Palladium-Catalyzed Enantioselective Alkoxycarbonylation of Propargylic Carbonates with (R)- or (S)-3,4,5-(MeO)3-MeOBIPHEP

Article abstract of DOI:10.1002/chem.201701194

(R)- and (S)-3,4,5-(MeO)₃-MeOBIPHEP have been identified as the efficient chiral ligands for the palladium-catalyzed highly enantioselective synthesis of 2,3-allenoates from different types of easily available racemic propargylic carbonates wit

Full text of DOI:10.1002/chem.201701194

A Journal of
Accepted Article
Title: Palladium-Catalyzed Enantioselective Alkoxycarbonylation
of Propargylic Carbonates with (R)- or (S)-3,4,5-(MeO)3-
MeOBIPHEP
Authors: Wanli Zhang and Shengming Ma
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Eur. J. 10.1002/chem.201701194
Link to VoR: http://dx.doi.org/10.1002/chem.201701194
Supported by

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
Palladium-Catalyzed Enantioselective Alkoxycarbonylation of
Propargylic Carbonates with (R)- or (S)-3,4,5-(MeO)3-MeOBIPHEP
Wanli Zhang[b] and Shengming Ma*[a,c]
Abstract: (R)- and (S)-3,4,5-(MeO)3-MeOBIPHEP have been
identified as the efficient chiral ligands for the palladium-catalyzed
highly enantioselective synthesis of 2,3-allenoates from easily
available different types of racemic propargylic carbonates with 90-
98% ee and decent yields. The potentials of the products have been
demonstrated with high chirality transfer efficiency.
mesylates in 69-90% yield and 80-99% ee (Scheme 1d);[9]
asymmetric olefination of ketenes is another option albeit using
at least a stoichiometric amount of chiral ylide (Scheme 1e).[10]
Catalytic enaotioselective synthesis is the most ideal strategy
in consideration of costs and atom economy. In the presence of
chiral phosphite ligand, chiral 2,3-allenoates can be synthesized
enatioselectively through Pd-catalyzed asymmetric β-hydride
elimination of the not-readily-available stereodefined enol
triflates (Scheme 1f).[11] However, only 20% ee was detected in
Allenes are a class of compounds characterized by two
cumulated carbon-carbon double bonds exhibiting extraordinary
activities as building blocks or even as chiral ligands in organic
synthesis.[1-2] This unique structure has also been found in a
great number of natural products and pharmaceutical molecules,
which gave rise to ample interest in the synthesis of allenes.[1a,3]
Recently, many methodologies for the synthesis of allenes have
been developed,[4] however, controlling the axial chirality in
trisubstitued allenes, especially the trisubstitued 2,3-allenoates,
which are extremely useful precursors for the synthesis of other
allenes due to the versatile reactivity of the ester functionality,
remains a hard nut to crack.[5] A common method to generate
optically active such compounds is through kinetic resolution of
racemic compounds (Scheme 1a):[6] Chiral trisubstituted
allenoates were recovered in the 1,3-dipolar cycloaddition of
racemic 2,3-allenoates using bisphosphoric acid catalyst with
35-48% yield and 85-99% ee, together with the products, 3-
methylenepyrrolidine derivatives, with 39-57% yield and 64-94%
ee; another efficient access to enantiomerically enriched
trisubstituted allenoates relies on the dynamic kinetic resolution-
based isomerization of 1-substituted 3-alkynoates with the
recovery of the starting 3-alkynoates even after 24 h, which is
barely possible to separate from 2,3-allenoates (Scheme 1b);[7]
another approach utilizes organozinc reagents as the
nucleophile through the corresponding SN2' substitution with
optically active propargylic mesylates (Scheme 1c).[8] With the
help of DMSO, 2,3-allenoates could be afforded with 87% yield
and 98% ee, whereas only one example of trisubstituted
allenoate was displayed; synthesis of optically active
trisubstituted allenoates may also be realized through Pd-
catalyzed alkoxycarbonylation of optically active propargylic
the
synthesis
of
trisubstituted
allenoates.
Applying
intermolecular addition of nitroalkanes to activated enynes to the
synthesis of chiral trisubstituted allenoates is also feasible
(Scheme 1g).[12] High yields and excellent enatioselectivities
were observed in the tandem addition/isomerization process,
albeit in some cases the alkynoate intermediates were detected,
which can be further transferred into allenoates under the
identical reaction conditions. Asymmetric C-H insertion of α-
diazoesters into terminal alkynes is an alternative access to
chiral trisubstituted allenoates (Scheme 1h).[13] Catalyzed by
copper(I) complexes and chiral cationic guanidinium salts,
enantiomerically enriched allenoates may be produced. Apart
from these, chiral trisubstituted allenoates may be synthesized
from the relatively complicated cyclopropenonylmethyl acetates
catalyzed by Lewis base with good yields and enatioselectivities
(Scheme 1i).[14]
In 2013, our laboratory disclosed a catalytic asymmetric
synthesis of 2,3-allenoates with ECNU-Phos starting from
propargylic carbonates.[15] However, the enantioselectivity is not
satisfactory in many cases. Herein, we report our recent results
in identifying (R)- or (S)-3,4,5-(MeO)3-MeOBIPHEP as the ligand
for a very general Pd-catalyzed highly enantioselective synthesis
of chiral trisubstituted allenoates from cheap and readily
available differently substituted 2-alkynylic carbonates generally
with 90~98% ee (Scheme 2).
[a] Prof. Dr. S. Ma
State Key Laboratory of Organometallic Chemistry,
Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences,
Scheme 2. Enantioselective synthesis of 2,3-allenoates from racemic
propargylic carbonates
345 Lingling Lu, Shanghai 200032, P. R. China.
E-mail: masm@sioc.ac.cn
[b] W. Zhang
Racemic methyl 1-phenyl-2-heptyn-1-yl carbonate [(±)-1a] was
used as the model compound with [(π-allyl)PdCl]2 as the catalyst
at room-temperature to investigate the ligand effect for this
methoxycarbonylation reaction. Our attempt was to finely tune
the electronic property of the phosphorus atoms in the BIPHEP
skeleton: Firstly, changing the aryl substituents of the
coordinating phosphorus atom from 3,5-dimethoxy to 3,5-
dimethyl [(R)-L1] leads to 90% recovery of the starting material,
(Ra)-2a was detected with only 4% yield (Table 1, entry 1). By
replacing the aryl substituents with 4-methylphenyl in order to
Shanghai Key Laboratory of Green Chemistry and Chemical Process,
College of Chemistry and Molecular Engineering,
East China Normal University,
3663 North Zhongshan Lu, Shanghai 200062, P. R. China
[c] Prof. Dr. S. Ma
Department of Chemistry, Fudan University,
220 Handan Lu, Shanghai 200433, P. R. China
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
d)
MsO
R1
R3
c)
MsO
Me
COOMe
87% yield
98% ee
1) 80-86% yield, 80-96% ee
2) 69-90% yield, 90-97% ee
3) 69-86% yield, 96-99% ee
b)
R3
COOR4
R1
90-96% yield
82-94% ee
e)
R1
R2
O
a)
R1
R2
R3
R1
R2
R3
chiral bisphosphoric acid
kinetic resolution

COOR4
COOR4
R2 = H
R1
R4OOC
R3
R2
COOEt
COOEt
35-48% yield
85-99% ee
+
R'
N
H
f)
R4OOC
39-57% yield
64-94% ee
R1
R1
O
OR4
O
R''
R' NO2
TfO
i)
R3
OAc
R3
64-84% yield
75-83% ee
R1
R3 = H, 60-91% yield, 57-94% ee
R3 = Bn, 30% conversion, 20% ee
COOR4
N2
NO2
R3
R'
R''
R4OOC
g)
R1
R1
h)
48-99% yield
64-94% ee
70-95% yield
86-98% ee
Scheme 1. Reported methods for the synthesis of chiral trisubstituted 2,3-allenoates
decrease the electron-density of the phosphorous atom, (R)-L2
2a was produced in 78% yield with only 92% ee (Table 1, entry
leads to inferior results (Table 1, entry 2). To our disappointment, 5).[15}
when electron-richer ligands (R)-3,5-i-Pr2-4-Me2N-MeOBIPHEP
With this optimized chiral ligand in hand, other experimental
[(R)-L3] and (R)-Ph-Garphos [(R)-L4] were surveyed, the
carbonate (±)-1a remains mostly unreacted and only trace
amount of the target product was detected (Table 1, entries 3
and 4). Interestingly, when 3,4,5-trimethoxy groups were
introduced, i.e., (R)-L5, after stirring at room temperature for 24
h, (Ra)-2a was obtained in 55% yield with 98% ee (Table 1, entry
6)! Inspired by this observation, the catalyst-loading was
increased in an attempt to raise the conversion of this
methoxycarbonylation progress. To our delight, when 3 mol%
[(π-allyl)PdCl]2 was used in combination with 9 mol% (R)-L5, the
desired product (Ra)-2a was obtained in 85% yield and 97% ee
with the starting material being completely converted (Table 1,
entry 7). By comparison, when (R)-ECNU-phos was used, (Ra)-
parameters were inspected to further optimize the reaction
conditions. Firstly, [(π-allyl)PdCl]2 was replaced by [(π-
cinnamyl)PdCl]2, the product was obtained with 58% yield and
97% ee (Table 2, entry 2). In consideration of the cost, [(π-
allyl)PdCl]2 was used for further study.[16] Among the solvents
surveyed, toluene was shown to be the best (Table 2, entries 3-
8); 1,4-dioxane was also effective, albeit with a decreased yield
and poorer enatioselectivity (Table 2, entry 3); the
enatioselectivity and yield dropped further when THF was used
(Table 2, entry 4); the methoxycarbonylation proceeded slowly in
DCM to afford only 19% of (Ra)-2a after 24 h of stirring (Table 2,
entry 5); when MTBE, DMF, or CH3CN was applied, the catalyst
system was ineffective with a trace amount of target products
being detected (Table 2, entries 6-8).
This article is protected by copyright. All rights reserved.

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
Table 2. Optimization of reaction conditions[a]
Table 1. Pd-catalyzed enantioselective methoxycarbonylation of propargylic
carbonates (±)-1a-ligand effect [a]
(Ra)-2a
Recovery of
Entry
Solvent
(±)-1a (%) [d]
Yield (%) [b]
ee (%) [c]
1
2 [e]
3
Toluene
Toluene
1,4-dioxane
THF
85
58
97
97
95
92
-
N.D.
20
70
N.D.
N.D.
56
4
50
5
DCM
19 [d]
N.D.
5 [d]
5 [d]
(Ra)-2a
6
MTBE
-
77
Recovery of
Entry
Ligand
(±)-1a (%) [b]
7
DMF
-
N.D.
81
Yield (%)
4 [b]
ee (%)
8
CH3CN
-
1
2
(R)-L1
(R)-L2
-
90
87
[a] Reaction conditions : (±)-1a (0.1 mmol), [(π-allyl)PdCl]2 (3 mol%), (R)-L5 (9
mol%) and LiF (1.1 equiv.) at 25 oC in toluene (2.0 mL) under 1 atm of CO
unless otherwise noted, THF = tetrahydrofuran, MTBE = methyl tert-butyl
ether, DMF = N,N’-dimethylformamide, DCM = dichloromethane. [b] Isolated
yield. [c] ee values of 2,3-allenoates were determined by HPLC. [d]
Determined by 1H NMR analysis using 1,3,5-trimethylbezene as the internal
standard. [e] 0.2 mmol (±)-1a, 1 mol% [(π- cinnamyl)PdCl]2, and 4 mol% (R)-
L5 were used.
6 [b]
-
3
(R)-L3
6 [b]
-
80
4
(R)-L4
4 [b]
-
92
5 [c]
6 [f]
7 [c]
(R)-ECNU-Phos
(R)-L5
78 [d]
55 [d]
85 [d]
92 [e]
98 [e]
97 [e]
21
enatioselectivities (Table 3, entries 8 and 9). The R2 group is
also very flexible: methyl, isopropyl, long-chain n-hexadecyl,
phenethyl, 4-chloroethyl, and cyclohexyl performed very well in
this reaction, affording the products with good yields and no less
than 92% ee (Table 3, entries 10-16). Compared to (R)-ECNU-
Phos, an impressive enantioselectivity has been observed
(Table 3, entries 1', 3', 7', and 13'). The reaction of the substrate
with Ar’ and R2 both being phenyl is very slow.
28
(R)-L5
N.D.
[a] Reaction conditions: (±)-1a (0.2 mmol), [(π-allyl)PdCl]2 (1 mol%), (R)-
Ligand (4 mol%) and LiF (1.1 equiv.) at 25 oC in toluene (2.0 mL) under 1
atm of CO unless otherwise noted. [b] Determined by 1H NMR analysis
using 1,3,5-trimethylbenzene as the internal standard. [c] 0.1 mmol (±)-1a
was used in combination with 3 mol% [(π-allyl)PdCl]2 and 9 mol% (R)-
Ligand. [d] Isolated yields. [e] ee values of 2,3-allenoates were determined
by HPLC. [f] The reaction was carried out with 0.1 mmol (±)-1a.
Furthermore when R1 group is methyl, allenoates 2q-s may be
accessed with ees higher than 91% using (R)-L5 (Table 4,
entries 1-3). Changing R1 group from methyl to ethyl, (Ra)-2t and
(Ra)-2u were provided with 90% ee using (R)-L5 (Table 4,
entries 4, 5). Further lengthening R1 group to n-butyl, n-hexyl,
and n-undecyl didn’t impact the enantioselectivity by (R)-L5,
affording allenoates with 90-93% ee. By contrast, (R)-ECNU-
phos resulted in these allenoates with only 83%-84% ee (Table
4, entries 5', 6', 7', 8', 9', and 10'). The lower yielding nature for
substrates with R1 being alkyl substituents may be caused by
the difficulty in removing leaving groups as compared with the
reaction of substrates with R1 being an aryl group, in which the
carbonate group is placed at benzylic position. In addition, it
should be noted that the ee of the recovered starting material is
15%, indicating that the reaction is at least pattically a kinetic
resolution process (eq. 1).
After further optimization, it is apparent that when 3 mol% [(π-
allyl)PdCl]2 and 9 mol% (R)-L5 were applied as the chiral
catalyst in toluene under 1 atm of CO with 1.1 eqiuv LiF as
additive, 2,3-allenoates (Ra)-2 can be obtained in the highest
yield and enantiopurity after 24 h of stirring at room temperature
(25 oC). With this optimized condition in hand, the substrate
scope has been investigated: When 1-aryl propargylic
carbonates were used, (R)-L5 exhibited excellent activity,
producing (Ra)-2 with very high enatioselectivities and recoveries
of starting materials were not detected. When the simple phenyl-
substitued substrate (±)-1a was applied, (R)-L5 resulted in 86%
yield and 97% ee on 1 mmol scale (Table 3, entry 1). Different
substituents may be introduced into the Ar' group: both the
electron-donating groups and electron-withdrawing groups are
well tolerated, affording the corresponding allenonates in good
yields with excellent enatioselectivities (Table 3, entries 2-5).
Aryl groups with m-Cl and p-Cl make no difference, furnishing
the target products (Ra)-2f and (Ra)-2g with 82~84% yields and
97-98% ee (Table 3, entries 6 and 7). The reactions of naphthyl-
substituted substrates 1h and 1i were easily carried out to afford
(Ra)-2h and (Ra)-2i with 80% yield and excellent
This article is protected by copyright. All rights reserved.

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
Table 4.
Substrate scope of enatioenriched allenoates synthesis from
(S)-L5 was also effective in this methoxycarbonylation
process, affording the S-products (Scheme 3). When Ar' group
is phenyl and phenyl substituted with electron-donating group,
the enantiomers could be obtained with similar yields and ees.
The chlorine-substituted substrate (±-1n) could be transformed
into the desired enantiomer with 97% ee. It is worth mentioning
that an allyl group can also be accommodated, affording (Sa)-
2o with 84% yield and 95% ee.
racemic 1-alkyl-substuituted propargylic carbonates (±)-1[a]
(±)-1
Yield of
ee of
Recovery
Table 3. Substrate scope of enatioenriched allenoates synthesis from
(Ra)-2 [b]
(Ra)-2 [c]
of (±)-1 [d]
Entry
racemic 1-aryl propargylic carbonates (±)-1 [a]
R1
Me
R2
1
2
i-Pr (1q)
23 (2q)
31 (2r)
24 (2s)
38 (2t)
38 (2u)
52 (2u)
25 (2v)
51 (2v)
27 (2w)
52 (2w)
24 (2x)
54 (2x)
27 (2y)
50 (2y)
35 (2z)
54 (2z)
92
91
92
90
90
85
92
84
90
84
91
83
93
84
90
84
66
54
61
49
60
26
66
21
67
18
65
15
58
22
56
15
Me
n-Bu (1r)
n-C6H13(1s)
n-Bu (1t)
3
Me
4
Et
5
Et
n-C8H17 (1u)
n-C8H17 (1u)
n-Pr (1v)
5' [e]
6 [f]
6' [e]
7 [f]
7' [e]
8 [f]
8' [e]
9 [f]
9' [e]
10 [f]
10' [e]
Et
n-Bu
n-Bu
n-Bu
n-Bu
n-C6H13
n-C6H13
n-C6H13
n-C6H13
n-C11H23
n-C11H23
(±)-1
Yield of
ee of
(Ra)-2 [b]
(Ra)-2 [c]
Entry
Ar'
R2
n-Pr (1v)
n-C7H15 (1w)
n-C7H15 (1w)
n-Bu (1x)
1
1' [d]
2
Ph
n-Bu (1a)
n-Bu (1a)
n-Bu (1b)
n-Pr (1c)
86 (2a)
77 (2a)
80 (2b)
88 (2c)
85 (2c)
72 (2d)
79 (2e)
84 (2f)
82 (2g)
87 (2c)
80 (2h)
80 (2i)
97
93
98
97
92
95
96
97
98
91
95
93
92
98
97
97
93
97
95
97
Ph
4-MeC6H4
3-MeOC6H4
3-MeOC6H4
4-NCC6H4
n-Bu (1x)
3
n-C8H17 (1y)
n-C8H17 (1y)
n-Pr (1z)
3' [e]
4 [f]
5 [f]
6
n-Pr (1c)
n-Bu (1d)
n-Bu (1e)
n-Bu (1f)
4-MeO2CC6H4
3-ClC6H4
4-ClC6H4
4-ClC6H4
1-naphthyl
2-naphthyl
Ph
n-Pr (1z)
7
n-Bu (1g)
n-Bu (1g)
n-Bu (1h)
n-C8H17 (1i)
Me (1j)
[a] Reaction conditions : (±)-1 (1.0 mmol), [(π-allyl)PdCl]2 (2 mol%), (R)-L5 (8
mol%) and LiF (1.1 equiv.) at 25 oC in toluene (5.0 mL) under 1 atm of CO
unless otherwise noted. [b] Isolated yield. [c] ee values of 2,3-allenoates were
determined by HPLC. [d] Determined by 1H NMR analysis using 1,3,5-
trimethylbenzene as the internal standard. [e] The reaction was carried out
with (R)-ECNU-phos. [f] The reactions were carried out at 20 oC, data for
reactions carried out at 25 oC are available in supporting information.
7' [g]
8 [h]
9 [h]
10
11
12
13
13' [i]
14
15
16
85 (2j)
Ph
i-Pr (1k)
84 (2k)
86 (2l)
Ph
n-C16H33 (1l)
(CH2)2Ph (1m)
(CH2)2Ph (1m)
(CH2)4Cl (1n)
allyl (1o)
Ph
81 (2m)
79 (2m)
83 (2n)
85 (2o)[g]
83 (2p)
Ph
Ph
Ph
4-EtC6H4
Cy (1p)
[a] Reaction conditions : (±)-1 (1.0 mmol), [(π-allyl)PdCl]2 (3 mol%), (R)-L5
(9 mol%) and LiF (1.1 equiv.) at 25 oC in toluene (5.0 mL) under 1 atm of
CO unless otherwise noted. [b] Isolated yield. [c] ee values of 2,3-allenoates
were determined by HPLC. [d] with (R)-ECNU-phos; 17% of 1a was
recovered.[15] [e] with (R)-ECNU-phos; 6% of 1c was recovered.[15] [f] The
reaction was carried out in 35 oC. [g] with (R)-ECNU-phos.[15] [h] The
reaction was carried out for 26 h. [i] with (R)-ECNU-phos; 10% of 1m was
recovered. [15]
Scheme 3. (S)-3,4,5-(MeO)3-MeOBIPHEP accelerated Pd-catalyzed
methoxycarbonylation
The practicality was demonstrated by applying 5 mmol of (±)-
1a, affording (Ra)-2a in 88% yield and 97% ee with the standard
catalytic formula (eq. 2).
This article is protected by copyright. All rights reserved.

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
[( -allyl)PdCl]2 (3 mol%)
stirred for 1 hour at room temperature, which was followed by the
addition of anhydrous LiF (143.3 mg, 5.5 mmol) (kept in a glove box) and
(±)-1a (1.2310 g, 5.0 mmol)/toluene (10 mL) sequentially. The mixture
was then frozen with a liquid nitrogen bath, degassed to remove the
argon inside completely, and refilled with CO by a balloon of CO for three
times. Then the solution was stirred at 25 oC for 24 h. After that, the
mixture was diluted with Et2O (25 mL), washed with brine (20 mL), and
dried over anhydrous Na2SO4. The resulting mixture was filtered through
a short column silica gel (5.0 cm) eluted with Et2O (50 mL), and
concentrated. The residue was purified by column chromatography on
silica gel to afford (Ra)-2a[15] (1.0129 g, 88%) as an oil [eluent: petroleum
ether (b.p. 60-90 oC)/ethyl ether = 250/1]: 97% ee (HPLC conditions: IC
column, hexane/i-PrOH = 200/1, 0.5 mL/min, λ = 214 nm, tR (minor) = 5.4
L5
(R)- (9 mol%)
H
COOMe
MeOOCO
Ph
LiF (1.1 equiv.)
(2)
n-Bu
Toluene
Ph
n-Bu
CO balloon
25 oC, 24 h
1a
( )-
2a
(Ra)-
5 mmol
88% yield
97% ee
1.2310 g
As a class of very useful compounds in organic synthesis, the
2,3-allenoates may be easily transformed into other versatile
chemicals with high ee (Scheme 4): treated with I2 at -15 oC, the
lactone (Ra)-3a could be afforded in 89% yield with 97% ee; in
the presence of DIBAL-H, (Ra)-2a may be transferred into
trisubstituted 2,3-allenol (Ra)-4a with 96% ee, which is the
versatile starting materials for halides, mesylates, tosylates,
amines, thiols, etc.;[17] (Ra)-2a may also undergo 1,2-addition
reaction with allyl magnesium chloride,[18] furnishing the chiral
tertiary α-allenols (Ra)-5a in 80% yield and 95% ee; reactions of
2,3-allenoates with organozinc compounds is an efficient access
to 5-benzylidenecyclohex-2-enones through double Michael
addition/cyclization:[19] after stirring for 2.5 h at room temperature,
(4S,6R)-(–)-Z-6a can be afforded with 87% ee, interestingly
utilizing the ethyl ester led to a much higher chirality transfer
efficiency, furnishing (4S, 6R)-(–)-Z-6b with 93% ee.
min, tR (major) = 6.9 min); [α]23D = -47.4 (c = 1.04, CHCl3) [93% ee, [α]21
D
= -47.3 (c = 1.15, CHCl3)] [15]; H NMR (400 MHz, CDCl3): δ = 7.38-7.22
1
(m, 5 H, Ar-H), 6.53 (t, J = 2.8 Hz, 1 H, =CH), 3.74 (s, 3 H, CH3), 2.45-
2.29 (m, 2 H, CH2), 1.53-1.32 (m, 4 H, 2 x CH2), 0.89 (t, J = 7.4 Hz, 3 H,
CH3); 13C NMR (100 MHz, CDCl3): δ = 212.1, 167.2, 132.5, 128.8, 127.7,
127.2, 104.3, 98.3, 52.2, 30.2, 28.6, 22.3, 13.8.
Acknowledgements
Financial support from National Natural Science Foundation of
China (grant No.21690063) are greatly appreciated.
Keywords: alkoxycarbonylation • allenoates • enatioselective
catalysis • palladium • propargylic carbonates
[1]
For selected reviews, see: (a) N. Krause, A. S. K. Hashimi, Modern
Allene Chemistry, Vol. 1, Wiley-VCH, Weinheim, 2004; (b) A. S. K.
Hashmi, Angew. Chem. 2000, 112, 3737-3740; Angew. Chem. Int. Ed.
2000, 39, 3590-3593; (c) R. Zimmer, C. U. Dinesh, E. Nandanan, F. A.
Khan, Chem. Rev. 2000, 100, 3067-3125; (d) J. A. Marshall, Chem.
Rev. 2000, 100, 3163-3185; (e) R. W. Bates, V. Satcharoen, Chem.
Soc. Rev. 2002, 31, 12-21; (f) L. K. Sydnes, Chem. Rev. 2003, 103,
1133-1150; (g) M. Tius, Acc. Chem. Res. 2003, 36, 284-290; (h) S. Ma,
Acc. Chem. Res. 2003, 36, 701-712; (i) L.-L. Wei, H. Xiong, R. P.
Hsung, Acc. Chem. Res. 2003, 36, 773-782. (j) S. Ma, Chem. Rev.
2005, 105, 2829-2871; (k) S. Ma, Aldrichim. Acta 2007, 40, 91-102; (l)
S. Ma, Acc. Chem. Res. 2009, 42, 1679-1688; (m) C. Aubert, L.
Fensterbank, P. Garcia, M. Malacria, A. Simonneau, Chem. Rev. 2011,
111, 1954-1993; (n) S. Yu, S. Ma, Angew. Chem. 2012, 124, 3128-
3167; Angew. Chem. Int. Ed. 2012, 51, 3074-3112; (o) J. Ye, S. Ma,
Acc. Chem. Res. 2014, 47, 989-1000.
Scheme 4. Synthetic applications of 2,3-allenoate (Ra)-2
[2]
For selected examples of using allenes as ligands or catalysts, see: (a)
I. Sato, Y. Matsueda, K. Kadowaki, S. Yonekubo, T. Shibata, K. Soai,
Helv. Chim. Acta. 2002, 85, 3383-3387; (b) S. Löhr, J. Averbeck, M.
Schurmann, N. Krause, Eur. J. Inorg. Chem. 2008, 552-556; (c) X. Pu,
X. Qi, J. M. Ready, J. Am. Chem. Soc. 2009, 131, 10364-10365; (d) F.
Cai, X. Pu, X. Qi, V. Lynch, A. Radha, J. M. Ready, J. Am. Chem. Soc.
2011, 133, 18066-18069; (e) A. Vanitcha, C. Damelincourt, G. Gontard,
N. Vanthuyne, V. M. Mansuy, L. Fensterbank, Chem. Commun. 2016,
52, 6785-6788.
In summary, we have succeeded in establishing a chiral
catalyst system consisting of [(π-allyl)PdCl]2 and (R) or (S)-
3,4,5-(MeO)3-MeOBIPHEP that facilitates the Pd-catalyzed
highly enantioselective alkoxycarbonylation of readily available
racemic propargylic carbonates, affording the optically active
2,3-allenoates with 90-98% ee. Further studies in this area are
being conducted in our laboratory.
[3]
[4]
For reviews on allenes in natural products and molecular materials,
see: (a) A. Hoffmann-Röder, N. Krause, Angew. Chem. 2004, 116,
1216–1236; Angew. Chem. Int. Ed. 2004, 43, 1196-1216; (b) P. Rivera-
Fuentes, F. Diederich, Angew. Chem. 2012, 124, 2872-2882; Angew.
Chem. Int. Ed. 2012, 51, 2818-2828.
Experimental Section
For reviews on the synthesis of allenes, see: (a) A. Hoffmann-Röder, N.
Krause, Angew. Chem. 2002, 114, 3057–3059; Angew. Chem. Int. Ed.
2002, 41, 2933-2935; (b) N. Krause, A. Hoffmann-Röder, Tetrahedron
2004, 60, 11671-11697; (c ) G. B. Hammond, ACS Symp. Ser. 2005,
911, 204-215; (d) K. M. Brummond, J. E. DeForrest, Synthesis 2007,
To a flame-dried Schlenk flask (100 mL) were added [(π-allyl)PdCl]2
(56.1 mg, 0.15 mmol) and (R)-L5 (438.2 mg, 0.45 mmol). After addition
of each chemical, the flask was degassed and refilled with argon for
three times to ensure the complete exclusion of air. Then freshly distilled
toluene (15 mL) was added under argon. The resulting mixture was
This article is protected by copyright. All rights reserved.

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
795-818; (e) M. Ogasawara, Tetrahedron: Asymmetry 2009, 20, 259-
271; (f) S. Yu, S. Ma, Chem. Commun. 2011, 5384-5418; (g) R. K. Neff,
D. E. Frantz, ACS Catal. 2014, 4, 519-528; (h) J. Ye, S. Ma, Org. Chem.
Front. 2014, 1, 1210-1224; (i) R. K. Neff, D. E. Frantz, Tetrahedron
2015, 71, 7-18.
[8]
[9]
K. Kobayashi, H. Naka, A. E. H. Wheatley, Y. Kondo, Org. Lett. 2008,
10, 3375-3377.
(a) J. A. Marshall, M. A. Wolf, J. Org. Chem. 1996, 61, 3238-3239; (b) J.
A. Marshall, G. S. Bartley, E. M. Wallace, J. Org. Chem. 1996, 61,
5729-5735; (c) J. A. Marshall, M. A. Wolf, E. M. Wallace, J. Org. Chem.
1997, 62, 367-371; (d) Y. Wang, S. Ma, Adv. Synth. Catal. 2013, 355,
741-750; (e) Y. Wang, W. Zhang, S. Ma, Org. Chem. Front. 2014, 1,
807-811.
[5]
For selected examples for the synthesis of trisubstitued allenes, see:
(a) Y. Matsumoto, M. Naito, Y. Uozumi, T. Hayashi, J. Chem. Soc.,
Chem. Commun. 1993, 1468-1469; (b) Z. Wan, S. Nelson, J. Am.
Chem. Soc. 2000, 122, 10470-10471; (c) B. D. Sherry, F. D. Toste, J.
Am. Chem. Soc. 2004, 126, 15978-15979; (d) M. Ogasawara, A. Okada,
S. Watanabe, L. Fan, K. Uetake, K. Nakajima, T. Takahashi,
Organometallics 2007, 26, 5025-5029; (e) R. V. Kolakowski, M.
Manpadi, Y. Zhang, T. J. Emge, L. Williams, J. Am. Chem. Soc. 2009,
131, 12910-12911; (f) W. Zhang, S. Zheng, N. Liu, J. B. Werness, I. A.
Guzei, W. Tang, J. Am. Chem. Soc. 2010, 132, 3664-3665; (g) C. M.
Sapu, J. E. Bäckvall, J. Deska, Angew. Chem. 2011, 123, 9905-9908;
Angew. Chem. Int. Ed. 2011, 50, 9731-9734; (h) M. Yang, N. Yokokawa,
H. Ohmiya, M. Sawamura, Org. Lett. 2012, 14, 816-819; (i) H. Li, D.
Müller, L. Guénée, A. Alexakis, Org. Lett. 2012, 14, 5880-5883; (j) J.
Dabrowski, F. Haeffner, A. Hoveyda, Angew. Chem. 2013, 125, 7848-
7853; Angew. Chem. Int. Ed. 2013, 52, 7694-7699; (k) M. Wang, Z. Liu,
X. Zhang, P. Tian, Y. Xu, T.-P. Loh, J. Am. Chem. Soc. 2015, 137,
14830-14833; (l) Y. Liu, X. Liu, H. Hu, J. Guo, Y. Xia, L. Lin, X. Feng,
Angew. Chem. 2016, 128, 4122-4126; Angew. Chem. Int. Ed. 2016, 55,
4054-4058; (m) Q. Yao, Y. Liao, Y. Lin, X. Lin, J. Ji, X. Liu, X. Feng,
Angew. Chem. 2016, 128, 1891-1895; Angew. Chem. Int. Ed. 2016, 55,
1859-1863; (n) W.-D. Chu, L. Zhang, Z. Zhang, Q. Zhou, F. Mo, Y.
Zhang, J. Wang, J. Am. Chem. Soc. 2016, 138, 14558-14561.
[10] (a) J. Yamazaki, T. Watanabe, K. Tanaka, Tetrahedron: Asymmetry
2001, 12, 669-675; (b) C. Li, X. Sun, Q. Jing, Y. Tang, Chem. Commun.
2006, 2980-2982; (c) C. Li, X. Wang, X. Sun, Y. Tang, J. Zheng, Z. Xu,
Y. Zhou, L. Dai, J. Am. Chem. Soc. 2007, 129, 1494-1495.
[11] I. T. Crouch, R. K. Neff, D. E. Frantz, J. Am. Chem. Soc. 2013, 135,
4970-4973.
[12] H. Qian, X. Yu, J. Zhang, J. Sun, J. Am. Chem. Soc. 2013, 135, 18020-
18023.
[13] Y. Tang, Q. Chen, X. Liu, G. Wang, L. Lin, X. Feng, Angew. Chem.
2015, 127, 9648 –9652; Angew. Chem. Int. Ed. 2015, 54, 9512-9516.
[14] Y. Wei, W. Zhao, Y. Yang, Z. Zhang, M. Shi, ChemCatChem. 2015, 7,
3340-3349.
[15] Y. Wang, W. Zhang, S. Ma, J. Am. Chem. Soc. 2013, 135, 11517-
11520.
[16] Recent price per gram according to J&K Chemicals: [(π-allyl)PdCl]2 vs.
[(π-cinnamyl)PdCl]2 = 784:1257 (in CNY).
[17] J. Ye, W. Fan, S. Ma, Chem. Eur. J. 2013, 19, 716-720.
[18] B. Chen, Z. Lu, G. Chai, C. Fu, S. Ma, J. Org. Chem. 2008, 73, 9486-
9489.
[19] Z. Lu, G. Chai, S. Ma, Angew. Chem. 2008, 120, 6134–6137; Angew.
Chem. Int. Ed. 2008, 47, 6045-6048.
[6]
[7]
J. Yu, W. Chen, L. Gong, Org. Lett. 2010, 12, 4050-4053.
T. Inokuma, M. Furukawa, T. Suzuki, T. Kimachi, Y. Kobayashi, Y.
Takemoto, ChemCatChem. 2012, 4, 983-985.
This article is protected by copyright. All rights reserved.

10.1002/chem.201701194
Chemistry - A European Journal
COMMUNICATION
COMMUNICATION
Wanli Zhang and Shengming Ma*
A
catalytic highly enantioselective
synthesis of 2,3-allenoates from easily
available racemic propargylic
Page No. – Page No.
carbonates utilizing (R)- or (S)-3,4,5-
Palladium-Catalyzed Enantioselective
Alkoxycarbonylation of Propargylic
Carbonates with (R)- or (S)-3,4,5-
(MeO)3-MeOBIPHEP
(MeO)3-MeOBIPHEP and Pd has
been developed, obtaining optically
active allenoates with 90-98% ee and
decent yields.
This article is protected by copyright. All rights reserved.