Tunable Bifunctional Phosphine-Squaramide Promoted Morita-Baylis-Hillman Reaction of N-Alkyl Isatins with Acrylates

Article abstract of DOI:10.1002/adsc.201500110

A series of highly tunable bifunctional phosphine-squaramide H-bond donor organocatalysts 6 has been synthesized from inexpensive and commercially available β-amino alcohols in moderate yields. Catalyst 6 can efficiently promote the asymmetric Morita-Baylis-Hillman (MBH) reaction of N-alkyl isatins with acrylate esters providing the chiral 3-substituted 3-hydroxy-2-oxindoles in good yields and enantioselectivities (up to 93 yield and 95 ee), in which the challenging substrate tert-butyl acrylate 9d, provided the best ee value to date. Moreover, this methodology was applied successfully in the synthesis of chiral cyclic spiropyrrolizidineoxindole and γ-butyrolactone derivatives without enantioselectivity deterioration. The possible mechanism of this MBH reaction was also investigated by ³¹PNMR, ESI-MS and KIE studies. The KIE experiments show that the electrophilic addition of N-methyl isatin to the complex of acrylate ester and phophine-squaramide is the rate-determing step of the asymmetric MBH reaction.

Full text of DOI:10.1002/adsc.201500110

UPDATES
DOI: 10.1002/adsc.201500110
Tunable Bifunctional Phosphine–Squaramide Promoted Morita–
Baylis–Hillman Reaction of N-Alkyl Isatins with Acrylates
Ze Dong,a Chao Yan,a Yongzhi Gao,a Chune Dong,a Guofu Qiu,a,*
and Hai-Bing Zhoua,b,*
a
State Key Laboratory of Virology, Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education,
Wuhan University School of Pharmaceutical Sciences, Wuhan, 430071, People’s Republic of China
E-mail: zhouhb@whu.edu.cn or chiral@whu.edu.cn
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
b
Shanghai, 200032, People’s Republic of China
Received: February 3, 2015; Revised: March 4, 2015; Published online: April 17, 2015
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201500110.
Abstract: A series of highly tunable bifunctional
phosphine-squaramide H-bond donor organocata-
lysts 6 has been synthesized from inexpensive and
commercially available b-amino alcohols in moder-
ate yields. Catalyst 6 f can efficiently promote the
asymmetric Morita–Baylis–Hillman (MBH) reac-
tion of N-alkyl isatins with acrylate esters providing
the chiral 3-substituted 3-hydroxy-2-oxindoles in
good yields and enantioselectivities (up to 93%
yield and 95% ee), in which the challenging sub-
strate tert-butyl acrylate 9d, provided the best ee
value to date. Moreover, this methodology was ap-
plied successfully in the synthesis of chiral cyclic
spiropyrrolizidineoxindole and g-butyrolactone de-
rivatives without enantioselectivity deterioration.
The possible mechanism of this MBH reaction was
also investigated by 31P NMR, ESI-MS and KIE
studies. The KIE experiments show that the electro-
philic addition of N-methyl isatin to the complex of
acrylate ester and phophine-squaramide is the rate-
determing step of the asymmetric MBH reaction.
alytic systems, such as cinchonine derivatives and
chiral phosphines as well (Figure 1).[2]
Among these, the enantioselective MBH reaction
of isatins was particularly attractive since the MBH
adducts,[3] 3-substituted 3-hydroxy-2-oxindoles, consti-
tute the core building blocks of many valuable drug
candidates.[4–5] In 2010, Zhou and coworkers reported
the first MBH reaction of isatin with acrolein cata-
lyzed by ß-isocupreidine 1a (ß-ICD) providing the ox-
indole derivatives in excellent enantioselectivity
(Figure 1).[6] Shi et al. reported the ß-ICD-catalyzed
asymmetric MBH reaction of 1-naphthyl acrylate with
isatins to generate the oxindoles in good ee values (up
to 94%).[7] Luꢀs group also applied ß-ICD to promote
the asymmetric MBH reaction of benzyl acrylate with
isatins.[8] As is well known, chiral phosphine organo-
catalysts have attracted considerable attention in
asymmetric catalytic synthesis;[9] particularly, amino
acid based bifunctional phosphine organocatalysts
have been widely explored in various reactions.[10] In
2011, Wu et al. employed the phosphino-thiourea or-
ganocatalyst to catalyze the reaction of isatin and ac-
rylate.[11] Following their previous work,[12] more re-
Keywords: Morita–Baylis–Hillman reaction; mecha-
nistic study; phosphine-squaramide
Introduction
The Morita–Baylis–Hillman (MBH) reaction is one of
À
the most valuable C C bond forming reactions in or-
ganic synthesis owing to its high efficiency in con-
struction of densely functionalized products in an
atom-economic manner.[1] In the last few years, the
asymmetric version of MBH reaction has been exten-
Figure 1. Reported chiral organocatalysts for the asymmetric
sively investigated by employing several different cat- MBH reaction
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UPDATES
Tunable Bifunctional Phosphine–Squaramide
Figure 2. Design of novel chiral phosphine squaramides
cently, Wu[13] and another group[14] developed several
chiral bifunctional phosphine–squaramide organocata-
lysts, which were efficient for the asymmetric MBH
reaction. Despite important progress in this area,
there is still room for improvement. For example,
these phosphine organocatalysts cannot be effectively
tuned.
As part of our projects in development of hydrogen
bond donor chiral squaramide organocatalysts,[15–16]
we are interested in exploring the potential of chiral
squaramide organocatalyst[17] in the asymmetric MBH
transformation. We envisioned that having the squar-
amide motif and the highly tunable phosphine moiety
within one molecule could synergistically activate the
substrates in stereocontrolled manner, which might
lead to high enantioselectivity. As shown in Figure 2,
simple incorporation of various substituents into
phenyl ring could alter the acidity of the squara-
mide.[18] Meanwhile, the diversity of b-aminophos-
phines could tune the catalytic activity by steric and
electronic effect as well.
Scheme 1. General synthetic route of phosphine-squaramide
organocatalysts
Table 1. Optimization of reaction conditions for catalyst
6a[a]
Herein, we report a series of highly tunable bifunc-
tional phosphine–squaramides from inexpensive,
easily obtained, commercially available b-amino alco-
hols and their application in the asymmetric catalyzed
MBH reactions of isatin with acrylates, providing the
MBH adducts in good yields and up to 95% ee. The
possible mechanism of this MBH reaction was also in-
vestigated by 31P NMR, ESI-MS and KIE studies.
Entry
Cat. [mol%]
Solvent
Yield [%][b]
ee [%][c]
1
2
3
4
5
6
7
8
7.5
5.0
2.5
1.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
THF
THF
THF
THF
CH2Cl2
toluene
CH3CN
acrylate
EA
EA
EA
EA
EA
96
87
54
18
51
18
60
30
77
87
90
13
17
82
82
84
86
81
85
80
79
85
87
84
92
82
Results and Discussion
9
10[d]
11[d,e]
12[d,g]
13[d,f,g]
The highly tunable phosphine–squaramides 6a–f were
prepared in 43-56% yields by the condensation of
ethyl squarate with the corresponding b-aminophos-
phines derived from b-aminoalcohols (Scheme 1).[19]
Firstly, the optimal reaction conditions of the enan-
tioselective MBH reaction were investigated by em-
ploying N-methyl isatin 8a with methyl acrylate 9a in
the presence of catalyst 6a, the results were illustrat-
ed in Table 1. To our delight, in the presence of
7.5 mol% of 6a, the reaction in THF at 108C for 2
days gave 10a in 96% yield and 82% ee (entry 1).
Lowering the catalyst loading to 1 mol% led to a sig-
[a]
Condition: 8a (0.2 mmol), 9a (0.4 mmol), solvent (1 mL),
6a, the mixture was stirred at r.t. for 48 hrs.
Isolated yield.
[b]
[c]
[d]
[e]
[f]
Determined by HPLC analysis.
1.0 mmol 9a was used.
r.t.
100 uL EA/THF (1:1).
08C.
[g]
nificant decrease in yield albeit with a slight increase were examined (entries 2 and 5-9). Ethyl acetate
in enantioselectivity (entry 4). Then Various solvents (EA) was proved to be the best solvent in terms of
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UPDATES
Ze Dong et al.
Table 2. Screening of catalysts[a]
tive process possibly due to the steric effect, affording
the product in 86% ee (entry 2). Lowering the reac-
tion temperature could slightly enhance enantioselec-
tivity (entries 3, 4 and 9 in parenthesis). Moreover,
other acrylate esters were also employed in this reac-
tion affording the corresponding products 10p–r in
excellent ees (entries 16-18). It is worth noting that
the challenging substrate t-butyl acrylate 9d, which
was reported to give moderate ee presumably due to
the bulky t-butyl group, gave 95% ee in our catalytic
system (entry 18).[13a] Furthermore, the MBH transfor-
mation of N-methyl isatin 8c with methyl acrylate 9a
on 0.8 mmol scale was conducted to explore the reac-
tion practicality; to our delight, even in the presence
of 2.5 mol% of 6 f, 10c was isolated in 90% yield and
92% ee (entry 22).
Entry
Cat.
Yield [%][b]
ee [%][c]
1
2
3
4
5
6
7
8
6a
6b
6c
6d
6e
6 f
7a
7b
90
86
78
90
90
90
89
79
84
83
69
84
90
94
62
32
To further illustrate the synthetic potential of this
methodology, the synthesis of a chiral polycyclic oxin-
dole and a g-butyrolactone were performed. As
shown in Figure 3, the asymmetric MBH adduct 10c
was treated with l-proline and isatin in methanol to
generate polycyclic compound 12 in 84% yield and
94% ee. This type of polycyclic compound has served
[a]
Condition: 8a (0.2 mmol), 9a (1.0 mmol), EA (1 mL),
Cat. 6 (0.01 mmol), the mixture was stirred at r.t. for 48
hrs.
Isolated yield.
Determined by HPLC analysis.
[b]
[c]
catalytic reactivity and enantioselectivity (entry 10). as a potential synthon for the preparation of drug in-
As expected, the lower reaction temperature did im- termediates and clinical pharmaceuticals.[20] Further-
prove the ee value (entries 12 and 13). Finally, we more, the product 10c can be easily reduced with
chose a 5 mol% catalyst loading and EA as the most sodium borohydride in THF to provide the g-butyro-
suitable solvent to do further screening.
lactone 11 in 62% yield and 92% ee, which have po-
Following the optimized reaction conditions, effi- tential activity in the inhibition of various bacteria
ciency of other bifunctional phosphine squaramides and fungi species.[21]
6b–f were evaluated, the results were shown in
Table 2.
The mechanism of the asymmetric catalytic MBH
reaction of N-alkyl isatin with acrylate ester by chiral
Catalyst 6 f, derived from l-tert-leucinol, was found phosphine squaramide was not entirely clear. During
to promote the MBH reaction of 8a with methyl acry- our manuscript prepararion, Wu reported the aza-
late 9a to give the product 10a in 90% yield and MBH reaction of isatin and acrylate ester and a plausi-
94% ee (entry 6). The l-valinol derived phosphine- ble TS was also proposed.[13b] To gain insight into this
squaramide catalysts 6a, 6c, 6d and l-phenylglycinol type of asymmetric transformation, several experi-
derived 6b exhibit inferior enantioselectivities (en- ments were performed. First, the key intermediate de-
tries 1–4). In contrast, when the single hydrogen bond tected by 31P NMR experiment (Support Information
donor catalyst 7a was used in the reaction, 10a was S1) is consistent with the intermediate formed by Mi-
formed in 89% yield and 62% ee (entry 7). Unfortu- chael reaction of the chiral tertiary phosphine in cata-
nately, 7b showed even lower catalytic activity for the lyst 6 f with butyl acrylate.
MBH reaction (entry 8). These results implied that
Furthermore, the suspension of catalyst 6 f with
the assembly of bulkier tert-butyl group and more butyl acrylate in EA was stirred about 10 min till the
electron-deficient phenyl amine benefits the enantio- reaction system became clear, the key zwitterionic in-
selectivity (comparion of catalyst 6 f with others).
termediate of m/z 721 was detected by ESI-MS, which
With the optimized reaction conditions in hand, we correlated to the authentic active species I in the
next carried out the MBH reaction of acrylate ester 9 MBH reaction. Then, the N-methyl isatin was added,
with various N-alkyl isatins 8 catalyzed by the bifunc- after 10 min, another intermediate m/z 882 was inter-
tional phosphine-squaramide organocatalyst 6 f. The cepted as well, which was potentially the triple adduct
results were summarized in Table 3. As shown in II.
Table 3, the reactions worked very well with isatins
To understand the possible pathway of this asym-
bearing either electron-withdrawing or electron-do- metric MBH reaction better, we performed the KIE
nating substituents on the phenyl ring and the desired experiments to discern the rate-limiting step of the
products can be obtained in good yields and enantio- MBH reaction catalyzed by tunable bifunctional
selectivities (89–95% ee) (entry 1, entries 3–15). 8b phosphine–squaramide catalyst 6 f. The carbon isotop-
with the substituent at the 4-position retard the reac- ic effect on both the reactants was investigated by em-
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UPDATES
Tunable Bifunctional Phosphine–Squaramide
Table 3. Substrate scope of the enantioselective MBH reactions catalyzed by 6 f[a]
Entry
Substrate 8
R1
R2
R3
Products 10, Yield [%][b]
ee [%][c]
1
2
3
4
5
6
7
8
8a
8b
8c
8d
8e
8 f
8g
8h
8i
H
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Et
allyl
Bn
iPr
n-pentyl
Me
Me
Me
allyl
Bn
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Et
10a, 92
10b, 75
10c, 92 (62)
10d, 93 (49)
10e, 84
10 f, 90
10g, 76
10h, 92
10i, 92 (43)
10j, 92
94
4-Br
5-Br
6-Br
7-Br
5-Me
5-MeO
5-F
5-Cl
7-Cl
H
H
H
H
H
H
H
H
H
86[e]
93 (95)[d]
94 (95)[d]
92
92
94
93
9
93 (94)[d]
93
10
11
12
13
14
15
16
17
18
19
20
21
22
8j
8k
8l
10k, 89
10l, 86
92
93
90
92
89
90
92
95
8m
8n
8o
8a
8a
8a
8l
8m
8a
8c
10m, 84
10n, 80
10o, 82
10p, 93
10q, 83
10r, 74
Bu
tBu
Me
Me
Me
Me
10l, 88
90[e]
87[e]
87[e]
92[f]
H
H
5-Br
10m, 86
10a, 87
10c, 90
Me
Me
[a]
Condition: 8 (0.1 mmol), 9 (0.5 mmol), EA (0.5 mL), 6 f (0.005 mmol), the mixture was stirred at r.t. for 48 hrs.
Isolated yield.
[b]
[c]
Determined by HPLC analysis using chiral columns, (R)-configuration was assigned by the sign of specific rotation with
that reported in the literature.[13a]
[d]
[e]
[f]
The results in parenthesis were obtained at 108C.
Cat. 6d was used.
The reaction was conducted in 0.8 mmol scale.
ploying Singletonꢀs NMR technique[22] at natural at 62% conversion of N-methyl isatin, the two re-
abundance (Figure 4). When the reaction proceeded maining reactants N-methyl isatin and butyl acrylate
were recovered and then the kinetic isotope effect ex-
periments were performed for butyl acrylate and N-
methyl isatin, respectively. A pronounced carbon iso-
tope effect was observed on the 3-carbon when the
13C ratio of recovered N-methyl isatin was compared
to
that
of
the
original
sample
(13C(recovered)/13C(original) at C3 =1.021). This ki-
netic isotope effect indicates the nucleophilic addition
of active species I to N-methyl isatin is the rate-limit-
ing step of the asymmetric MBH reaction.
Figure 3. Synthetic applications of the MBH adduct
Figure 4. KIEs of two reactants
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UPDATES
Ze Dong et al.
Figure 5. Proposed transition state of the MBH reaction
Based on these results, a proposed mechanism is in the asymmetric MBH reaction of N-alkyl isatins
shown in Figure 5. The chiral tertiary phosphine first with acrylate esters. This methodology was applied
add to butyl acrylate, generating reactive intermediate successfully in the further synthesis of chiral polycyc-
I, which then interacts with isatin through hydrogen lic oxindole and g-butyrolactone derivatives. To gain
bonding leading to the key intermediate TS which further mechanistic insight, we have intercepted two
possibly exists as cyclic phosphinoyl associated enola- critical catalytic active intermediates with the aid of
te.[13b,23] Then the nucleophilic attack of the enolate to the ESI-MS and determined the authentic catalytic
the isatin carbonyl affords species II. In the following active species by tracing the catalytic cycle through
elimination of the catalyst, the desired product is 31P NMR. In combination with the KIE study, we
formed, completing the catalytic cycle.
have identified the rate-limiting step of the asymmet-
ric MBH reaction catalyzed by bifunctional phos-
phine–squaramide catalyst. Investigation of further
application of this kind of organocatalyst to the con-
struction of other pharmaceutically active substances
Conclusions
In conclusion, we have prepared a series of novel bi- is in progress and will be reported in a due course.
functional phosphine–squaramide organocatalysts
from commercially available b-amino alcohols. These
chiral catalysts exhibited excellent enantioselectivity
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UPDATES
Tunable Bifunctional Phosphine–Squaramide
Crude cyclic sulfamidite (3.0 mmol) (prepared above) was
Experimental Section
dissolved in CH3CN (6.0 mL) and cooled to 088C. Then a cat-
alytic amount of RuCl3·nH2O (9.0 mg) was added and
NaIO4 (4.5 mmol) was added in portions at this temperatur-
e,followed by water (6.0 mL). The resulting mixture was al-
lowed to warm to room temperature for another 1 h stirring.
The reaction endpoint was the change of color from black
to orange. The reactive mixture was poured into water and
the aqueous phase was extracted with diethyl ether; the
combined organic layer was washed with brine and dried
over anhydrous Na2SO4. Removal of solvent afforded the
cyclic sulfamidate as a solid.
(S)-tert-Butyl 4-isopropyl-1,2,3-oxathiazolidine-3-carboxyl-
ate 2,2-dioxide (3a): white solid, (517 mg, 65% yield);
1H NMR (400 MHz, CDCl3) d 4.58 (m, 1H), 4.40 (m, 1H),
4.20 (m, 1H), 2.27 (m, 1H), 1.56 (s, 9H), 1.03 (d, J=6.8 Hz,
3H), 0.98 (d, J=7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d 149.1, 85.4, 67.0, 62.0, 30.0, 27.9, 18.0, 16.5.
General Information
Analytical-grade solvents and amino alcohols were pur-
chased and used as received. Catalyst 6 was obtained in mul-
tiple steps synthesis from commercially available amino al-
cohols and squaric acid as described below. Column chroma-
tography purifications were performed using 230–400 mesh
silica gel. Enantiomeric excesses (ees) were determined by
HPLC analysis with AD-H chiral column (250 cm
”
4.6 mm), AS-H chiral column (250 cm ” 4.6 mm), OJ-H
chiral column (250 cm ” 4.6 mm) or Chiralcel OD-H chiral
column (250 cm ” 4.6 mm), as indicated. Optical rotation
was reported as follows: [a] (c g/100 mL, solvents). NMR
spectra were measured at 400 MHz for 1H spectra and
100 MHz for 13C spectra by Bruker NMR instrument (Bio-
spin 2.1) and calibrated from residual solvent signal. HRMS
was also acquired with the indicated source. IR spectra were
obtained by FT-IR.
(S)-tert-Butyl 4-phenyl-1,2,3-oxathiazolidine-3-carboxylate
1
2,2-dioxide (3b): white solid, (565 mg, 63% yield); H NMR
(400 MHz, CDCl3) d 7.41 (s, 5H), 5.29 (m, 1H), 4.88 (m,
1H), 4.41 (m, 1H), 1.43 (s, 9H); 13C NMR (100 MHz,
CDCl3) d 148.29, 136.9, 129.2, 126.2, 85.6, 71.8, 60.8, 27.8.
(S)-tert-Butyl 4-(tert-butyl)-1,2,3-oxathiazolidine-3-carbox-
ylate 2,2-dioxide (3c): white solid, (597 mg, 71% yield);
1H NMR (400 MHz, CDCl3) d 4.60 (m, 1H), 4.49 (d, J=
9.6 Hz, 1H), 4.18 (d, J=6.0 Hz, 1H), 1.56 (s, 9H), 1.01 (s,
9H); 13C NMR (100 MHz, CDCl3) d 150.1, 85.4, 67.7, 65.1,
35.5, 27.8, 25.7.
General procedure for the synthesis of carbamates 2
To a stirred solution of b-amino alcohol (10 mmol) and
Na2CO3 (20 mmol) in THF (20 mL) and water (15 mL) was
added Boc2O (11 mmol) in THF (25 mL) in the ice-water
bath. After the consumption of b-amino alcohol, the result-
ing suspension was poured into water (80 mL) and extracted
with CH2Cl2 (80 mL ” 3), then dried over anhydrous
Na2SO4. Filtration followed by solvent evaporation afforded
Boc-protected amino alcohols, which are pure enough with-
out further purification.
General procedure for the synthesis of phosphino
carbamates 4
(S)-tert-Butyl (1-hydroxy-3-methylbutan-2-yl)-carbamate
1
(2a): colorless oil, (1.87 g, 92% yield); H NMR (400 MHz,
A solution of KPPh2 (0.5m in THF, 1.65 mmol) was added
drop wise to a solution of 3 (1.5 mmol) in THF (15 mL),
which had been cooled to À788C. After addition, the mix-
ture was stirred at À608C for 0.5 h, then slowly warmed to
room temperature and stirred overnight. H2SO4 (10 mL, 2N)
and brine (20%, 30 mL) were added to the mixture, which
was stirred at room temperature for 1 h. Saturated sodium
carbonate was added to neutralize the mixture and make
the solution basic. The aqueous layer was extracted with
CH2Cl2 (50 mL ” 3). The combined organic layer was
washed with brine and dried over anhydrous Na2SO4. The
filtrate was evaporated to almost dryness, and then purifica-
tion was carried out by flash chromatography on silica gel
(petroleum ether to petroleum ether/EA 20:1 (v/v)).
CDCl3) d 4.86 (s, 1H), 3.64 (m, 2H), 3.42 (s, 1H), 3.09 (s,
1H), 1.86 (m, 1H), 1.45 (s, 9H), 0.98–0.91 (m, 6H);
13C NMR (100 MHz, CDCl3) d 156.8, 79.5, 63.9, 57.9, 28.4,
27.4, 19.5, 18.5.
(S)-tert-Butyl (2-hydroxy-1-phenylethyl)carbamate (2b):
white solid, (2.21 g, 93% yield); 1H NMR (400 MHz,
CDCl3) d 7.31 (m, 5H), 5.38 (s, 1H), 4.76 (s, 1H), 3.78 (s,
2H), 2.87 (s, 1H), 1.43 (s, 9H); 13C NMR (100 MHz, CDCl3)
d 156.1, 139.5, 128.7, 127.7, 126.6, 80.0, 66.6, 56.9, 28.5.
(S)-tert-Butyl (1-hydroxy-3,3-dimethylbutan-2-yl)- carba-
mate (2c): white solid (2.02 g, 92% yield); 1H NMR
(400 MHz, CDCl3) d 4.71 (s, 1H), 3.82 (m, 1H), 3.48 (m,
2H), 2.55 (m, 1H), 1.46 (s, 9H), 0.94 (s, 9H); 13C NMR
(100 MHz, CDCl3) d 157.2, 79.5, 63.0, 61.0, 33.7, 28.4, 26.8.
(S)-tert-Butyl
(1-(diphenylphosphino)-3-methylbutan-2-
yl)carbamate (4a):[10o] colorless oil, (390 mg, 70% yield);
1H NMR (400 MHz, CDCl3) d 7.50–7.26 (m, 10H), 4.39 (d,
J=7.2 Hz, 1H), 3.60 (m, 1H), 2.33–2.10 (m, 2H), 1.90 (m,
1H), 1.41 (s, 9H), 0.86 (m, 6H); 31P NMR (162 MHz,
CDCl3) d À22.94.
General procedure for the synthesis of cyclic
sulfamidates 3
A solution of Boc-protected amino alcohol 2 (3.0 mmol) in
CH3CN (10 mL) was added slowly to the mixture of SOCl2
(7.5 mmol) in CH3CN (30 mL) at À408C under Argon at-
mosphere. Subsequently pyridine (15 mmol) was added at
this temperature. Then the reaction system was allowed to
warm to room temperature and stirred for another 3 h. The
reaction was concentrated and then water (10 mL) was
added. The aqueous layer was extracted with CH2Cl2
(10 mL ” 3). The combined organic layer was washed with
brine and dried over anhydrous Na2SO4. The solvent was re-
moved to give the crude cyclic sulfamidite as orange oil.
(S)-tert-Butyl (2-(diphenylphosphino)-1-phenylethyl)car-
bamate (4b):[24] white solid, (395 mg, 65% yield); H NMR
1
(400 MHz, CDCl3) d 7.43–7.23 (m, 15H), 5.01 (s, 1H), 4.70
(s, 1H), 2.53 (m, 2H), 1.39 (s, 9H); 31P NMR (162 MHz,
CDCl3) d À23.46.
(S)-tert-Butyl (1-(diphenylphosphino)-3,3-dimethylbutan-
2-yl)carbamate (4c):[24] white solid, (414 mg, 72% yield);
1H NMR (400 MHz, CDCl3) d 7.36–7.19 (m, 10H), 4.24 (d,
J=10.4 Hz, 1H), 3.52–3.35 (m, 1H), 2.33–2.24 (m, 1H), 1.86
Adv. Synth. Catal. 2015, 357, 2132 – 2142
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2137

UPDATES
Ze Dong et al.
(m, 1H), 1.34 (s, 9H), 0.77 (s, 9H); 31P NMR (162 MHz,
CDCl3) d À20.83.
162.8, 142.3 (d, J=6.1 Hz), 141.3, 138.2, 138.0, 137.9, 137.8,
133.3, 133.1, 132.9, 131.9, 131.6, 131.4, 129.3, 129.2, 129.04,
129.02, 128.95, 128.2, 127.7, 126.9, 124.9, 122.2, 118.5, 115.3,
56.5 (d, J=19.1 Hz), 35.9 (d, J=13.5 Hz); HRMS (MALDI/
DHB) Calcd for C32H24F6N2O2P ([M+H]+): 613.1480;
found: 613.1474; FTIR (KBr) nmax (cmÀ1): 3418, 3140, 3070,
2925, 1795, 1670, 1562.
General procedure for the synthesis of phosphino
amines 5
CF3CO2H (7.5 mmol) was added to
a solution of 4
Catalyst (6c): white solid, (199 mg, 56% yield); m.p. 243–
(0.3 mmol) in CH2Cl2 (10 mL) slowly at 08C and the mix-
ture was stirred for 1 h, then allowed to warm to room tem-
perature and stirred for 4 h. All the volatiles were removed
under vacuum. Saturated Na2CO3 solution was added in the
ice-water bath to neutralize the mixture and make it basic.
The aqueous layer was extracted with CH2Cl2 (10 mL ” 3).
The combined organic layer was washed with brine and
dried over anhydrous Na2SO4. Filtration and removal of sol-
vent gave the crude product as colorless oil, which was then
isolated by flash chromatography on silica gel (petroleum
ether/EA, 2:1 to 1:1 (v/v)).
1
2458C; [a]2D0 = +44.2 (c 0.16, DMSO); H NMR (400 MHz,
[D6]DMSO) d 8.07 (m, 3H), 7.31 (m, 12H), 4.87 (s, 2H),
3.96 (s, 1H), 2.45 (m, 1H), 2.36–2.21 (m, 1H), 1.87 (s, 1H),
0.83 (m, 6H); 31P NMR (162 MHz, [D6]DMSO) d-22.14;
13C NMR (100 MHz, [D6]DMSO) d 182.8, 182.7, 168.6,
167.1, 143.1, 138.7 138.6, 138.4, 138.3, 133.1, 133.0, 132.9,
132.8, 131.1, 130.8, 129.2, 129.0, 128.91, 128.85, 128.78, 127.8,
125.1, 122.4, 121.7, 57.3 (d, J=13.7 Hz), 46.1, 34.0 (d, J=
11.5), 32.3 (d, J=12.6), 19.3, 17.2; HRMS (MALDI/DHB)
Calcd for C30H28F6N2O2P ([M+H]+): 593.1793; found:
593.1787; FTIR (KBr) nmax (cmÀ1): 3167, 3070, 2965, 1793,
1644, 1562.
(S)-1-(Diphenylphosphino)-3-methylbutan-2-amine
(5a):[19] colorless oil, (72 mg, 88% yield); 1H NMR
(400 MHz, CDCl3) d 7.51–7.13 (m, 10H), 2.64–2.47 (m, 1H),
2.25 (m, 1H), 1.93–1.81 (m, 1H), 1.69–1.56 (m, 1H), 1.38 (s,
2H), 0.80 (m, 6H); 31P NMR (162 MHz, CDCl3) d À21.50.
(S)-2-(Diphenylphosphino)-1-phenylethanamine (5b):[25]
colorless oil, (82 mg, 90% yield); 1H NMR (400 MHz,
CDCl3) d 7.50–7.23 (m, 15H), 3.97 (m, 1H), 2.52 (m, 1H),
2.41 (m, 1H), 1.92 (s, 2H); 31P NMR (162 MHz, CDCl3) d
À21.91.
Catalyst (6d): white solid, (138 mg, 50% yield); m.p. 251–
1
2528C. [a]2D0 = +36.8 (c 0.11, DMSO); H NMR (400 MHz,
[D6]DMSO) d 9.38 (s, 1H), 7.57–7.14 (m, 15H), 4.17–3.95
(m, 1H), 2.35 (m, 1H), 1.93 (m, 1H), 0.90 (t, J=6.6 Hz,
6H); 31P NMR (162 MHz, [D6]DMSO) d À21.89. 13C NMR
(100 MHz, [D6]DMSO) d 183.6, 180.5, 169.4, 169.2, 159.6,
157.2, 138.5, 138.41, 138.36, 138.3, 135.9 (d, J=2.2 Hz),
133.2, 133.1, 133.0, 132.9, 129.2, 129.1, 129.0, 128.9, 120.0 (d,
J=8.0 Hz), 116.5, 116.3, 58.0 (d, J=18.3 Hz), 34.0 (d, J=
8.0 Hz), 32.4 (d, J=13.0 Hz), 19.4, 17.2; HRMS (MALDI/
DHB) Calcd for C27H27FN2O2P ([M+H]+): 461.1794; found:
461.1788; FTIR (KBr) nmax (cmÀ1): 3419, 3180, 3053, 2924,
1794, 1657, 1569.
(S)-1-(Diphenylphosphino)-3,3-dimethylbutan-2-amine
(5c):[19] colorless oil, (81 mg, 95% yield); 1H NMR
(400 MHz, CDCl3) d 7.47–7.10 (m, 10H), 2.46–2.27 (m, 2H),
1.75–1.62 (m, 1H), 1.47 (s, 2H), 0.77 (s, 9H); 31P NMR
(162 MHz, CDCl3) d À19.56 (s, 1H).
Catalyst (6e): white solid, (128 mg, 45% yield); m.p. 282–
1
2848C. [a]2D0 = +49.1 (c 0.11, DMSO); H NMR (400 MHz,
General procedure for the synthesis of bifunctional
phosphine-squaramide catalysts 6
[D6]DMSO) d 9.30 (s, 1H), 7.48–7.17 (m, 15H), 4.03–3.87
(m, 1H), 2.58 (m, 1H), 2.15 (m, 1H), 0.91 (s, 9H); 31P NMR
(162 MHz, [D6]DMSO) d À20.16; 13C NMR (100 MHz,
[D6]DMSO) d 183.5, 180.5, 169.6, 162.9, 159.6, 157.2, 138.7,
138.6, 138.3, 138.1, 135.9 (d, J=2.3 Hz), 133.3, 133.2, 133.1,
133.0, 129.3, 129.01, 128.99, 128.9, 128.8, 120.0 (d, J=
8.0 Hz), 116.6, 116.3, 61.4 (d, J=15.7 Hz), 36.1 (d, J=
7.3 Hz), 30.0 (d, J=12.1 Hz), 26.0; HRMS (MALDI/DHB)
Calcd for C28H29FN2O2P ([M+H]+): 475.1951; found:
475.1945; FTIR (KBr) nmax (cmÀ1): 3425, 3192, 3054, 2962,
1793, 1657, 1563.
Under an argon atmosphere, to a solution of squaramide
ester (0.6 mmol) in CH2Cl2 (5 mL) was added the solution
of corresponding b-amino phosphine (0.6 mmol) in CH2Cl2
(2 mL). After stirring for five days at room temperature, the
solid was filtered and washed by CH2Cl2 three times to
afford phosphine-squaramide catalyst as a white solid.
Catalyst (6a): white solid, (180 mg, 52% yield); m.p. 230–
1
2328C; [a]2D0 = +11.7 (c 0.10, DMSO); H NMR (400 MHz,
[D6]DMSO) d 9.90 (s, 1H), 8.00 (s, 2H), 7.68 (s, 1H), 7.65(s,
1H), 7.51–7.17 (m, 10H), 4.05 (m, 1H), 2.48–2.31 (m, 1H),
1.99–1.88 (m, 1H), 1.20 (m, 1H), 0.91 (m, 6H); 31P NMR
(162 MHz, [D6]DMSO) d À21.66; 13C NMR (100 MHz,
[D6]DMSO) d 184.6, 180.7, 170.2, 162.2, 141.4, 138.4, 138.3,
138.2, 137.9, 133.3, 133.14, 133.07, 132.95, 132.0, 131.7, 129.3,
129.1, 129.0, 128.9, 125.2, 122.3, 118.4, 115.1, 58.4 (d, J=
15.2), 33.9 (d, J=7.4), 32.3 (d, J=12.3), 19.4, 17.2; HRMS
(MALDI/DHB) Calcd for C29H26F6N2O2P ([M+H]+):
579.1636; found: 579.1630; FTIR (KBr) nmax (cmÀ1): 3443,
3194, 3070, 2962, 1799, 1657, 1581.
Catalyst (6 f): white solid, (163 mg, 46% yield); m.p. 267–
1
2698C; [a]2D0 = +28.0 (c 0.16, DMSO); H NMR (400 MHz,
[D6]DMSO) d 9.84 (s, 1H), 8.01 (s, 2H), 7.68 (s, 1H), 7.64
(d, J=10.4 Hz), 7.49–7.10 (m, 10H), 3.95 (m, 1H), 2.60 (d,
J=14.5 Hz, 1H), 2.19 (t, J=12.2 Hz, 1H), 0.92 (s, 9H);
31P NMR (162 MHz, [D6]DMSO)
d
À20.28; 13C NMR
(100 MHz, [D6]DMSO) d 189.3, 185.5, 175.1, 166.7, 146.3,
143.4, 143.3, 142.9, 142.8, 138.1, 138.0, 137.9, 137.8, 136.8,
136.4, 134.2, 133.8, 133.7, 129.8, 127.0, 123.1, 119.9, 66.5 (d,
J=15.9 Hz), 40.8 (d, J=7.2 Hz), 34.7 (d, J=11.9 Hz), 30.8;
HRMS (MALDI/DHB) Calcd for C30H27F6N2O2P ([M+
H]+): 593.1793; found: 593.1787; FTIR (KBr) nmax (cmÀ1):
3403, 3144, 3070, 1965, 1798, 1657, 1580.
Catalyst (6b): white solid, (158 mg, 43% yield); m.p. 240–
1
2428C; [a]2D0 = +14.5 (c 0.12, DMSO); H NMR (400 MHz,
[D6]DMSO) d 10.03 (s, 1H), 8.28 (m, 1H), 7.99 (s, 2H), 7.68
(s, 1H), 7.52–7.27 (m, 15H), 5.27 (s, 1H), 3.04–2.91 (m, 1H),
2.83 (m, 1H); 31P NMR (162 MHz, [D6]DMSO) d À22.85;
13C NMR (100 MHz, [D6]DMSO) d 184.5, 180.9, 169.0,
2138
asc.wiley-vch.de
ꢁ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2015, 357, 2132 – 2142

UPDATES
Tunable Bifunctional Phosphine–Squaramide
1H NMR (400 MHz, CDCl3) d 7.15–7.03 (m, 2H), 6.74 (d,
J=7.5 Hz, 1H), 6.67 (s, 1H), 6.50 (s, 1H), 3.90 (s, 1H), 3.55
(s, 3H), 3.15 (s, 3H); 13C NMR (100 MHz, CDCl3) d 175.4,
165.0, 146.6, 136.8, 131.4, 130.7, 127.3, 119.5, 107.6, 77.3,
52.1, 26.7; HRMS (MALDI/DHB) Calcd for C13H13BrNO4
([M+H]+): 326.0028; found: 326.0022; FTIR (KBr) nmax
(cmÀ1): 3394, 3058, 2923, 2853, 1704, 1605, 1458.
(R)-Methyl 2-(5-bromo-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10c): yellow oil, (30.0 mg, 92% yield); HPLC
(Chiralpak AD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1,
General procedure for the synthesis of bifunctional
phosphine-squaramide catalysts 7
Under argon atmosphere, to a solution of diethyl squarate
(1.0 mmol) in EtOH (5 mL) was added the solution of cor-
responding b-amino phosphine (1.0 mmol) in EtOH (5 mL),
after stirring for 2 days at room temperature, the desired
product was isolated by flash chromatography on silica gel
(petroleum ether/EA, 6:1 to 4:1 (v/v)).
Catalyst (7a): colorless oil, (352 mg, yield 89%); [a]2D0 =
1
À10.0 (c 0.22, CH2Cl2); H NMR (400 MHz, CDCl3) d 7.50–
254 nm):
tmajor =22.482 min, tminor =15.680 min, ee=93%;
7.23 (m, 10H), 6.87 (m, 1H), 4.62 (m, 2H), 3.55 (m, 1H),
2.50–2.28 (m, 2H), 1.96–1.91 (m, 1H), 1.30 (t, J=7.2 Hz,
3H), 0.92 (m, 6H); 31P NMR (162 MHz, CDCl3) d À21.84,
À23.35; 13C NMR (100 MHz, CDCl3) d 189.3, 182.5, 176.9,
172.0, 137.9 (d, J=2.5 Hz), 137.3 (d, J=2.5 Hz), 133.2, 133.0,
132.7, 132.5, 129.1, 128.9, 128.7, 128.63, 128.61, 128.57, 69.5,
59.1 (d, J=13.9 Hz), 34.1 (d, J=7.1 Hz), 32.4 (d, J=
14.5 Hz), 19.1, 17.2, 15.7; HRMS (MALDI/DHB) Calcd for
C23H27NO3P ([M+H]+): 396.1729; found: 396.1723; FTIR
(KBr) nmax (cmÀ1): 3250, 3028, 2960, 1804, 1703, 1607.
[a]20 =À42.6 (c 0.12, CH2Cl2); H NMR (400 MHz, CDCl3)
d 7D.45 (m, 1H), 7.26 (m, 1H), 6.74 (d, J=8.3 Hz, 1H), 6.58
(s, 1H), 6.49 (s, 1H), 4.30 (s, 1H), 3.63 (s, 3H), 3.22 (s, 3H);
13C NMR (100 MHz, CDCl3) d 176.1, 164.8, 143.5, 138.7,
132.9, 131.4, 128.4, 127.1, 115.6, 110.2, 76.0, 52.2, 26.6;
HRMS (ESI Positive) Calcd for C13H12BrNNaO4 ([M+
Na]+): 347.9847; found: 347.9842; FTIR (KBr) nmax (cmÀ1):
3367, 3068, 2924, 2853, 1716, 1610.
1
(R)-Methyl 2-(6-bromo-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10d): light yellow solid, (30.2 mg, 93% yield);
HPLC (Chiralpak OD-H column, 90:10 nhexane/iPrOH,
1 mLminÀ1, 254 nm): tmajor =10.940 min, tminor =21.407 min,
ee=94%; [a]2D0 =À61.7 (c 0.10, CH2Cl2); m.p. 122–1238C;
1H NMR (400 MHz, CDCl3) d 7.16 (m, 1H), 7.01 (m, 2H),
6.56 (s, 1H), 6.46 (s, 1H), 4.42 (s, 1H), 3.62 (s, 3H), 3.20 (s,
3H); 13C NMR (100 MHz, CDCl3) d 176.4, 164.9, 145.8,
138.8, 128.4, 128.2, 125.8, 125.1, 123.9, 112.3, 75.7, 52.1, 26.6:
HRMS (ESI Positive) Calcd for C13H12BrNNaO4 ([M+
Na]+): 347.9847; found: 347.9842; FTIR (KBr) nmax (cmÀ1):
3380, 3035, 2923, 2852, 1710, 1606.
Catalyst (7b): colorless oil, (326 mg, 80% yield); [a]2D0 = +
1
18.5 (c 0.18, CH2Cl2); H NMR (400 MHz, CDCl3) d 7.47–
7.27 (m, 10H), 6.83 (d, J=10.4 Hz, 1H), 4.67 (m, 1H), 4.53
(m, 1H), 3.42 (m, 1H), 2.49 (m, 1H), 2.29–2.16 (m, 1H),
1.29 (t, J=7.1 Hz, 3H), 0.91 (s, 9H); 31P NMR (162 MHz,
CDCl3) d À20.18, À21.13; 13C NMR (100 MHz, CDCl3) d
189.3, 182.5, 176.8, 172.4, 138.3, 136.9, 133.6, 133.4, 132.5,
132.2, 129.2, 128.8, 128.7, 128.61, 128.59, 128.5, 69.4, 62.3 (d,
J=13.5 Hz), 36.1 (d, J=6.2 Hz), 29.9 (d, J=13.5 Hz), 25.9,
15.7; HRMS (MALDI/DHB) Calcd for C24H29NO3P ([M+
H]+): 410.1885; found: 410.1890; FTIR (KBr) nmax (cmÀ1):
3254, 3066, 2925, 1801, 1693, 1602.
(R)-Methyl 2-(7-bromo-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10e): yellow oil, (27.4 mg, 84% yield); HPLC
(Chiralpak AD-H, 90:10 nhexane:iPrOH, 1 mLminÀ1,
General procedure of the asymmetric MBH reaction
254 nm):
tmajor =22.670 min, tminor =15.670 min, ee=92%;
[a]2D0 =À63.8 (c 0.21, CH2Cl2); H NMR (400 MHz, CDCl3)
d 7.42 (dd, J=8.2, 1.0 Hz, 1H), 7.06 (dd, J=7.3, 1.0 Hz,
1H), 6.87 (t, J=7.7 Hz, 1H), 6.56 (s, 1H), 6.48 (s, 1H), 4.49
(s, 1H), 3.63 (s, 3H), 3.60 (s, 3H); 13C NMR (100 MHz,
CDCl3) d 177.1, 164.9, 141.8, 139.0, 135.7, 132.5, 128.2, 124.2,
122.9, 102.9, 75.4, 52.1, 30.1; HRMS (ESI Positive) Calcd for
C13H12BrNNaO4 ([M+Na]+): 347.9847; found: 347.9842;
FTIR (KBr) nmax (cmÀ1): 3348, 2994, 2952, 2852, 1715, 1608.
1
To a solution of catalyst (3.0 mg, 5 mol%) in ethyl acetate
(0.5 mL) at room temperature was added acrylate ester
(0.5 mmol); after 10 min, when the solution became clear,
N-alkyl isatin (0.1 mmol) was added. The reaction was
monitored by TLC until the N-alkyl isatin disappeared.
Then the resulting mixture was condensed on a rotary evap-
orator and the target compounds were purified by flash
chromatography on silica gel (petroleum ether/EA, 4:1 (v/
v)). The ee values were determined by HPLC with chiral
column.
(R)-Methyl
2-(3-hydroxy-1,5-dimethyl-2-oxoindolin-3-
yl)acrylate (10 f):[11] yellow oil, (23.5 mg, 90% yield); HPLC
(Chiralpak AD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1,
(R)-Methyl 2-(3-hydroxy-1-methyl-2-oxoindolin-3-yl)acry-
late (10a):[11] yellow solid, (22.7 mg, 92% yield); HPLC
(Chiralpak OD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1,
254 nm):
tmajor =22.670 min, tminor =15.670 min, ee=92%;
1
[a]2D0 =À40.0 (c 0.10, CH2Cl2); H NMR (400 MHz, CDCl3)
d 7.11 (d, J=7.8 Hz, 1H), 6.98 (s, 1H), 6.74 (d, J=7.9 Hz,
1H), 6.55 (s, 1H), 6.46 (s, 1H), 4.33 (s, 1H), 3.62 (s, 3H),
3.20 (s, 3H), 2.28 (s, 3H); 13C NMR (100 MHz, CDCl3) d
176.4, 165.1, 142.1, 139.3, 132.6, 130.3, 129.4, 127.8, 124.6,
108.4, 76.3, 52.0, 26.5, 21.0; FTIR (KBr) nmax (cmÀ1): 3363,
3118, 2923, 2853, 1705, 1624.
254 nm):
tmajor =11.958 min, tminor =19.848 min, ee=94%;
[a]20 =À49.6 (c 0.10, CH2Cl2); m.p. 126–1288C; 1H NMR
(40D0 MHz, CDCl3) d 7.31 (t, J=8.4 Hz, 1H), 7.16 (d, J=
7.2 Hz, 1H), 7.04 (5, J=7.5 Hz, 1H), 6.85 (d, J=7.8 Hz,
1H), 6.55 (s, 1H), 6.46 (s, 1H), 4.37 (s, 1H), 3.61 (s, 3H),
3.22 (s, 3H); 13C NMR (100 MHz, CDCl3) d 176.5, 165.1,
144.5, 139.2, 130.2, 129.5, 127.9, 123.8, 123.0, 108.7, 76.2,
52.1, 26.4; FTIR (KBr) nmax (cmÀ1): 3377, 3067, 2924, 2853,
1700, 1615, 1495.
(R)-Methyl 2-(3-hydroxy-5-methoxy-1-methyl-2-oxoindo-
lin-3-yl)acrylate (10g): yellow oil, (21.7 mg, 76% yield);
HPLC
(Chiralpak
AD-H,
90:10
nhexane/iPrOH,
1 mLminÀ1, 254 nm): tmajor =31.612 min, tminor =25.908 min,
ee=94%; [a]2D0 =À31.8 (c 0.13, CH2Cl2); 1H NMR
(400 MHz, CDCl3) d 6.78–6.68 (m, 1H), 6.72–6.68 (m, 2H),
6.48 (s, 1H), 6.39 (s, 1H), 4.43 (s, 1H), 3.68 (s, 3H), 3.55 (s,
3H), 3.14 (s, 3H); 13C NMR (100 MHz, CDCl3) d 176.4,
(R)-Methyl 2-(4-bromo-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10b): yellow solid, (24.4 mg, 75% yield);
HPLC
(Chiralpak
OD-H,
90:10
nhexane/iPrOH,
1 mLminÀ1, 254 nm): tmajor =27.384 min, tminor =18.037 min,
ee=86%; [a]2D0 =À24.3 (c 0.10, CH2Cl2); m.p. 135–1378C;
Adv. Synth. Catal. 2015, 357, 2132 – 2142
ꢁ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2139

UPDATES
Ze Dong et al.
165.0, 156.3, 139.2, 137.8, 130.7, 128.0, 114.5, 111.1, 109.1,
76.6, 55.8, 52.1, 29.7, 26.5; HRMS (MALDI/DHB) Calcd for
C14H16NO5 ([M+H]+): 278.1028; found: 278.1023; FTIR
(KBr) nmax (cmÀ1): 3315, 2997, 2924, 2852, 1709, 1605.
(R)-Methyl 2-(5-fluoro-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10h): yellow oil, (24.4 mg, 92% yield); HPLC
(Chiralpak AD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1,
76.1, 52.0, 42.7; HRMS (ESI Positive) Calcd for
C15H15NO4Na ([M+Na]+): 296.0899; found: 296.0893; FTIR
(KBr) nmax (cmÀ1): 3321, 3120, 2947, 2925, 2851, 1700, 1612.
(R)-Methyl 2-(1-benzyl-3-hydroxy-2-oxoindolin-3-yl)acry-
late (10m):[11] yellow solid, (27.2 mg, 84% yield); HPLC
(Chiralpak
OD-H
column,
90:10
nhexane/iPrOH,
1 mLminÀ1, 254 nm): tmajor =11.150 min, tminor =15.542 min,
ee=90%; [a]2D0 =À35.3 (c 0.10, CH2Cl2); m.p. 134–1358C;
1H NMR (400 MHz, CDCl3) d 7.38 (d, J=7.1 Hz, 2H), 7.34–
7.23 (m, 3H), 7.21–7.12 (m, 2H), 6.98 (t, J=7.5 Hz, 1H),
6.70 (d, J=7.8 Hz, 1H), 6.59 (s, 1H), 6.48 (s, 1H), 4.91 (m,
2H), 4.25 (s, 1H), 3.56 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 176.6, 165.1, 143.7, 139.1, 135.5, 130.1, 129.6, 128.8, 128.2,
127.6, 123.8, 123.1, 109.8, 76.2, 52.0, 44.2; FTIR (KBr) nmax
(cmÀ1): 3414, 3060, 2955, 2924, 2853, 1708, 1611.
254 nm):
tmajor =21.943 min, tminor =15.282 min, ee=93%;
1
[a]20 =À47.5 (c 0.12, CH2Cl2); H NMR (400 MHz, CDCl3)
d 7D.02 (m, 1H), 6.92 (dd, J=7.5, 2.6 Hz, 1H), 6.78 (m, 1H),
6.57 (s, 1H), 6.48 (s, 1H), 4.52 (s, 1H), 3.63 (s, 3H), 3.22 (s,
3H); 13C NMR (100 MHz, CDCl3) d 176.3, 164.9, 160.6,
158.2, 140.4, 138.9, 131.1, 128.2, 116.3, 116.1, 112.2, 112.0,
109.2, 76.2, 52.1, 26.6; HRMS (MALDI/DHB) Calcd for
C13H13FNO4 ([M+H]+): 266.0829; found: 266.0823; FTIR
(KBr) nmax (cmÀ1): 3353, 2955, 2924, 2853, 1711, 1620.
(R)-Methyl 2-(3-hydroxy-1-isopropyl-2-oxoindolin-3-yl)-
acrylate (10n): light yellow solid, (22.0 mg, 80% yield);
(R)-Methyl 2-(5-chloro-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10i):[11] yellow oil, (25.9 mg, 92% yield);
HPLC
(Chiralpak
AD-H,
90:10
nhexane/iPrOH,
HPLC
(Chiralpak
AD-H,
90:10
nhexane/iPrOH,
1 mLminÀ1, 254 nm): tmajor =15.788 min, tminor =13.372 min,
ee=92%; [a]2D0 =À10.7 (c 0.10, CH2Cl2). m.p. 120–1228C;
1H NMR (400 MHz, CDCl3) d 7.20 (t, J=7.6 Hz, 1H), 7.08
(d, J=7.0 Hz, 1H), 6.99–6.85 (m, 2H), 6.48 (s, 1H), 6.39 (s,
1H), 4.59–4.40 (m, 1H), 4.21 (s, 1H), 3.51 (s, 3H), 1.43 (m,
6H); 13C NMR (100 MHz, CDCl3) d 176.1, 164.9, 143.2,
139.4, 130.0, 129.8, 127.9, 124.1, 122.4, 110.2, 75.9, 51.9, 44.2,
19.1, 19.0; HRMS (ESI Positive) Calcd for C15H17NO4Na
([M+Na]+): 298.1055; found: 298.1050; FTIR (KBr) nmax
(cmÀ1): 3461, 3329, 3054, 2983, 2941, 2852, 1716, 1610.
1 mLminÀ1, 254 nm): tmajor =20.000 min, tminor =14.042 min,
ee=93%; [a]2D0 =À44.7 (c 0.10, CH2Cl2); 1H NMR
(400 MHz, CDCl3) d 7.22 (dd, J=4.0, 4.0 Hz, 1H), 7.06 (d,
J=4.0 Hz, 1H), 6.71 (d, J=12.0 Hz, 1H),6.50 (s, 1H), 6.41
(s, 1H), 4.46 (s, 1H), 3.56 (s, 3H), 3.14 (s, 3H); 13C NMR
(100 MHz, CDCl3) d 176.2, 164.9, 143.0, 138.8, 131.2, 130.0,
128.3, 128.3, 124.4, 109.7, 76.0, 52.1, 26.6; FTIR (KBr) nmax
(cmÀ1): 3316, 3075, 2952, 2914, 2853, 1707, 1611.
(R)-Methyl 2-(7-chloro-3-hydroxy-1-methyl-2-oxoindolin-
3-yl)acrylate (10j): yellow oil, (25.9 mg, 92% yield); HPLC
(Chiralpak AD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1,
(R)-Methyl 2-(3-hydroxy-2-oxo-1-pentylindolin-3-yl)acry-
late (10o): light yellow solid, (24.8 mg, 82% yield); HPLC
254 nm):
t
major =14.862 min,
t
minor =11.283 min, ee=93%;
(Chiralpak
OD-H
column, nhexane/iPrOH,
90:10
1
[a]2D0 =À68.9 (c 0.14, CH2Cl2); H NMR (400 MHz, CDCl3)
d 7.24 (dd, J=8.2, 1.2 Hz, 1H), 7.03 (dd, J=7.3, 1.2 Hz,
1H), 6.98–6.87 (m, 1H), 6.58 (s, 1H), 6.48 (s, 1H), 4.47 (s,
1H), 3.63 (s, 3H), 3.59 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 176.9, 164.9, 140.3, 139.0, 132.4, 132.3, 128.2, 123.8, 122.3,
116.0, 75.5, 52.1, 29.9; HRMS (MALDI/DHB) Calcd for
C13H13ClNO4 ([M+H]+): 282.0533; found: 282.0528; FTIR
(KBr) nmax (cmÀ1): 3355, 2997, 2953, 2924, 2853, 1716, 1609.
(R)-Methyl 2-(1-ethyl-3-hydroxy-2-oxoindolin-3-yl)acry-
late (10k):[11] light yellow solid, (23.3 mg, 89% yield);
1 mLminÀ1, 254 nm):
t
major =10.672 min, tminor =6.512 min,
ee=89%; [a]2D0 =À40.0 (c 0.10, CH2Cl2); m.p. 101–1028C;
1H NMR (400 MHz, CDCl3) d 7.29 (m, 1H), 7.21–7.12 (m,
1H), 7.00 (t, J=7.5 Hz, 1H), 6.86 (d, J=7.8 Hz, 1H), 6.54
(s, 1H), 6.44 (s, 1H), 4.35 (s, 1H), 3.77–3.63 (m, 2H), 3.60
(s, 3H), 1.79–1.64 (m, 2H), 1.37 (m,4H), 0.95–0.85 (m, 3H);
13C NMR (100 MHz, CDCl3) d 176.3, 165.0, 144.0, 139.3,
130.0, 129.8, 127.9, 123.9, 122.7, 108.9, 76.1, 51.9, 40.3, 29.1,
26.8, 22.4, 14.0; HRMS (ESI Positive) Calcd for C12
H10NO4Na ([M+Na]+): 255.0508; found: 255.0504; FTIR
(KBr) nmax (cmÀ1): 3345, 3265, 3059, 2955, 2926, 2857, 1715,
1612.
HPLC
(Chiralpak
OD-H,
90:10
nhexane/iPrOH,
1 mLminÀ1, 254 nm):
t
major =9.233 min,
tminor =12.063 min,
ee=92%; [a]2D0 =À55.3 (c 0.10, CH2Cl2); m.p. 123–1258C;
1H NMR (400 MHz, CDCl3) d 7.30 (m, 1H), 7.20–7.11 (m,
1H), 7.01 (m, 1H), 6.87 (d, J=7.8 Hz, 1H), 6.56 (s, 1H),
6.46 (s, 1H), 4.37 (s, 1H), 3.82 (m, 1H), 3.70 (m, 1H), 3.59
(s, 3H), 1.29 (t, J=7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) d 176.1, 165.0, 143.6, 139.3, 130.1, 129.8, 128.0, 123.9,
122.8, 108.7, 76.1, 51.9, 34.9, 12.2; FTIR (KBr) nmax (cmÀ1):
3327, 3055, 2981, 1950, 2852, 1698, 1612.
(R)-Ethyl 2-(3-hydroxy-1-methyl-2-oxoindolin-3-yl)acry-
late (10p):[13a] yellow oil, (24.3 mg, 93% yield); HPLC (Chir-
alpak OD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1, 254 nm):
t
major =10.970 min, tminor =17.285 min, ee=90%; [a]2D0 =À39.9
(c 0.17, CH2Cl2); 1H NMR (400 MHz, CDCl3) d 7.25 (m,
1H), 7.09 (d, J=7.3 Hz, 1H), 6.96 (t, J=7.5 Hz, 1H), 6.77
(d, J=7.8 Hz, 1H), 6.50 (s, 1H), 6.36 (s, 1H), 4.35–4.21 (m,
1H), 4.03–3.85 (m, 2H), 3.15 (s, 3H), 1.04 (t, J=7.1 Hz,
3H); 13C NMR (100 MHz, CDCl3) d 176.4, 164.6, 144.5,
139.4, 130.1, 129.6, 127.8, 123.8, 123.0, 108.6, 76.2, 61.0, 26.4,
13.8; FTIR (KBr) nmax (cmÀ1): 3356, 2924, 2853, 1708, 1613.
(R)-Butyl 2-(3-hydroxy-1-methyl-2-oxoindolin-3-yl)acry-
late (10q):[13a] yellow oil, (24.0 mg, 83% yield); HPLC (Chir-
alpak OD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1, 254 nm):
(R)-Methyl 2-(1-allyl-3-hydroxy-2-oxoindolin-3-yl)acrylate
(10l): light yellow solid, (23.5 mg, 80% yield); HPLC (Chir-
alpak OD-H, 90:10 nhexane/iPrOH, 1 mLminÀ1, 254 nm):
t
major =8.380 min, tminor =12.428 min, ee=93%; [a]2D0 =À48.0
(c 0.10, CH2Cl2); m.p. 127–1288C; 1H NMR (400 MHz,
CDCl3) d 7.32–7.25 (m, 1H), 7.21–7.11 (m, 1H), 7.02 (m,
1H), 6.85 (d, J=7.8 Hz, 1H), 6.56 (s, 1H), 6.46 (s, 1H), 5.87
(m, 1H), 5.37 (dd, J=17.2, 1.1 Hz, 1H), 5.24 (dd, J=10.3,
1.1 Hz, 1H), 4.40 (m, 1H), 4.29 (m, 1H), 4.24 (s, 1H), 3.61
(s, 3H); 13C NMR (100 MHz, CDCl3) d 176.2, 165.0, 143.7,
139.2, 131.2, 130.0, 129.5, 128.0, 123.8, 123.0, 117.9, 109.6,
t
major =18.030 min, tminor =25.602 min, ee=92%; [a]2D0 =À30.0
(c 0.08, CH2Cl2); 1H NMR (400 MHz, CDCl3) d 7.24 (m,
1H), 7.09 (d, J=7.3 Hz, 1H), 6.95 (t, J=7.5 Hz, 1H), 6.77
(d, J=7.8 Hz, 1H), 6.50 (s, 1H), 6.36 (s, 1H), 4.30 (s, 1H),
3.99–3.80 (m, 2H), 3.14 (s, 3H), 1.45–1.34 (m, 2H), 1.13 (m,
2140
asc.wiley-vch.de
ꢁ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2015, 357, 2132 – 2142

UPDATES
Tunable Bifunctional Phosphine–Squaramide
2H), 0.83–0.76 (m, 3H); 13C NMR (100 MHz, CDCl3) d
176.5, 164.7, 144.5, 139.4, 130.1, 129.6, 127.9, 123.8, 123.0,
108.6, 76.2, 64.9, 30.4, 26.4, 19.0, 13.7; FTIR (KBr) nmax
(cmÀ1): 3342, 3058, 2958, 2926, 2854, 1709, 1613.
(R)-tert-Butyl 2-(3-hydroxy-1-methyl-2-oxoindolin-3-yl)-
acrylate (10r):[13a] yellow oil, (21.4 mg, 74% yield); HPLC
(Chiralpak AS-H, 90:10 nhexane/iPrOH, 0.8 mLminÀ1,
Acknowledgements
We are grateful to the NSFC (81172935, 81373255), the Key
Project of Ministry of Education (313040), Hubei Provinceꢀs
Outstanding Medical Academic Leader Program, the Scien-
tific and Technological Innovative Research Team of Wuhan
(2013070204020048), and the Fundamental Research Funds
254 nm):
t
major =13.903 min,
tminor =9.243 min, ee=95%;
for
the
Central
Universities
(201130602020002,
[a]2D0 =À8.8 (c 0.09, CH2Cl2); H NMR (400 MHz, CDCl3) d
7.34 (m, 1H), 7.20 (d, J=7.4 Hz, 1H), 7.04 (d, J=0.7 Hz,
1H), 6.84 (d, J=7.8 Hz, 1H), 6.51 (s, 1H), 6.28 (s, 1H), 3.90
(s, 1H), 3.22 (s, 3H), 1.24 (s, 9H); 13C NMR (100 MHz,
CDCl3) d 176.2, 164.0, 144.4, 140.3, 130.1, 129.8, 127.2, 123.9,
123.0, 108.4, 81.8, 76.2, 27.7, 26.4; FTIR (KBr) nmax (cmÀ1):
3339, 3058, 2954, 2924, 2853, 1711, 1613.
1
2042014kf0204) for support of this research.
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tmajor =13.877 min, tminor =
1
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Calcd for C25H25BrN3O5 ([M+H]+): 526.0978; found:
526.0938.
Adv. Synth. Catal. 2015, 357, 2132 – 2142
ꢁ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2141

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ꢁ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2015, 357, 2132 – 2142