hz, CH2ꢀP), 45.1 (NCH2), 66.7 (d, 3JPC = 5.0 Hz,
OCH2), 123.8 (d, 2JPC = 8.8 Hz, CH2dCH), 125.2 (d, 3JPC = 13.8 Hz,
CH2dCH); 31P NMR (81 MHz, CDCl3): δ 60.37. MS-FAB, m/z (%):
259([M ꢀ Br]+, 100). Anal. Calcd for C12H24BrN2O2P: C, 42.49; H,
7.13; N, 8.26; P, 9.13. Found C, 42.54; H, 7.12; N, 8.25; P, 9.10.
Allyl(bis(diethylamino))methylphosphonium Bromide (25b). Yield:
75%; amorphous solid (hexane); 1H NMR (300 MHz, CDCl3): δ 1.21 (t,
J = 6.9 Hz, 12H), 2.26 (d, J = 13.2 Hz, 3H), 3.11ꢀ3.29 (m, 8H), 3.65 (dd,
3JHH = 6 Hz, 2JPH = 16.8 Hz, 2H), 5.44ꢀ5.49 (m, 1H), 5.69ꢀ5.75 (m,
2H); 13C NMR (125 MHz, CDCl3): δ 10.0(d, 1JPC = 84.3 Hz, CH3ꢀP),
14.0 (NCH2CH3), 30.0 (d, 1JPC = 77.9 Hz, CH2ꢀP), 40.0 (NCH2CH3),
124.3(d, 2JPC = 7.5 Hz, CH2dCH), 124.6 (d, 3JPC = 13.8 Hz, CH2dCH);
31P NMR (81MHz, CDCl3): δ62.1. MS-FAB, m/z (%):231([M ꢀ Br]+,
100). Anal. Calcd for C12H28BrN2P: C, 46.31; H, 9.07; N, 9.00; P, 9.95.
Found C, 46.33; H, 9.04; N, 8.99; P, 10.0.
3JHH = 13.8 Hz, 2JPH = 3.6 Hz, 1H), 6.95 (dd, 3JHH = 13.8 Hz, 3JPH
=
9.6 Hz, 1H), 7.11 (t, 3JHH = 7.5 Hz, 1H), 7.24 (t, 3JHH = 7.5 Hz, 2H),
7.57 (dd, JHH = 7.5 Hz, JPH = 7.5 Hz, 2H); 13C NMR (125 MHz,
3
3
2
C6D6): δ 14.3 (CH3), 40.8 (d, JPC = 12.6 Hz, NꢀCH3), 64.9
(OꢀCH2), 98.2 (d, 1JPC = 17.6 Hz, CHꢀP), 127.3 (PPh2), 128.1 (d,
3JPC = 3.8 Hz, PPh2), 130.1 (d, 2JPC = 13.8 Hz, PPh2), 143.1 (d, 1JPC
=
2.5 Hz, PPh2), 160.0 (d, JPC = 71.7 Hz, EtOꢀCHdCH); 31P NMR
(81 MHz, C6D6) δ 54.5. Anal. Calcd for C12H18NOP: C, 64.56; H
8.13; N, 6.27; P, 13.87. Found C, 64.59; H, 8.15 ; N, 6.24; P, 13.90.
Allyl(dimethylamino)(2-ethoxyvinyl)(methyl)phosphonium Bromide
2
1
(22a). Yield: 100%; amorphous solid; H NMR (300 MHz, CDCl3):
δ 1.30 (t, 3JHH = 7.2 Hz, 3H), 2.20 (d, JPH = 13.2 Hz, 3H), 2.76 (d,
3
3JPH = 10.8 Hz, 6H), 3.33ꢀ3.65 (m, 2H), 4.18 (q, 3JHH = 7.2 Hz, 2H),
3
2
5.09 (dd, JHH = 13.5 Hz, JPH = 12.3 Hz, 1H), 5.35ꢀ5.48 (m, 2H),
5.62ꢀ5.69 (m, 1H), 7.62 (dd, 3JHH = 13.5 Hz, 3JPH = 11.1 Hz, 1H); 13
C
NMR (125 MHz, CDCl3): δ 9.55 (1JPC = 69.1 Hz, PCH3), 14.5 (CH3),
30.9 (d, 1JPC = 64.1 Hz, PꢀCH2), 37.4 (NꢀCH3), 68.9 (OꢀCH2), 81.3
(d, 1JPC = 112 Hz, CHꢀP), 124.1 (d, 3JPC = 12.6 Hz, CH2dCH), 124.4
(d, 2JPC = 10 Hz, CH2dCH), 166.8 (d, 2JPC = 18.9 Hz, EtOꢀCHdCH);
31P NMR (81 MHz, CDCl3) δ 52.9; Anal. Calcd for C10H21NOPBr:
C, 42.57; H, 7.50; N, 4.96; Br, 28.32; P, 10.98. Found C, 42.59; H, 7.53;
N, 4.95; Br, 28.41; P, 11.03.
Methyl(dimorpholin-4-yl)prop-1-enylphosphonium Bromide (26a).
To a solution of 20a (0.88 g, 2.6 mmol) in pyridine (20 mL), 3 drops of
Et3N was added and the reaction mixture was refluxed for 4 h. The
reaction mixture was evaporated; the residue was washed with ether.
1
Yield: 63.6%; amorphous solid (diethyl ether); H NMR (500 MHz,
4
2
CDCl3): δ 2.05 (d, JPH = 6 Hz, 3H), 2.40 (d, JPH = 13.5 Hz, 3H),
3.19 (br m, 8H), 3.64 (br m, 8H), 6.3 (dd, 3JHH = 18 Hz, 2JPH = 21 Hz,
1H), 6.93ꢀ7.05 (m, 1H); 13C NMR (125 MHz, CDCl3): δ 10.5 (d,
1JPC = 85.5 Hz, CH3ꢀP), 21.3 (d, 3JPC = 21.4 Hz, CH3), 44.9 (NCH2),
66.6 (d, 3JPC = 5 Hz, OCH2), 113.0 (d, 1JPC = 120.7 Hz, CH), 156.8 (d,
2JPC = 6.3 Hz, CH); 31P NMR (81 MHz, CDCl3) δ 52.6. MS-FAB, m/z
(%): 259([M ꢀ Br]+, 100). Anal. Calcd for C12H24BrN2O2P: C, 42.49;
H, 7.13; N, 8.26; P, 9.13. Found C, 42.50; H, 7.09; N, 8.25; P, 9.14.
(4-(Dimethylamino)buta-1,3-dienyl)(methyl)dimorpholin-4-yl-
phosphonium Bromide (27a). Yield: 70%; amorphous solid; 1H NMR
(300 MHz, CDCl3): δ 2.33 (d, 2JPH = 12.6 Hz, 3H), 3.0 (br s, 6H), 3.21
(br s, 8H), 3.74 (br s, 8H), 4.75 (dd, 2JPH = 19.2 Hz, 3JHH = 16.5 Hz,
1H), 5.26 (t, 3JHH = 12 Hz, 1H), 7.39 (d, 3JHH = 12 Hz, 1H), 7.46ꢀ7.61
Allyl(dimethylamino)(2-ethoxyvinyl)(phenyl)phosphonium Bromide
1
(22b). Yield: 100%; amorphous solid; H NMR (300 MHz, CDCl3):
δ 1.38 (t, 3JHH = 7.2 Hz, 3H), 2.89 (d, 3JPH = 11.1 Hz, 6H), 4.00 (dd,
2
3
3JHH = 7.2 Hz, JPH = 16.5 Hz, 2H), 4.35 (q, JHH = 7.2 Hz, 2H),
5.34ꢀ5.39 (m, 1H), 5.49ꢀ5.53 (m, 2H), 5.62ꢀ5.69 (m, 1H), 7.58 (dd,
3JHH = 13.8 Hz, 3JPH = 10.8 Hz, 1H), 7.54ꢀ7.89 (m, 5H); 13C NMR
(125 MHz, CDCl3): δ 14.5 (CH3), 30.9 (d, 1JPC = 66.6 Hz, PꢀCH2),
38.4 (NꢀCH3), 69.5 (OꢀCH2), 79.9 (d, 1JPC = 112 Hz, CHꢀP), 120.9
1
(d, JPC = 104 Hz, PPh2), 124.1 (d, 2JPC = 8.8 Hz, CH2dCH), 124.5
(d, 3JPC = 15.1 Hz, CH2dCH), 130.1 (d, 3JPC = 12.6 Hz, PPh2), 132.5
2
4
(d, JPC = 11.3 Hz, PPh2), 134.7 (d, JPC = 2.5 Hz, PPh2), 168.2 (d,
2JPC = 18.9 Hz, EtOꢀCHdCH); 31P NMR (81 MHz, CDCl3) δ 48.4;
MS-FAB, m/z (%): 265([M ꢀ Br]+, 10); Anal. Calcd for C15H23-
NOPBr: C, 52.34; H, 6.73; Br, 23.21; N, 4.07; P, 9.00. Found C, 52.32;
H, 6.77; Br, 23.10; N, 4.05; P, 9.08.
1
(m, 1H); 13C NMR (125 MHz, CDCl3): δ 10.6 (d, JPC = 86.3 Hz,
CH3ꢀP), 44.8 (NCH2), 66.7 (d, 3JPC = 5.0 Hz, OCH2), 83.5 (d, 1JPC
=
131.3 Hz, CHꢀP), 97.6 (d, 3JPC = 26.4 Hz, C(3)), 155.26 (C(4)), 157.2
2
(d, JPC = 12.9 Hz, C(2)), NMe2 signals are not observed; 31P NMR
N,N,1-Trimethyl-1λ5-phosphinin-1-amine (23a). Yield: 53.0%; oil;
(81 MHz, CDCl3) δ 55.2. MS-FAB, m/z (%): 314([M ꢀ Br]+, 100).
Anal. Calcd for C15H29BrN3O2P: C, 45.69; H, 7.41; N, 10.66; P, 7.86.
Found C, 45.67; H, 7.43; N, 10.75; P, 7.89.
2
1H NMR (300 MHz, C6D6): δ 1.26 (d, JPH = 14.4 Hz, 3H), 2.0 (d,
3JPH = 11.4 Hz, 6H), 4.41 (dd, 3JHH = 11.1 Hz, 2JPH = 12 Hz, 2H), 5.64
(dtt, 4JPH3 = 3 Hz, 3JHH = 7.8 Hz, 4JHH = 0.6 Hz, 1H), 7.39 (ddd, 3JHH
=
3
7.8 Hz, JHH = 11.1 Hz, JPH = 34.2 Hz, 2H); 13C NMR (125 MHz,
Bis(diethylamino)(4-(dimethylamino)buta-1,3-dienyl)methylphos-
1
C6D6): δ 17.6 (d, 1JPC = 91.8 Hz, PCH3), 35.6 (NCH3), 72.4 (d, 1JPC
=
phonium Bromide (27b). Yield: 100%; amorphous solid; H NMR
(300 MHz, CDCl3): δ 1.12ꢀ1.21 (m, 12H), 2.10 (d, 2JPH = 12.9 Hz,
3
108 Hz, C(2), C(6)), 98.6 (d, JPC = 22.6 Hz, C(4)), 139.6 (C(3),
C(5)); 31P NMR (81 MHz, C6D6) δ 24.4. MS-EI, m/z (%): 155(M+,
1), 59(1), 45(75), 44(100), 43(20), 42(20), 41(3), 38(1), 32(12),
30(3); Anal. Calcd for C8H14NP: C, 61.92; H, 9.09; N, 9.03; P, 19.96.
Found C, 61.90; H, 9.13; N, 9.00; P, 20.03.
2
3H), 2.96 (br s, 6H), 3.05ꢀ3.18 (m, 8H), 4.83 (dd, JPH = 20.4 Hz,
3JHH = 16.2 Hz, 1H), 5.20 (t, 3JHH = 9 Hz, 1H), 7.29ꢀ7.41 (m, 2H); 13
C
1
NMR (125 MHz, CDCl3): δ 12.7 (d, JPC = 89.3 Hz, CH3ꢀP), 14.2
(CH3), 39.9 (d, 2JPC = 3.8 Hz, NCH2), 87.8 (d, 1JPC = 137 Hz, CHꢀP),
97.1 (d, 3JPC = 26.4 Hz, C(3)), 154.6 (C(4)), 155.3 (d, 2JPC = 10.1 Hz,
C(2)), NMe2 signals are not observed; 31P NMR (81 MHz, CDCl3)
δ 55.2. MS-FAB, m/z (%): 281([M ꢀ Br]+, 100). Anal. Calcd for
C15H33BrN3P: C, 49.18; H, 9.08; N, 11.47; P, 8.46. Found C, 49.20; H,
9.11; N, 11.54; P, 8.55.
N,N-Dimethyl-1-phenyl-1λ5-phosphinin-1-amine (23b). Yield: 76.0%;
oil; 1H NMR (500 MHz, C6D6): δ 2.1 (d, 3JPH = 12.5 Hz, 6H), 4.61 (dd,
3JHH = 11 Hz, 2JPH = 10.5 Hz, 2H), 5.70 (dt, 4JPH = 2.5 Hz, 3JHH = 7.5 Hz,
3
3
1H), 6.99ꢀ7.09 (m, 3H), 7.44 (ddd, JHH = 7.5 Hz, JHH = 11 Hz,
3JPH = 34.5 Hz, 2H), 7.49ꢀ7.52 (m, 2H); 13C NMR (125 MHz, C6D6):
δ 35.1 (d, 2JPC = 3.8 Hz, NCH3), 70.7 (d, 1JPC = 110.7 Hz, C(2), C(6)),
99.3 (d, 3JPC = 21.4 Hz, C(4)), 128.5 (d, 3JPC = 13.8 Hz, PPh2), 129.8 (d,
4JPC = 2.5 Hz, PPh2), 131.3 (d, 2JPC = 10.0 Hz, PPh2), 139.8 (C(3), C(5)),
PPh2 (i) signal are not observed; 31P NMR (81 MHz, C6D6) δ 30.4. MS-
EI, m/z (%): 217(M+, 32), 174(12), 173(100), 171(18), 128(12), 95(17),
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental procedures, char-
b
acterization data for the compounds obtained, and crystallographic
6132
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The Journal of Organic Chemistry
ARTICLE
details. This material is available free of charge via the Internet at
http://pubs.acs.org
’ AUTHOR INFORMATION
Corresponding Author
*Email: a.kostyuk@enamine.net
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