Half-sandwich rare-earth metal tris(alkyl) ate complexes catalyzed phosphaguanylation reaction of phosphines with carbodiimides: An efficient synthesis of phosphaguanidines

Article abstract of DOI:10.1039/c5nj01136a

The phosphaguanylation reaction of phosphines with carbodiimides catalyzed by half-sandwich yttrium tris(trimethylsilylmethyl) ate complexes is achieved for the first time to efficiently prepare phosphaguanidines. The catalyst system of the yttrium ate complex displays better catalytic activity than those of neutral yttrium complexes.

Full text of DOI:10.1039/c5nj01136a

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Half-sandwich rare-earth metal tris(alkyl) ate
complexes catalyzed phosphaguanylation reaction
of phosphines with carbodiimides: an efficient
synthesis of phosphaguanidines†
Cite this:DOI: 10.1039/c5nj01136a
Wangyang Ma,a Ling Xu,a Wen-Xiong Zhang*ab and Zhenfeng Xia
Received (in Montpellier, France)
6th May 2015,
Accepted 22nd May 2015
The phosphaguanylation reaction of phosphines with carbodiimides catalyzed by half-sandwich yttrium
tris(trimethylsilylmethyl) ate complexes is achieved for the first time to efficiently prepare phosphaguanidines.
The catalyst system of the yttrium ate complex displays better catalytic activity than those of neutral
yttrium complexes.
DOI: 10.1039/c5nj01136a
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with the less electrophilic N,N0-dialkyl or N-alky-N0-aryl carbo-
diimides cannot be achieved without suitable catalysts; there-
Introduction
The catalytic guanylation reaction of amines with carbodiimides fore, the search and design of suitable catalyst systems for the
(CGAC reaction) has become a hot area of research, because CPPC reaction are in high demand.
it provides a straightforward and atom-economical route to
In 2006, Hou et al. reported the first CPPC reactions catalyzed
prepare guanidines (RNQC(NR0R00)NHR).1–3 In contrast, the via alkali metal bis(trimethylsilyl)amides [MN(SiMe3)2] (1: M = Li,
catalytic phosphaguanylation reaction of phosphines with car- Na, and K) (Fig. 1 shows the structure of complexes 1–8).9 The
bodiimides (hereafter as CPPC reaction), which is also known heavier group 2 catalysts, 2 and 3, were tested by Hill and
as catalytic addition of phosphines to carbodiimides or hydro- Barrett. The homoleptic alkaline earth (Ca, Sr and Ba) amides 2
phosphination of carbodiimides, has received considerably less displayed higher activity than b-the diketiminato calcium
attention, although this reaction provides an atom-economical complex 3.10 The triamidoamine-supported zirconium complex 4
synthesis of phosphaguanidines (R02PC(QNR)NHR). These phos- showed moderate activity for the CPPC reaction.11 In the attempt to
phaguanidines, as analogues of guanidines, are widely used as test the rare-earth metals, the half-sandwich lanthanum amino-
building blocks of ancillary ligands for many transition metal benzyl complex 5-La was found by Hou et al. to display the highest
species.4,5 Initially, this catalyst-free direct phosphaguanylation activity among the rare-earth metals because of its largest ionic
reaction of diphenylphosphine with an N,N0-diaryl substituted
carbodiimide was reported to afford the phosphaguanidine in a
low yield under rather harsh conditions.6 Recently, the direct
phosphaguanylation reaction of the active hydrogen heptaphos-
phide dianion [HP7]2ꢀ with RNQCQNR (R = 2,6-diisopropylphenyl
(Dipp), iPr, and Cy) was reported to afford the functionalized cluster
anions [P7C(QNR)NHR]2ꢀ.7 Very recently, the stoichiometric NaH-
mediated phosphaguanylation of phosphine boranes with carbodi-
imides provided an alternative synthesis of phosphaguanidines by
the removal of the borane using 1,4-diazabicyclo[2.2.2]octane
(DABCO).8 The phosphaguanylation reaction of phosphines
a Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of
Bioorganic Chemistry and Molecular Engineering, College of Chemistry,
Peking University, Beijing 100871, China. E-mail: wx_zhang@pku.edu.cn
b State Key Laboratory of Elemento-Organic Chemistry, Nankai University,
Tianjin, 300071, China
† Electronic supplementary information (ESI) available: The detailed experi-
mental synthesis and characterization. CCDC 1047716 (9i). For ESI and crystal-
Fig. 1 The reported catalyst precursors for the CPPC reaction.
lographic data in CIF or other electronic format see DOI: 10.1039/c5nj01136a
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radius (1.032 Å for La3+); however, the corresponding yttrium entries 2–4). Low yields were found when the reaction was carried
complexes 5-Y and 6-Y (0.900 Å for Y3+) showed evidently lower out at room temperature (Table 1, entry 5) or under low catalyst
activity.12 Schmidt et al. reported the CPPC reaction using loading (1 mol%) (Table 1, entry 6). All of these complexes with
homoleptic a-metalated N,N-dimethylbenzylamine lanthanum different metal centers (Er, Tm and Lu) had catalytic activities
complex 7-La, in which three N,N-dimethylbenzylamine ligands (Table 1, entries 7–9). The ate complex 8-Y showed better catalytic
were released via protonolysis with phosphines to yield the active activity than the neutral yttrium complexes such as the half-
La–P species.13 All these reported catalyst systems involved only the sandwich constrained-geometry complex 6-Y, mono-Cp complex
neutral metal amides or alkyl complexes. We reported the synthesis 10-Y, and tris(trimethylsilylmethyl) complex Y(CH2TMS)3(THF)2.
and structural characterization of half-sandwich rare-earth metal The comparison clearly shows the significance of combining
tris(trimethylsilylmethyl) ate complexes bearing one 1-phenyl-2,3,4,5- cyclopentadiene-based ligands and ate complexes (Table 1,
tetrapropylcyclopentadienyl ligand and their catalytic application entries 4 and 11–13).
in CGAC reactions to construct guanidines.14 We envision that
these ate complexes, which might have the advantages of the
Substrate scope
neutral metal amides and alkyl complexes, could serve as good
catalyst precursors for the CPPC reaction to construct phospha-
guanidines. Herein, we report these results.
The anionic rare-earth complex 8-Y was chosen for the CPPC
reaction, and representative results are summarized in Table 2.
Various carbodiimides could be applied to the present condi-
tions. When symmetric N,N0-dialkylcarbodiimides such as DIC
and N,N0-dicyclohexylcarbodiimide (DCC) were utilized, the
Results and discussion
Condition screening
Table 2 Substrate scopea,b
As a control experiment, barely mixing diphenylphosphine and
N,N0-diisopropylcarbodiimide (DIC) in the absence of catalysts
resulted in no phosphaguanidine product, even at 140 1C for
24 h in C6D5Cl (Table 1, entry 1). However, when a small amount
of 8-Y was added, the corresponding phosphaguanidine 9a can
be detected by 31P NMR (Table 1, entries 2–6). Both polar solvent
(THF) and non-polar solvents (benzene and toluene) were tested,
and it was revealed that THF was the best option probably owing
to the excellent solubility for the rare-earth complex (Table 1,
Table 1 Condition screeninga
Entry Cat. (mol%)
Solvent Temp. (1C) Time (h) Yieldb (%)
1
2
3
4
5
6
7
8
0
C6D5Cl 140
24
7
7
1
1
1
1
1
1
0
78
67
97
35
45
52
68
49
62
86
65
66
8-Y (3)
8-Y (3)
8-Y (3)
8-Y (3)
8-Y (1)
8-Er (3)
8-Tm (3)
8-Lu (3)
8-Y (5)
6-Y (3)
10-Y (3)
C6D6
Tol-d8
80
80
THF-d8 80
THF-d8 r.t.
THF-d8 80
THF-d8 80
THF-d8 80
THF-d8 80
THF-d8 r.t.
THF-d8 80
THF-d8 80
9
10
11
12
13
12
1
8
Y(CH2TMS)3(THF)2 THF-d8 80
3
a
Conditions: phosphine, 0.53 mmol; carbodiimide, 0.50 mmol, THF,
a
b
c
Conditions: diphenylphosphine, 0.23 mmol; N,N0-diisopropylcarbo- 5 mL, unless otherwise noted. Isolated yield. 6 mol% catalyst, 24 h.
b
d
diimide, 0.20 mmol. Determined by 31P NMR.
Carbodiimide, 1 mmol.
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corresponding phosphaguanidines (9a, 9b, 9g, 9h, and 9k–m) for accepting nucleophilic attack of the phosphine. The phos-
were obtained in excellent yields under the relatively mild phaguanylation products originating from bulky carbodiimides
conditions. In the case of N-ethyl-N0-tert-butylcarbodiimides such as N,N0-bis(2,6-diisopropylphenyl)carbodiimide and diphenyl-
(9c), this CPPC reaction need higher catalyst loadings and long phosphine, were not observed probably owing to the steric
reaction time probably due to the steric hindrance of the tert- hindrance at the nitrogen atom, which prevents the coordina-
butyl group. Unsymmetric N-aryl-N0-alkyl carbodiimides, such tion of the carbodiimide to the rare-earth metal center. Most
as N-phenyl-N0-cyclopentyl, N-phenyl-N0-cyclohexyl, N-p-tol-N0- diarylphosphines could be utilized in this reaction to afford
cyclohexyl, N-phenyl-N0-cycloheptyl, N-phenyl-N0-cyclooctyl and the corresponding products (9a–r) in good yields. The dialkyl-
N-phenyl-N0-CH2-cyclohexyl carbodiimides, could also be applied phosphines such as di-iso-butylphosphine could not be applied
to construct phosphaguanidines (9d–f, 9i, 9j and 9n–r), but probably due to the decreased acidity compared to diaryl-
higher catalyst loadings and long reaction time were required phosphines. When the primary phosphine PhPH2 was treated
owing to the low electrophilicity of N-alky-N0-aryl carbodiimides with one equivalent of DIC, both mono- and double-addition
products iPrNQC(PHPh)(NHiPr), PhP{iPrNQC(NHiPr)}2 could
be detected by 31P NMR (mono-addition product: ꢀ62.1 ppm
and double-addition product: ꢀ34.9 ppm). When the amount
of DIC was increased to 2 equivalents, the double-addition
product 9s can be obtained exclusively in 93% yield.
Although phosphaguanidines could, in principle, have eight
possible isomers, Esyn-(a,b), Eanti-(a,b), Zsyn-(a,b), and Zanti
-
(a,b),15 all of the 1H, 13C and 31P NMR spectra of 9a–r indicated
only one isomer in solution. X-ray single crystal diffraction
analysis of phosphaguanidine 9i reveals it is an Esyn-(a) isomer
with the phenyl group placed on the CQN double bond in the
solid state (Fig. 2).
To gain further insight into the mechanism of the CPPC
reaction, we conducted a stoichiometric reaction by in situ NMR
monitoring. The original spectra of 8-Y in THF-d8 without TMS
internal standard is illustrated in Fig. 3a. The double peaks of
Fig. 2 ORTEP drawing of 9i with 30% ellipsoids. Hydrogen atoms, except
that on nitrogen atom N2, are omitted for clarity.
Fig. 3 In situ NMR spectra of stoichiometric reaction. (a) 8-Y; (b) 8-Y + 3DIC at room temperature for 12 h; (c) 8-Y + 3Ph2PH at room temperature for
12 h; (d) 8-Y + 3Ph2PH at room temperature for 24 h; (e) 8-Y + 3Ph2PH + 3DIC at 80 1C for 1 h; (f) (8-Y + 3Ph2PH + 3DIC) + 3Ph2PH at room temperature
for 15 min.
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ꢀ1.19 ppm and single peak of ꢀ0.13 ppm were ascribed to CH2 The fast coordination and disassociation of DIC to the yttrium
and CH3 of CH2SiMe3, respectively. When 8-Y was treated with center in THF was probably out of the NMR time scale, so the
1
3 equivalents of DIC, the H NMR spectra showed the peaks of evident chemical shifts of DIC were not observed, which was
DIC remained unchanged after 12 h at room temperature consistent with the observation of Fig. 3e. Then, the coordina-
(Fig. 3b). This result shows that the insertion of DIC into the tion of phosphine might yield the adduct C. The intramolecular
Y–CH2SiMe3 alkyl bond does not occur at room temperature. nucleophilic attack of the Y–P bond on the central carbon of the
However, when 8-Y was treated with 3 equivalents of Ph2PH, coordinate carbodiimide and the protonolysis with the R2P–H bond
the reaction mixture turned light yellow immediately. After 12 h released the phosphaguanidine product 9 and regenerated A to
at room temperature, the 1H NMR spectra showed that the finish the catalytic cycle.
integral of the CH2SiMe3 groups decreased and the peak of SiMe4
was observed at 0 ppm (Fig. 3c). After 24 h at room temperature,
1
the H NMR spectra showed that the peaks of CH2SiMe3 almost
Conclusions
disappeared (Fig. 3d). The formation of SiMe4 resulted from
In summary, we have reported a half-sandwich yttrium tris(trimethyl-
silylmethyl) ate complex catalyzed phosphaguanylation reaction
of phosphines with carbodiimides to efficiently prepare phos-
phaguanidines. The present yttrium catalyst system is easier to
prepare and cheaper than those reported using neutral lanthanum
complexes. It displays the best catalytic activity among the
known yttrium complexes probably owing to the cooperative
effect between the anionic yttrium core and cationic lithium
moiety. Further investigation on the mechanism and catalytic
application is underway.
the acid–base reaction between the phosphine P–H bond and
Y–CH2SiMe3 alkyl bond. The comparative results show that the
acid–base reaction between the P–H bond and Y–CH2SiMe3 alkyl
bond is faster than the insertion of the carbodiimide into the
Y–CH2SiMe3 alkyl bond at room temperature. This result also
indicated that all of the three CH2SiMe3 groups in 8-Y were
involved in the acid–base reaction. Subsequent addition of 3
equivalents of DIC led apparently to the doublet peak at 1.16
ppm and multiplet peak at 3.47 ppm for CH3 and CH of DIC in
1
the H NMR spectrum, respectively (Fig. 3e). After heating this
mixture at 80 1C for 1 h, no evident change in 1H NMR spectrum
was observed, which indicated that DIC did not insert into the Y–P
bond. Interestingly, when another 3 equivalents of Ph2PH were
added into the abovementioned solution, all the peaks belonging
to the iPr moiety of DIC changed within 15 min (Fig. 3f). The
peaks of CH3 and CH of DIC shifted to 0.93 ppm and 4.04 ppm,
which were consistent with the corresponding chemical shifts of
the iPr of phosphaguanidine 9a. After the addition of an excess
of Ph2PH and DIC in 1 : 1 ratio, the catalytic formation of
phosphaguanidine 9a was evidently observed.
Experimental section
General considerations
All reagents were purchased from commercial sources and used
without treatment, unless otherwise indicated. All reactions were
conducted under a slightly positive pressure of dry nitrogen
using standard Schlenk line techniques or under a nitrogen
atmosphere in a Vigor (SG 1200/750TS-F) glovebox. The nitrogen
in the glove box was constantly circulated through a copper/
molecular sieves catalyst unit. The oxygen and moisture concentra-
tions in the glovebox atmosphere were monitored by an O2/H2O
Combi-Analyzer to ensure both were always below 1 ppm. Unless
otherwise noted, all starting materials were commercially available
and were used without further purification. Solvents were purified
by an Mbraun SPS-800 Solvent Purification System and dried over
fresh Na chips in the glovebox. Organometallic samples for NMR
spectroscopic measurements were prepared in the glovebox by
use of J. Young valve NMR tubes (Wilmad 528-JY). 1H, 13C NMR
and 31P spectra were recorded using Bruker-400 spectrometer
A possible reaction mechanism for the CPPC reaction was
proposed and is shown in Scheme 1. The formation of the active
phosphide species A might undergo two possible pathways:
(i) the acid–base reaction between a phosphine and 8-Y, and
(ii) the insertion of the carbodiimide into the Y-alkyl bond
followed by protonolysis yielding an amidine and Y-phosphido
complex A. The insertion pathway can be excluded, because the
acid–base reaction is faster than the insertion reaction, according
to the experimental results shown in Fig. 3b and c. The coordina-
tion of carbodiimides took place to form the coordinate species B.
1
(FT, 400 MHz for H; 100 MHz for 13C and 160 MHz for 31P) at
room temperature. High-resolution mass spectra (HRMS) were
recorded with a Bruker Apex IV FTMS mass spectrometer using
an ESI (electrospray ionization) source.
NMR tube reaction
In a glovebox, a J. Young valve NMR tube was charged with 8-Y
(5.7 mg, 0.006 mmol), THF (0.5 mL), diphenylphosphine (43 mg,
0.23 mmol), and N,N0-diisopropylcarbodiimide (25 mg, 0.20 mmol).
The tube was taken out of the glovebox and then heated at 80 1C
in an oil bath for 1 h. The formation of the phosphaguanidine
was monitored by 31P NMR spectroscopy.
Scheme 1 A plausible mechanism for the CPPC reaction.
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Preparative scale reaction
iPrN
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9
Q
C{P(C6H4Me-2)2}(NHiPr) (9g) . Colorless solid, iso-
lated yield 88% (150 mg); 1H NMR (400 MHz, C6D6, Me4Si):
In a glovebox, the mixture of a THF solution (1 mL) of 8-Y
(14.4 mg, 0.015 mmol) and a THF solution (2 mL) of diphenyl-
phosphine (99 mg, 0.53 mmol) was added to a Schlenk tube.
Then, N,N0-diisopropylcarbodiimide (63 mg, 0.5 mmol) was
added to the abovementioned reaction mixture. The Schlenk
tube was taken outside the glovebox, and the mixture was stirred
at 80 1C for 1 h. After the stirring, the solvent was removed under
reduced pressure. The residue was extracted with hexane and
filtered to give a clean solution. After the removal of the solvent
under vacuum, the residue was recrystallized in hexane to provide
the phosphaguanidine 9a. Compounds 9b–s were prepared in a
d = 0.94 (d, J = 6.4 Hz, 6H; CH(CH3)2), 1.33 (d, J = 5.4 Hz,
6H; CH(CH3)2), 2.41 (s, 6H; Me), 3.72 (d, J = 6.4 Hz, 1H; NH),
4.34–4.47 (m, 2H; CH), 6.92–7.06 (m, 8H; C6H4) ppm.
3
Q
CyN C{P(C6H4Me-2)2}(NHCy) (9h). Colorless solid, isolated
yield 87% (183 mg); 1H NMR (400 MHz, C6D6, Me4Si): d = 0.89–
1.94 (m, 20H; Cy), 2.45 (s, 6H; Me), 3.90 (d, 3J = 7.0 Hz, 1H; NH),
4.08–4.26 (m, 2H, CH), 6.98–7.07 (m, 8H; C6H4) ppm; 13C NMR
3
(100 MHz, C6D6, Me4Si): d = 21.3 (d, Jpc = 21.7 Hz), 24.7,
3
25.3, 26.1, 26.4, 32.7, 35.9, 49.1, 60.9 (d, Jpc = 35.2 Hz), 126.8,
3
2
129.6, 130.6 (d, Jpc = 4.5 Hz), 143.0 (d, Jpc = 25.9 Hz), 151.8
(d, Jpc = 30.2 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6): d =
1
similar procedure.
ꢀ32.9 ppm; HRMS: m/z calcd for C27H38N2P: 421.2767 [M + H]+;
9
Q
iPrN C(PPh2)(NHiPr) (9a) . Colorless solid, isolated yield
found: 421.2754.
97% (151 mg); 1H NMR (400 MHz, C6D6, Me4Si): d = 0.96
(d, J = 6.4 Hz, 6H; CH(CH3)2), 1.26 (d, J = 6.1 Hz, 6H;
CH(CH3)2), 3.66 (d, 3J = 6.3 Hz, 1H; NH), 4.29–4.47 (m, 2H;
CH), 7.01–7.08 (m, 6H; C6H5), 7.44–7.49 (m, 4H; C6H5) ppm;
1H NMR (400 MHz, THF-d8, Me4Si): d = 0.92 (d, J = 2.7 Hz, 6H;
CH(CH3)2), 0.94 (d, J = 3.0 Hz, 6H; CH(CH3)2), 3.52 (d, 3J = 6.4 Hz,
Q
PhN C{P(C6H4Me-4)2}{NH–(CH2)5} (9i). Colorless solid,
1
isolated yield 84% (168 mg); H NMR (400 MHz, C6D6, Me4Si):
d = 1.28–1.90 (m, 8H; –(CH2)4–), 1.98 (s, 6H; Me), 4.52 (d, J =
3
6.4 Hz, 1H; NH), 4.61–4.65 (m, 1H; CH), 6.84–6.86 (m, 1H;
C6H5), 6.89 (d, J = 7.6 Hz, 4H; C6H4), 7.12 (d, J = 4.7 Hz, 4H;
C6H5), 7.39 (t, J = 7.6 Hz, 4H; C6H4) ppm; 13C NMR (100 MHz,
1H; NH), 3.98–4.08 (m, 2H; CH), 7.34–7.40 (m, 10H; C6H5) ppm.
4
C6D6, Me4Si): d = 21.1, 23.8, 33.3, 53.8, 122.2, 123.3 (d, Jpc
=
9
Q
CyN C(PPh2)(NHCy) (9b) . Colorless solid, isolated yield
3
1
1.8 Hz), 128.5, 129.8 (d, Jpc = 7.0 Hz), 132.1 (d, Jpc = 14.3 Hz),
1
95% (186 mg); H NMR (400 MHz, C6D6, Me4Si): d = 0.95–1.92
(m, 20H; Cy), 3.82 (d, J = 6.8 Hz, 1H; NH), 4.07–4.19 (m, 2H;
2
3
134.5 (d, Jpc = 20.3 Hz), 139.4, 152.1 (d, Jpc = 11.9 Hz), 157.4
3
(d, Jpc = 37.1 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6): d =
1
CH), 7.02–7.09 (m, 6H; C6H5), 7.49–7.52 (m, 4H; C6H5) ppm.
ꢀ16.2 ppm; HRMS: m/z calcd for C26H30N2P: 401.2141 [M + H]+;
found: 401.2129. Single crystals of 9i suitable for X-ray analysis
were grown in THF–hexane for 1 day at room temperature.
9
Q
tBuN C(PPh2)(NHEt) (9c) . Colorless solid, isolated yield 83%
(130 mg); 1H NMR (400 MHz, C6D6, Me4Si): d = 1.31 (t, J = 7.2 Hz,
3H; CH2CH3), 1.36 (s, 9H; C(CH3)3), 3.77–3.83 (m, 3H, NH and
Q
PhN C{P(C6H4Me-4)2}(NHCy) (9j). Colorless solid, isolated
CH2CH3), 7.01–7.06 (m, 6H; C6H5), 7.45–7.49 (m, 4H; C6H5) ppm.
yield 81% (168 mg); 1H NMR (400 MHz, C6D6, Me4Si): d = 0.88–
1.42 (m, 10H; Cy), 2.00 (s, 6H; Me), 4.26–4.30 (m, 1H; CH),
4.50 (d, 3J = 7.2 Hz, 1H; NH), 6.83–6.88(m, 1H; C6H5), 6.91
(d, J = 7.6 Hz, 4H; C6H4), 7.12 (d, J = 4.5 Hz, 4H; C6H5), 7.42
(t, J = 7.6 Hz, 4H; C6H4) ppm; 13C NMR (100 MHz, C6D6, Me4Si):
9
Q
PhN C(PPh2)(NHCy) (9d) . Colorless solid, isolated yield
1
85% (164 mg); H NMR (400 MHz, C6D6, Me4Si): d = 0.88–1.94
(m, 10H; Cy), 4.22–4.24 (m, 1H; CH), 4.38 (d, J = 7.0 Hz, 1H;
3
NH), 6.84 (t, J = 7.6 Hz, 1H; C6H5), 7.03–7.11 (m, 10H; C6H5),
7.44 (t, J = 6.3 Hz, 4H; C6H5) ppm.
4
d = 21.1, 24.8, 26.0, 32.7, 49.9, 122.1, 123.4 (d, Jpc = 1.7 Hz),
Q
3
1
PhN C(PPh2){NH–(CH2)5} (9e). Colorless solid, isolated
128.5, 129.8 (d, Jpc = 7.1 Hz), 132.1 (d, Jpc = 14.4 Hz), 134.5
yield 83% (155 mg); 1H NMR (400 MHz, C6D6, Me4Si):
(d, 2Jpc = 20.3 Hz), 139.4, 152.1 (d, 3Jpc = 12.0 Hz), 156.8 (d, 1Jpc
=
3
36.7 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6): d = ꢀ15.9 ppm;
d = 1.23–1.87 (m, 8H; –(CH2)4–), 4.38 (d, J = 6.3 Hz, 1H; NH),
HRMS: m/z calcd for C27H32N2P: 415.2298 [M + H]+; found:
4.55–4.61 (m, 1H; CH), 6.83–6.87 (m, 1H; C6H5), 7.00–7.12
(m, 10H; C6H5), 7.38–7.43 (m, 4H; C6H5) ppm; 13C NMR
(100 MHz, C6D6, Me4Si): d = 23.8, 33.2, 53.9, 122.3, 123.3
415.2287.
9
Q
iPrN C{P(C6H4Me-4)2}(NHiPr) (9k) . Colorless solid, iso-
4
3
lated yield 95% (162 mg); 1H NMR (400 MHz, C6D6, Me4Si):
(d, Jpc = 1.8 Hz), 128.6, 128.9 (d, Jpc = 6.8 Hz), 129.4, 134.4
2
1
3
(d, Jpc = 20.1 Hz), 135.3 (d, Jpc = 15.5 Hz), 151.9 (d, Jpc
=
d = 1.00 (d, J = 6.4 Hz, 6H; CH(CH3)2), 1.28 (d, J = 6.1 Hz,
12.1 Hz), 156.8 (d, 1Jpc = 36.7 Hz) ppm; 31P{1H} NMR (160 MHz,
C6D6): d = ꢀ14.6 ppm; HRMS: m/z calcd for C24H26N2P:
373.1828 [M + H]+; found: 373.1817.
3
6H; CH(CH3)2), 2.02 (s, 6H; Me), 3.79 (d, J = 6.6 Hz, 1H; NH),
4.34–4.51 (m, 2H; CH), 6.93 (d, J = 7.5 Hz, 4H; C6H4), 7.44
(t, J = 7.7 Hz, 4H; C6H4) ppm.
Q
p-tolN C(PPh2)(NHCy) (9f). Colorless solid, isolated yield
Q
CyN C{P(C6H4Me-4)2}(NHCy) (9l). Colorless solid, isolated
1
yield 91% (191 mg); 1H NMR (400 MHz, C6D6, Me4Si): d = 0.93–
1.98 (m, 20H; Cy), 2.02 (s, 6H; Me), 3.94 (d, 3J = 7.0 Hz, 1H; NH),
4.13–4.24 (m, 2H; CH), 6.96 (d, J = 7.6 Hz, 4H; C6H4), 7.49
85% (170 mg); H NMR (400 MHz, C6D6, Me4Si): d = 0.96–1.95
(m, 10H; Cy), 2.07 (s, 3H; Me), 4.25–4.26 (m, 1H; CH), 4.35 (d, 3J =
6.6 Hz, 1H; NH), 6.89–7.05 (m, 10H; C6H5), 7.43–7.45 (m, 4H;
C6H4) ppm; 13C NMR (100 MHz, C6D6, Me4Si): d = 20.9, 24.6,
(t, J = 7.6 Hz, 4H; C6H4) ppm; 13C NMR (100 MHz, C6D6, Me4Si):
4
3
3
26.0, 32.6, 49.8, 123.1 (d, Jpc = 1.6 Hz), 128.9 (d, Jpc = 6.8 Hz),
129.2, 129.4, 131.1, 134.4 (d, 2Jpc = 20.0 Hz), 135.5 (d, 1Jpc = 15.8 Hz),
149.4 (d, 3Jpc = 12.5 Hz), 156.1 (d, 1Jpc = 36.3 Hz) ppm; 31P{1H} NMR
(160 MHz, C6D6): d = ꢀ14.9 ppm; HRMS: m/z calcd for C26H30N2P:
401.2141 [M + H]+; found: 401.2144.
d = 21.1, 24.7, 25.3, 26.2, 26.4, 32.7, 35.8, 49.2, 60.2 (d, Jpc
=
33.6 Hz), 129.8 (d, 3Jpc = 7.0 Hz), 132.5 (d, 1Jpc = 13.2 Hz), 134.4
(d, Jpc = 19.7 Hz), 139.2, 152.8 (d, Jpc = 31.8 Hz) ppm; 31P{1H}
2
1
NMR (160 MHz, C6D6): d = ꢀ19.5 ppm; HRMS: m/z calcd for
C
27H38N2P: 421.2767 [M + H]+; found: 421.2760.
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New J. Chem.

C{P(C6H3Me2-3,5)2}(NHiPr) (9m) . Colorless solid, 122.2, 123.3 (d, 4Jpc = 1.2 Hz), 128.5, 128.9 (d, 3Jpc = 6.8 Hz), 129.4,
Q
iPrN
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9
isolated yield 85% (157 mg); H NMR (400 MHz, C6D6, Me4Si): 134.4 (d, 2Jpc = 20.1 Hz), 135.3 (d, 1Jpc = 15.6 Hz), 151.9 (d, 3Jpc
=
1
d = 1.03 (d, J = 6.4 Hz, 6H; CH(CH3)2), 1.32 (d, J = 6.1 Hz, 12.2 Hz), 156.1 (d, 1Jpc = 37.5 Hz) ppm; 31P{1H} NMR (160 MHz,
6H; CH(CH3)2), 2.03 (s, 12H; Me), 3.91 (d, 3J = 6.6 Hz, 1H; NH), C6D6): d = ꢀ14.3 ppm; HRMS: m/z calcd for C27H32N2P: 415.2298
4.37–4.54 (m, 2H, CH), 6.75 (s, 2H; C6H3), 7.28 (d, J = 8.0 Hz, 4H; [M + H]+; found: 415.2289.
Q
PhP{iPrN C(NHiPr)}2 (9s). Colorless oil, isolated yield 93%
C6H3) ppm.
PhN C{P(C6H4Me-4)2}{NH–(CH2)7} (9n). Colorless solid, (168 mg); 1H NMR (400 MHz, C6D6, Me4Si): d = 0.98 (d, J =
Q
1
isolated yield 87% (186 mg); H NMR (400 MHz, C6D6, Me4Si): 6.1 Hz, 6H; CH(CH3)2), 1.08 (d, J = 6.1 Hz, 6H; CH(CH3)2), 1.22
d = 1.23–1.97 (m, 12H; –(CH2)6–), 2.01 (s, 6H; Me), 4.44–4.45 (m, (d, J = 6.1 Hz, 6H; CH(CH3)2), 1.34 (d, J = 6.1 Hz, 6H; CH(CH3)2),
1H; CH), 4.55 (d, 3J = 7.2 Hz, 1H; NH), 6.82–6.86 (m, 1H; C6H5), 4.24–4.36 (m, 6H; CH and NH), 7.04–7.10 (m, 3H; C6H5), 7.51–
6.92 (d, J = 7.7 Hz, 4H; C6H4),7.09 (d, J = 4.6 Hz, 4H; C6H5), 7.41 7.55 (m, 2H; C6H5) ppm; 13C NMR (100 MHz, C6D6, Me4Si):
4
4
(t, J = 7.7 Hz, 4H; C6H4) ppm; 13C NMR (100 MHz, C6D6, Me4Si): d = 22.4 (d, Jpc = 2.9 Hz), 25.3 (d, Jpc = 8.0 Hz), 42.9, 52.6 (d,
d = 21.1, 24.3, 28.1, 34.5, 52.1, 122.0, 123.3 (d, Jpc = 1.7 Hz), 3Jpc = 36.9 Hz), 129.2 (d, Jpc = 6.4 Hz), 129.6, 133.3 (d, Jpc
=
4
3
1
3
1
2
1
128.4, 129.8 (d, Jpc = 7.0 Hz), 132.0 (d, Jpc = 14.3 Hz), 134.4 17.6 Hz), 134.0 (d, Jpc = 19.1 Hz), 151.4 (d, Jpc = 35.4 Hz);
(d, 2Jpc = 20.3 Hz), 139.4, 152.1 (d, 3Jpc = 12.0 Hz), 156.6 (d, 1Jpc
=
31P{1H} NMR (160 MHz, C6D6): d = ꢀ34.9 ppm; HRMS: m/z calcd
36.7 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6): d = ꢀ15.9 ppm; for C20H36N4P: 363.2672 [M + H]+; found: 363.2669.
HRMS: m/z calcd for C28H34N2P: 429.2454 [M + H]+; found:
429.2444.
X-ray diffraction analysis
Q
PhN C(PPh2){NH–(CH2)7} (9o). Colorless solid, isolated yield
Data collections for 9i were performed at 180 K with a Super-
Nova diffractometer using graphite-monochromated Mo Ka
radiation (l = 0.71073 Å). Using Olex2, the structure of 9i was
solved with the Superflip structure solution program using
Charge Flipping and refined with the XL refinement package
using Least Squares minimization. Refinement was performed
on F2 anisotropically for all the non-hydrogen atoms by the full-
matrix least-squares method. The hydrogen atoms were placed
at the calculated positions and were included in the structure
calculation without further refinement of the parameters.
Crystallographic data (excluding structure factors) have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication number: CCDC 1047716.
1
93% (186 mg); H NMR (400 MHz, C6D6, Me4Si): d = 1.21–1.90
(m, 12H; –(CH2)6–), 4.43 (br, 2H; CH and NH), 6.82–6.86 (m, 1H;
C6H5), 7.03–7.10 (m, 10H; C6H5), 7.42–7.45 (m, 4H; C6H5) ppm;
13C NMR (100 MHz, C6D6, Me4Si): d = 24.2, 28.1, 34.4, 52.1, 122.2,
123.3 (d, 4Jpc = 1.7 Hz), 128.5, 128.9 (d, 3Jpc = 6.9 Hz), 129.4, 134.4
(d, 2Jpc = 20.1 Hz), 135.2 (d, 1Jpc = 15.6 Hz), 151.9 (d, 3Jpc = 12.2 Hz),
1
156.1 (d, Jpc = 36.9 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6):
d = ꢀ14.3 ppm; HRMS: m/z calcd for C26H30N2P: 401.2141
[M + H]+; found: 401.2131.
Q
PhN C(PPh2)(NHCH2Cy) (9p). Colorless solid, isolated yield
1
81% (162 mg); H NMR (400 MHz, C6D6, Me4Si): d = 0.65–1.58
(m, 11H; Cy), 3.31 (t, J = 5.8 Hz, 2H; CH2), 4.46 (t, J = 5.0 Hz,
1H; NH), 6.81–6.85 (m, 1H; C6H5), 7.03–7.10 (m, 10H; C6H5),
7.40–7.44 (m, 4H; C6H5) ppm; 13C NMR (100 MHz, C6D6, Me4Si):
4
d = 26.1, 26.7, 30.9, 37.6, 48.5, 122.1, 123.2 (d, Jpc = 1.6 Hz),
Acknowledgements
3
2
128.5, 128.9 (d, Jpc = 6.8 Hz), 129.4, 134.4 (d, Jpc = 20.1 Hz),
135.0 (d, 1Jpc = 15.4 Hz), 151.9 (d, 3Jpc = 11.9 Hz), 157.3 (d, 1Jpc
=
This work was supported by the Natural Science Foundation of
China and the ‘‘973’’ program from National Basic Research
Program of China (2012CB821600).
36.2 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6): d = ꢀ13.5 ppm;
HRMS: m/z calcd for C26H30N2P: 401.2141 [M + H]+; found:
401.2141.
Q
PhN C{P(C6H4Me-4)2}{NH–(CH2)8} (9q). Colorless solid,
1
isolated yield 80% (177 mg); H NMR (400 MHz, C6D6, Me4Si):
Notes and references
d = 1.30–1.92 (m, 14H; –(CH2)7–), 2.00 (s, 6H; Me), 4.45 (br, 1H;
CH), 4.56 (d, 3J = 7.1 Hz, 1H; NH), 6.82–6.87 (m, 1H; C6H5),
6.92 (d, J = 7.6 Hz, 4H; C6H4), 7.10 (d, J = 4.4 Hz, 4H; C6H5), 7.42
1 For selected reviews of CGAC reaction, see: (a) L. Xu, W.-X.
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Zhang, L. Xu and Z. Xi, Chem. Commun., 2015, 51, 254;
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4
˜
d = 21.1, 23.9, 25.7, 27.4, 32.1, 51.2, 122.1, 123.4 (d, Jpc
=
(c) C. Alonso-Moerno, A. Antinolo, F. Carrillo-Hermosilla
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1
1.5 Hz), 128.5, 129.8 (d, Jpc = 7.0 Hz), 132.1 (d, Jpc = 14.4 Hz),
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2
3
134.4 (d, Jpc = 20.3 Hz), 139.4, 152.1 (d, Jpc = 12.0 Hz), 156.5
(d, Jpc = 36.9 Hz) ppm; 31P{1H} NMR (160 MHz, C6D6): d =
1
ꢀ15.9 ppm; HRMS: m/z calcd for C29H36N2P: 443.2611 [M + H]+;
found: 443.2602.
Q
PhN C(PPh2){NH–(CH2)8} (9r). Colorless solid, isolated yield
1
88% (182 mg); H NMR (400 MHz, C6D6, Me4Si): d = 1.28–1.85
(m, 14H; –(CH2)7–), 4.44 (br, 2H; CH and NH), 6.82–6.86 (m, 1H;
C6H5), 7.03–7.11 (m, 10H; C6H5), 7.42–7.45 (m, 4H; C6H5) ppm;
13C NMR (100 MHz, C6D6, Me4Si): d = 23.8, 25.7, 27.5, 31.9, 51.2,
New J. Chem.
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This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem.