Palladium-Catalyzed Asymmetric 1,6-Addition of Diarylphosphines to Allylidenemalonates for Chiral Phosphine Synthesis

Article abstract of DOI:10.1055/s-0035-1562456

A pincer-palladium-catalyzed asymmetric 1,6-addition of diarylphosphines to allylidenemalonates has been developed for the synthesis of chiral allylic phosphines with up to 89% ee under mild conditions.

Full text of DOI:10.1055/s-0035-1562456

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–F
paper
A
X. Wei et al.
Paper
Synthesis
Palladium-Catalyzed Asymmetric 1,6-Addition of Diarylphos-
phines to Allylidenemalonates for Chiral Phosphine Synthesis
Xu Weia
Junzhu Lub
Wei-Liang Duan*c
Ph2P
Pd
PPh2
OAc
a School of Chemical and Environmental Engineering, Shanghai
Institute of Technology, Shanghai 201418, P. R. of China
b School of Pharmacy, East China University of Science and
Technology, 130 Meilong Road, Shanghai 200237,
P. R. of China
c State Key Laboratory of Organometallic Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences,
345 Lingling Road, Shanghai 200032, P. R. of China
wlduan@mail.sioc.ac.cn
H3B
O
PAr2
O
(1) 5 mol% (S,S)-Pd cat.
toluene, rt, 24 h
tBuO
tBuO
R
tBuO
tBuO
R
HPAr2
+
(2) Me2S·BH3
O
O
up to 71% yield, 89% ee
Received: 14.04.2016
Accepted after revision: 02.06.2016
Published online: 10.08.2016
We have previously studied asymmetric phosphorus
addition to electron-deficient alkenes for chiral phosphine
synthesis.10a During investigation of the diphenylphosphine
reaction with α,β-unsaturated carboxylic esters, no reactiv-
ity was observed because of the low electrophilicity of sub-
strate 1a (Scheme 1).10a Subsequently, an electron-with-
drawing group was introduced into the substrate to in-
crease its reactivity; however, again no reaction occurred
with 1b (Scheme 1). It is worth mentioning that Leung and
co-workers described a palladacycle-catalyzed enantiose-
lective hydrophosphination of substituted methylidene-
malonate ester 1b with excellent enantioselectivity (96%
ee).11 They also reported the asymmetric addition of di-
phenylphosphine to α,β,γ,δ-unsaturated malonic ester 5a,
in which the 1,4-adduct was generated by the use of a pal-
ladacycle catalyst and the 1,6-adduct was produced with a
pincer palladium catalyst.10b,c The regioselectivity (1,6-ad-
dition versus 1,4-addition) can be controlled by using dif-
ferent types of palladium catalysts. In the current study, we
develop pincer-palladium-catalyzed12 asymmetric addition
of diarylphosphines to allylidenemalonates, which furnish-
es chiral allylic phosphine derivatives with good enantiose-
lectivity in moderate yield.
Our studies began with the reaction of allylidene-
malonate 5a with diphenylphosphine in the presence of
pincer palladium catalyst 4.10a Due to the possible steric
hindrance between the two bulky ester groups of 5a and
the phenyl groups of the phosphine nucleophile on the pal-
ladium catalyst, phosphorus nucleophiles would attack 5a
at the less hindered δ-position rather than the more elec-
tron-deficient β-position. Indeed, the reaction generated
the 1,6-adduct 6 as the major product (Table 1, entry
1).10a,13 Screening of the solvent provided no improvement
in the ee and regioselectivity of the reaction (Table 1, en-
tries 2–5). Malonates with other ester groups were subse-
quently tested. Experimental results revealed that 5b bear-
DOI: 10.1055/s-0035-1562456; Art ID: ss-2016-h0251-op
Abstract A pincer-palladium-catalyzed asymmetric 1,6-addition of di-
arylphosphines to allylidenemalonates has been developed for the syn-
thesis of chiral allylic phosphines with up to 89% ee under mild condi-
tions.
Key words asymmetric 1,6-addition, pincer palladium catalyst, chiral
phosphines, allylidenemalonates
Chiral phosphines are widely used in catalysis as ligands
coordinated to transition metals and as organocatalysts for
controlling reactivity and stereoselectivity.1 Therefore, dis-
covering new methods for preparing optically active phos-
phorus compounds is essential and important. Asymmetric
catalysis may provide more opportunities to offer efficient
protocols compared to conventional methods which are
usually based on the resolution of racemates with stoichio-
metric chiral reagents.2 Asymmetric conjugate addition of
phosphorus nucleophiles to electron-deficient alkenes is a
direct method to construct chiral phosphines.3,4 Most suc-
cessful examples have been reported for 1,4-addition5 rath-
er than for 1,6-addition.6 This may be due to the electronic
difference at the β-position and the δ-position of the sub-
strates. In general, 1,4-addition occurs more preferentially
than 1,6-addition in numerous reported examples. By con-
trast, asymmetric 1,6-addition can be realized by carefully
adjusting substrate structures or developing new catalysts.
Recently, successful examples have been disclosed, includ-
ing transition-metal-catalyzed addition of carbon nucleo-
philes to α,β,γ,δ-unsaturated systems and organocatalyzed
1,6-addition.7–9 By contrast, phosphorus nucleophiles re-
main less explored in 1,6-addition reactions.10
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–F

B
X. Wei et al.
Paper
Synthesis
(1) (S,S)-Pd cat. 4
(2 mol%)
THF, rt, 2–24 h
O
O
O
PPh2
Ph
EtO
Ph
+
HPPh2
EtO
(2) aq H2O2, rt
Ph2P
Pd
PPh2
R
R
1.2 equiv
2a
3
OAc
1a: R = H
1b: R = CO2Et
no reaction
Pd catalyst 4
Scheme 1 Our previous work
ing methyl ester groups provided a 1:1 mixture of the 1,4-
and 1,6-adducts with moderate ee (Table 1, entry 6). By
contrast, 5d with bulky tert-butyl ester groups provided the
1,6-adduct 6 in highest ee and highest regioselectivity (Ta-
ble 1, entry 8). To improve product yield, the catalyst load-
ing and amount of 5d were increased to 5 mol% and 4
equivalents, respectively, which furnished the 1,6-adduct in
70% yield with 89% ee (Table 1, entries 9 and 10).
The substrate scope was explored under the optimum
conditions, and the results are shown in Table 2. Substrates
that bear an alkyl, fluoro, chloro, bromo or methoxy moiety
can be tolerated, and afford the corresponding products in
moderate yield with good ee (Table 2, entries 1–9). For the
nucleophilic component, the secondary phosphine with 4-
methoxy groups was examined in the reaction with 5d; the
1,6-adduct 6 was isolated in 53% yield with relatively low
enantioselectivity (Table 2, entry 10).
A possible catalytic cycle is depicted in Scheme 2. First,
the diarylphosphine 2 reacts with the pincer palladium cat-
alyst 4 to produce a nucleophilic palladium–diarylphosphi-
do intermediate.4a Then, this nucleophile attacks substrate
5d at the δ-position to avoid the higher steric hindrance
when such a nucleophile attacks at the β-position of the
substrate. Finally, protonolysis of the resulting palladium–
phosphine complex with acetic acid releases the 1,6-adduct
and regenerates the palladium catalyst.
In summary, we have developed an asymmetric 1,6-ad-
dition of diarylphosphines to allylidenemalonates using a
pincer palladium catalyst. The corresponding chiral allylic
phosphine derivatives were produced with moderate to
high enantioselectivity.
Table 1 Palladium-Catalyzed Addition of Diphenylphosphine to Allylidenemalonates 5
HPPh2
(0.1 mmol)
(1) (S,S)-Pd cat. 4
(2 mol%)
solvent, rt, 24 h
BH3
H3B
O
O
PPh2
Ph
O
PPh2
RO
RO
Ph
+
RO
RO
RO
Ph
(2) Me2S·BH3 (3 equiv)
rt, 2 h
O
O
RO
O
6
7
1.2 equiv
5a: R = Et; 5b: R = Me
5c: R = iPr; 5d: R = tBu
Entry
Substrate
Solvent
Yielda (%) of 6
Ratio of 6/7
eeb (%) of 6
1
5a
5a
5a
5a
5a
5b
5c
5d
5d
5d
toluene
THF
68
70
63
74
50
34
55
32
70
70
9:1
4:1
43
3
2
3
CH2Cl2
Et2O
3:1
15
13
5
4
5:1
5
MeCN
toluene
toluene
toluene
toluene
toluene
5:1
6
1:1
38
73
88
89
89
7
15:1
15:1
15:1
15:1
8
9c,d
10c,e
a Isolated yield.
b Determined by chiral HPLC (hexane/2-propanol).
c Catalyst 4 (5 mol%) used.
d 5d (2 equiv) used.
e 5d (4 equiv) used.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–F

C
X. Wei et al.
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Synthesis
Table 2 Palladium-Catalyzed Addition of Diarylphosphines to Di-tert-
butyl Allylidenemalonates
and the resulting solution was stirred for 24 h. Then, Me2S·BH3 (2 M
in THF; 0.15 mL, 0.30 mmol) was added, and the resulting solution
was stirred for 2 h. The excess borane was quenched with H2O and
the mixture was extracted with EtOAc. The organic phase was
washed with saturated aq NaCl solution, dried over MgSO4, filtered
and concentrated under reduced pressure. The residue was purified
by silica gel preparative TLC (hexane/EtOAc, 10:1) to afford the 1,6-
adduct as a white solid.
H3B
O
O
PAr2
R
(1) (S,S)-4 (5 mol%)
toluene, rt, 24 h
tBuO
tBuO
R
HPAr2
+
tBuO
(2) Me2S·BH3 (3 equiv)
rt, 2 h
tBuO
O
O
6
5, 2.0 equiv
2, 0.1 mmol
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-phenyl-1-propen-
1-yl]propanedioate–Borane Complex (Table 2, Entry 1)
Entry
R
Ar
Ph
Yielda (%)
70
eeb (%)
1
2
3
4
5
6
7
8
9
10
Ph
89
80
66
83
89
86
88
87
78
62
White solid; yield: 37 mg (0.070 mmol, 70%).
4-MeC6H4
4-MeOC6H4
3-MeC6H4
3-MeOC6H4
4-BrC6H4
3-FC6H4
Ph
51
53
58
63
56
61
71
50
53
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 80:20; flow = 1.0 mL/min); tR = 4.8 (major enantiomer),
5.6 min (minor enantiomer); 89% ee.
[α]D20 –31.0 (c 1.00, CH2Cl2).
1H NMR (400 MHz, CDCl3): δ = 7.90–7.80 (m, 2 H), 7.55–7.16 (m, 9 H),
7.14 (d, JHH = 6.8 Hz, 2 H), 7.06 (d, JHH = 6.4 Hz, 2 H), 6.11 (ddd, J = 14.8,
9.2, 6.8 Hz, 1 H), 5.73 (ddd, J = 14.8, 8.0, 2.8 Hz, 1 H), 4.44 (dd, J = 15.2,
8.8 Hz, 1 H), 3.77 (d, J = 8.4 Hz, 1 H), 1.37 (s, 9 H), 1.36 (s, 9 H), 0.88 (br,
3 H).
Ph
Ph
Ph
Ph
Ph
3-ClC6H4
2-naphthyl
Ph
Ph
Ph
13C NMR (100 MHz, CDCl3): δ = 167.1 (d, JCP = 1.8 Hz), 166.9 (d, JCP
2.2 Hz), 135.8 (d, JCP = 1.5 Hz), 133.7 (d, JCP = 8.5 Hz), 133.0 (d, JCP = 8.6
=
4-MeOC6H4
a Isolated yield.
Hz), 131.6 (d, JCP = 2.6 Hz), 131.1 (d, JCP = 2.6 Hz), 130.6, 129.6 (d, JCP
4.8 Hz), 128.8 (d, JCP = 9.7 Hz), 128.4 (d, JCP = 9.7 Hz), 128.3 (d, JCP
52.7 Hz), 128.2 (d, JCP = 2.2 Hz), 127.4 (d, JCP = 2.6 Hz), 127.3 (d, JCP
=
=
=
b Determined by chiral HPLC (hexane/2-propanol).
52.7 Hz), 127.1 (d, JCP = 10.8 Hz), 82.04, 81.98, 57.3 (d, JCP = 1.1 Hz),
47.9 (d, JCP = 30.0 Hz), 27.95, 27.93.
31P{1H} NMR (162 MHz, CDCl3): δ = 23.9 (m).
HRMS (ESI): m/z [M + NH4]+ calcd for C32H44BNO4P: 547.3132; found:
547.3121.
O
HOAc
P
transphosphination
Ar2PH
tBuO
Ph
C
Pd PAr2
P
tBuO
O
2
5d
P
addition
C
Pd OAc
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-(4-methylphenyl)-
1-propen-1-yl]propanedioate–Borane Complex (Table 2, Entry 2)
4
P
White solid; yield: 28 mg (0.051 mmol, 51%).
O
PAr2
P
Ph
C
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 90:10; flow = 1.0 mL/min); tR = 5.1 (major enantiomer),
6.8 min (minor enantiomer); 80% ee.
tBuO
tBuO
Ph
Pd
P
P
Ar2
OtBu
O
protonolysis
HOAc
[α]D20 –31.6 (c 1.00, CH2Cl2).
O
tBuO
1H NMR (400 MHz, CDCl3): δ = 7.82 (t, JHH = 8.0 Hz, 2 H), 7.52–7.41 (m,
5 H), 7.37 (t, JHH = 7.2 Hz, 1 H), 7.27 (td, J = 8.0, 2.0 Hz, 2 H), 6.95 (s, 4
H), 6.07 (ddd, J = 15.6, 8.8, 7.2 Hz, 1 H), 5.70 (ddd, J = 15.6, 8.4, 3.2 Hz,
1 H), 4.41 (dd, J = 15.6, 8.8 Hz, 1 H), 3.76 (d, JHH = 8.8 Hz, 1 H), 2.25 (s,
3 H), 1.38 (s, 9 H), 1.36 (s, 9 H), 0.88 (br, 3 H).
O
Scheme 2 Proposed catalytic cycle
13C NMR (100 MHz, CDCl3): δ = 167.1 (d, JCP = 1.8 Hz), 166.9 (d, JCP
=
Commercially available reagents were used without further purifica-
tion. Solvents were treated prior to use according to standard meth-
ods. 1H NMR, 13C NMR and 31P NMR spectra were recorded at room
temperature in CDCl3 on a Varian instrument (400 MHz, 100 MHz and
162 MHz, respectively) with TMS as internal standard. HRMS analy-
ses were conducted on a Bruker Daltonics APEXIIITM ESI-FTICRMS
mass spectrometer. Preparative TLC was performed on silica gel (300–
400 mesh).
2.6 Hz), 137.0 (d, JCP = 2.6 Hz), 133.7 (d, JCP = 8.2 Hz), 133.0 (d, JCP = 8.2
Hz), 132.6 (d, JCP = 1.7 Hz), 131.5 (d, JCP = 2.6 Hz), 131.0 (d, JCP = 2.2 Hz),
130.8, 129.5 (d, JCP = 4.8 Hz), 128.9 (d, JCP = 2.3 Hz), 128.8 (d, JCP = 9.3
Hz), 128.5 (d, JCP = 50.1 Hz), 128.4 (d, JCP = 9.7 Hz), 127.5 (d, JCP = 52.4
Hz), 126.9 (d, JCP = 10.8 Hz), 82.0, 81.9, 57.3 (d, JCP = 1.5 Hz), 47.5 (d,
JCP = 29.9 Hz), 27.96, 27.94, 21.2 (d, JCP = 0.7 Hz).
31P{1H} NMR (162 MHz, CDCl3): δ = 23.5 (m).
HRMS (ESI): m/z [M + NH4]+ calcd for C33H46BNO4P: 561.3288; found:
561.3291.
Asymmetric Phosphorus Addition Catalyzed by Pincer Palladium
4 (Table 2); Typical Procedure
Diarylphosphine (0.10 mmol) was added to a solution of (S,S)-palladi-
um catalyst 4 (3.4 mg, 5 μmol Pd) and an α,β,γ,δ-unsaturated dicar-
boxylic ester 5 (0.20 mmol) in toluene (2.0 mL) at room temperature,
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–F

D
X. Wei et al.
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Synthesis
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-(4-methoxyphe-
nyl)-1-propen-1-yl]propanedioate–Borane Complex (Table 2, En-
try 3)
1H NMR (400 MHz, CDCl3): δ = 7.83 (t, JHH = 8.0 Hz, 2 H), 7.60–7.26 (m,
8 H), 7.05 (t, JHH = 8.0 Hz, 1 H), 6.72–6.64 (m, 3 H), 6.06 (ddd, J = 15.2,
9.2, 6.0 Hz, 1 H), 5.72 (ddd, J = 15.2, 8.4, 3.2 Hz, 1 H), 4.41 (dd, J = 14.8,
8.8 Hz, 1 H), 3.78 (d, JHH = 8.4 Hz, 1 H), 3.65 (s, 3 H), 1.38 (s, 9 H), 1.36
(s, 9 H), 0.90 (br, 3 H).
White solid; yield: 30 mg (0.053 mmol, 53%).
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 90:10; flow = 1.0 mL/min); tR = 7.0 (major enantiomer),
11.6 min (minor enantiomer); 66% ee.
[α]D20 –40.9 (c 1.00, CH2Cl2).
1H NMR (400 MHz, CDCl3): δ = 7.82 (t, JHH = 8.8 Hz, 2 H), 7.60–7.25 (m,
8 H), 6.97 (dd, J = 8.4, 1.6 Hz, 2 H), 6.68 (d, JHH = 8.1 Hz, 2 H), 6.06 (ddd,
J = 15.6, 8.4, 6.0 Hz, 1 H), 5.70 (ddd, J = 15.6, 8.4, 3.2 Hz, 1 H), 4.41 (dd,
J = 15.6, 8.8 Hz, 1 H), 3.76 (d, JHH = 8.4 Hz, 1 H), 3.73 (s, 3 H), 1.38 (s, 9
H), 1.36 (s, 9 H), 0.93 (br, 3 H).
13C NMR (100 MHz, CDCl3): δ = 167.1 (d, JCP = 1.3 Hz), 166.9 (d, JCP
2.2 Hz), 158.8 (d, JCP = 2.6 Hz), 133.7 (d, JCP = 8.2 Hz), 133.0 (d, JCP = 8.2
Hz), 131.5 (d, JCP = 2.6 Hz), 131.1 (d, JCP = 2.2 Hz), 130.8, 130.7 (d, JCP
2.4 Hz), 128.8 (d, JCP = 9.7 Hz), 128.45 (d, JCP = 53.0 Hz), 128.44 (d, JCP
9.7 Hz), 127.6 (d, JCP = 1.4 Hz), 127.4 (d, JCP = 52.3 Hz), 126.9 (d, JCP
10.7 Hz), 113.6 (d, JCP = 1.9 Hz), 82.01, 81.96, 57.3 (d, JCP = 1.5 Hz),
55.3, 47.0 (d, JCP = 30.7 Hz), 27.94, 27.91.
13C NMR (100 MHz, CDCl3): δ = 167.1 (d, JCP = 1.9 Hz), 166.9 (d, JCP
=
2.6 Hz), 159.3 (d, JCP = 1.8 Hz), 133.7 (d, JCP = 8.2 Hz), 133.0 (d, JCP = 8.2
Hz), 132.7 (d, JCP = 8.5 Hz), 131.6 (d, JCP = 2.3 Hz), 131.1 (d, JCP = 2.3 Hz),
130.5, 129.2 (d, JCP = 1.9 Hz), 128.8 (d, JCP = 9.7 Hz), 128.6 (d, JCP = 9.7
Hz), 128.3 (d, JCP = 52.7 Hz), 127.5 (d, JCP = 52.7 Hz), 127.2 (d, JCP = 10.8
Hz), 122.1 (d, JCP = 5.2 Hz), 114.5 (d, JCP = 4.5 Hz), 113.8 (d, JCP = 2.2 Hz),
82.04, 81.99, 57.3 (d, JCP = 1.5 Hz), 55.2, 48.0 (d, JCP = 30.0 Hz), 27.95,
27.94.
31P{1H} NMR (162 MHz, CDCl3): δ = 24.6 (m).
HRMS (ESI): m/z [M + NH4]+ calcd for C33H46BNO5P: 577.3237; found:
=
577.3242.
=
=
=
Di-tert-butyl 2-[(1E)-3-(4-Bromophenyl)-3-(diphenylphosphino)-
1-propen-1-yl]propanedioate–Borane Complex (Table 2, Entry 6)
White solid; yield: 34 mg (0.056 mmol, 56%).
31P{1H} NMR (162 MHz, CDCl3): δ = 18.9 (m).
HRMS (ESI): m/z [M + NH4]+ calcd for C33H46BNO5P: 577.3237; found:
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 90:10; flow = 1.0 mL/min); tR = 6.4 (major enantiomer),
10.0 min (minor enantiomer); 86% ee.
[α]D20 –26.3 (c 1.00, CH2Cl2).
577.3243.
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-(3-methylphenyl)-
1-propen-1-yl]propanedioate–Borane Complex (Table 2, Entry 4)
1H NMR (400 MHz, CDCl3): δ = 7.85–7.82 (m, 2 H), 7.55–7.38 (m, 10
H), 6.93 (d, JHH = 6.8 Hz, 2 H), 6.10–6.00 (m, 1 H), 5.72 (ddd, J = 15.2,
8.0, 6.8 Hz, 1 H), 4.41 (dd, J = 15.2, 8.8 Hz, 1 H), 3.77 (d, JHH = 8.8 Hz, 1
H), 1.38 (s, 9 H), 1.36 (s, 9 H), 0.90 (br, 3 H).
White solid; yield: 32 mg (0.058 mmol, 58%).
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 90:10; flow = 1.0 mL/min); tR = 4.9 (major enantiomer),
6.2 min (minor enantiomer); 83% ee.
[α]D20 –31.1 (c 1.00, CH2Cl2).
1H NMR (400 MHz, CDCl3): δ = 7.83 (t, JHH = 8.0 Hz, 2 H), 7.52–7.41 (m,
4 H), 7.36–7.23 (m, 4 H), 7.10 (t, JHH = 7.2 Hz, 1 H), 6.95 (d, JHH = 7.2 Hz,
1 H), 6.86–6.81 (m, 2 H), 6.10 (ddd, J = 15.2, 9.2, 6.4 Hz, 1 H), 5.72
(ddd, J = 15.2, 8.4, 3.6 Hz, 1 H), 4.40 (dd, J = 15.2, 9.6 Hz, 1 H), 3.78 (d,
JHH = 8.4 Hz, 1 H), 2.18 (s, 3 H), 1.38 (s, 9 H), 1.36 (s, 9 H), 0.88 (br, 3 H).
13C NMR (100 MHz, CDCl3): δ = 167.0 (d, JCP = 1.5 Hz), 166.8 (d, JCP
2.3 Hz), 134.9 (d, JCP = 1.1 Hz), 133.6 (d, JCP = 8.6 Hz), 133.2 (d, JCP = 8.2
Hz), 133.0 (d, JCP = 8.1 Hz), 131.7 (d, JCP = 2.6 Hz), 131.4, 131.3 (d, JCP
=
=
1.3 Hz), 131.2 (d, JCP = 4.8 Hz), 130.0, 128.9 (d, JCP = 10.0 Hz), 128.6 (d,
JCP = 10.0 Hz), 127.9 (d, JCP = 52.5 Hz), 127.7 (d, JCP = 10.4 Hz), 127.2 (d,
JCP = 52.8 Hz), 82.2, 82.1, 57.3 (d, JCP = 1.1 Hz), 47.3 (d, JCP = 30.1 Hz),
28.0, 27.9.
31P{1H} NMR (162 MHz, CDCl3): δ = 24.4 (m).
HRMS (ESI): m/z [M + NH4]+ calcd for C32H43BBrNO4P: 625.2237;
13C NMR (100 MHz, CDCl3): δ = 167.1 (d, JCP = 1.9 Hz), 166.9 (d, JCP
=
found: 625.2238.
2.7 Hz), 137.7 (d, JCP = 2.3 Hz), 135.5 (d, JCP = 1.5 Hz), 133.7 (d, JCP = 8.0
Hz), 133.0 (d, JCP = 8.3 Hz), 131.5 (d, JCP = 2.3 Hz), 131.4 (d, JCP = 8.7 Hz),
131.0 (d, JCP = 2.3 Hz), 130.7, 130.4 (d, JCP = 5.0 Hz), 128.8 (d, JCP = 9.5
Hz), 128.4 (d, JCP = 53.0 Hz), 128.3 (d, JCP = 9.9 Hz), 128.0 (d, JCP = 2.2
Hz), 127.4 (d, JCP = 52.7 Hz), 127.0 (d, JCP = 11.0 Hz), 126.6 (d, JCP = 5.0
Hz), 82.00, 81.97, 57.3 (d, JCP = 1.5 Hz), 47.8 (d, JCP = 29.8 Hz), 27.93,
27.91, 21.4.
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-(3-fluorophenyl)-
1-propen-1-yl]propanedioate–Borane Complex (Table 2, Entry 7)
White solid; yield: 33 mg (0.061 mmol, 61%).
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 80:20; flow = 1.0 mL/min); tR = 5.4 (major enantiomer),
6.4 min (minor enantiomer); 88% ee.
31P{1H} NMR (162 MHz, CDCl3): δ = 23.5 (m).
[α]D20 –29.9 (c 1.00, CH2Cl2).
HRMS (ESI): m/z [M + NH4]+ calcd for C33H46BNO4P: 561.3288; found:
1H NMR (400 MHz, CDCl3): δ = 7.86–7.80 (m, 2 H), 7.55–7.38 (m, 6 H),
7.29 (td, J = 8.0, 2.4 Hz, 2 H), 7.12–7.07 (m, 1 H), 6.84 (d, JHH = 8.0 Hz, 2
H), 6.77 (dd, J = 10.0, 2.0 Hz, 1 H), 6.06 (ddd, J = 15.6, 9.2, 6.4 Hz, 1 H),
5.74 (ddd, J = 15.6, 8.8, 3.2 Hz, 1 H), 4.44 (dd, J = 15.2, 8.8 Hz, 1 H), 3.78
(d, JHH = 8.8 Hz, 1 H), 1.38 (s, 9 H), 1.36 (s, 9 H), 0.90 (br, 3 H).
561.3292.
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-(3-methoxyphe-
nyl)-1-propen-1-yl]propanedioate–Borane Complex (Table 2,
Entry 5)
13C NMR (100 MHz, CDCl3): δ = 167.0 (d, JCP = 1.4 Hz), 166.8 (d, JCP
=
White solid; yield: 35 mg (0.063 mmol, 63%).
2.2 Hz), 133.6 (d, JCP = 8.2 Hz), 132.9 (d, JCP = 8.5 Hz), 131.7 (d, JCP = 2.6
Hz), 131.3 (d, JCP = 2.6 Hz), 130.0, 129.6 (dd, J = 8.2, 2.0 Hz), 128.9 (d,
JCP = 9.7 Hz), 128.6 (d, JCP = 9.6 Hz), 127.9 (d, JCP = 52.4 Hz), 127.7 (d,
JCP = 10.8 Hz), 127.0 (d, JCP = 52.4 Hz), 125.4 (d, JCP = 3.4 Hz), 125.3 (d,
JCP = 2.2 Hz), 116.5 (dd, JCF = 22.6 Hz, JCP = 4.8 Hz), 114.3 (dd, JCF = 20.8
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 90:10; flow = 1.0 mL/min); tR = 6.4 (major enantiomer),
7.8 min (minor enantiomer); 89% ee.
[α]D20 –19.2 (c 1.00, CH2Cl2).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–F

E
X. Wei et al.
Paper
Synthesis
Hz, JCP = 3.0 Hz), 82.2, 82.1, 57.3 (d, JCP = 1.5 Hz), 47.6 (dd, JCP = 30.2 Hz,
JCF = 2.3 Hz,), 27.94, 27.93.
31P{1H} NMR (162 MHz, CDCl3): δ = 25.0 (m).
The ee was determined on a Daicel Chiralpak IC column (hexane/
2-propanol, 98:2; flow = 0.5 mL/min); tR = 88.9 (major enantiomer),
101.0 min (minor enantiomer); 62% ee.
[α]D20 –39.1 (c 1.00, CH2Cl2).
HRMS (ESI): m/z [M + NH4]+ calcd for C32H43BFNO4P: 565.3038; found:
565.3045.
1H NMR (400 MHz, CDCl3): δ = 7.74 (t, JHH = 9.2 Hz, 2 H), 7.35–7.22 (m,
3 H), 7.22–7.15 (m, 2 H), 7.10–7.02 (m, 2 H), 7.00 (dd, J = 8.4, 1.2 Hz, 2
H), 6.78 (dd, J = 8.4, 1.2 Hz, 2 H), 6.08 (ddd, J = 14.8, 8.8, 6.8 Hz, 1 H),
5.69 (ddd, J = 14.8, 8.4, 3.2 Hz, 1 H), 4.34 (dd, J = 15.2, 9.2 Hz, 1 H), 3.83
(s, 3 H), 3.77 (d, JHH = 8.4 Hz, 1 H), 3.76 (s, 3 H), 1.38 (s, 9 H), 1.36 (s, 9
H), 0.90 (br, 3 H).
Di-tert-butyl 2-[(1E)-3-(3-Chlorophenyl)-3-(diphenylphosphino)-
1-propen-1-yl]propanedioate–Borane Complex (Table 2, Entry 8)
White solid; yield: 40 mg (0.071 mmol, 71%).
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 80:20; flow = 1.0 mL/min); tR = 4.0 (major enantiomer),
4.5 min (minor enantiomer); 87% ee.
[α]D20 –42.1 (c 1.00, CH2Cl2).
1H NMR (400 MHz, CDCl3): δ = 7.83 (d, J = 8.4 Hz, 2 H), 7.55–7.36 (m, 6
H), 7.30 (t, J = 7.2 Hz, 2 H), 7.12 (t, JHH = 7.2 Hz, 1 H), 7.08 (t, JHH = 8.0
Hz, 1 H), 6.97 (d, JHH = 8.0 Hz, 1 H), 6.96 (s, 1 H), 6.06 (ddd, J = 15.6, 8.8,
7.6 Hz, 1 H), 5.75 (ddd, J = 15.6, 8.4, 2.8 Hz, 1 H), 4.41 (dd, J = 15.2, 8.8
Hz, 1 H), 3.78 (d, JHH = 8.4 Hz, 1 H), 1.38 (s, 9 H), 1.36 (s, 9 H), 0.92 (br,
3 H).
13C NMR (100 MHz, CDCl3): δ = 167.1 (d, JCP = 1.9 Hz), 166.9 (d, JCP
2.6 Hz), 162.1 (d, JCP = 2.3 Hz), 161.7 (d, JCP = 2.2 Hz), 135.4 (d, JCP = 9.3
=
Hz), 134.6 (d, JCP = 9.3 Hz), 130.9, 129.6 (d, JCP = 4.8 Hz), 128.8 (d, JCP
9.7 Hz), 128.1 (d, JCP = 2.2 Hz), 127.2 (d, JCP = 2.6 Hz), 126.8 (d, JCP
10.8 Hz), 119.4 (d, JCP = 57.7 Hz), 118.2 (d, JCP = 57.6 Hz), 114.4 (d, JCP
=
=
=
10.7 Hz), 114.0 (d, JCP = 10.0 Hz), 82.0, 81.9, 57.4 (d, JCP = 1.1 Hz), 55.4,
55.3, 48.5 (d, JCP = 30.9 Hz), 27.94, 27.90.
31P{1H} NMR (162 MHz, CDCl3): δ = 21.2 (m).
HRMS (ESI): m/z [M + NH4]+ calcd for C34H48BNO6P: 607.3343; found:
607.3338.
13C NMR (100 MHz, CDCl3): δ = 167.0 (d, JCP = 1.9 Hz), 166.7 (d, JCP
=
2.7 Hz), 137.8 (d, JCP = 1.2 Hz), 133.9 (d, JCP = 2.6 Hz), 133.6 (d, JCP = 8.4
Hz), 132.9 (d, JCP = 8.7 Hz), 131.7 (d, JCP = 2.6 Hz), 131.4 (d, JCP = 2.3 Hz),
129.8, 129.6 (d, JCP = 4.5 Hz), 129.4 (d, JCP = 2.2 Hz), 128.9 (d, JCP = 9.8
Hz), 128.84 (d, JCP = 52.7 Hz), 128.83 (d, JCP = 6.0 Hz), 128.6 (d, JCP = 9.9
Hz), 127.7, 127.5 (d, JCP = 2.7 Hz), 126.8 (d, JCP = 52.7 Hz), 82.2, 82.1,
57.3 (d, JCP = 1.1 Hz), 47.5 (d, JCP = 29.2 Hz), 27.92, 27.90.
Acknowledgment
We are grateful for financial support from the National Science Foun-
dation of China (20902099, 21172238 and 21472218) and SIOC.
31P{1H} NMR (162 MHz, CDCl3): δ = 24.3 (m).
Supporting Information
HRMS (ESI): m/z [M + NH4]+ calcd for C32H43BClNO4P: 581.2742;
found: 581.2749.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1562456.
S
u
p
p
ortiInfogrmoaitn
S
u
p
p
o
nrtogI
f
rmoaitn
Di-tert-butyl 2-[(1E)-3-(Diphenylphosphino)-3-(2-naphthyl)-1-
propen-1-yl]propanedioate–Borane Complex (Table 2, Entry 9)
White solid; yield: 29 mg (0.050 mmol, 50%).
References
The ee was determined on a Daicel Chiralpak AD column (hexane/
2-propanol, 80:20; flow = 1.0 mL/min); tR = 4.5 (major enantiomer),
6.2 min (minor enantiomer); 78% ee.
[α]D20 –29.8 (c 1.00, CH2Cl2).
1H NMR (400 MHz, CDCl3): δ = 7.86 (dd, JHH = 8.8, 7.2 Hz, 2 H), 7.76–
7.71 (m, 1 H), 7.62 (d, JHH = 8.8 Hz, 2 H), 7.55–7.36 (m, 8 H), 7.32 (t, JHH
= 7.2 Hz, 1 H), 7.25–7.20 (m, 3 H), 6.21 (ddd, J = 15.2, 9.2, 7.2 Hz, 1 H),
5.77 (ddd, J = 15.6, 8.4, 3.2 Hz, 1 H), 4.62 (dd, J = 15.2, 8.8 Hz, 1 H), 3.80
(d, JHH = 8.4 Hz, 1 H), 1.36 (s, 9 H), 1.35 (s, 9 H), 0.92 (br, 3 H).
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HRMS (ESI): m/z [M + NH4]+ calcd for C36H46BNO4P: 597.3288; found:
597.3288.
Di-tert-butyl 2-{(1E)-3-[Bis(4-methoxyphenyl)phosphino]-3-phe-
nyl-1-propen-1-yl}propanedioate–Borane Complex (Table 2, Entry
10)
White solid; yield: 31 mg (0.053 mmol, 53%).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–F

F
X. Wei et al.
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Synthesis
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–F