Transformations of diphenylphosphinothioic acid tertiary amides mediated by directed ortho metallation

Article abstract of DOI:10.1039/c2ob25395j

ortho-Lithiation of N,N-diisopropyl-P,P-diphenylphosphinothioic amide using n-BuLi in the presence of TMEDA in diethyl ether followed by electrophilic trapping is described as an efficient method for the synthesis of ortho-functionalised derivatives in high yields. The structural modification of the phosphinothioic amide includes C-X (X = P, S, Si, Sn, I) and C-C bond forming reactions with a large variety of electrophiles. Additional applications based on functional group transformations are also reported. They include imine formation, desulfurization and Suzuki cross-coupling reactions on selected compounds.

Full text of DOI:10.1039/c2ob25395j

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PAPER
Transformations of diphenylphosphinothioic acid tertiary amides mediated
by directed ortho metallation†‡
Hajar el Hajjouji,a Eva Belmonte,a Jesús García-López,a Ignacio Fernández,a María José Iglesias,a
Laura Roces,b,c Santiago García-Granda,b Anas El Laghdachd and Fernando López Ortiz*a
Received 23rd February 2012, Accepted 1st June 2012
DOI: 10.1039/c2ob25395j
ortho-Lithiation of N,N-diisopropyl-P,P-diphenylphosphinothioic amide using n-BuLi in the presence of
TMEDA in diethyl ether followed by electrophilic trapping is described as an efficient method for the
synthesis of ortho-functionalised derivatives in high yields. The structural modification of the
phosphinothioic amide includes C–X (X = P, S, Si, Sn, I) and C–C bond forming reactions with a large
variety of electrophiles. Additional applications based on functional group transformations are also
reported. They include imine formation, desulfurization and Suzuki cross-coupling reactions on selected
compounds.
1. Introduction
Directed ortho metallation (DoM) through an organolithium
base followed by electrophilic quench is a well established
method for the rational elaboration of aromatic rings.1,2 The
lithiation is promoted by a Directing Metallation Group (DMG).
This is a polar functional group that determines the reaction con-
ditions suitable for performing the deprotonation and the regio-
selectivity that can be achieved. In contrast to the extensively
investigated applications of carbon-based DMGs, mainly tertiary
carboxamide3,2c,h and oxazoline4 groups, the structural modifi-
cation of P-aryl rings via DoM reactions is less developed. The
PvO group of phosphine oxides is perhaps the phosphorus-
based DMG most studied.5 DoM reactions of phosphine oxides
in combination with aryl-coupling reactions represent a valuable
Fig. 1 P-Based DMGs.
method for synthesising chelating diphosphines containing an
atropisomeric biaryl scaffold. These compounds have found
widespread uses as chiral ligands in asymmetric catalysis.6 Other
P-based functional groups showing the ability of participating in
DoM reactions of a P-phenyl ring are phosphine–borane
complexes,7 phosphorus ylides,5a,8 phosphazenes,9 phosphinic10
and phosphinothioic amides,11 phosphonates12 and phosphonic13
and thiophosphonic amides.14 They are represented in Fig. 1,
together with the most accepted mechanism of DoM reactions,
the so called complex-induced proximity effect (CIPE).15 In this
model, the reactive groups are brought into proximity before the
actual deprotonation takes place by forming a complex due to
the coordination of the lithium ion of the base to the DMG of
the substrate.
Besides the classical applications of ortho anions 1 in carbon–
carbon and carbon–heteroatom bond-forming reactions via elec-
trophilic quench to give derivatives 2 (Scheme 1), ortho-lithiated
compounds bearing a PvX (X = N, O and S) group have been
used as C,X chelating ligands. Lithium/metal transmetallation
reactions of these anions with a variety of metal halides afford
complexes 3 containing five-membered metallacycles in which
aÁrea de Química Orgánica, Universidad de Almería, Carretera de
Sacramento, 04120 Almería, Spain. E-mail: flortiz@ual.es;
Fax: +34 950015481; Tel: +34 950015478
bDepartamento de Química Física y Analítica, Universidad de Oviedo,
Avda. Julián Clavería 8, 33006, Spain
cServicios Científico Técnicos, Universidad de Oviedo, 33006 Oviedo,
Spain
dDépartement de Chimie, Faculté des Sciences, Université Abdelmalek
Essaâdi, BP. 2121, Mhannech II, 93002 Tétouan, Morocco
†Dedicated to Prof. F. Palacios on occasion of his 60th birthday.
1
‡Electronic supplementary information (ESI) available: H, 13C and 31P
NMR spectra of the new products and crystallographic data for 9 and 12.
CCDC 847136 (9), 847125 (12). For ESI and crystallographic data in
CIF or other electronic format see DOI: 10.1039/c2ob25395j
This journal is © The Royal Society of Chemistry 2012
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phosphinothioic amides was required. Here, we describe a
general method for the directed ortho lithiation of these organo-
phosphorus compounds, the introduction into the N–P(vS)-
phenyl framework of large structural diversity through reaction
of the ortho anion with a variety of electrophiles (alkyl,
tin, silicon, and phosphorus halides, sulfur, diiodoethane,
benzaldehyde, benzophenone and DMF) and the conversion of
ortho-functionalised products into more elaborated molecules
via functional group transformation reactions (condensation,
desulfurization and cross-coupling). Chiral phosphinothioic
amides were also investigated. However, ortho-lithiation
proceeded without diastereoselectivity.
Scheme 1 Synthetic applications of ortho-lithiated organophosphorus
compounds.
2. Results and discussion
Optimisation of the DoM reaction of 7
As the onset of our work we sought to replace the expensive and
hazardous t-BuLi by the more convenient alkyllithium bases
s-BuLi or n-BuLi. Decreasing the size of the base may favor the
nucleophilic attack to the phosphorus leading to products of type
6. In order to minimize this competing reaction we selected N,N-
diisopropyl-P,P-diphenylphosphinothioic amide 7 as starting
material. The bulky isopropyl groups would hinder the approach
of the base to the electrophilic phosphorus center and the
absence of N–Me or N–CH2Ph groups (present in 4a and 4b)
would preclude the possibility of lithiation at the N–Cα posi-
tion.19 Compound 7 was prepared in a yield of 55% by refluxing
diisopropylamine and chlorodiphenylphosphine in toluene in the
presence of triethylamine during 2 h followed by reaction with
elemental sulfur overnight.20
The performance of the lithiation of 7 was established by
quenching the anion with Me3SnCl. It is a very good electrophile
that proved to be very efficient for trapping ortho-lithiated phos-
phinic amides.10g The results of the optimisation of the DoM
reaction of 7 are shown in Table 1. The first attempt of ortho-
lithiation with s-BuLi in THF at 0 °C during 2 h was unsatisfac-
tory. The desired product was formed in a conversion of 6%
Scheme 2 DoM of phosphinothioic amides under the conditions of
Yoshifushi et al.11.
the strength of the X⋯M bond can be tuned to the donor ability
of the heteroatom present in the PvX moiety. Examples of this
chemistry have been reported for almost all PvX derivatives
mentioned above, the exceptions being phosphonic amides and
phosphinothioic amides.
The previous description shows that efficient DoM processes
have been established for the phosphorus-based DMGs included
in Fig. 1 and the elaboration of the corresponding anions pro-
vided access to a great chemical diversity. The only exception is
the phosphinothioic amide group. Yoshifuji et al.11 achieved the
ortho-lithiation of diphenylphosphinothioic amides 4 by treat-
ment with an excess of tert-butyllithium in dimethoxymethane
in the presence of one equivalent of TMEDA at −10 °C
(Scheme 2). The site of lithiation was identified by quenching
the anion with D2O and MeI. In this way, compounds 5 were
obtained in moderate to good yield. Using s-BuLi as base pro-
duced a decrease in the reaction yield (15% of 5b). Most impor-
tantly, in the reaction of 4c with n-BuLi (in THF) followed by
quenching with MeI only the product of nucleophilic attack of
the base to the phosphorus atom and subsequent PCα-methyl-
ation 6 was observed.
Table 1 Optimisation of the ortho-lithiation-stannilation of
phosphinothioic amide 7
To the best of our knowledge, no further uses of ortho-lithium
phosphinothioic amides in organic and organometallic chemistry
have been reported. However, some features of the N–PvS
functional group make it attractive for synthetic applications
with respect to the N–PvO analogues. Desulfurization16 can be
achieved under milder reaction conditions than deoxygenation of
phosphinic amides to give P(III) derivatives17 and the presence of
the soft sulfur atom may enhance the selectivity for coordinating
to soft metal ions.18
Entry RLi
Solvent t1 (h) T1 (°C)
t2 (h) T2 (°C) 9(%)a
1
2
3
4
5
6
7
8
s-BuLi THFb
2
1
2
2
2
2
2
2
0
−90
2
0.5
0
−90
−15
−15
0
6
0
n-BuLi Toluene
n-BuLi Toluene
n-BuLi Toluene
n-BuLi Toluene
n-BuLi Et2O
−90 → −15 0.5
30
74
74
93
96
71
−15
0
2
2
2
2
2
−90 → 0
0
0
0
0
0
n-BuLi Et2O
n-BuLi Et2Ob
We have reported the use of ortho-lithiated phosphazenes9g
and phosphinic amides10d as C–C–P–X pincer ligands (X = N, O).
In order to explore the coordination properties of the analogous
C–C–P–S system an efficient procedure for the DoM of
a Conversion established on the basis of the 31P{1H}-NMR spectrum of
the crude reaction product. b TMEDAwas not used.
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Table 2 Products of ortho-lithiation-electrophilic trapping of
phosphinothioic amide 7
(entry 1). Next, we decided to apply DoM conditions similar to
those successfully employed in the asymmetric ortho-deprotona-
tion of phosphinic amides,10g i.e., n-BuLi was used as base in
toluene at −90 °C in the presence of 5 equiv of TMEDA as
achiral surrogate of the chelating diamine (−)-sparteine (entry 2).
After quenching the reaction at −90 °C unchanged 7 was fully
retrieved. When the reaction was repeated and allowed to reach
−15 °C ortho-stannylated 9 was obtained in a conversion of
30% (entry 3). Conversion increases to 74% when both the
lithiation and quench steps are performed at −15 °C (entry 4).
Raising the temperature of the process to 0 °C leads to the same
conversion (entry 5). Significantly, at this rather high temperature
for a lithiation reaction the phosphinothioic amide DMG resists
attack by the base. Phosphine thioxides structurally similar to 6
are not observed. This suggests that TMEDA coordinates to the
Li ion of the base to give a bulky complex [n-BuLi·TMEDA]n
that cannot access the phosphorus atom blocked by the large
NiPr2 moiety.21 Since n-BuLi exists as a bis-TMEDA-solvated
dimer in Et2O/TMEDA solutions,22 we also assayed the DoM
reaction of 7 with this combination of reagents and solvent.
Phosphinothioic amide 7 and n-BuLi in Et2O in the presence of
5 equiv of TMEDA were mixed at −90 °C and the temperature
was allowed to rise to 0 °C during 2 h. The subsequent addition
of Me3SnCl furnished the desired product 9 in a conversion of
93% (entry 6). The precautionary use of low temperature is not
necessary. When the reaction was performed at 0 °C under other-
wise the same experimental conditions, compound 9 was
obtained in a conversion of 96% (entry 7). Moreover, the
process can be carried out in a 1 g scale with the same efficiency
(conversion of 97%). The use of a relatively large amount of the
complexing agent (5 equiv) seems to be necessary, since the
conversion decreased to 71% when only 2 equiv of TMEDA
were employed (entry 8).
Entry E+
E
Comp. Conv. (%) Yield (%)
1
2
3
4
5
6
7
8
Me3SnCla
Me3Sn
Me2SnCl
Me3Si
Ph2P
I
SH
SCH2Ph
Me
Et
CHvO
PhCHOH 19
Ph2C–O 20
9
97
50
76
70
80
40
65
64
a,b
Me2SnCl2
Me3SiCl
Ph2PClc
ICH2CH2I
S8
S8 + BnBr
MeI
10
11
12
13
14
15
16
17
18
94
70
71d
82
35 (19)e
69
100
50
100
98g
100
82
38
78
52
9
EtI
10
11
12
DMFf
PhCHvO
Ph2CvOh
88
a Reaction time with the electrophile of 2 h. b 1.8 Equiv of electrophile
were used. c Reaction time with the electrophile of 3 h. d 12% Of a
mixture of P-epimeric disulfides 21 (meso : rac, ratio of 1 : 1) was also
obtained. e Chromatographic purification produced the dimerization of
thiol 14 to give disulfide 21. f 3 Equiv of electrophile were used.
g Mixture of diastereoisomers in a ratio 18 : 82. h 5 Equiv of electrophile
were used.
The standard quenching conditions consisted of treating anion
8 with 1.5 equiv of electrophile during 30 min at 0 °C. In some
cases, the amount of electrophile added and the time of contact
with the anion were slightly varied to improve the performance
of the synthesis. Purification of the desired compounds was
achieved by flash column chromatography. Carbon–heteroatom
bond forming reactions of 8 through halide displacement pro-
cesses were extended to electrophiles such as Me2SnCl2,
Me3SiCl and Ph2PCl (entries 2–4). In this way, the respective
ortho-functionalised phosphinothioic amides 10, 11 and 12 were
obtained in good yields, except for the chlorostannyl derivative
10. After some experimentation, we found that compound 10
could be isolated in an acceptable yield of 40% at best by using
1.8 equiv of electrophile. ortho-Iodination of 8 with 1,2-di-
iodoethane proceeded to give 13 which was isolated in a 70%
yield after purification (entry 5).
The introduction of an SH group was accomplished by
addition of sulfur to the toluene solution of 8. The ortho-
mercapto derivative 14 was formed in a 71% conversion (entry 6),
together with 12% of the disulfide 21 (1 : 1 mixture of two dia-
stereoisomers arising from the chirality of the phosphorus
atoms). Isolation of 14 proved to be cumbersome. Column
chromatography purification on silica gel promoted the conver-
sion of thiol 14 into disulfides 21. Disulfide formation could be
avoided by in situ alkylation with benzyl bromide of the sulfide
generated in the reaction of 8 with S8. This “one-pot” reaction
The structure of 9 was assigned based on the mass spectrum
and NMR data. Some key aspects are the 119Sn satellites
observed in the 31P NMR spectrum (3J
P = 37.9 Hz) and the
119Sn31
presence of three Hortho (δ 7.91 ppm, 2H; δ 8.12 ppm, 1H), two
pairs of diastereotopic methyl groups (δ 1.18 and 1.37 ppm) and
the expected singlet for the SnMe3 group (δ 0.16 ppm) in the
1H NMR spectrum. The results above show that optimal ortho-
lithiation of 7 requires a much higher temperature (0 °C) than the
analogous phosphinic amide (−90 °C),10g which indicates that
the N–PvS group is a less powerful DMG than the N–PvO
moiety. This behavior can be explained based on the CIPE
model. In contrast to the matched pair of hard centers rep-
resented by the combination oxygen/Li+ in DoM of phosphinic
amides, the soft sulfur atom of 7 will co-ordinate weakly to the
hard Li+. As a consequence, a loose complex will be formed
between 7 and the base producing a rather small acidity increase
of the ortho proton through the inductive effect.
ortho-Functionalisation of 7 using DoM methodology
Once experimental conditions were established for the high yield
synthesis of ortho-stannyl diphenylphosphinothioic amide 9 via
DoM of 7, we investigated the scope of the method. With this
aim, the ortho-lithiated species 8 was treated with a variety of
electrophiles providing products 9–18 in moderate to high yields
(Table 2).
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afforded the S-protected compound 15 in 69% isolated yield.
Anion 8 participated also very efficiently in carbon–carbon bond
construction by treatment with a series of C-based electrophiles.
Methyl iodide, dimethylformamide and benzophenone reacted
with 8 quantitatively leading after purification to the ortho-func-
tionalised phosphinothioic amide derivatives 16, 18 and 20,
respectively, in high yields (entries 8, 10 and 12). In the case of
the ketone, the alkoxide generated in the addition of the ortho
anion to the carbonyl group undergoes a cyclocondensation by
attack on the phosphorus atom of the N–PvS moiety and sub-
sequent elimination of the diisopropylamide group yielding the
thiophosphalactone 20. Quenching 8 with benzaldehyde pro-
vided a mixture of two diastereoisomeric hydroxy(phenyl)-
methyl derivatives 19 (conversion of 98%) in a ratio 18 : 82
(entry 11). The major isomer was isolated after precipitation
from diethyl ether in 52% yield. Using ethyl iodide as electro-
phile the reaction reached only 50% conversion (entry 9). The
ortho-ethyl compound 17 was isolated through column chrom-
atography in a 38% yield. All new compounds were character-
ized based on their spectroscopic data. Additionally, the crystal
structures of 9 and 12 were determined through X-ray diffraction
measurements (ESI‡).
The products in Table 2 demonstrate the usefulness of the new
DoM methodology for accessing ortho-functionalised phosphi-
nothioic amides showing wide structural diversity. Furthermore,
these compounds can be considered as precursors for further
manipulations via metal-mediated cross-coupling reactions23 or
functional group transformations for synthesising more complex
molecules.
Scheme 3 Synthesis and DoM-stannylation of 24 and 26.
ortho-Lithiation–stannylation of 24 using standard reaction con-
ditions (Table 2) proceeded with a conversion of 73%. However,
the major product formed 28 (47%) arise from the nucleophilic
attack of the base to the phosphorus and subsequent PCα-stanny-
lation. The ortho-stannylphosphinothioic amides 27 were
obtained in a disapointing conversion of 26% as a mixture of
diastereoisomers in a ratio 1 : 1.3. The formation of 28 suggests
that the phosphorus atom of 24 is more accessible than that of
the diisopropyl derivative 7. This side-reaction would be mini-
mized using the chiral phosphinothioic amide 26 as starting
material.
The DoM reaction of 26 proved to be challenging. Application
of the experimental conditions optimised for 7 (Table 1, entry 7)
afforded a complex mixture of products (conversion of 90%).
The absence of 119Sn satellites in the 31P NMR spectrum of the
crude reaction mixture indicated that neither ortho- nor NCα-
stannylation had taken place. After some trial and error exper-
iments the best results were obtained by treating 26 with n-BuLi
in diethyl ether in the presence of 5 equiv of TMEDA during
12 h at −40 °C followed by addition of Me3SnCl at the same
temperature. After reaction during 2 h, stannanes 29 were
obtained in 36% conversion as a 1 : 1 mixture of diastereo-
isomers (Scheme 3). The same performance was observed when
toluene was used as solvent (conversion of 31%, dr 1 : 1). The
results obtained indicate that the efficient synthesis of chiral
ortho-functionalised phosphinothioic amides requires a different
approach. This topic is currently under investigation.
DoM reaction with chiral phosphinothioic amides 24 and 26
ortho-Lithiation of 7 implies the desymmetrization of the
Ph2PvS moiety. To augment the scope of the DoM process of
phosphinothioic amides we decided to explore the introduction
of asymmetry. We have previously shown that the ortho-lithia-
tion of diphenylphosphinic amides can be carried out both in a
diastereo-10d and enantioselective manner.10g The stereoselecti-
vity observed ranged from low (dr 1 : 1 to 5 : 1) to moderate
(ee 60%). The enantioselective DoM of phosphinic amides is
achieved with [n-BuLi·(−)-sparteine] in toluene at −90 °C, i.e.,
experimental conditions unsuited to the lithiation of 7 (Table 1,
entry 2). Hence, we focused on the asymmetric DoM of chiral
phosphinothioic amides 24 and 26 which contain easily accessi-
ble chiral auxiliaries. Compound 24 was synthesized in a two-
steps process consisting of the reaction of (S)-1-phenylethan-
amine 22 with Ph2PCl followed by treatment with S8 to give
(S)-P,P-diphenyl-N-(1-phenylethyl)phosphinothioic amide 23.
This compound was transformed into the N-methyl derivative 24
via deprotonation with NaH and subsequent addition of MeI
(Scheme 3). The phosphinothioic amide 25 was prepared in 42%
yield through a “one-pot” reaction involving deprotonation of
the C2-symmetric amine (S)-bis((S)-1-phenylethyl)amine 24
with n-BuLi in THF followed by reaction with chlorodiphenyl-
phosphine and subsequent transformation into the PvS deriva-
tive by treatment with S8 (Scheme 3).
Applications of ortho-functionalised thiophosphinic amides
The DoM methodology developed with phosphinothioic amide
7 afforded compounds 9–20 containing functional groups that
can be further elaborated to synthesize more complex molecules.
As for compound 7, Me3SnCl was used as electrophile for
establishing the site and extent of ortho-lithiation of 24 and 26.
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the presence of the metal. The IR and 31P NMR data of the
phosphinothioic amide moiety of 31 and 32 are quite similar.
These results suggest that in complex 32 the ligand is acting as a
bidentate N,O donor.
Aminophosphines are important compounds with applications
in diverse fields.25 This type of products can be accessed via
desulfurization of ortho-functionalised phosphinothioic amides.
Desulfurization of 13 was achieved smoothly through S-methyl-
ation followed by treatment with HMPT (eqn (2)).16f,26 The reac-
tion proceeds quantitatively. Aminophosphine 33 was isolated in
85% yield after chromatographic purification. Finally, the partici-
pation of the ortho-iodo derivative 13 in a palladium-catalyzed
Suzuki cross-coupling reaction was investigated.27 The reaction
of 13 with phenylboronic acid 34 in the presence of 5 mol% of
palladium(II) acetate in toluene at reflux during 48 h affords the
biphenylic compound 35 in a yield of 72%.
3. Conclusions
In conclusion, we have achieved the efficient ortho-lithiation of
phosphinothioic amides through reaction with n-butyllithium in
diethyl ether in the presence of an excess of TMEDA at 0 °C.
Quenching the anion with a variety of carbon- and heteroatom-
centered electrophiles afforded ortho-functionalised derivatives
showing large structural diversity. The ortho substituents intro-
duced in this way include Me3Sn, Me2SnCl, Me3Si, Ph2P, SH,
SCH2Ph, I, Me, Et, CHO, PhCHOH and Ph2C–O. This
methodology provides access to more complex molecules via
additional manipulations. This statement has been demonstrated
via imine formation followed by copper(I) complexation,
desulfurization and cross-coupling reactions on selected
substrates. In all cases, the new derivatives were obtained in high
yield without affecting the thiophosphinic amide moiety. Further
work in progress is aimed at developing alternative methods for
accessing to chiral phosphinothioic amides via DoM reactions
and to extend the applications of the ortho-lithiated species as
pincer C,S ligands for the synthesis of metal complexes
possessing activity as catalysts.
Scheme 4 Condensation, desulfurization and cross-coupling reactions
on ortho-functionalised phosphinothioic amides 13 and 18.
As representative examples of the transformations that can be
performed, we describe here the application of carbaldehyde
derivative 18 to the synthesis of an S,N,O tridentate ligand and
two derivatization reactions of the ortho-iodophosphinothioic
amide 13, namely desulfurization and palladium-catalyzed
Suzuki-coupling reactions (Scheme 4).
Condensation of aldehyde 18 with o-aminophenol in ethanol
as solvent takes place quantitatively in 6 h. Elimination of the
slight excess of aminophenol used via semipreparative HPLC
gives the imine 31 in 88% isolated yield (eqn (1)). Compound
31 can be envisaged as a tridentate ligand having an S,N,O
donor set.24 Preliminary assays on the ability of 31 to coordinate
1
to metal ions were performed in an NMR tube. The H and 31P
Experimental section
NMR spectra of a 1 : 1 mixture of 31 and CuBr in CD2Cl2 solu-
tion showed the presence of a single species. All signals
appeared broadened as compared with the free ligand and the
chemical shifts were very similar to those of 31. The high resolu-
tion mass spectrum of this species is characterized by an ion at
m/z 499.1032 appropriate for the cation (MCu+) of a 1 : 1
complex 32.
Reactions involving organolithium reagents were performed
under an inert atmosphere of nitrogen using Schlenk techniques.
Anhydrous solvents were obtained via elution through a solvent
column drying system. Commercial reagents were distilled prior
to their use, except organolithium bases. TLC was performed on
Merck plates with aluminium backing and silica gel 60 F254
.
Metal–ligand bonding was also supported by the IR and 13C
NMR spectra. The major changes are observed for the azo-
methine group: the IR absorption is shifted to lower wavenum-
bers in the complex (Δν(31–32) = 22 cm−1) and the carbon
signal could not be detected in the 13C NMR spectrum (signal
too broad). Small changes in the OH absorption band in the IR
spectrum and the Cipso linked to the oxygen in the 13C NMR
spectrum of 32 indicate that the oxygen atom is also coordinated
to the metal. The OH signal could not be identified in the
1H NMR spectrum. Most probably it was too wide to be
detected. In contrast, the PvS group seems to be unaffected by
Chromatographic separations were performed through semipre-
parative HPLC or column chromatography using silica gel 60
(40–63 μm). Melting points were recorded on a Büchi B-540
capillary melting point apparatus. Mass spectra were determined
by atmospheric pressure chemical ionization (APCI). High resol-
ution mass spectrometry (HRMS) spectra were measured using a
LC/MSD-TOF
Agilent
Technologies
instrument.
1H
(300.13 MHz), 13C (75.47 MHz) and 31P (121.47 MHz) NMR
spectra were measured on a Bruker Avance DPX300 at room
temperature using CDCl3 or CD2Cl2 as solvent. Chemical shifts
1
are referred to internal tetramethylsilane for H and 13C and to
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external 85% H3PO4 for 31P. IR spectra were run on a FTIR
Mattson Genesis II spectrophotometer. Elemental analyses were
performed in an Elementar Vario Micro analyser.
Hz, C) ppm. 31P NMR (121.47 MHz) δ 63.7 ppm. HRMS (ESI)
calcd for C18H25NPS: 318.1445 (MH+), found: 318.1430.
Synthesis
of
(S)-P,P-diphenyl-N-(1-phenylethyl)phosphi-
nothioic amide 23. The same procedure described for the syn-
thesis of 7 was employed, except that the reaction was
performed at 0 °C during 30 min using (S)-1-phenylethanamine
22 (1.54 mL, 6 mmol) as amine reagent. Yield after chromato-
graphy (ethyl acetate–hexane 1 : 1) 53%. Yellow oil. IR (KBr)
X-Ray crystallographic studies of 9 and 12
A suitable crystal of 9 and 12 was covered in Paratone-N and
mounted onto a micromount. The crystal was transferred directly
to the cold N2 stream at 100 K of a CCD diffractometer with
CuKα (λ = 1.54184 Å) (compound 9) or MoKα (λ =
0.71073 Å) (compound 12). The intensities were measured using
the oscillation method. The crystal structures were solved by
Direct Methods. The refinement was performed using full-matrix
least squares on F2. All non-H atoms were anisotropically
refined. All H atoms were geometrically placed riding on their
parent atoms with isotropic displacement parameters set to 1.2
times the Ueq of the atoms to which they are attached (1.5 for
methyl groups).
Crystallographic calculations were carried out by the X-Ray
Team, at the University of Oviedo, using the following pro-
grams: Bruker SMART28 for data collection and cell refinement
and Bruker SAINT28 for data reduction for 12; CrysAlisPro CCD
and RES29 for data collection, cell refinement, data reduction
and empirical absorption correction for compound 9; SIR-9230
for structure solution; XABS231 for refined absorption correction
for compound 12; SHELXL-9732 for structure refinement;
WinGX33 publication routines and enCIFer34 for prepare
materials for publication; PLATON35 for the geometrical calcu-
lations; ORTEP-336 for windows for molecular graphics. Crystal
data and structure refinement details for all complexes are out-
lined on Tables S1 and S2.‡ Crystallographic data (excluding
structure factors) for the structures reported in this paper are
available as ESI: CCDC: 847136 (9), CCDC: 847125 (12).‡
3261, 694 cm−1 1H NMR (300.13 MHz, CDCl3) δ 1.55 (d,
.
2
3
3JHH 6.7 Hz, 3H), 2.85 (dd, JPH 4.7, JHH 8.5 Hz, 1H), 4.6 (m,
1H), 7.2–7.54 (m, 11HAr), 7.9 (m, 2HAr), 8.06 (m, 2HAr) ppm.
13C NMR (75.47 MHz) δ 25.4 (d, 3JPC 3.7 Hz, CH3), 51.7 (CH),
3
126.3 (CH), 127.1 (CH), 128.2 (d, JPC 12.9 Hz, CH), 128.4 (d,
4
3JPC 12.9 Hz, CH), 128.5 (CH), 131.5 (d, JPC 2.9 Hz, CH),
2
4
131.6 (d, JPC 11.0 Hz, CH), 131.7 (d, JPC 3.1 Hz, CH), 131.8
2
1
(d, JPC 11.3 Hz, CH), 134.2 (d, JPC 102.5 Hz, C), 134.9 (d,
1JPC 102.1 Hz, C), 145.0 (d, JPC 6.9 Hz, C). 31P NMR
3
(121.47 MHz)
δ
59.3 ppm.37 HRMS (ESI) calcd for
C20H21NPS: 338.1132 (MH+), found: 338.1132.
Synthesis of (S)-N-methyl-P,P-diphenyl-N-(1-phenylethyl)-
phosphinothioic amide 24. To a solution of 23 (0.3 g,
0.89 mmol) in THF (10 mL), 0.071 g of NaH (1.78 mmol) were
added at 0 °C. The deprotonation was allowed to proceed during
1 h and then MeI (0.11 mL, 1.78 mmol) was added. The reaction
was stirred during two additional hours. Then, methanol was
added to quench the excess of NaH. The crude reaction mixture
was poured into water, extracted with dichloromethane (3 ×
20 mL) and the organic layers dried over anhydrous Na2OS4.
Solvent evaporation under vacuum afforded a crude product,
which was purified by column chromatography. Yield after
chromatography (ethyl acetate–hexane 1 : 5) 53%. Colourless oil.
IR (KBr) 718 cm−1
.
1H NMR (300.13 MHz, CDCl3) δ 1.61
3
3
3
(d, JHH 7.0 Hz, 3H), 2.38 (d, JPH 12.7 Hz, 3H), 4.97 (dq, JPH
3
10.9, JHH 7.0 Hz, 1H), 7.26–7.56 (m, 11HAr), 7.98 (m, 2HAr),
8.04 (m, 2HAr) ppm. 13C NMR (75.47 MHz) δ 16.31 (d, JPC
3
Synthesis of N,N-diisopropyl-P,P-diphenylphosphinothioic
amide 7
2
2
1.5 Hz, CH3), 28.6 (d, JPC 3.0 Hz, CH3), 53.6 (d, JPC 4.2 Hz,
CH), 127.0 (CH), 127.6 (CH), 128.2 (CH), 128.4 (d, JPC 13.0
3
4
4
Compound 7 has been prepared previously.20 Spectroscopic data
were not reported. We used a different method for synthesizing
7. Under stirring, chlorodiphenylphosphine (6.48 mL,
35.4 mmol) was added to a solution of diisopropylamine (5 mL,
35.4 mmol) and triethylamine (12.33 mL, 88.5 mmol) in dry
toluene (120 mL) at room temperature. The reaction was heated
at 120 °C during 2 h and then was cooled down to 0 °C. Sulfur
S8 (1.26 g, 38.9 mmol of atomic S) was added slowly as a solid
under a flow of nitrogen. The reaction mixture was stirred at
room temperature during 12 h. Extraction with dichloromethane
(3 × 20 mL) followed by solvent evaporation under vacuum
afforded a crude product, which was purified by precipitation
from diethyl ether.
Hz, CH), 131.4 (d, JPC 1.9 Hz, CH), 131.5 (d, JPC 2.0 Hz,
2
2
CH), 132.1 (d, JPC 10.7 Hz, CH), 132.1 (d, JPC 10.7 Hz, CH),
1
1
133.3 (d, JPC 103.3 Hz, C), 133.6 (d, JPC 102.7 Hz, C), 141.6
3
(d, JPC 7.5 Hz, C). 31P NMR (121.47 MHz) δ 69.6 ppm.
HRMS (ESI) calcd for C21H23NPS: 352.1289 (MH+), found:
352.1275.
Synthesis of P,P-diphenyl-N,N-bis((S)-1-phenylethyl)phosphi-
nothioic amide 26. To a solution of (1S)-1-phenyl-N-[(1S)-1-
phenylethyl]ethanamine 25 (1.14 g, 5.07 mmol) in THF
(30 mL) at −35 °C, n-BuLi was added dropwise (3.8 mL,
6.08 mmol, 1.6 M in hexane). After 30 min, this solution was
added dropwise into a solution of chlorodiphenylphosphine
(1.11 mL, 6.08 mmol) in THF (30 mL) at −78 °C. The mixture
was allowed to warm to room temperature during 2 h. Then, the
reaction was cooled to 0 °C and sulfur S8 (0.20 g, 6.08 mmol of
atom S) was added slowly as a solid under a flow of nitrogen.
The reaction mixture was stirred at room temperature during
12 h. Extraction with dichloromethane (3 × 20 mL) followed by
solvent evaporation under vacuum afforded a crude product,
Yield after precipitation 67%. White solid. Mp 147–148 °C.
IR (KBr) 970, 755, 711, 671 cm−1
.
1H NMR (300.13 MHz,
3
3
3
CDCl3) δ 1.24 (d, JHH 6.7 Hz, 12H), 3.58 (ds, JPH 16.3, JHH
6.7 Hz, 2H), 7.49–7.39 (m, 6HAr), 8.06–8.17 (m, 4HAr) ppm.
3
13C NMR (75.47 MHz) δ 23.0 (d, JPC 3.3 Hz, CH3), 48.7 (d,
3
4
2JPC 4.1 Hz, CH), 128.0 (d, JPC 12.8 Hz, CH), 131.2 (d, JPC
2.9 Hz, CH), 132.5 (d, 2JPC 10.7 Hz, CH), 135.00 (d, 1JPC 102.1
5652 | Org. Biomol. Chem., 2012, 10, 5647–5658
This journal is © The Royal Society of Chemistry 2012

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P-(2-(Chlorodimethylstannyl)phenyl)-N,N-diisopropyl-P-phenyl-
phosphinothioic amide 10. Yield after precipitation from diethyl
ether 40%. White solid. Mp 178–182 °C (decomp). IR (KBr)
which was purified by flash column chromatography (eluent:
ethyl acetate–hexane 1 : 10).
Yield after chromatography (ethyl acetate–hexane 1 : 10) 42%.
977, 759, 709, 664 cm−1
.
1H NMR (300.13 MHz, CDCl3)
White solid. Mp 82–83 °C. IR (KBr) 927, 752, 719, 697 cm−1
.
3
3
1H NMR (300.13 MHz, CDCl3) δ 1.86 (d, JHH 7.1 Hz, 6H),
δ 0.63 (s, 3H), 1.07 (s, 3H), 1.16 (d, JHH 6.8 Hz, 6H), 1.30 (d,
3
3
3JHH 6.8 Hz, 6H′), 3.61 (ds, JPH 16.5, JHH 6.8 Hz, 2H),
3
3
4.87 (dc, JPH 17.7, JHH 7.1 Hz, 2H), 6.83–6.90 (m, 4HAr),
6.98–7.07 (m, 2HAr), 7.25–7.10 (m, 7HAr), 7.56–7.43
3
7.68–7.41 (m, 5HAr), 7.96 (m, 2HAr), 8.05 (ddd, JPH 10.5,
3JHH 7.5, JHH 1.4 Hz, 1HAr), 8.80 (ddd, JPH 4.2, JHH 7.5,
4
3
3
3
3
4
(m, 3HAr), 7.69 (ddd, JPH 13.6, JHH 8.5, JHH 1.3 Hz, 2HAr),
4JHH 1.4 Hz, 1HAr) ppm. 13C NMR (75.47 MHz) δ 7.2 (CH3),
3
3
4
8.17 (ddd, JPH 9.6, JHH 7.7, JHH 1.8 Hz, 2HAr) ppm.
4
3
13C NMR (75.47 MHz) δ 19.4 (d, JPC 2.7 Hz, CH3), 54.9
3
8.4 (d, JPC 3.0 Hz, CH3), 22.7 (d, JPC 3.6 Hz, CH3), 23.3
3
2
3
2
3
(d, JPC 3.6 Hz, CH3), 49.2 (d, JPC 3.6 Hz, CH), 128.0 (d, JPC
(d, JPC 3.9 Hz, CH), 127.0 (s, CH), 127.1 (d, JPC 12.7 Hz,
3
3
CH), 127.8 (s, CH), 127.9 (d, 3JPC 13.0 Hz, CH), 128.0 (s, CH),
11.4 Hz, CH), 128.3 (d, JPC 13.2 Hz, CH), 131.2 (d, JPC 10.8
Hz, CH), 131.6 (d, JPC 3.0 Hz, CH), 131.8 (d, JPC 101.5 Hz,
C), 132.5 (d, JPC 3.0 Hz, CH), 133.4 (d, JPC 11.4 Hz, CH),
4
1
4
4
130.6 (d, JPC 3.0 Hz, CH), 131.6 (d, JPC 3.0 Hz, CH), 131.9
4
2
1
2
2
(d, JPC 98.0 Hz, C), 133.4 (d, JPC 3.3 Hz, CH), 133.5 (d, JPC
2.9 Hz, CH), 134.1 (d, 1JPC 106.3 Hz, C), 142.7 (d, 3JPC 4.4 Hz,
CH) ppm. 31P NMR (121.47 MHz) δ 66.4 ppm. MS (API-ES),
m/z: 442 (M + 1). Analysis: calculated (%) for C28H28NPS:
C, 76.16; H, 6.39; N, 3.17; S, 7.26. Found: C, 75.85; H, 6.47;
N, 2.99; S, 6.95.
1
2
137.5 (d, JPC 112.3 Hz, C), 139.3 (d, JPC 19.2 Hz, CH), 149.4
(d, JPC 28.8 Hz, C) ppm. 31P NMR (121.47 MHz) δ 72.5
2
31
P
(d, 3J119
31.7 Hz) ppm. HRMS (ESI) calcd for
Sn
C20H29NPSSn: 466.0780 (M − Cl+), found: 466.0773.
N,N-Diisopropyl-P-phenyl-P-(2-(trimethylsilyl)phenyl)phos-
phinothioic amide 11. Yield after purification through semipre-
parative HPLC using acetonitrile as eluent at a flow rate of 6 mL
min−1 65%. White solid. Mp 98–99 °C; IR (KBr) 1241, 962,
General procedure for the synthesis of ortho-functionalised
phosphinothioic amides 9–19, 21 and thiophosphalactone
20. Over a solution of N,N-diisopropyl-P,P-diphenylphosphi-
nothioic amide 7 (300 mg, 0.946 mmol) and TMEDA (0.71 mL,
4.73 mmol) in dry diethyl ether (30 mL) at 0 °C was added a
solution of n-BuLi (0.89 mL of a 1.6 M solution in hexane,
1.42 mmol). After 2 h of metallation at 0 °C was added 1.5
equiv (1.42 mmol) of the corresponding electrophile (for the
reaction of lithiated 7 with dichlorodimethylstannane, N,N-
dimethylformamide and benzophenone the number of equiva-
lents were 1.8, 3 and 5, respectively). The reaction mixture was
stirred at 0 °C during 30 min (for the reaction of lithiated 7 with
chlorotrimethylstannane and dichlorodimethylstannane this time
was increased to 2 h and 3 h, respectively) and then quenched
with MeOH. The reaction mixture was poured into water and
extracted with dichloromethane (2 × 15 mL). The organic layers
were dried over Na2SO4 and concentrated in vacuo. 1H,
1H{31P}, and 31P{1H} NMR spectra of the crude reaction were
always measured in order to determine the conversion of the
process. The crude mixture was purified by flash column chrom-
atography (silica gel), by semipreparative HPLC or by precipi-
tation from diethyl ether.
1
839, 752, 726, 693, 675 cm−1. H NMR (300.13 MHz, CDCl3)
3
3
δ 0.10 (s, 9H), 1.12 (d, JHH 6.8 Hz, 6H), 1.43 (d, JHH 6.8 Hz,
3
3
6H), 3.72 (ds, JPH 16.4, JHH 6.8 Hz, 2H), 7.35–7.51 (m,
5HAr), 7.77–7.91 (m, 3HAr), 7.99–8.13 (m, 1HAr) ppm.
13C NMR (75.47 MHz) δ 2.7 (CH3), 23.4 (d, 3JPC 4.7 Hz, CH3),
3
2
23.5 (d, JPC 3.7 Hz, CH3), 48.7 (d, JPC 4.8 Hz, CH), 127.2 (d,
3JPC 12.0 Hz, CH), 127.8 (d, JPC 12.6 Hz, CH), 129.4 (d, JPC
3
4
4
2
3.3 Hz, CH), 130.9 (d, JPC 2.9 Hz, CH), 131.1 (d, JPC 11.5
2
1
Hz, CH), 132.7 (d, JPC 11.0 Hz, CH), 136.4 (d, JPC 94.6 Hz,
3
1
C), 137.8 (d, JPC 17.4 Hz, CH), 141.39 (d, JPC 105.9 Hz, C),
146.0 (d, JPC 22.7 Hz, C) ppm. 31P NMR (121.47 MHz)
2
δ 65.2 ppm. HRMS (ESI) calcd for C21H33NPSSi: 390.1841
(MH+), found: 390.1842.
P-(2-(Diphenylphosphino)phenyl)-N,N-diisopropyl-P-phenyl-
phosphinothioic amide 12. Yield after chromatography (ethyl
acetate–hexane 1 : 20) 64%. White solid. Mp 150–155 °C. IR
1
(KBr) 970, 752, 720, 695, 670 cm−1. H NMR (300.13 MHz,
3
3
CDCl3) δ 1.14 (d, JHH 6.8 Hz, 6H), 1.47 (d, JHH 6.8 Hz, 6H),
3
3
N,N-Diisopropyl-P-phenyl-P-(2-(trimethylstannyl)phenyl)-
phosphinothioic amide 9. Yield after precipitation from diethyl
ether 80%. White solid. Mp 106–107 °C. IR (KBr) 996, 755,
3.86 (ds, JPH 16.6, JHH 6.8 Hz, 2H), 7.04–7.12 (m, 2HAr),
7.13–7.33 (m, 11HAr), 7.40–7.73 (m, 3HAr), 7.78–7.89 (m,
2HAr) ppm. 13C NMR (75.47 MHz) δ 23.4 (d, JPC 1.7 Hz,
3
1
3
2
712, 693, 670 cm−1. H NMR (300.13 MHz, CDCl3) δ 0.16 (s,
CH3), 23.7 (d, JPC 2.9 Hz, CH3), 48.8 (d, JPC 4.6 Hz, CH),
127.5 (s, CH), 127.8 (d, JPC 12.9 Hz, CH), 127.8 (d, JPC 7.0
3
3
3
3
9H), 1.18 (d, JHH 6.8 Hz, 6H), 1.37 (d, JHH 6.8 Hz, 6H), 3.68
(dh, 3JPH 16.0, 3JHH 6.8 Hz, 2H), 7.49–7.35 (m, 5HAr), 7.82 (m,
1HAr), 7.91 (ddd, 3JPH 13.1, 3JHH 6.8, 4JHH 1.6 Hz, 4HAr), 8.12
(m, 1HAr) ppm. 13C NMR (75.47 MHz) δ 2.8 (CH3), 23.2 (d,
3
Hz, CH), 127.9 (d, JPC 7.3 Hz, CH), 128.0 (s, CH), 128.4 (dd,
3JPC 11.7 Hz, 4JPC 1.2 Hz, CH), 130.8 (dd, 4JPC 2.9 Hz, 3JPC 1.0
4
2
Hz, CH), 130.6 (d, JPC 3.0 Hz, CH), 130.8 (dd, JPC 10.2 Hz,
3JPC 2.9 Hz, CH3), 23.6 (d, JPC 2.9 Hz, CH3), 48.7 (d, JPC 4.1
3JPC 7.7 Hz, CH), 131.5 (dd, JPC 11.1 Hz, JPC 3.2 Hz, CH),
3
2
2
5
3
3
Hz, CH), 126.8 (d, JPC 11.2 Hz, CH), 127.7 (d, JPC 12.4 Hz,
132.9 (d, 2JPC 18.0 Hz, CH), 133.5 (d, 2JPC 20.0 Hz, CH), 137.1
4
4
1
4
1
CH), 129.8 (d, JPC 3.3 Hz, CH), 131.1 (d, JPC 2.9 Hz, CH),
131.6 (d, 2JPC 11.2 Hz, CH), 133.3 (d, 2JPC 11.2 Hz, CH), 134.9
(d, 1JPC 95.7 Hz, C), 138.5 (d, 3JPC 19.9 Hz, CH), 141.0 (d, 1JPC
(dd, JPC 98.2 Hz, JPC 2.2 Hz, C), 137.4 (d, JPC 16.5 Hz, C),
1
3
2
139.5 (d, JPC 16.2 Hz, C), 139.5 (dd, JPC 12.0 Hz, JPC 2.4
2
1
Hz, CH), 141.6 (dd, JPC 23.9 Hz, JPC 14.4 Hz, C), 142.8 (dd,
111.9 Hz, C), 150.4 (d, JPC 27.7 Hz, C) ppm. 31P NMR
1JPC 103.4 Hz, JPC 29.4 Hz, C) ppm. 31P NMR (121.47 MHz)
2
2
3 119 31
Sn
3
3
(121.47 MHz) δ 68.3 (d, J
37.9 Hz) ppm. HRMS (ESI)
P
δ −17.5 (d, JPC 25.1 Hz, P(III)), 63.3 (d, JPC 25.1 Hz, PvS)
ppm. MS (API-ES), m/z: 502 (M + 1). Analysis: Calculated (%)
calcd for C21H33NPSSn: 482.1093 (MH+), found: 482.1077.
This journal is © The Royal Society of Chemistry 2012
Org. Biomol. Chem., 2012, 10, 5647–5658 | 5653

View Online
3
3
3
for C30H33NP2S: C, 71.83; H, 6.63; N, 2.79; S, 6.39. Found: C,
72.02; H, 6.64; N, 2.79; S, 6.21.
(d, JHH 6.8 Hz, 6H), 2.38 (s, 3H), 3.78 (ds, JPH 16.6, JHH 6.8
3
Hz, 2H), 7.27 (m, 2HAr), 7.51–7.37 (m, 4HAr), 7.79 (ddd, JPH
3
4
3
3
14.8, JHH 7.8, JHH 1.3 Hz, 2H), 7.89 (ddd, JPH 13.2, JHH
8.2, JHH 1.5 Hz, 2H) ppm. 13C NMR (75.47 MHz) δ 22.5 (d,
4
P-(2-Iodophenyl)-N,N-diisopropyl-P-phenylphosphinothioic
amide 13. Yield after precipitation from diethyl ether 70%.
White solid. Mp 133–134 °C; IR (KBr) 970, 752, 720, 694,
3JPC 4.1 Hz, CH3), 23.4 (d, JPC 1.8 Hz, CH3), 23.6 (d, JPC 2.9
3
3
2
3
Hz, CH3), 48.7 (d, JPC 4.7 Hz, CH), 125.2 (d, JPC 12.4 Hz,
CH), 128.1 (d, JPC 12.6 Hz, CH), 130.8 (d, JPC 3.1 Hz, CH),
1
3
668 cm−1. H NMR (300.13 MHz, CDCl3) δ 1.14 (d, JHH 6.8
3
4
3
3
3
4
2
Hz, 6H), 1.46 (d, JHH 6.8 Hz, 6H), 3.81 (ds, JPH 16.8, JHH
6.8 Hz, 2H), 7.12 (m, 1HAr), 7.54–7.40 (m, 4HAr), 7.88 (m,
2HAr), 8.01 (ddd, 3JPH 13.8, 3JHH 6.2, 4JHH 2.0 Hz, 1HAr), 8.07
131.0 (d, JPC 2.9 Hz, CH), 131.1 (d, JPC 10.1 Hz, CH), 131.5
2
3
(d, JPC 11.2 Hz, CH), 132.7 (d, JPC 11.8 Hz, CH), 133.4
(d, 1JPC 102.9 Hz, C), 136.3 (d, 1JPC 95.3 Hz, C), 141.9 (d, 2JPC
12.0 Hz, C) ppm. 31P NMR (121.47 MHz) δ 62.0 ppm. HRMS
(ESI) calcd for C19H27NPS: 332.1602 (MH+), found: 332.1596.
(ddd, JPH 7.8, JHH 4.4, JHH 1.0 Hz, 1HAr) ppm. 13C NMR
3
3
4
(75.47 MHz) δ 23.3 (d, 3JPC 1.5 Hz, CH3), 23.5 (d, 3JPC 2.7 Hz,
2
2
CH3), 48.9 (d, JPC 4.7 Hz, CH), 100.5 (d, JPC 10.5 Hz, C),
127.5 (d, 4JPC 10.9 Hz, CH), 128.1 (d, 3JPC 13.0 Hz, CH), 130.9
(d, 4JPC 2.9 Hz, CH), 131.7 (d, 3JPC 2.9 Hz, CH), 132.0 (d, 2JPC
P-(2-Ethylphenyl)-N,N-diisopropyl-P-phenylphosphinothioic
amide 17. Yield after chromatography (ethyl acetate–hexane
1 : 50) 38%. White solid. Mp 116–118 °C. IR (KBr) 664 cm−1
.
3
1
10.9 Hz, CH), 132.7 (d, JPC 9.7 Hz, CH), 134.2 (d, JPC 99.2
1H NMR (300.13 MHz, CDCl3, 25 °C) δ 1.11 (t, JHH 7.4 Hz,
3
1
2
Hz, C), 137.1 (d, JPC 106.7 Hz, C), 143.6 (d, JPC 9.9 Hz, CH)
ppn. 31P NMR (121.47 MHz) δ 68.0 ppm. HRMS (ESI) calcd
for C18H24NPSI: 444.0412 (MH+), found: 444.0413.
3
3
3H), 1.16 (d, JHH 6.8 Hz, 6H), 1.43 (d, JHH 6.8 Hz, 6H), 2.7
3
3
(m, 1H), 2.85 (m, 1H), 3.76 (ds, JPH 16.4, JHH 6.8 Hz, 2H),
7.2–7.54 (m, 6HAr), 7.79 (m, 1HAr), 7.89 (m, 2HAr) ppm. 13C
3
N,N-Diisopropyl-P-(2-mercaptophenyl)-P-phenylphosphi-
nothioic amide 14. Conversion 71%. Identified from the crude
reaction mixture. IR (KBr) 674 (PvS) 2318, 976, 751, 695,
NMR (75.47 MHz) δ 14.7 (CH3), 23.5 (d, JPC 1.7 Hz, CH3),
3
3
23.6 (d, JPC 2.8 Hz, CH3), 27.1 (d, JPC 4.8 Hz, CH2), 48.8
2
3
(d, JPC 4.7 Hz, CH), 125.0 (d, JPC 12.5 Hz, CH), 128.0
1
3
672 cm−1. H NMR (300.13 MHz, CDCl3) δ 1.23 (d, JHH 6.9
Hz, 6H), 1.42 (d, 3JHH 6.9 Hz, 6H), 3.79 (ds, 3JPH 16.7 Hz, 3JHH
6.9 Hz, 2H), 6.78 (d, 4JPH 0.8 Hz, 1HAr), 7.16–7.24 (m, 1HAr),
3
3
(d, JPC 12.7 Hz, CH), 130.5 (d, JPC 11.6 Hz, CH), 130.7
4
2
(d, JPC 3.0 Hz, CH), 131.1 (d, JPC 10.6 Hz, CH), 131.2
4
2
(d, JPC 3.0 Hz, CH), 131.5 (d, JPC 11.0 Hz, CH), 133.0
(d, 1JPC 103.1 Hz, C), 137.1 (d, 1JPC 96.3 Hz, C), 148.1 (d, 2JPC
12.0 Hz, C) ppm. 31P NMR (121.47 MHz) δ 62.1 ppm. HRMS
(ESI) calcd for C20H29NPS: 346.1758 (MH+), found: 346.1745.
3
3
7.25–7.56 (m, 5HAr), 7.60 (ddd, JPH 14.5 Hz JHH 7.8 Hz,
4JHH 1.3 Hz, 1HAr), 7.89 (ddd, 3JPH 13.6 Hz, 3JHH 8.2 Hz, 4JHH
1.5 Hz, 2HAr) ppm. 13C NMR (75.47 MHz) δ 23.6 (d, JPC 2.8
3
3
2
Hz, CH3), 23.7 (d, JPC 2.2 Hz, CH3), 49.0 (d, JPC 4.8 Hz,
CH), 124.4 (d, JPC 11.7 Hz, CH), 128.1 (d, JPC 13.0 Hz, CH),
130.8 (d, JPC 99.0 Hz, C), 131.0 (d, JPC 2.6 Hz, CH), 131.2
3
3
P-(2-Formylphenyl)-N,N-diisopropyl-P-phenylphosphinothioic
amide 18. Yield after precipitation from diethyl ether 78%.
White solid. Mp 112–113 °C. IR (KBr) 2876, 2770, 1692, 976,
1
4
4
2
(d, JPC 3.0 Hz, CH), 132.1 (d, JPC 11.1 Hz, CH), 132.60 (d,
755, 719, 699, 671 cm−1
.
1H NMR (300.13 MHz, CDCl3,
3JPC 10.2 Hz, CH), 132.7 (d, JPC 9.5 Hz, CH), 134.7 (d, JPC
2
1
3
3
99.0 Hz, C), 138.9 (d, JPC 10.4 Hz, C) ppm. 31P NMR
2
25 °C) δ 1.20 (d, JHH 6.6 Hz, 6H), 1.43 (d, JHH 6.8 Hz, 6H),
3.75 (ds, JPH 17.2, JHH 6.8 Hz, 2H), 7.55–7.42 (m, 3HAr),
3
3
(121.47 MHz) δ 62.7 ppm.
3
7.65–7.59 (m, 2HAr), 7.81 (m, 1HAr), 7.94 (ddd, JPH 13.4,
3JHH 7.8, JHH 1.4 Hz, 2HAr), 8.06 (m, 1HAr), 10.74 (s, 1H)
4
P-(2-(Benzylthio)phenyl)-N,N-diisopropyl-P-phenylphosphi-
nothioic amide 15. Yield after purification through semiprepara-
tive HPLC acetonitrile–water 95 : 5 as eluent at a flow rate of
8 mL min−1 65%. Colourless oil; IR (KBr) 971, 748, 694,
ppm. 13C NMR (75.47 MHz) δ 23.2 (d, JPC 2.2 Hz, CH3), 23.4
3
3
2
3
(d, JPC 2.5 Hz, CH3), 49.1 (d, JPC 4.6 Hz, CH), 128.3 (d, JPC
3
2
12.7 Hz, CH), 129.2 (d, JPC 9.9 Hz, CH), 131.0 (d, JPC 8.5
Hz, CH), 131.4 (d, JPC 2.7 Hz, CH), 131.5 (d, JPC 3.0 Hz,
CH), 131.8 (d, JPC 11.1 Hz, CH), 132.2 (d, JPC 11.8 Hz, CH),
1
3
671 cm−1. H NMR (300.13 MHz, CDCl3) δ 1.17 (d, JHH 6.8
4
3
Hz, 6H), 1.43 (d, 3JHH 6.8 Hz, 6H), 3.79 (ds, 3JPH 16.5 Hz, 3JHH
6.8 Hz, 2H), 4.00 (d, JHH 12.9 Hz, 1H), 4.07 (d, JHH 12.9 Hz,
1H), 7.12–7.51 (m, 11HAr), 7.84–7.92 (m, 3HAr) ppm. 13C
2
4
2
2
1
2
136.3 (d, JPC 96.3 Hz, C), 138.3 (d, JPC 8.6 Hz, C), 138.4 (d,
1JPC 100.0 Hz, C), 191.0 (d, JPC 6.2 Hz, CH) ppm. 31P NMR
3
3
3
NMR (75.47 MHz) δ 23.5 (d, JPC 1.9 Hz, CH3), 23.6 (d, JPC
(121.47 MHz)
δ
58.1 ppm. HRMS (ESI) calcd for
2.8 Hz, CH3), 39.76 (s, CH2), 48.80 (d, 2JPC 4.8 Hz, CH), 125.2
C19H25NOPS: 346.1394 (MH+), found: 346.1394.
3
3
(d, JPC 11.9 Hz, CH), 126.97 (s, CH), 127.9 (d, JPC 13.0 Hz,
CH), 128.2 (s, CH), 129.1 (s, CH), 130.5 (d, JPC 3.0 Hz, CH),
131.0 (d, JPC 2.7 Hz, CH), 131.4 (d, JPC 11.1 Hz, CH), 131.7
4
P-(2-(Hydroxy(phenyl)methyl)phenyl)-N,N-diisopropyl-P-
phenylphosphinothioic amide 19. Yield after precipitation from
diethyl ether 52%. White solid. Mp 181–183 °C. IR (KBr) 3360,
4
2
2
3
(d, JPC 9.6 Hz, CH), 132.1 (d, JPC 10.0 Hz, CH), 135.3 (d,
710 cm−1. H NMR (300.13 MHz, CDCl3, 25 °C) δ 1.20 (d,
1
1JPC 105.7 Hz, C), 136.3 (d, JPC 100.4 Hz, C), 136.9 (s, C),
1
3JHH 6.8 Hz, 6H), 1.48 (d, JHH 6.8 Hz, 6H), 3.85 (ds, JPH
3
3
2
141.5 (d, JPC 10.28 Hz, C) ppm. 31P NMR (121.47 MHz)
3
16.8, JHH 6.8 Hz, 2H), 4.87 (bs, 1H), 6.18 (s, 1H), 7.03–7.29
δ 61.7 ppm. HRMS (ESI) calcd for C25H31NPS2: 440.1635
(MH+), found: 440.1634.
(m, 6HAr), 7.37–7.59 (m, 5HAr), 7.94–8.09 (m, 3HAr) ppm.
13C NMR (75.47 MHz) δ 23.4 (d, JPC 2.9 Hz, CH3), 23.8 (d,
3
2
3
N,N-Diisopropyl-P-phenyl-P-(o-tolyl)phosphinothioic amide
16. Yield after precipitation from diethyl ether 82%. White
3JPC 1.8 Hz, CH3), 49.1 (d, JPC 4.5 Hz, CH), 69.3 (d, JPC 5.8
3
Hz, CH), 126.3 (CH), 126.6 (CH), 126.7 (d, JPC 11.3 Hz, CH),
solid. Mp 115–116 °C. IR (KBr) 974, 753, 691, 663 cm−1
.
127.7 (CH), 128.2 (d, 3JPC 12.9 Hz, CH), 130.6 (d, 2JPC 8.4 Hz,
1H NMR (300.13 MHz, CDCl3) δ 1.12 (d, 3JHH 6.8 Hz, 6H), 1.43
CH), 131.6 (d, JPC 11.0 Hz, CH), 131.7 (d, JPC 2.9 Hz, CH),
3
4
5654 | Org. Biomol. Chem., 2012, 10, 5647–5658
This journal is © The Royal Society of Chemistry 2012

View Online
4
2
132.0 (d, JPC 3.0 Hz, CH), 132.3 (d, JPC 11.4 Hz, CH), 134.2
(d, 3JPC 11.6 Hz, CH), 127.3 (d, 3JPC 11.5 Hz, CH), 127.8 (CH),
128.0 (CH), 128.1 (CH), 128.2 (CH), 128.3 (d, JPC 12.6 Hz,
1
1
3
(d, JPC 100.0 Hz, C), 135.8 (d, JPC 95.9 Hz, C), 142.0 (C),
148.6 (d, JPC 12.3 Hz, C) ppm. 31P NMR (121.47 MHz)
CH), 128.4 (d, JPC 12.8 Hz, CH), 129.9 (d, JPC 3.3 Hz, CH),
2
3
4
4
2
δ 61.2 ppm. HRMS (ESI) calcd for C25H31NOPS: 424.1864
130.0 (d, JPC 3.1 Hz, CH), 131.3 (d, JPC 11.7 Hz, CH), 131.3
(MH+), found: 424.1864.
(d, JPC 11.3 Hz, CH), 131.3 (d, JPC 3.1 Hz, CH), 131.4 (d,
2
4
4JPC 3.1 Hz, CH), 132.0 (d, JPC 10.8 Hz, CH), 132.2 (d, JPC
2
2
1
1
1,3,3-Triphenyl-1,3-dihydrobenzo[c][1,2]oxaphosphole 1-
sulfide 20. Yield after precipitation from diethyl ether 88%. Mp
10.6 Hz, CH), 133.7 (d, JPC 98.3 Hz, C), 134.3 (d, JPC 97.9
3
3
Hz, C), 138.3 (d, JPC 19.6 Hz, CH), 138.5 (d, JPC 19.8 Hz,
93–94 °C. IR (KBr) 963, 861, 739, 700, 637 cm−1. H NMR
1
1
1
CH), 139.4 (d, JPC 110.7 Hz, C), 139.8 (d, JPC 110.5 Hz, C),
3
3
(300.13 MHz, CDCl3) δ 7.42–7.21 (m, 12HAr), 7.62–7.48 (m,
141.5 (d, JPC 4.7 Hz, C), 141.7 (d, JPC 7.1 Hz, C), 150.6 (d,
2JPC 26.9 Hz, C) ppm. 31P NMR (121.47 MHz) δ 72.6 (major),
73.1 (minor) ppm. HRMS (ESI) calcd for C24H31NPSSn:
516.0943 (MH+), found: 516.0943.
6HAr), 7.71 (dd, JPH 9.9, JHH 7.5 Hz, 1HAr) ppm. 13C NMR
3
3
3
3
(75.47 MHz) δ 97.8 (d, JPC 4.9 Hz, C), 125.6 (d, JPC 11.9 Hz,
CH), 127.4 (CH), 128.0 (CH), 128.1 (d, JPC 14.3 Hz, CH),
128.2 (CH), 128.2 (d, JPC 12.8 Hz, CH), 128.3 (CH), 128.4
(CH), 128.6 (CH), 129.7 (d, JPC 12.4 Hz, CH), 131.4 (d, JPC
13.2 Hz, CH), 131.9 (d, JPC 3.1 Hz, CH), 132.0 (d, JPC 2.9
Hz, CH), 132.8 (d, JPC 100.3 Hz, C), 134.3 (d, JPC 107.1 Hz,
3
2
3
2
Procedure for the synthesis of o-stannylphosphinothioic amide
29. Over a solution of 26 (30 mg, 0.068 mmol) and TMEDA
(0.20 mL, 0.340 mmol) in dry diethyl ether (5 mL) at −40 °C,
was added a solution of n-BuLi (0.06 mL of a 1.6 M solution in
hexane, 0.102 mmol). After 12 h of metallation at −40 °C was
added 20 mg (0.102 mmol) of chlorotrimethylstannane. The
reaction mixture was stirred at −40 °C during 2 h and then
quenched with MeOH. The reaction mixture was poured into
water and extracted with dichloromethane (2 × 15 mL). The
organic layers were dried over Na2SO4 and concentrated
4
4
1
1
3
3
C), 142.2 (d, JPC 2.5 Hz, C), 144.1 (d, JPC 2.5 Hz, C), 147.1
(d, JPC 17.2 Hz, C) ppm. 31P NMR (121.47 MHz) δ 94.1 ppm.
2
HRMS (ESI) calcd for C25H20OPS: 399.0973 (MH+), found:
399.0968.
N,N′-(Disulfanediylbis(2,1-phenylene))bis(N,N-diisopropyl-P-
phenylphosphinothioic amide) 21. Yield after chromatography
(ethyl acetate–hexane 1 : 9) 35% (mixture 1 : 1 of diastereo-
isomers). White solid. Mp 100–107 °C (decomp). IR (KBr) 974,
1
1
in vacuo. H, H{31P}, and 31P{1H} NMR spectra of the crude
reaction were always measured in order to determine the conver-
sion of the process. The crude mixture was purified by flash
column chromatography on silica gel. The best results were
obtained using ethyl acetate–hexane 1 : 10 as eluent. This pro-
cedure yielded a mixture containing 29 (1 : 1 ratio of diastereo-
isomers) as the major component.
745, 719, 694, 672 cm−1 1H NMR (300.13 MHz, CDCl3,
.
25 °C) δ 1.20 (m, 12H), 1.39 (m, 12H), 3.79 (m, 4H), 7.17–7.23
(m, 2HAr), 7.23–7.32 (m, 2HAr), 7.38–7.52 (m, 6HAr),
7.64–7.75 (m, 4HAr), 7.84–7.93 (m, 4HAr) ppm. 13C NMR
(75.47 MHz) δ 23.6 (d, 3JPC 2.9 Hz, CH3), 23.6 (d, 3JPC 2.9 Hz,
3
3
CH3), 23.6 (d, JPC 2.5 Hz, CH3), 23.7 (d, JPC 2.5 Hz, CH3),
1
2
2
Conversion 36% (mixture 1 : 1 of diastereoisomers). H NMR
48.9 (d, JPC 4.7 Hz, CH), 49.0 (d, JPC 4.7 Hz, CH), 125.0 (d,
(300.13 MHz, CDCl3) δ 0.17 (s, 9H), 0.18 (s, 9H), 1.65 (d, 3JHH
3JPC 11.6 Hz, CH), 125.1 (d,3JPC 11.4 Hz, CH), 128.0 (d, JPC
3
3
3
3
3
7.1 Hz, 6H), 1.89 (d, JHH 7.1 Hz, 6H), 4.92 (dq, JPH 15.6,
13.0 Hz, CH), 128.4 (d, JPC 15.7 Hz, CH), 128.6 (d, JPC 15.7
Hz, CH), 131.1 (d, JPC 3.1 Hz, CH), 131.1 (d, JPC 2.9 Hz,
3JHH 7.1 Hz, 2H), 5.00 (dq, JPH 16.4, JHH 7.1 Hz, 2H),
6.81–6.89 (m, 4HAr), 6.89–6.98 (m, 2HAr), 7.04–7.61 (m,
34HAr), 7.64–8.23 (m, 8HAr). 13C NMR (75.47 MHz) δ −2.6
3
3
4
4
4
4
CH), 131.5 (d, JPC 2.7 Hz, CH), 131.5 (d, JPC 2.7 Hz, CH),
2
2
131.8 (d, JPC 9.3 Hz, CH), 131.8 (d, JPC 9.5 Hz, CH), 132.1
4
4
3
3
3
(d, JPC 0.8 Hz, CH3), −2.3 (d, JPC 0.6 Hz, CH3), 19.7 (d, JPC
(d, JPC 11.2 Hz, CH), 132.1 (d, JPC 11.2 Hz, CH), 133.7 (d,
3
2
1JPC 104.8 Hz, C), 133.9 (d, JPC 104.6 Hz, C), 134.9 (d, JPC
1
1
2.9 Hz, CH3), 20.5 (d, JPC 1.7 Hz, CH3), 55.3 (d, JPC 3.8 Hz,
2
3
99.0 Hz, C11), 135.1 (d, 1JPC 99.2 Hz, C11), 141.7 (d, 2JPC 10.1
CH), 55.3 (d, JPC 4.2 Hz, CH), 126.2 (d, JPC 11.8 Hz, CH),
126.5 (d, JPC 11.2 Hz, CH), 126.8 (s, CH), 126.9 (d, JPC 12.7
3
3
Hz, C6), 141.8 (d, JPC 10.1 Hz, C) ppm. 31P NMR
2
3
Hz, CH), 126.9 (s, CH), 127.7 (s, CH), 127.8 (d, JPC 12.8 Hz,
(121.47 MHz) δ 60.6, 60.4 ppm. HRMS (ESI) calcd for
CH), 127.9 (s, CH), 127.9 (s, CH), 128.5 (s, CH), 129.5 (d, 4JPC
C36H47N2P2S4: 697.2097 (MH+), found: 697.2072.
4
4
3.5 Hz, CH), 130.1 (d, JPC 3.7 Hz, CH), 130.5 (d, JPC 2.9 Hz,
4
1
Procedure for the synthesis of o-stannylphosphinothioic amide
27. The general method described above for the synthesis of
compounds 9–21 was applied to the preparation of 27 using
phosphinothioic amide 24 (0.26 g 0.75 mmol) as starting
material. Yield after chromatography (CH2Cl2–hexane 30 : 70)
20% (mixture 1 : 1.3 of diastereoisomers). Oil. IR (KBr)
CH), 131.0 (d, JPC 2.8 Hz, CH), 132.8 (d, JPC 101.3 Hz, C),
133.1 (d, 2JPC 10.9 Hz, CH), 133.2 (d, 2JPC 12.5 Hz, CH), 133.7
2
2
(d, JPC 10.6 Hz, CH), 133.9 (d, JPC 11.5 Hz, CH), 134.3 (d,
1JPC 98.4 Hz, C), 138.1 (d, JPC 20.1 Hz, CH), 138.5 (d, JPC
3
3
1
1
20.3 Hz, CH), 139.7 (d, JPC 108.3 Hz, C), 139.9 (d, JPC 113.9
Hz, C), 142.4 (d, JPC 4.4 Hz, C), 142.8 (d, JPC 4.1 Hz, C),
3
3
720 cm−1. H NMR (300.13 MHz, CDCl3, 25 °C) δ δ 0.16 (s,
150.2 (d, JPC 27.7 Hz, C), 150.4 (d, JPC 29.0 Hz, C) ppm.
1
2
2
9H), 0.17 (s, 9H), 1.61 (d, JHH 7.0 Hz, 3H), 1.62 (d, JHH 7.0
Hz, 3H), 2.34 (d, 3JPH 11.6 Hz, 3H), 2.36 (d, 3JPH 11.0 Hz, 3H),
4.98 (dq, 3JPH 10.2, 3JHH 7.0 Hz, 1H), 5.08 (dq, 3JPH 12.0, 3JHH
7.0 Hz, 1H), 7.24–7.22 (m, 2 × 10HAr), 7.59–7.93 (m, 2 ×
4HAr) ppm. 13C NMR (75.47 MHz) δ −3.7 (CH3), −3.6 (CH3),
31P NMR (121.47 MHz) δ 70.7, 72.6 ppm.
3
3
Procedure for the synthesis of imine 31. Over a solution of 18
(100 mg, 0.29 mmol) in ethanol (5 mL) at room temperature,
was added 2-aminophenol 30 (35 mg, 0.32 mmol). The reaction
was stirred during 6 h. Then, EtOH was removed under reduced
2
3
16.0 (CH3), 17.1 (d, JPC 2.1 Hz, CH3), 29.1 (d, JPC 3.2 Hz,
3
2
1
1
CH3), 29.2 (d, JPC 3.8 Hz, CH3), 53.2 (d, JPC 4.2 Hz, CH),
pressure. H, H{31P}, and 31P{1H} NMR spectra of the crude
2
53.9 (d, JPC 4.3 Hz, CH), 127.0 (CH), 127.1 (CH), 127.2
reaction were measured in order to determine the conversion of
This journal is © The Royal Society of Chemistry 2012
Org. Biomol. Chem., 2012, 10, 5647–5658 | 5655

View Online
the process. The crude mixture was purified by semipreparative
HPLC to give 92 mg of imine 31.
during 1 h. Afterward, solvent was removed under reduced
pressure to yield an oil that was purified by column flash chrom-
atography over silica gel. In this way, 78 mg of aminophosphine
33 were obtained.
Yield after chromatography (dichloromethane) 85%. Mp
118–119 °C. IR (KBr) 1120, 964, 746, 696, 510 cm−1. 1H NMR
(300.13 MHz, CD2Cl2, 25 °C) δ 1.03 (d, 3JHH 6.5 Hz, 6H), 1.26
(E)-P-(2-(((2-Hydroxyphenyl)imino)methyl)phenyl)-N,N-diiso-
propyl-P-phenylphosphinothioic amide 31. Yield after semipre-
parative HPLC (acetonitrile as eluent, flow rate of 8 mL min−1
)
73%. Yellow oil. IR (KBr) 3414, 1619, 975, 751, 707,
1
3
669 cm−1. H NMR (300.13 MHz, CD2Cl2) δ 1.22 (d, JHH 6.9
3
3
3
(d, JHH 6.5 Hz, 6H), 3.63 (ds, JPH 10.6 Hz, JHH 6.5 Hz, 2H),
Hz, 6H), 1.46 (d, 3JHH 6.9 Hz, 6H), 3.79 (ds, 3JPH 17.5 Hz, 3JHH
6.9 Hz, 2H), 6.64 (dd, JHH 8.1 Hz, JHH 1.5 Hz, 1HAr), 6.76
3
4
7.03 (dt, JHH 7.6 Hz, JHH 1.8 Hz, 1HAr), 7.29–7.41 (m,
5HAr), 7.45 (tt, JHH 7.6 Hz, JHH = JPH 1.0 Hz, 1HAr), 7.67
3
4
3
4
4
3
3
4
3
3
4
(ddd, JHH 8.1 Hz, JHH 7.4 Hz, JHH 1.3 Hz, 1HAr), 6.93 (dd,
(ddd, JHH 7.6 Hz, JPH 2.3 Hz, JHH 1.8 Hz, 1HAr), 7.85 (ddd,
3JHH 8.1 Hz, JHH 1.3 Hz, 1HAr), 7.14 (ddd, JHH 8.1 Hz, JHH
4
3
3
3JHH 7.6 Hz, JPH 3.2 Hz, JHH 1.0 Hz, 1HAr) ppm. 13C NMR
4
4
4
(75.47 MHz) δ 23.6 (d, 3JPC 7.7 Hz, CH3), 24.4 (d, 3JPC 5.2 Hz,
7.4 Hz, JHH 1.5 Hz, 1HAr), 7.43–7.56 (m, 3HAr), 7.60 (tdd,
3JHH 7.5 Hz, JPH 2.0 Hz, JHH 1.5 Hz, 1HAr), 7.67 (ttd, JHH
4
4
3
2
2
CH3), 47.6 (d, JPC 10.3 Hz, CH), 102.3 (d, JPC 40.5 Hz, C),
127.7 (CH), 128.1 (d, JPC 7.0 Hz, CH), 128.3 (CH), 129.4
(CH), 132.7 (d, JPC 4.1 Hz, CH), 133.2 (d, JPC 20.9 Hz, CH),
139.1 (d, JPC 8.1 Hz, C), 140.0 (d, JPC 2.7 Hz, CH), 144.3 (d,
1JPC 16.3 Hz, C) ppm. 31P NMR (121.47 MHz) δ 48.3 ppm.
HRMS (ESI) calcd for C18H24NPI: 412.0691 (MH+), found:
412.0686.
4
5
5
3
7.5 Hz, JHH = JPH 1.5 Hz, JHH 0.6 Hz, 1HAr), 7.84 (ddd,
3JPH 14.6 Hz, JHH 7.5 Hz, JHH 1.5 Hz, 1HAr), 7.93–8.05 (m,
3
4
2
2
3
4
4
1
3
2HAr), 8.40 (ddd, JHH 7.5 Hz, JPH 5.0 Hz, JHH 1.5 Hz,
1HAr), 9.48 (s, 1H) ppm. 13C NMR (75.47 MHz) δ 23.0 (d,
3JPC 1.8 Hz, CH3), 23.3 (d, JPC 2.4 Hz, CH3), 49.0 (d, JPC 4.5
3
2
3
Hz, CH), 114.6 (CH), 116.6 (CH), 120.0 (CH), 128.2 (d, JPC
12.6 Hz, CH), 128.6 (d, JPC 10.2 Hz, CH), 128.8 (CH), 130.1
3
3
2
(d, JPC 12.1 Hz, CH), 131.1 (d, JPC 8.7 Hz, CH), 131.2 (d,
Procedure for the synthesis of P-(biphenyl-2-yl)-N,N-diisopro-
4JPC 3.0 Hz, 2 × CH), 131.9 (d, JPC 11.1 Hz, CH), 135.5 (C),
2
pyl-P-phenylphosphinothioic amide 35. To
a solution of
136.4 (d, 1JPC 99.1 Hz, C), 136.7 (d, 1JPC 96.1 Hz, C), 138.0 (d,
Pd(OAc)2 (2.6 mg, 5% mol, 11.3 μmol) in dry toluene (10 mL)
were added K2CO3 (62 mg, 0.452 mmol), P-(2-iodophenyl)-N,N-
diisopropyl-P-phenylphosphinothioic amide 13 (100 mg,
0.226 mmol) and PhB(OH)2 34 (41 mg, 0.339 mmol). The reac-
tion mixture was stirred at 120 °C for 48 h and then was cooled
to room temperature. A 31P-NMR spectrum of an aliquot was
measured in CDCl3 to determine the conversion of the process.
Solvent evaporation under reduced pressure provided a yellow
solid that was purified by column chromatography on silica gel
furnishing 64 mg of biphenyl 35.
2JPC 8.7 Hz, C), 153.4 (C), 156.5 (d, JPC 6.6 Hz, C) ppm. 31P
3
NMR (121.47 MHz) δ 59.4 ppm. HRMS (ESI) calcd for
C25H30N2OPS: 437.1816 (MH+), found: 437.1820.
Procedure for the synthesis of complex 32. Over a solution of
31 (40 mg, 0.09 mmol) in CD2Cl2 (0.5 mL) at 25 °C was added
copper(I) bromide (13 mg, 0.09 mmol). The mixture was stirred
for 1 min and the brown solution formed was analyzed by NMR
spectroscopy. Then, the solvent was removed under reduced
pressure affording 50 mg of complex 32. Yield 94%. Brown
solid. Mp 103 °C. IR (KBr) 3417, 1597, 976, 751, 706,
Yield after chromatography (ethyl acetate–hexane, 1 : 3) 72%.
Colourless oil. IR (KBr) 970, 750, 692, 661 cm−1
.
1H NMR
1
3
668 cm−1. H NMR (300.13 MHz, CD2Cl2) δ 1.21 (d, JHH 6.4
3
Hz, 6H), 1.45 (d, 3JHH 6.4 Hz, 6H), 3.78 (ds, 3JPH 23.3 Hz, 3JHH
6.4 Hz, 2H), 6.58 (d, JHH 7.4 Hz, 1HAr), 6.77 (t, JHH 7.4 Hz,
1HAr), 6.93 (d, JHH 7.4 Hz, 1HAr), 7.12 (t, JHH 7.4 Hz,
1HAr), 7.45–7.59 (m, 3HAr), 7.63 (t, JHH 7.5 Hz, 1HAr), 7.70
(300.13 MHz, CD2Cl2) δ 1.04 (d, JHH 6.8 Hz, 6H), 1.44 (d,
3
3
3JHH 6.8 Hz, 6H), 3.63 (ds, JPH 17.2 Hz, JHH 6.8 Hz, 2H),
6.95–7.01 (m, 3HAr) 7.04–7.14 (m, 2HAr), 7.15–7.23 (m,
1HAr), 7.28–7.35 (m, 1HAr), 7.36–7.44 (m, 2HAr), 7.50–7.59
(m, 2HAr), 7.62–7.74 (m, 2HAr), 8.27–8.40 (m, 1HAr) ppm.
3
3
3
3
3
3
3
3
(t, JHH 7.3 Hz, 1HAr), 7.89 (dd, JPH 14.4 Hz, JHH 7.4 Hz,
3
13C NMR (75.47 MHz) δ 22.7 (d, JPC 2.1 Hz, CH3), 23.3 (d,
3
3
1HAr), 7.99 (dd, JPH 13.0 Hz, JHH 6.8 Hz, 2HAr), 8.32
3JPC 2.5 Hz, CH3), 48.8 (d, 2JPC 4.5 Hz, CH), 126.8 (CH), 126.9
(d, 3JPC 12.0 Hz, CH), 127.2 (CH), 127.0 (s, CH), 127.2 (d, 3JPC
3
4
(t, JHH = JPH 7.3 Hz, 1HAr), 9.26 (s, 1H) ppm. 13C NMR
(75.47 MHz) δ 23.0 (d, 3JPC 1.8 Hz, CH3), 23.3 (d, 3JPC 2.4 Hz,
CH3), 49.0 (d, 2JPC 4.5 Hz, CH), 114.6 (CH), 116.6 (CH), 120.0
(CH), 128.2 (d, 3JPC 12.6 Hz, CH), 128.6 (d, 3JPC 10.2 Hz, CH),
128.8 (CH), 130.1 (d, 3JPC 12.1 Hz, CH), 131.1 (d, 2JPC 8.7 Hz,
4
4
12.8 Hz, CH), 129.9 (d, JPC 2.9 Hz, CH), 130.1 (d, JPC 0.6
4
2
Hz, CH), 130.7 (d, JPC 2.9 Hz, CH), 131.6 (d, JPC 11.2 Hz,
2
3
CH), 132.2 (d, JPC 9.9 Hz, CH), 133.0 (d, JPC 11.2 Hz, CH),
1
1
4
2
134.1 (d, JPC 103.5 Hz, C), 134.4 (d, JPC 95.1 Hz, C), 141.3
CH), 131.2 (d, JPC 3.0 Hz, 2 × CH), 131.9 (d, JPC 11.1 Hz,
CH), 135.5 (C), 136.4 (d, JPC 99.1 Hz, C), 136.7 (d, JPC 96.1
Hz, C), 138.0 (d, JPC 8.7 Hz, C), 153.4 (C), 156.5 (d, JPC 6.6
Hz, C) ppm. 31P NMR (121.47 MHz) δ 59.4 ppm. HRMS (ESI)
calcd for C25H29N2OPSCu: 499.1034 (MCu+), found: 499.1032.
(d, JPC 3.3, C), 145.2 (d, JPC 11.2 Hz, C) ppm. 31P NMR
(121.47 MHz) δ 62.0 ppm. HRMS (ESI) calcd for C24H29NPS:
394.1758 (MH+), found: 394.1746.
3
2
1
1
2
3
Procedure for the synthesis of 1-(2-iodophenyl)-N,N-diisopro-
pyl-1-phenylphosphinamine 33. To a solution of 13 (100 mg,
0.226 mmol) in dry dichloromethane (20 mL) was added methyl
triflate (51 μL, 0.452 mmol) under an inert atmosphere. The
resulting solution was stirred at room temperature during 24 h.
Then tris(dimethylamino)phosphine (HMPT) was added (82 μL,
0.452 mmol) and the reaction mixture was stirred at 25 °C
Acknowledgements
We thank the Ministerio de Ciencia e Innovación and FEDER
program for financial support (projects: CTQ2008-117BQU,
CTQ2011-27705, MAT2010-15094, PTA-2009-2346-I and
CSD2006-015, Consolider Ingenio 2010, “Factoría de Cristaliza-
ción”). H.H. thanks Ministerio de Asuntos Exteriores, AECID
5656 | Org. Biomol. Chem., 2012, 10, 5647–5658
This journal is © The Royal Society of Chemistry 2012

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for a pre-doctoral fellowship. I.F. thanks the Ramón y Cajal
program for financial support.
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