Synthesis of Nonsymmetric Iminophosphonamines by Kirsanov Condensation

Article abstract of DOI:10.1055/s-0039-1690242

Despite the growing interest in iminophosphonamines R ₂ P(NHR′)(NR′), nonsymmetric examples bearing different N,N′-substituents are quite rare and have been prepared exclusively by the Staudinger reaction. We report here the synthesis of a series of new iminophosphonamines Ph ₂ P(NHR)(NR′) (R = Me, t -Bu, o -Tol; R′ = p -Tol, o -Tol, 2,6-Xyl, 2,6-Diip, p -Ts) showing that the Kirsanov condensation is a viable and simpler approach, although with some limitations. This method allows the synthesis to be accomplished in a one-pot manner via stepwise double amination of a trihalophosphorane and permits the introduction of at least one sterically bulky N-substituent. The second amination step is shown to be highly sensitive to: (a) the steric bulk of the amine, and (b) the acidity of the aminohalophosphonium intermediate.

Full text of DOI:10.1055/s-0039-1690242

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2019, 51, A–H
paper
A
en
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
Synthesis of Nonsymmetric Iminophosphonamines by Kirsanov
Condensation
Tat’yana A. Peganova
R
Alexander M. Kalsin*
0
0
0
0-0
0
0
2-7
0
2
7-
6
5
5
0
N
Ph2P
R'NH2
– H+
+ H+
Russian Academy of Sciences, A. N. Nesmeyanov Institute of
Organoelement Compounds, Vavilov Str. 28, 119991 Moscow,
Russian Federation
Br
slow
R
N
R
Br2
kalsin@ineos.ac.ru
NH
Ph2PCl
Ph2P
Br
Ph2P
R'NH2
fast
+ 2 RNH2
Br
NH
R'
R
– H+
NH
Ph2P
Br
Isolated yields
58–80% in one pot
NH
R'
Received: 17.09.2019
Accepted after revision: 17.10.2019
Published online: 31.10.2019
tion of secondary phosphanes11 and aminophosphanes12
with organoazides and the Kirsanov condensation of bro-
mophosphonium salts with primary amines13 followed by
deprotonation of diaminophosphonium salts formed in the
first step (Scheme 1). The Staudinger reaction is more ver-
satile and allows nonsymmetric iminophosphonamines
having sterically hindered N,N′-substituents to be ob-
tained.3,9,10,14 The Kirsanov reaction is simpler to implement
as it does not require dangerous disubstituted phosphanes
and azides. However, its drawback is typical to nucleophilic
substitution reactions. In particular the yields are very low
for amines with electron-withdrawing or sterically bulky
substituents. Thus, even bis(o-tolylamino)phosphonium13c
and bis(tert-butylamino)phosphonium13a salts can be ob-
tained only after prolonged heating in moderate-to-low
yields. Furthermore, no reports on the synthesis of non-
symmetric iminophosphonamines by this reaction can be
found in the literature; some authors even claim this ap-
proach to be not viable.15
DOI: 10.1055/s-0039-1690242; Art ID: ss-2019-c0535-op
Abstract Despite the growing interest in iminophosphonamines
R2P(NHR′)(NR′), nonsymmetric examples bearing different N,N′-sub-
stituents are quite rare and have been prepared exclusively by the
Staudinger reaction. We report here the synthesis of a series of new
iminophosphonamines Ph2P(NHR)(NR′) (R = Me, t-Bu, o-Tol; R′ = p-Tol,
o-Tol, 2,6-Xyl, 2,6-Diip, p-Ts) showing that the Kirsanov condensation is
a viable and simpler approach, although with some limitations. This
method allows the synthesis to be accomplished in a one-pot manner
via stepwise double amination of a trihalophosphorane and permits the
introduction of at least one sterically bulky N-substituent. The second
amination step is shown to be highly sensitive to: (a) the steric bulk of
the amine, and (b) the acidity of the aminohalophosphonium interme-
diate.
Key words Kirsanov condensation, nonsymmetric iminophos-
phonamines, steric effects, aminohalophosphonium
The interest in iminophosphonamines Ph2P(NR)(NHR′)
has been constantly growing due to their potential use as
superbases in asymmetric Brønsted base organocatalysis1
and as 2-N,N chelate ligands for the synthesis of transition
metal iminophosphonamides. The latter have been report-
ed as active catalysts for alkene polymerization,2 3,4-selec-
tive polymerization of isoprene,3 alkene oligomerization,4
ethene dimerization,2c cyclopropanation,5 and aziridina-
tion,6 as well as for Tsuji–Trost cross-coupling7 and ace-
tophenone transfer hydrogenation.8 Nonsymmetric imino-
phosphonamines bearing different N,N′-substituents have
been efficiently utilized in the Kumada cross-coupling of
aryl Grignard reagents with aryl chlorides and fluorides9
and in controlling regio- and stereoselectivity in the polym-
erization of isoprene.10
Staudinger reaction
R'N3
– N2
R'N3
– N2
NR'
R2PH
R2P
R2P
NHR'
NHR'
Kirsanov condensation
2 R'NH2 / 2 B:
– 2 BH+
NHR'
B:
NR'
R2PBr2Cl
R2P
R2P
Br
– BH+
NHR'
NHR'
Scheme 1 Synthetic approaches to iminophosphonamines
Here we report on the synthesis of a series of new non-
symmetric iminophosphonamines obtained by double ami-
nation of trihalodiphenylphosphorane with primary
aryl/alkyl amines (Scheme 2) and discuss the limitations of
this method. Although the substitution of halogen in the
highly polar P–Hal bond at the phosphorus atom with good
nucleophiles is generally thought to be a fast process, our
Generally, there are two major approaches to the syn-
thesis of iminophosphonamines, i.e. the Staudinger reac-
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
tion of strongly donating N-alkyl substituent. Their chemi-
cal shifts [ = 2.94 (1a), 2.73 (1b), 2.10 (1c)] depend on the
electron-donor properties of aryl groups (Ar = p-Tol, Xyl,
Diip, respectively). The IR spectra of 1a–c in the solid state
feature a characteristic band of NH stretching vibrations NH
at 3354–3356 cm–1. The iminophosphonamines 1a–c were
isolated in good yields 58–72%, the only side products were
the corresponding aminophosphine oxides Ph2P(O)(NHAr)
5a–c and Ph2P(O)(NHMe) formed as a result of hydrolysis of
the monoaminophoshonium intermediate13c or the target
product by adventitious traces of water during the work-up
procedures.
N
Ph2P
NH
N
N
Ph2P
Ph2P
NH
Me
NH
Me
1a
1d
1b
1c
Me
HN
Ph2P
N
N
Ph2P
Ph2P
NH
NH
O2
S
N
1e
1f
Scheme 2 Nonsymmetric iminophosphonamines reported in this article
The first amination step proceeds smoothly with the
arylamines used, including sterically congested examples.
The 31P NMR monitoring showed that even with the bulki-
est 2,6-DiipNH2 the amination is accomplished within 2 h
at room temperature forming aminobromophosphonium
salt [Ph2PBr(NHAr)]Br (2c; P = 57.7, Figure S1(a) in the
Supporting Information) in more than 90% yield. The sec-
ond amination step with highly nucleophilic methylamine
is also fast and the corresponding iminophosphonamine is
formed within 1 h.
results show that it is possible to carry out double amina-
tion in a controllable stepwise way.
Nonsymmetric iminophosphonamines 1a–c were readi-
ly synthesized in a straightforward manner by one-pot
stepwise amination with ArNH2 [Ar = p-Tol; 2,6-Me2C6H3
(Xyl); 2,6-iPr2C6H3 (Diip)] and methylamine of trihalophos-
phorane prepared in situ from chlorodiphenylphosphane
and bromine in dichloromethane (Scheme 3).
However, replacing methylamine with sterically more
demanding and less nucleophilic p-toluidine did not result
in the formation of nonsymmetric diaminophosphonium
salts 3g and 3h bearing bulky 2,6-Xyl and 2,6-Diip substitu-
ents, respectively; instead, both reactions produced exclu-
sively symmetric di-p-tolylaminophosphonium salt 3i
(Scheme 4).
Ar
N
Ar
Br
MeNH2
(excess)
NH
2 ArNH2
Br2
Ph2PCl
[Ph2PClBr2]
Ph2P
Ph2P
1a–c
CH2Cl2
– ArNH3+Cl–
– MeNH3+Br–
Br
NH
Me
2
(58–72%)
Scheme 3 One-pot synthesis of 1a–c
The 31P NMR monitoring of this reaction (Figure S1, in
the Supporting Information) shows that the addition of p-
toluidine to the in situ generated 2c resulted in precipita-
The compounds 1a–c were fully characterized by 31P,
13C, 1H NMR and elemental analysis. In the 31P NMR spectra
the phosphorus resonance of 1a–c is observed at  = +7.3 to
–7.6 similar to P = –3.5 reported earlier for Ph2P(N-p-
Tol)(NH-p-Tol) (1i).16 In the 1H NMR the NH resonances are
significantly upfield shifted in comparison to  = 5.55 for 1i,
reflecting the decrease of NH acidity due to the introduc-
tion of p-TolNH3 Br– and formation of a new compound
+
with the phosphorus resonance significantly upfield shifted
to P = –1.6, which is a typical region for iminophos-
phonamines. It appeared that the first equivalent of p-tolui-
dine rapidly deprotonates 2b, 2c to form bromo(imi-
no)phosphoranes 4b, 4c (Scheme 5). The latter can further
Br
NH-2,6-Xyl
NH2
Ph2P
Br
H
N
H
N
Ph2P
3g
Br
2b
Br
HN
2 p-TolNH2
2 ArNH2
[Ph2PClBr2]
Ph2P
– ArNH3+Cl–
– ArNH3+Br–
– ArNH2
HN
3i
Br
H
N
Br
NH-2,6-Diip
Ph2P
NH2
Ph2P
N
H
Br
2c
3h
Scheme 4 Attempted synthesis of 3g and 3h
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

C
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
Br
NHAr
p-TolNH2
Ph2P
– ArNH2
NH-p-Tol
a
Br
3g, Ar = 2,6-Xyl
3h, Ar = 2,6-Diip
NHAr
NAr
Br
p-TolNH2
p-TolNH2
Ph2P
Ph2P
3i
– p-TolNH3+Br–
Br
b
4b, Ar = 2,6-Xyl
4c, Ar = 2,6-Diip
2b, Ar = 2,6-Xyl
2c, Ar = 2,6-Diip
Br
p-TolNH2
Ph2P
– ArNH2
N-p-Tol
4a
Scheme 5 Possible reaction pathways to 3i
react stepwise with 2 equiv of p-toluidine by SN2 substitu-
tion reaction of bromide and of the bulky amine via either
unstable nonsymmetric diaminophosphonium salts 3g, 3h
(path a), or bromo(imino)phosphorane 4a (path b).
ide. Apparently, the reaction proceeds via aminobromo-
phosphonium salt 2a (Scheme 6) rather than via sterically
congested aminodiarylphosphonium intermediate 3h
(Scheme 5, path a).
To investigate further this mechanism, we synthesized
compound 4c by the reaction of Ph2PClBr2, generated in si-
tu, with 3 equiv of 2,6-DiipNH2. Although the isolated prod-
uct 4c (P = –3.2 in C6D6) contained cumulatively 15–20% of
impurities (Figure S2a in the Supporting Information) and
cannot be purified further due to its high solubility even in
hexane, the major impurity (ca. 10%) observed at P = –1.0
is tentatively the related chloro(imino)phosphorane
Ph2PCl(N-2,6-Diip) (4c′) that gives further the same diami-
nophosphonium salt but with Cl– counterion (see below). It
is worth mentioning that a similarly small downfield shift
of 31P resonances have been reported for Ph2PCl(N-SiMe3)17
Indeed, we have shown that p-toluidine cannot
substitute bulky 2,6-DiipNH2 even in the sterically more ac-
cessible diaminophosphonium salt [Ph2P(NH-2,6-Diip)-
(NHMe)]Br (3c) generated in situ. Thus, the reaction of 1c
+
with p-TolNH3 Br– in CH2Cl2 results in the quick dissolution
of the ammonium salt and upfield shift of the 31P NMR res-
onance from P = –3.1 to P = 39.8 due to the formation of
3c, while no further reaction occurred with p-toluidine re-
leased even after heating for 2 days (Figure S3 in the Sup-
porting Information). Hence, if the formation of diamino-
phosphonium salt 3 is hampered due to steric reasons, the
bulkier amino group at the phosphorus atom can be substi-
tuted with the sterically less hindered one exclusively via
the intermediate 2.
Nevertheless, bromide substitution in 4c with p-tolui-
dine can be initiated by replacing dichloromethane with
polar aprotic acetonitrile, although in this solvent concur-
rent transamination occurs as a side reaction. Thus, the re-
flux of 4c and 1 equiv p-toluidine in acetonitrile for 8 h re-
sulted in about 60% conversion into mostly diaminophos-
phonium salts 3i and 3h (7:1), showing 31P NMR
resonances at P = 24.7 and 26.7, respectively (Figure S4a, in
the Supporting Information). This assignment was further
supported by the ESI-HRMS spectrum recorded for the re-
action solution, in which the molecular peaks at m/z
397.1797, 467.2573 and 378.1949 correspond to the [M +
H+] of 3i (calcd m/z 397.1834), 3h (calcd m/z 467.2616) and
5c (calcd m/z 378.1987), respectively, with the latter two
peaks being significantly less intensive (Figure S4b). Unfor-
tunately, we were not able to isolate pure 3h from the reac-
tion mixture due to its low content. Thus, this method does
not appear to be a convenient route to nonsymmetric steri-
cally hindered aminodiarylphosphonium salts, as polar
aprotic solvent accelerates substitution of both bromide
and bulky amino substituents giving rise to a mixture of di-
aminophosphonium salts that are difficult to separate.
1
and Ph2PBr(N-SiMe3).18 The H (Figure S2b) and 13C NMR
(Figure S2c) spectra correspond well to the formula of 4c
with the resonances observed close to the related imino-
phosphonamine 1c, and show no resonance that can be at-
tributed to the NH group. The mass spectrum (Figure S2d)
of the solid sample showed molecular peaks with m/z 439
(4c), 395 (4c′) and 377, the latter being attributed to the
corresponding aminophosphine oxide 5c formed due to hy-
drolysis.
Surprisingly, 4c does not react with p-toluidine even
under reflux for 4 h in CH2Cl2. Among the alkylamines test-
ed (MeNH2 and t-BuNH2), only methylamine reacted with
4c to give expectedly 1c. On the other hand, 4c does react
+
with p-toluidine in the presence of p-TolNH3 Br– to give 3i
(Scheme 6). This implies that the first step in Scheme 3 is
partially reversible and, in fact, p-toluidine reacts with a re-
sidual amount of 2c, as amine is much better leaving group
in SN2 substitution reactions than a negatively charged am-
p-TolNH3+Br–
Br
Br
p-TolNH2
p-TolNH2
2c
3i
4c
Ph2P
– DiipNH2
p-TolNH2
NH-p-Tol
2a
Scheme 6 The mechanism of 3i formation
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

D
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
(Alkylamino)bromophosphonium salts [Ph2PBr(NHR)]Br
2 have lower acidity than their arylamino analogues and
are not deprotonated to 4 by primary amines, similarly to
what has been observed earlier for diaminophosphonium
salts 3.16 This was successfully employed in the synthesis of
nonsymmetric iminophosphonamine [Ph2P(NHtBu)(N-p-
Tol)] (1d). Thus, the amination of the intermediate 2d,
which does not undergo deprotonation, with p-toluidine
readily gives the corresponding nonsymmetric diamino-
phosphonium salt [Ph2P(NHtBu)(NH-p-Tol)]Br (3d) in 80%
yield after 18 h at room temperature (Scheme 7, path A).
This salt can be quantitatively deprotonated with Et2NH to
give 1d. Alternatively, the amination of the intermediate 2a
with tert-butylamine is very slow due to its fast deprotona-
tion to the less electrophilic 4a, and the product 1d was ob-
tained in only 15% yield after 70 h of reflux (Scheme 7, path
B).
the in situ prepared 2d to give 3e in 77% yield after 3 days at
room temperature, while no reaction was observed with
bulkier 2,6-XylNH2 even under reflux for several days
(Scheme 8). Further deprotonation of diaminophosphoni-
um salt 3e with Et2NH yields quantitatively iminophos-
phonamine 1e. The reported earlier low yield of 23% for the
corresponding symmetric diaminophosphonium salt
[Ph2P(NH-o-Tol)2]Br (3j)13c can now be explained by the re-
duced reactivity of bromo(imino)phosphorane [Ph2PBr(N-
o-Tol)] (4e) formed by deprotonation of [Ph2PBr(NH-
o-Tol)]Br intermediate (2e).
It has to be noted that the satisfactory elemental analy-
sis for diaminophosphonium salt 3d can be obtained con-
sidering it to be a mixed salt Br–/Cl– (85–90/15–10%) mean-
ing that in the intermediate 2d bromide is partially substi-
tuted with chloride, either in the counterion or in the P–Hal
moiety, similarly to the impurity of 4c′ observed in the syn-
thesis of 4c.
As the final example, the nonsymmetric iminophos-
phonamine 1f bearing bulky o-tolyl and electron-with-
drawing p-tosyl groups was synthesized by the reaction of
the in situ prepared 2e with 2 equiv of TsNHNa in THF
(Scheme 9). Despite the relatively small bulkiness and high
nucleophilicity of p-TsNH–19 relative to amines,20 the re-
duced electrophilicity of the intermediate 4e is responsible
for slowing down this reaction; the product was isolated in
61% yield after prolonged reflux for 1.5 days in THF.
Expectedly, increasing the bulk of the arylamines in-
volved in the amination of tert-butylamino-substituted salt
2d retards the reaction. Thus, o-toluidine slowly reacts with
Br
Br
2 tBuNH2
H
N
2 p-TolNH2
Br
Ph2P
Ph2P
(80%)
HN
NH
path A
3d
2d
Et2NH
[Ph2PClBr2]
(100%)
In summary, with this study we have shown that the
synthesis of nonsymmetric diaminophosphonium salts and
the corresponding iminophosphonamines by Kirsanov con-
densation is possible because the rates of the two consecu-
tive amination steps differ significantly. Typically to SN2 re-
actions, the bulkiness of the first amino-substituent intro-
duced retards the second amination step, allowing to avoid
undesirable double amination with the same amine that
would lead to symmetric product. However, such steric ef-
fects limit the scope of the reaction to iminophos-
phonamines containing no more than one bulky amino
group. When two bulky amines are used, the reaction ei-
ther stops at the formation of aminobromophosphonium
salt after the first amination step or yields symmetric di-
aminophosphonium salt bearing two least sterically en-
cumbered amino moieties as a result of the concurrent sub-
stitution of the bulkier amine. One complication that has to
be considered, is facile deprotonation of acidic (arylami-
no)bromophosphonium intermediates with the excess of
path B
Br
3 tBuNH2
(15%)
N
NH-p-Tol
Ph2P
Ph2P
NH
Br
2a
2 p-TolNH2
1d
Scheme 7 Two synthetic pathways to 1d
Br
H
N
2 o-TolNH2
N
Et2NH
Ph2P
Ph2P
NH
NH
3e (77%)
1e
2d
Br
H
N
Ph2P
2,6-XylNH2
NH
Scheme 8 Reaction of 2d with bulky arylamines
H
N
Br
Ph2P
N
N-o-Tol
NH-o-Tol
Br2
Ph2PCl
TsNHNa
TsNHNa
Ph2P
Ph2P
O2S
ΔT, slow
Br
Br
2 o-TolNH2
2e
4e
1f (61%)
Scheme 9 Synthesis of 1f
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

E
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
amine to less reactive zwitterionic bromophosphonimines.
Therefore, nonsymmetric N-alkyl/N-aryl iminophos-
phonamines can be obtained much faster and with higher
yields, when alkylamine is used at the first amination step.
Although the Staudinger reaction is more versatile and can
deal with wider variety of amines, including sterically en-
cumbered and poorly nucleophilic ones, the Kirsanov con-
densation can offer effective simpler one-pot route from
commercially more accessible compounds to iminophos-
phonamines having one sterically bulky N-substituent, and
thus deserves its place in the chemists’ toolbox.
1H NMR (CDCl3):  = 7.91 (dd, 3JHH = 7.2 Hz, 3JHP = 12.0 Hz, 4 H, o-HPh),
7.46 (td, 3JHH = 7.2 Hz, 5JHP = 1.6 Hz, 2 H, p-HPh), 7.37 (td, 3JHH = 7.6 Hz,
3
4JHP = 3.2 Hz, 4 H, m-HPh), 6.92 (d, JHH = 8.4 Hz, 2 H, C6H4), 6.88 (d,
3JHH = 8.4 Hz, 2 H, C6H4), 2.94 (br s, 1 H, NH), 2.68 (d, 3JHP = 12.0 Hz, 3
H, NHMe), 2.24 (s, 3 H, MeTol).
13C NMR (CDCl3):  = 148.3 (d, 2JCP = 3.7 Hz, i-C-NTol), 132.2 (d, 2JCP = 9.2
1
4
Hz, o-CHPh), 131.7 (d, JCP = 126 Hz, i-CPh), 131.5 (d, JCP = 2.7 Hz, p-
CHPh), 129.5 (s, -CHTol), 128.7 (d, 3JCP = 12.3 Hz, m-CHPh), 126.8 (s, i-C-
MeTol), 123.3 (d, 3JCP = 17.9 Hz, -CHTol), 26.9 (s, NHMe), 20.7 (s, MeTol).
31P NMR (CDCl3):  = 7.3.
Anal. Calcd for C20H21N2P: C, 74.98; H, 6.61; N, 8.74. Found: C, 74.85;
H, 6.69; N, 8.58.
Ph2P(NHMe)(N-2,6-Me2C6H3) (1b)
All manipulations were carried out using standard Schlenk tech-
niques under an atmosphere of dry argon. Absolute solvents were
used for the synthesis; solvents were purified by standard methods
and distilled under argon prior to use. The 1H, 31P, and 13C NMR spec-
tra were obtained on Bruker Avance 600 or Bruker Avance 400 spec-
trometers and referenced to the residual signals of deuterated solvent
(1H and 13C), and to 85% H3PO4 (31P, external standard). IR spectra for
were recorded on a Shimadzu IR Prestige21 FTIR spectrophotometer
equipped with an MCT detector cooled with liquid N2, ATR accessory
(MIRacle with a Diamond/ZnSe Crystal Plate Pike®) or in KBr pellets.
The original NMR and IR spectra are given in the Supporting Informa-
tion in Figures S5–S12. The EI mass spectrum for 4c was obtained on a
Finnigan MAT Incos 50 mass spectrometer with direct sample inlet
into the ion source at 70 eV ionization energy. HRMS of the reaction
sample (4c + p-toluidine) were registered on Bruker micrOTOF Q in-
strument equipped with electrospray ionization (ESI) ion source. The
measurements were performed in positive mode with HV capillary at
4.5 kV, spray shield offset at –0.5 kV, and scan range of m/z 50–3000.
The elemental analyses were carried out on a Carlo Erba 1106 CHN
analyzer.
Synthesized analogously from 2,6-dimethylaniline (2.50 mL, 2.45 g,
20 mmol). After filtering off the MeNH3Br salt, the filtrate was evapo-
rated to dryness. Most impurities were removed by washing the resi-
due with Et2O (3 × 10 mL). Finally, it was extracted with warm ben-
zene (~60 mL), the filtrate was concentrated to 7–10 mL to result in
precipitation. The precipitate was filtered off, washed with benzene
(2 × 2 mL) and dried under vacuum to give 1b (2.70 g). Second crop of
1b (1.16 g) was precipitated by treating the filtrate with 3 volumes of
Et2O. Total yield: 3.86 g (58%).
IR (KBr): 3357, 3076, 3058, 2956, 2919, 2820, 1589, 1475, 1467, 1436,
1428, 1291, 1274, 1116, 1096, 1035, 1027 cm–1
IR (ATR): 3355 cm–1 (NH).
.
1H NMR (CDCl3):  = 7.74 (dd, 3JHH = 8.0 Hz, 3JHP = 10.6 Hz, 4 H, o-HPh),
3
7.47 (br t, JHH ~ 7 Hz, 2 H, p-HPh), 7.40 (m, 4 H, m-HPh), 6.94 (d,
3JHH = 7.2 Hz, 2 H, m-C6H3), 6.88 (t, 3JHH = 7.2 Hz, 1 H, p-C6H3), 2.72 (d,
3JHP = 11.2 Hz, 3 H, NHMe), 2.73 (overlap, 1 H, NH), 2.19 (s, 6 H, MeXyl).
13C NMR (CDCl3):  = 147.2 (d, 2JCP = 1.0 Hz, i-C-NXyl), 133.4 (s, i-C-MeX-
yl), 132.1 (d, 2JCP = 9.0 Hz, o-CHPh), 131.3 (d, 4JCP = 2.6 Hz, p-CHPh), 128.5
3
4
(d, JCP = 12.4 Hz, m-CHPh), 127.8 (d, JCP = 1.8 Hz, m-CHXyl), 118.6 (d,
5JCP = 3.0 Hz, p-CHXyl), 27.4 (d, 2JCP = 1.3 Hz, NHMe), 20.9 (s, MeXyl).
Ph2P(NHMe)(N-p-Tol) (1a); Typical Procedure for
Ph2P(NHMe)(NAr) 1a–c
31P NMR (CDCl3):  = –3.6.
Anal. Calcd for C21H23N2P: C, 75.43; H, 6.93; N, 8.38. Found: C, 75.24;
H, 7.01; N, 8.26.
To a solution of Ph2PCl (3.60 mL, 4.42 g, 20 mmol) in CH2Cl2 (15 mL), a
solution of Br2 (1.0 mL, 3.2 g, 20 mmol) in CH2Cl2 (15 mL) was added
dropwise with stirring at r.t., and the mixture was stirred for 1.5 h.
Then a solution of p-toluidine (4.28 g, 40 mmol) in CH2Cl2 (40 mL)
was added dropwise to the suspension of Ph2PClBr2. The mixture was
stirred overnight. The precipitated p-TolNH3+Cl– was filtered off under
argon and washed with CH2Cl2 (3 × 20 mL). The filtrate was trans-
ferred to another flask, cooled down to –30 °C, and to it was added
dropwise a cold freshly prepared 2.7 M MeNH2 in CH2Cl2 solution (30
mL, 80 mmol). The mixture was allowed to warm to r.t. and stirred
overnight. The precipitate of MeNH3+Br– was filtered off and washed
with CH2Cl2 (3 × 10 mL). The combined filtrate was concentrated to ~7
mL, the white precipitate was filtered off and washed with cold
CH2Cl2 (3 × 2 mL) and dried under vacuum to give Ph2P(NHMe)(N-p-
Tol) (1a) (3.94 g). The mother liquor was evaporated to dryness, then
extracted with warm Et2O (3 × 10 mL) and filtered off. The filtrate was
concentrated to 10 mL, the precipitate was filtered off and washed
with Et2O (2 × 2 mL) and dried under vacuum to give a second crop of
0.69 g. Total yield: 4.63 g (72%).
Ph2P(NHMe)(N-2,6-iPr2C6H3) (1c)
Synthesized analogously from 2,6-diisopropylaniline (3.75 mL, 3.54 g,
20 mmol). After filtering off the MeNH3Br salt, the filtrate was evapo-
rated to dryness and the residue was extracted with benzene (~40
mL). The benzene suspension was filtered to remove residual ammo-
nium salts and was concentrated to 3 mL followed by treating with
Et2O (10 mL). The solution was left to crystallize in the fridge over-
night. The crystalline solid obtained was filtered off, washed with
cold Et2O (2 × 3 mL) and dried under vacuum; yield: 2.32 g (59%).
IR (KBr): 3356, 3076, 3051, 2978, 2956, 2860, 1585, 1462, 1432, 1380,
1339, 1290, 1119, 1097, 1028 cm–1
IR (ATR): 3354 cm–1 (NH).
.
1H NMR (CDCl3):  = 7.76 (dd, 3JHH = 8.0 Hz, 3JHP = 12.0 Hz, 4 H, o-HPh),
7.35 (d, 3JHH = 7.6 Hz, 2 H, m-C6H3), 7.19 (overlap. m, 2 H, p-HPh), 7.14
(overlap m, 4 H, m-HPh), 6.88 (overlap, 1 H, p-C6H3), 3.78 (sept,
3
3
3JHH = 6.8 Hz, 2 H, CHMe2), 2.40 (dd, JHP = 11.6 Hz, JHH = 6.0 Hz, 3 H,
IR (KBr): 3056, 2913, 2810, 1607, 1502, 1436, 1294, 1273, 1117, 1099,
3
3
NHMe), 2.10 (dq, JHP = 9.6 Hz, JHH = 5.6 Hz, 1 H, NH), 1.36 (d,
1025 cm–1
.
3JHH = 6.8 Hz, 12 H, CHMe2).
IR (ATR): 3356 cm–1 (NH).
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

F
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
2
13C NMR (CDCl3):  = 144.1 (d, JCP = 1.8 Hz, i-C-NDiip), 142.3 (d,
successive drying under vacuum; yield: 7.1 g (80%). The elemental
analysis well corresponds to a 85:15 mixture of bromide and chloride
salts.
3JCP = 6.3 Hz, i-C-iPrDiip), 132.2 (d, JCP = 127 Hz, i-CPh), 132.1 (d,
1
4
2JCP = 9.2 Hz, o-CHPh), 131.3 (d, JCP = 2.7 Hz, p-CHPh), 128.5 (d,
4
3JCP = 12.4 Hz, m-CHPh), 122.6 (d, JCP = 2.2 Hz, m-CHDiip), 119.2 (d,
IR (KBr): 3025, 2974, 2804, 1710, 1612, 1515, 1439, 1422, 1391, 1356,
5JCP = 3.2 Hz, p-CHDiip), 28.2 (s, CHMe2), 27.4 (d, JCP = 1.7 Hz, NHMe),
2
1278, 1223, 1193, 1116, 1067, 1053, 1026, 952 cm–1
.
23.9 (s, CHMe2).
31P NMR (CDCl3):  = –7.6.
2
1H NMR (CDCl3):  = 9.38 (d, JHP = 12.8 Hz, 1 H, NHTol), 8.19 (dd,
3
3
3JHH = 7.6 Hz, JHP = 13.2 Hz, 4 H, o-HPh), 7.55 (t, JHH = 7.2 Hz, 2 H, p-
Anal. Calcd for C25H31N2P: C, 76.89; H, 8.00; N, 7.17. Found: C, 76.94;
H, 8.04; N, 7.11.
H
Ph), 7.46 (td, 3JHH = 7.2 Hz, 4JHP = 3.6 Hz, 4 H, m-HPh), 7.25 (d, 3JHH = 8.0
Hz, 2 H, C6H4), 6.83 (d, 3JHH = 8.0 Hz, 2 H, C6H4), 5.79 (d, 2JHP = 10.8 Hz,
1 H, NHBut), 2.28 (s, 3 H, MeTol), 1.25 (s, 9 H, tBu).
Synthesis of Ph2P(NHtBu)(N-p-Tol) (1d); Method A
13C NMR (CDCl3):  = 135.6 (d, 2JCP = 1.5 Hz, i-C-NTol), 133.8 (d, 4JCP = 2.7
Hz, p-CHPh), 132.8 (d, 2JCP = 11.6 Hz, o-CHPh), 132.7 (s, i-C-MeTol), 129.6
The monoaminophosphorane [Ph2PBr(NH-p-Tol)]Br (20 mmol) was
prepared in situ and separated from p-TolNH3+Cl– precipitate, as de-
scribed above. To this solution an excess of t-BuNH2 (8.4 mL, 5.85 g,
80 mmol) was added and the mixture was refluxed for 70 h. The pre-
cipitate of t-BuNH3Br was filtered off and washed with CH2Cl2 (3 × 10
mL). The filtrate was evaporated to dryness, the residue was extracted
with Et2O (3 × 20 mL) and the resulting solution was kept in the fridge
overnight. The precipitate was filtered off and discarded, the filtrate
was concentrated to 20 mL and left in the fridge overnight again to
give crude product, which was then recrystallized twice (Et2O) and
dried under vacuum to give pure Ph2P(NHtBu)(N-p-Tol); yield: 1.05 g
(15%).
3
1
(s, -CTol), 129.4 (d, JCP = 14.0 Hz, m-CHPh), 125.1 (d, JCP = 128 Hz, i-
C
Ph), 121.3 (d, 3JCP = 7.3 Hz, -CTol), 55.9 (d, 2JCP = 3.8 Hz, CMe3), 31.5 (d,
3JCP = 4.4 Hz, CMe3), 20.7 (s, MeTol).
31P NMR (CDCl3):  = 27.0.
Anal. Calcd for C23H28Br0.85Cl0.15N2P: C, 63.26; H, 6.46; N, 6.41; Br,
15.55. Found: C, 63.39; H, 6.49; N, 6.46; Br, 15.5.
[Ph2P(NHtBu)(NH-o-Tol)]Br (3e)
Synthesized analogously from o-toluidine (4.4 mL, 4.44 g, 41.2 mmol).
The work up procedure was the same except that the crystallization
from CH2Cl2 gave a solvate, from which the solvent molecule cannot
be removed even after drying under vacuum for 2 d at 50 °C; yield: 7.8
g (77%).
IR (KBr): 3340, 3072, 3052, 2978, 2960, 2920, 1605, 1505, 1440, 1381,
1336, 1219, 1111, 1052, 985 cm–1
IR (ATR): 3338 cm–1 (NH).
.
IR (KBr): 3054, 2970, 2762, 1606, 1588, 1495, 1439, 1397, 1374, 1288,
1H NMR (CDCl3):  = 8.01 (dd, 3JHH = 6.8 Hz, 3JHP = 10.8 Hz, 4 H, o-HPh),
7.37–7.46 (m, 6 H, m-HPh, p-HPh), 6.92 (d, 3JHH = 8.0 Hz, 2 H, C6H4), 6.86
(d, 3JHH = 8.0 Hz, 2 H, C6H4), 2.95 (d, 2JHP = 6.4 Hz, 1 H, NH), 2.24 (s, 3 H,
MeTol), 1.21 (s, 9 H, CMe3).
1268, 1243, 1229, 1188, 1114, 1052, 1025, 964 cm–1
.
2
1H NMR (CDCl3):  = 8.73 (d, JHP = 9.6 Hz, 1 H, NHTol), 8.03 (dd,
3
3
3JHH = 7.6 Hz, JHP = 13.2 Hz, 4 H, o-HPh), 7.64 (t, JHH = 7.2 Hz, 2 H, p-
H
Ph), 7.53 (td, 3JHH = 7.2 Hz, 4JHP = 3.6 Hz, 4 H, m-HPh), 7.05 (d, 3JHH = 7.2
1
13C NMR (CDCl3):  = 148.6 (s, i-C-NTol), 134.5 (d, JCP = 128 Hz, i-CPh),
Hz, 1 H, C6H4), 6.94 (t, 3JHH = 7.2 Hz, 1 H, C6H4), 6.86 (d, 3JHH = 7.2 Hz, 1
H, C6H4), 6.76 (d, 3JHH = 7.2 Hz, 1 H, C6H4), 6.11 (s, 1 H, NHBut), 2.37 (s,
3 H, MeTol), 1.20 (s, 9 H, tBu).
132.1 (d, 2JCP = 9.0 Hz, o-CHPh), 131.1 (d, 4JCP = 1.9 Hz, p-CHPh), 129.3 (s,
3
-CHTol), 128.5 (d, JCP = 12.3 Hz, m-CHPh), 126.2 (s, i-C-MeTol), 123.7
3
(d, JCP = 20.0 Hz, -CHTol), 52.8 (s, CMe3), 32.2 (s, CMe3), 20.7 (s,
4
13C NMR (CDCl3):  = 135.5 (s, i-C-MeTol), 134.3 (d, JCP = 1.7 Hz, p-
NHMe).
31P NMR (CDCl3):  = –3.7.
CHPh), 134.0 (d, 2JCP = 7.2 Hz, i-C-NTol), 133.2 (d, 2JCP = 11.4 Hz, o-CHPh),
131.3 (s, m-CHTol), 129.4 (d, 3JCP = 13.7 Hz, m-CHPh), 125.9 (d, 1JCP = 124
Hz, i-CPh), 125.5 (s, m′-CHTol), 124.7 (s, p-CHTol), 124.4 (d, 3JCP = 3.1 Hz,
o-CHTol), 55.5 (d, 2JCP = 3.0 Hz, CMe3), 31.6 (d, 3JCP = 4.1 Hz, CMe3), 19.4
(s, MeTol).
Anal. Calcd for C23H27N2P: C, 76.22; H, 7.51; N, 7.73. Found: C, 76.09;
H, 7.41; N, 7.51.
Synthesis of Ph2P(NHtBu)(N-p-Tol) (1d); Typical Procedure for the
Synthesis of Ph2P(NHtBu)(NAr) (1d, Ar = p-Tol; 1e, Ar = o-Tol) by
Method B
31P NMR (CDCl3):  = 29.7.
Anal. Calcd for C23H28BrN2P·0.8CH2Cl2: C, 55.91; H, 5.84; N, 5.48.
Found: C, 55.94; H, 5.91; N, 5.41.
[Ph2P(NHtBu)(NHp-Tol)]Br (3d); Typical Procedure
Ph2P(NHtBu)(N-p-Tol) (1d) by Deprotonation of 3d; Typical Proce-
To a solution of Ph2PCl (3.6 mL, 4.42 g, 20 mmol) in CH2Cl2 (15 mL), a
solution of Br2 (1.0 mL, 3.2 g, 20 mmol) in CH2Cl2 (15 mL) was added
dropwise. The mixture was stirred for 1.5 h at r.t. to give a suspension,
to which a solution of t-BuNH2 (4.2 mL, 2.93 g, 40 mmol) in CH2Cl2
(15 mL) was added over 30 min. The mixture was stirred overnight,
then the precipitate was filtered off and washed with CH2Cl2 (2 × 5
mL). A solution of p-toluidine (4.28 g, 40 mmol) in CH2Cl2 (30 mL) was
added dropwise to the combined filtrate at r.t. and the suspension
formed was left overnight. The precipitate was filtered off, washed
with CH2Cl2 (3 × 10 mL) and discarded. The filtrate was evaporated to
dryness, the residue was dissolved in acetone (40 mL) and left for
overnight in the fridge. The white crystalline formed was filtered off,
washed with acetone (3 × 7 mL) and dried under vacuum to give ace-
tone solvate 3d·0.5Me2CO. The solvent-free product was then ob-
tained by precipitating it from CH2Cl2 solution with excess Et2O and
dure for 1d,e
To a suspension of 3d (0.88 g, 2.0 mmol) in benzene (40 mL) neat
Et2NH (0.22 mL, 0.155 g, 2.1 mmol) was added, and the mixture was
stirred at r.t. for 2 h. The precipitate of Et2NH2Br was filtered off and
washed with benzene (3 × 3 mL). The filtrate was evaporated and the
residue was dried in vacuo; yield: 0.72 g (~100%).
Ph2P(NHtBu)(N-o-Tol) (1e)
Obtained analogously from 3e (0.88 g, 2.0 mmol); yield: 0.70 g (98%).
IR (KBr): 3317, 3076, 3058, 2972, 2960, 2921, 1590, 1484, 1437, 1339,
1220, 1121, 1059, 990 cm–1
IR (ATR): 3315 cm–1 (NH).
.
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

G
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
3
3
4
1H NMR (C6D6):  = 8.07 (ddd, JHH = 7.6 Hz, JHP = 11.6 Hz, JHH = 2.0
Then a solution of 2,6-diisopropylaniline (11.3 mL, 10.62 g, 60 mmol)
in CH2Cl2 (40 mL) was added dropwise to the suspension of Ph2PClBr2,
and the mixture was stirred overnight. The precipitated ammonium
salt was filtered off and washed with CH2Cl2 (3 × 20 mL). The filtrate
was evaporated to dryness and the residue was dissolved in hexane
(30 mL). The precipitate of residual ammonium salt and aminophos-
phine oxide Ph2P(O)(NH-2,6-Diip) was filtered off and discarded, the
filtrate was evaporated and the oily residue was dried under vacuum;
yield: 8.4 g (80–85% purity) (out of 8.8 g in theory).
Hz, 4 H, o-HPh), 7.43 (d, 3JHH = 7.2 Hz, 1 H, C6H4), 7.12 (t, 3JHH = 7.2 Hz, 1
H, C6H4), 7.00–7.06 (m, 6 H, m-HPh, p-HPh), 6.92 (t, JHH = 7.2 Hz, 1 H,
3
3
C6H4), 6.88 (d, JHH = 7.2 Hz, 1 H, C6H4), 2.88 (s, 3 H, MeTol), 2.62 (d,
2JHP = 6.8 Hz, 1 H, NH), 1.01 (s, 9 H, tBu).
13C NMR (C6D6):  = 149.8 (s, i-C-NTol), 135.3 (d, JCP = 127 Hz, i-CPh),
1
3
2
132.9 (d, JCP = 24.8 Hz, i-C-MeTol), 132.1 (d, JCP = 9.0 Hz, o-CHPh),
131.7 (s, m′-CHTol), 130.4 (d, 4JCP = 1.8 Hz, p-CHPh), 128.3 (d, 3JCP = 12.3
Hz, m-CHPh), 125.9 (s, m-CHTol), 122.1 (d, 3JCP = 11.4 Hz, o-CHTol), 117.7
(s, p-CHTol), 52.4 (s, CMe3), 31.6 (d, 3JCP = 3.6 Hz, CMe3), 20.0 (s, MeTol).
3
3
1H NMR (C6D6):  = 7.77 (dd, JHH = 7.2 Hz, JHP = 14.4 Hz, 4 H, o-HPh),
7.20 (d, 3JHH = 7.8 Hz, 2 H, m-C6H3), 7.09 (td, 3JHH = 7.8 Hz, 5JHP = 1.2 Hz,
31P NMR (C6D6):  = –6.5.
3
3
1 H, p-C6H3), 6.97 (t, JHH = 7.2 Hz, 2 H, p-HPh), 6.92 (td, JHH = 7.2 Hz,
Anal. Calcd for C23H27N2P: C, 76.22; H, 7.51; N, 7.73. Found: C, 76.29;
H, 7.54; N, 7.43.
4JHP = 4.8 Hz, 4 H, m-HPh), 3.68 (sept, JHH = 6.6 Hz, 2 H, CHMe2), 1.22
3
(d, 3JHH = 6.6 Hz, 12 H, CHMe2).
13C NMR (C6D6):  = 141.6 (br d, 3JCP = 10.0 Hz, i-C-iPrDiip), 140.3 (s, i-C-
Ph2P(NH-o-Tol)(N-p-Ts) (1f)
1
N
Diip), 133.6 (d, JCP = 126 Hz, i-CPh), 132.0 (s, p-CHPh), 131.5 (d,
To a solution of Ph2PCl (1.80 mL, 2.21 g, 10 mmol) in CH2Cl2 (10 mL), a
solution of Br2 (0.5 mL, 1.56 g, 10 mmol) in CH2Cl2 (10 mL) was added
dropwise with stirring at r.t., and the mixture was stirred for 1.5 h.
Then the suspension of Ph2PClBr2 formed was cooled down to 0 °C
and a solution of o-toluidine (2.13 mL, 2.14 g, 20 mmol) in CH2Cl2 (15
mL) was added dropwise over 0.5 h. The mixture was allowed to
warm up to r.t. and stirred overnight. The precipitated o-TolNH3+Cl–
was filtered off under argon and washed with CH2Cl2 (3 × 10 mL); the
filtrate was reacted further with suspension of p-TsNHNa in THF pre-
pared in situ by treating p-TsNH2 (3.42 g, 20 mmol) with NaH (0.80 g,
60% suspension in oil, 20 mmol) in THF (100 mL) at r.t. overnight. The
suspension was refluxed for ~35 h, then hot mixture was filtered
through a G4 fritted glass filter, and the solid was washed with hot
THF (3 × 20 mL). The filtrate was concentrated to ~10 mL and was left
in the fridge overnight. The precipitate was filtered off, washed with
cold THF (3 × 3 mL) and dried under vacuum to give the product (1.9
g). An additional crop of the product was obtained by treating the
mother liquor solution with Et2O (10 mL). The product was recrystal-
lized (THF) to give pure 1 as off-white microcrystalline; yield: 2.81 g
(61%).
2JCP = 11.1 Hz, o-CPh), 128.5 (d, 3JCP = 14.6 Hz, m-CPh), 123.3 (d, 4JCP = 3.0
Hz, m-CHDiip), 121.9 (br s, p-CHDiip), 28.7 (s, CHMe2), 23.9 (s, CHMe2).
31P NMR (C6D6):  = –3.1.
MS (EI, 70 eV): m/z (%) = 439 (10) [M] (4c), 395 (60) [M′] (4c′), 377
(40) [M – Br + OH], 359 (100) [M – HBr].
Funding Information
This work was supported by the Russian Science Foundation (grant
No. 19-13-00459). NMR studies, spectral characterization, elemental
analysis were performed with the financial support from Ministry of
Science and Higher Education of the Russian Federation using the
equipment of Center for molecular composition studies of INEOS RAS.
R
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Supporting Information
Supporting information for this article is available online at
IR (KBr): 3378, 3240, 3056, 2917, 1602, 1584, 1496, 1442, 1388, 1375,
https://doi.org/10.1055/s-0039-1690242.
S
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o
n
1268, 1242, 1191, 1141, 1119, 1110, 1086, 949 cm–1
IR (ATR): 3250 cm–1 (NH).
.
References
1H NMR (CDCl3):  = 7.92 (dd, 3JHH = 7.6 Hz, 3JHP = 13.6 Hz, 4 H, o-HPh),
3
3
5
7.57 (d, JHH = 8.0 Hz, 2 H, SO2C6H4), 7.54 (td, JHH = 7.6 Hz, JHP = 1.6
(1) (a) Kögel, J. F.; Kneusels, N.-J.; Sundermeyer, J. Chem. Commun.
2014, 50, 4319. (b) Gao, X.; Han, J.; Wang, L. Org. Lett. 2015, 17,
4596.
3
4
Hz, 2 H, p-HPh), 7.44 (td, JHH = 7.2 Hz, JHP = 4.0 Hz, 4 H, m-HPh), 7.10
(d, 3JHH = 7.6 Hz, 1 H, o-HTol), 6.97 (d, 3JHH = 8.0 Hz, 2 H, SO2C6H4), 6.82
(t, 3JHH = 7.6 Hz, 1 H, p-HTol), 6.68 (t, 3JHH = 7.6 Hz, 1 H, m-HTol), 6.57 (d,
(2) (a) Keim, W.; Appel, R.; Storeck, A.; Krüger, C.; Goddard, R.
Angew. Chem., Int. Ed. Engl. 1981, 20, 116; Angew. Chem. 1981,
93, 11191. (b) Schubbe, R.; Angermund, K.; Fink, G.; Goddard, R.
Macromol. Chem. Phys. 1995, 196, 467. (c) Stapleton, R. L.; Chai,
J.; Taylor, N. J.; Collins, S. Organometallics 2006, 25, 2514.
(d) Collins, S.; Ziegler, T. Organometallics 2007, 26, 6612.
(e) Stapleton, R. A.; Chai, J.; Nuanthanom, A.; Flisak, Z.; Nele, M.;
Ziegler, T.; Rinaldi, P. L.; Soares, J. B. P.; Collins, S. Macromole-
cules 2007, 40, 2993. (f) Vollmerhaus, R.; Shao, P.; Taylor, N. J.;
Collins, S. Organometallics 1999, 18, 2731. (g) Tomaszewski, R.;
Vollmerhaus, R.; Al-Humydi, A.; Wang, Q.; Taylor, N. J.; Collins,
S. Can. J. Chem. 2006, 84, 214.
(3) Li, S.; Miao, W.; Tang, T.; Dong, W.; Zhang, X.; Cui, D. Organome-
tallics 2008, 27, 718.
(4) (a) Albahily, K.; Fomitcheva, V.; Gambarotta, S.; Korobkov, I.;
Murugesu, M.; Gorelsky, S. I. J. Am. Chem. Soc. 2011, 133, 6380.
(b) Albahily, K.; Fomitcheva, V.; Shaikh, Y.; Sebastiao, E.;
Gorelsky, S. I.; Gambarotta, S.; Korobkov, I.; Duchateau, R.
2
3JHH = 7.6 Hz, 1 H, m′-HTol), 5.74 (d, JHP = 5.2 Hz, 1 H), 2.36 (s, 3 H,
MeTs), 2.28 (s, 3 H, MeTol).
13C NMR (CDCl3):  = 142.6 (s, i-C-STs), 140.8 (s, i-C-MeTs), 135.6 (d,
4
2JCP = 1.5 Hz, i-C-NTol), 133.1 (d, JCP = 2.8 Hz, p-CHPh), 132.4 (d,
3
2JCP = 10.8 Hz, o-CHPh), 130.7 (s, p-CHTol), 129.1 (d, JCP = 13.7 Hz, m-
CHPh), 128.1 (d, 1JCP = 132 Hz, i-CPh), 128.7 (s, CHTs), 127.7 (d, 3JCP = 8.1
Hz, i-C-Me), 126.6 (s, m′-CHTol), 125.9 (s, CHTs), 122.9 (s, m-CHTol),
119.5 (d, 3JCP = 4.2 Hz, o-CHTol), 21.4 (s, MeTs), 18.0 (s, MeTol).
31P NMR (CDCl3):  = 12.1.
Anal. Calcd for C26H25N2O2PS: C, 67.81; H, 5.47; N, 6.08. Found: C,
67.81; H, 5.53; N, 6.11.
Ph2PBr(N-2,6-iPr2C6H3) (4c)
To a solution of Ph2PCl (3.60 mL, 4.42 g, 20 mmol) in CH2Cl2 (15 mL), a
solution of Br2 (1.0 mL, 3.2 g, 20 mmol) in CH2Cl2 (15 mL) was added
dropwise with stirring at r.t., and the mixture was stirred for 1.5 h.
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–H

H
T. A. Peganova, A. M. Kalsin
Paper
Synthesis
Organometallics 2011, 30, 4201. (c) Albahily, K.; Licciulli, S.;
Gambarotta, S.; Korobkov, I.; Chevalier, R.; Schuhen, K.;
Duchateau, R. Organometallics 2011, 30, 3346.
(12) (a) Scherer, O. J.; Klusmann, P. Angew. Chem., Int. Ed. Engl. 1968,
7, 541; Angew. Chem. 1968, 80, 560. (b) Scherer, O. J.; Schieder,
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