Synthesis, X-ray crystallography, and reactions of N-acyl and N-carbamoyl succinimides

Article abstract of DOI:10.1080/00397911.2012.690061

A collection of N-acyl and N-carbamoyl succinimides were prepared by acylation of succinimide with acyl chlorides or by ethylene dichloride (EDC) coupling of carboxylic acids. The x-ray crystal structures of N-benzoyl and N-p-nitrobenzoyl succinimides were determined. The N-acyl succinimides were effective in acylating primary amines, a secondary amine, and an aromatic amine. Copyright

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Synthesis, X-Ray Crystallography, and
Reactions of N-Acyl and N-Carbamoyl
Succinimides
Cassie A. Goodman a , Joel B. Eagles a , Leandre Rudahindwa a ,
Christopher G. Hamaker a & Shawn R. Hitchcock a
a Department of Chemistry , Illinois State University , Normal ,
Illinois , USA
Accepted author version posted online: 26 Jan 2013.Published
online: 03 Jun 2013.
To cite this article: Cassie A. Goodman , Joel B. Eagles , Leandre Rudahindwa , Christopher G.
Hamaker & Shawn R. Hitchcock (2013): Synthesis, X-Ray Crystallography, and Reactions of N-Acyl
and N-Carbamoyl Succinimides, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 43:16, 2155-2164
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Synthetic Communications1, 43: 2155–2164, 2013
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2012.690061
SYNTHESIS, X-RAY CRYSTALLOGRAPHY, AND
REACTIONS OF N-ACYL AND N-CARBAMOYL
SUCCINIMIDES
Cassie A. Goodman, Joel B. Eagles, Leandre Rudahindwa,
Christopher G. Hamaker, and Shawn R. Hitchcock
Department of Chemistry, Illinois State University, Normal, Illinois, USA
GRAPHICAL ABSTRACT
Abstract A collection of N-acyl and N-carbamoyl succinimides were prepared by acylation
of succinimide with acyl chlorides or by ethylene dichloride (EDC) coupling of carboxylic
acids. The x-ray crystal structures of N-benzoyl and N-p-nitrobenzoyl succinimides
were determined. The N-acyl succinimides were effective in acylating primary amines, a
secondary amine, and an aromatic amine.
Supplemental materials are available for this article. Go to the publisher’s online edition
of Synthetic Communications1 to view the free supplemental file.
Keywords Acyl transfer; aminolysis; N-acyl succinimide; N-carbamoyl succinimide
INTRODUCTION
There are a multitude of well-known methods for the efficient acylation of
amines to form amides, primarily as a means of protection[1] or functionalization.[2]
Among these methods are the Schotten–Baumann reaction and its variants,[3] the
Sheehan reaction[4] [N,N-dicyclohexylcarbodiimide (DCC) and its variants and
additives], the use of benzotriazoles, directly with a coupling agent [DCC, ethylene
dichloride (EDC), etc.] or in an activated form such as benzotriazol-1-yloxy)tris(di-
methylamino)phosphonium hexafluoro-phosphate (BOP).[5] Alternatively, activated
esters may be employed to accomplish the goal of amide formation as well. Common
activated esters such as p-nitrophenyl 1,[6] perfluorophenyl 2,[7] 2,4,5-trichlorophenyl
3,[8] and succinimido 4[9] have proven to be very useful reagents (Fig. 1). In addition to
Received March 1, 2012.
Address correspondence to Shawn R. Hitchcock, Department of Chemistry, Illinois State
University, Normal, IL 61790-4160, USA. E-mail: hitchcock@ilstu.edu
2155

2156
C. A. GOODMAN ET AL.
Figure 1. Activated esters and activated amides.
these reagents there are less-employed activated amides that include acyl imidazoles
5,[10] acyl triazoles 6,[11] and acyl succinimides 7.[12] Acyl imidazoles are often
prepared from carbonyldiimidazole and are transient in their preparation and usage.
Acyl triazoles have recently been developed and employed by Katritzky et al.[11a] and
Yang and Birman.[11b] Interestingly, N-acyl succinimides[12] have been known since
1900 when Tafel and Stern first prepared N-acetyl succinimide (7, R ¼ -CH3).[12h] This
work was soon followed by a report by Titherley in 1904 on the synthesis of the
related N-benzoyl succinimide.[12g]
The first documented systematic application of acyl succinimides as acylating
agents was disclosed by Leach and coworkers in 1972. Their interest was focused
on conducting hydrolysis reactions and acylation reactions under aqueous
conditions using n-butylamine[12b] as a model for selective acylations of lysine
residues[12c] derived from bovine serum albumin and bovine pancreatic ribonuclease
(Scheme 1).
Scheme 1. Reaction of acyl succinimides with n-butylamine and bovine serum albumin.

N-ACYL AND N-CARBAMOYL SUCCINIMIDES
2157
Scheme 2. Samarium(II) iodide–mediated coupling with acyl succinimides.
In 2009, Taaning et al.[12a] employed N-acetyl succinimide 7a and N-trimethyla-
cetyl succinimides 12 in samarium(II) iodide–mediated conjugate addition to acryla-
mides (Scheme 2). To date, there has not been a more complete study on the acyl
transfer process with acyl succinimides. This article describes the synthesis, x-ray
crystallographic analysis, and reaction of a series of acyl succinimides and carbamoyl
succinimides (synthesis and reactivity).
Leach and coworkers prepared N-acyl succinimides by treatment of succini-
mide with either anhydrides at reflux temperatures, acyl chlorides at 0 ꢀC, or reflux
in pyridine. This process yielded N-acyl succinimides 7a–e in 25 to 60%. In this work,
the synthesis of the N-acyl succinimides was conducted by acylation of succinimide
with an acyl chloride and dimethylaminopyridine (DMAP) in a dichloromethane
solution with triethylamine at low temperature (Scheme 3).
The new conditions afforded N-acyl succinimides 18a–c and N-carbamoyl
succinimides 18e–f in isolated yields that ranged from 56 to 97% (Table 1). All succi-
nimides were obtained as crystalline solids. We also pursued the direct conversion of
carboxylic acids to their corresponding N-acyl succinimides by reaction with EDC,
DMAP, and succinimide. Using these conditions, N-benzoyl succinimide 18b was
synthesized in 56% yield after purificiation, and N-phthaloylglycyl succinimide 18d
was prepared in 38% yield. The lower yield was attributed to the poor solubility
of 18d in most organic solvents. In general, the isolated N-acyl and N-carbamoyl
succinimides were all well-defined solids that were stable at room temperature. In fact,
N-acyl succinimides 18b and 18c were subjected to x-ray crystallographic studies.
X-ray crystal structures for 18b and 18c were obtained. ORTEP diagrams are
shown in Figs. 2 and 3, respectively, and the crystallographic parameters are given in
Scheme 3. Synthesis of N-acyl succinimides.

2158
C. A. GOODMAN ET AL.
Table 1. Synthesis of N-acyl and N-carbamoyl succinimides 18a–f
Entry
R
Method
Compound
Yield (%)a
MP (ꢀC)
1
2
3
4
5
6
7
CH3CH2-
C6H5-
C6H5-
A
A
B
A
B
A
A
18a
18b
18b
18c
18d
18e
18f
56
66
56
53
38
97
79
34–36
122–124
128–130
55–58
p-NO2C6H4-
Phthaloylglycine
t-BuO-
223 (dec.)
82–84
185–187
C6H5CH2O-
aAll yields are reported after purification.
Table 2. In compound 18b, the angle between the mean plane of the succinimide
moiety (C1–C2–N3–C4–C5–O12–O13) and the mean plane of the acyl moiety
(N3–C14–O15–C16) is 41.37(6)ꢀ while the angle in compound 18c is 46.71(8)ꢀ
Figure 2. X-ray crystal structure of N-benzoyl succinimide (18b). Thermal ellipsoids are shown at the 50%
probability level.
Figure 3. X-ray crystal structure of N-p-nitrobenzoyl succinimide 18c. Thermal ellipsoids are shown at the
50% probability level.

N-ACYL AND N-CARBAMOYL SUCCINIMIDES
2159
Table 2. Crystallographic data for 18b and 18c
Parameter
18b
18c
Empirical formula
Formula weight
Temperature (K)
C
11H9NO3
203.19
C11H8N2O5
248.19
298 (2)
295 (2)
0.71073
˚
Wavelength (A)
Crystal system
0.71073
Monoclinic
P21=c
Monoclinic
P21=c
Space group
˚
a (A)
˚
12.475 (3)
9.999 (2)
7.2090 (10)
6.9917 (13)
21.924 (2)
97.625 (7)
1095.3 (3)
4
b (A)
˚
c (A)
b (ꢀ)
Volume (A )
7.9261 154)
103.12 (2)
962.8 (3)
3
˚
Z
4
1.402
Dcalc (Mg mꢁ3
)
1.505
0.122
512
m (MoKa) (mmꢁ1
F(000)
)
0.104
424
Crystal size (mm3)
h limits (ꢀ)
Limiting indices
0.54 ꢂ 0.45 ꢂ 0.41
1.68–25.47
0 ꢃh ꢄ 15
0 ꢃk ꢄ 12
ꢁ9 ꢃl ꢄ 9
1868
0.51 ꢂ 0.49 ꢂ 0.42
1.87–25.45
0 ꢃh ꢄ 8
0 ꢃk ꢄ 8
ꢁ26 ꢃ l ꢄ 26
2203
Reflections collected
Independent reflections (Rint
Data=restraints=parameters
Goodness of fit on F2
)
1784 (0.111)
1784 = 0 = 136
1.036
2031 (0.025)
2031 = 0 = 164
1.083
Final R indices [I > 2r(I)]
R1 ¼ 0.0391
wR2 ¼ 0.0957
R1 ¼ 0.0717
wR2 ¼ 0.1073
0.188 and ꢁ0.167
R1 ¼ 0.0374
wR2 ¼ 0.1003
R1 ¼ 0.0517
wR2 ¼ 0.113
0.065 and ꢁ0.198
Final R indices (all data)
ꢁ3
˚
Largest diff peak and hole (e A
)
(Fig. 4 illustrates an overlay of the two related structures).[13] This indicates that the
external carbonyl group of the acyl component deviates significantly from planarity
with the carbonyls of the succinimide group, suggesting that there is very little res-
onance contribution between the carbonyls. It must be noted that the conformations
of 18b and 18c depicted in Figs. 1 and 2 may be a reflection of crystal packing forces
Figure 4. Overlay of x-ray crystal structures of 18b and 18c.

2160
C. A. GOODMAN ET AL.
associated with the solid state. The conformation of these N-acyl succinimides
may be different in the solution state. This would suggest improved acyl transfer
for N-acylsuccinimides over the related N-acyloxazolidinones, which require Lewis
acid catalysis for success.[14]
Crystallographic data for compounds 18b and 18c have been deposited with the
Cambridge Crystallographic Data Centre as CCDC 831987 and 831988. These data
can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.
html, or from the Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK; fax: þ44 1223 336033; or e-mail: deposit@ccdc.cam.
ac.uk.
With the succinimides in hand, acylation reactions were conducted. To this end,
succinimides 18a–c were reacted with a variety of amines (primary, secondary,
aromatic) with triethylamine at room temperature to form amides 19–34 in yields ran-
ging from 35 to 94% (Table 3). The use of triethylamine reactions of 18a–c with
primary amines, including sec-butylamine and tert-butylamine, afforded the corre-
sponding amides in good yields. Pyrrolidine also proved to be a good substrate
for the acyl transfer process as well. The use of N-propanoyl to acylate p-anisidine
met with limited success with an isolated yield of 35%. In contrast, the use of N-benzoyl
succinimide to prepare the benzamide of p-anisidine afforded a yield of 91%. Ultimately,
this suggests that the acyl transfer process can be made to be chemoselective. It should
Table 3. Acylation with N-acyl succinimides 18a–c
Entry
Succinimide
Amine
Compound
Yield (%)a
MP (ꢀC)
1
2
18a
18a
18a
18a
18a
18b
18b
18b
18b
18b
18b
18c
18c
18c
18c
18c
Benzylamine
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
71
66
86
90
35
79
78
85
74
94
91
90
86
87
94
59
n=a
87–91
Tert-Butylamine
1-Phenylethylamine
Pyrrolidine
3
51–57
n=a
78–85
4
5
p-Anisidine
Benzylamine
6
103–105
135–138
116–118
83–85
7
tert-Butylamine
1-Phenylethylamine
sec-Butylamine
Pyrrolidine
8
9
10
11
12
13
14
15
16
n=a
p-Anisidine
Benzylamine
158–160
132–135
147–150
105–109
108–110
n=a
tert-Butylamine
1-Phenylethylamine
sec-Butylamine
Pyrrolidine
aAll yields are reported after purification.

N-ACYL AND N-CARBAMOYL SUCCINIMIDES
2161
Table 4. Acylation with N-carbamoyl succinimides 18e and 18f
Entry
Succinimide
Amine
Compound
Yield (%)a
MP (ꢀC)
1
2
3
4
5
6
7
8
18e
18e
18e
18e
18f
18f
18f
18f
Benzylamine
1-Phenylethylamine
Pyrrolidine
35
36
37
38
39
40
41
42
75
55
43
59
72
56
43
73
162–165
140–142
n=a
sec-Butylamine
tert-Butylamine
1-Phenylethylamine
sec-Butylamine
Pyrrolidine
145–147
n=a
44–48
43–45
n=a
aAll yields are reported after purification.
be noted that there is an increase in the reactivity of the N-acyl succinimide in the
order of N-propanoyl < N-benzoyl < N-p-nitrobenzoyl. The greater reactivity of the
p-nitrobenzoyl system is attributed to the enhanced electrophilicity of the carbonyl
resulting from the electronic effect of the nitro- group.
There was also interest in determining the efficiency of the acyl transfer process
using the N-carbamoyl succinimides as transfer agents. Thus, compounds 18e and
18f were reacted with amines using the same conditions that had been developed
for the acyl transfer reactions of 18a–c (Table 4). The purified yields of the resultant
carbamates 35–42 were lower than those of the amides 19–34. This may be the result
of lower reactivity of the carbonyl of the carbamoyl group bound to the succinimide.
These collected results suggest that the acyl transfer process with these compounds
might be subject to Lewis acid catalysis.
In summary, we have prepared a series of N-acyl and N-carbamoyl succini-
mides. X-ray crystal structures were obtained for N-benzoyl and N-p-nitrobenzoyl
succinimides (18b and 18c). Aminolysis of these succinimides was successful with
primary amines and pyrrolidine but yielded limited success with p-anisidine.
EXPERIMENTAL
1
All reactions were run under a nitrogen atmosphere. All H and 13C NMR
spectra were recorded in CDCl3 or dimethylsulfoxide-d6 (DMSO-d6). Chemical shifts
were reported in parts per million (d scale), and coupling constant (J values) are
listed in hertz (Hz). Tetramethylsilane (TMS) was used as internal standard
(d ¼ 0 ppm). Infrared (IR) spectra are reported in reciprocal centimeters (cmꢁ1
)
and are measured either as nujol mull or a neat liquid. Melting points were recorded
on a Mel-Temp apparatus and are uncorrected. High-resolution mass spectra were
obtained from the mass spectrometry laboratory, School of Chemical Science,
University of Illinois, Urbana-Champaign.

2162
C. A. GOODMAN ET AL.
X-Ray Crystallography
Crystal and data collection parameters are given in Table 2. Data for 18b and
18c were collected on a Bruker-Nonius CAD4=Mach3 diffractometer at room tem-
perature. Data collection and cell refinement were performed using CAD4 express.[15]
Data reduction was carried out using XCAD4.[16] Unit cell parameters were obtained
from a least-squares refinement of 25 centered reflections. Solution and data analysis
were performed using the WinGX software package. The structures were solved by
direct methods using SIR-92.[17] The refinements were completed using the program
SHELXL-97.[18] Hydrogen atoms were assigned positions based on the geometries of
their attached carbons.
Typical Experimental Procedure for N-Acyl and N-Carbamoyl
Succinimide Preparation via Acyl Chlorides
Succinimide (2.00 g, 20.2 mmol), CH2Cl2 (100 mL), TEA (5.63 mL, 40.4 mmol),
and DMAP (0.617 g, 5.05 mmol) were placed in a flame-dried, nitrogen-purged,
250-mL, round-bottom flask equipped with magnetic stir bar at room temperature.
The mixture was then cooled to 0 ꢀC, and propanoyl chloride was added (1.93 mL,
22.2 mmol). The resulting mixture was allowed to stir overnight, treated with 1 M
HCl (50 mL) and a saturated brine solution (50 mL), and dried over anhydrous
MgSO4, and the solvents were removed in vacuo.
N-Propanoyl Succinimide (18a)
The crude material was dissolved in chloroform and treated with silica to
remove polar impurities. The resulting mixture was then gravity filtered, and solvents
were removed in vacuo, and recrystallized (CH2Cl2=hexanes) to yield 1.890 g (56%) of
1
the title compound as a yellow solid. Mp ¼ 34–36 ꢀC. H NMR (400 MHz, CDCl3):
d ¼ 1.20 (t, J ¼ 7.2 Hz, 3H), 2.80 (s, 4H), 2.91 (q, J ¼ 7.3 Hz, 2H). 13C NMR
(125 MHz, DMSO-d6): d 7.70, 28.52, 29.44, 31.34, 173.94, 175.35, 179.33. IR (nujol
mull): 1810, 1752, 1713 cmꢁ1. ESI HRMS for C7H9NO3: calcd. (M þ Naþ)
178.0480; found 178.0481.
Typical Experimental Procedure for N-Acyl Succinimide Preparation
via EDC Coupling
Benzoic acid (1.00 g, 8.19 mmol), CH2Cl2 (41 mL), EDC (1.73 g, 9.01 mmol),
DMAP (0.25 g, 2.1 mmol), and succinimide (1.22 g, 12.3 mmol) were placed in a
flame-dried, nitrogen-purged, 250-mL, round-bottom flask with magnetic stir bar
at room temperature.The resulting mixture was allowed to stir overnight. The mixture
was extracted with methylene chloride. Organic extracts were washed with 1 M HCl
and a saturated brine solution and then dried over anhydrous MgSO4. Solvents were
removed in vacuo.
N-Phthaloyl Succinimide (18d)
The title compound was obtained as a white solid (38%). Mp ¼ 223 ꢀC (dec.).
1H NMR (400 MHz, CDCl3): d 2.88 (s, 4H), 4.98 (s, 2H), 7.76 (dd, J ¼ 5.5 Hz,

N-ACYL AND N-CARBAMOYL SUCCINIMIDES
2163
J ¼ 2.4 Hz, 2H), 7.90 (dd, J ¼ 5.4 Hz, J ¼ 2.4 Hz, 2H). 13C NMR (100 MHz, DMSO-
d6): d 28.67, 42.94, 123.44, 131.39, 134.86, 166.43, 167.12, 175.28. IR (nujol mull):
1824, 1755, 1710, 716 cmꢁ1. ESI HRMS for C14H10N2O5: calcd. (M þ Naþ)
309.0487; found 309.0484.
Typical Experimental Procedure for Amide Preparation
N-Propanoyl succinimide (0.50 g, 3.2 mmol), CH2Cl2 (10 mL), TEA (0.45 mL,
3.2 mmol), and benzylamine (0.39 mL, 3.5 mmol) were placed in a flame-dried,
nitrogen-purged 100-mL, round-bottom flask with magnetic stir bar at room tem-
perature. The resulting mixture was allowed to stir overnight. The mixture was
extracted with methylene chloride. Organic extracts were washed with 1 M HCl
and a saturated brine solution, and then dried over anhydrous MgSO4. The solvents
were removed in vacuo.
N-Benzylpropanamide [19)[19]
The crude material was purified by flash column chromatography (hexanes=
1
EtOAc, 6:4) to yield 0.3728 g (71%) as a colorless oil. H NMR (500 MHz, CDCl3):
d 1.18 (t, J ¼ 7.6 Hz, 3H), 2.24 (q, J ¼ 7.6 Hz, 2H), 4.43 (d, J ¼ 5.7, 2H), 5.79 (broad
singlet, 1H), 7.27 (m, 3H), 7.33 (m, 2H). 13C NMR (125 MHz, CDCl3): d 9.86, 29.71,
43.60, 127.49, 127.82, 128.70, 138.43, 173.56.
Experimental data and NMR spectra are collected in the Supporting Infor-
mation, available online.
ACKNOWLEDGMENTS
The authors acknowledge Gregory G. Griffin for his technical assistance. The
authors also thank the Petroleum Research Fund as directed by the American
Chemical Society.
REFERENCES
1. Wuts, P. G. M.; Greene, T. W. Green’s Protective Groups in Organic Synthesis, 4th ed.;
Wiley and Sons: New York, 2007; Chap. 7, p. 773–802.
2. Smith, M. B.; March, J. March’s Advanced Organic Chemistry, 6th ed.; Wiley and Sons:
New York, 2007; Chap. 16, pp. 1427–1439.
3. (a) Georg, G. I.; Boge, T. C.; Cheruvallath, Z. S.; Harriman, G. C. B.; Hepperle, M.; Park,
H.; Himes, R. H. Bioorg. Medi. Chem. Lett. 1994, 4, 335–338; (b) Woodward, R. B.;
Doering, W. E. J. Am. Chem. Soc. 1945, 67, 860–874; (c) Baumann, E. Ber. Dtsch. Chem.
Ges. 1886, 19, 3218–3222; (d) Schotten, C. Ber. Dtsch. Chem. Ges. 1884, 17, 2544–2547.
4. (a) Zhu, J.; Razler, T. M.; Xu, Z.; Conlon, D. A.; Sortore, E. W.; Fritz, A. W.;
Demerzhan, R.; Sweeney, J. T. Org. Process Res. Dev. 2011, 15, 438–442; (b) Hajiwara,
D.; Miyake, H.; Igari, N.; Karino, M.; Maeda, Y.; Fujii, T.; Matsuo, M. J. Med. Chem.
1994, 37, 2090–2099; (c) Sheehan, J. C.; Preston, J.; Cruickshank, P. A. J. Am. Chem.
Soc. 1965, 87, 2492–2493; (d) Sheehan, J. C.; Hess, G. P. J. Am. Chem. Soc. 1955, 77,
1067–1068.

2164
C. A. GOODMAN ET AL.
5. (a) Carpino, L. A.; El-Faham, A.; Albericio, F. J. Org. Chem. 1995, 60, 3561–3564; (b)
Konig, W.; Geiger, R. Ber. Dtsch. Chem. Ges. 1970, 103, 788–798; (c) Konig, W.; Geiger,
R. Ber. Dtsch. Chem. Ges. 1970, 103, 2024–2033.
6. (a) Wu, X.; Ling, C.-C.; Bundle, D. R. Org. Lett. 2004, 6, 4407–4410; (b) Lucente, G.;
Romeo, A. Chem. Comm. 1971, 1605–1607; (c) Bodansky, M.; du Vigneaud, V. J. Am.
Chem. Soc., 1959, 81 (21), 5688–5691.
7. Kessler, D.; Roth, P. J.; Theato, P. Langmuir 2009, 25, 10068–10076.
8. (a) Feldman, K. S.; Sambandam, A.; Bowers, K. E.; Appel, H. M. J. Org. Chem. 1999, 64,
5794–5803; (b) Pless, J.; Boissonnas, R. A. Helv. Chim. Acta 1963, 46, 1609–1625; (c)
Guttman, S.; Boissonnas, R. A. Helv. Chim. Acta 1963, 46, 1626–1637.
9. (a) Lockett, M. R.; Phillips, M. F.; Jarecki, J. L.; Peelen, D.; Smith, L. M. Langmuir, 2008,
24, 69–75; (b) Anderson, J. W.; Zimmerman, J. E.; Callahan, F. M. J. Am. Chem. Soc.
1964, 86, 1839–1842.
10. Larrive-Aboussafy, C.; Jones, B. P.; Price, K. E.; Hardink, M. A.; McLaughlin, R. W.;
Lillie, B. M.; Hawkins, J. M.; Vaidyanathan, R. Org. Lett. 2010, 12, 324–327.
11. (a) Katritzky, A. R.; Fedoseyenko, D.; Kim, M. S.; Steel, P. J. Tetrahedron: Asymmetry
2010, 21, 51–57; (b) Yang, X.; Birman, V. B. Org. Lett. 2009, 11, 1499–1502.
12. (a) Taaning, R. H.; Lindsay, K. B.; Schiott, B.; Daasbjerg, K.; Skrydstrup, T. J. Am.
Chem. Soc. 2009, 131, 10253–10262; (b) Boyd, H.; Calder, I. C.; Leach, S. J.; Milligan,
B. Int. J. Peptide Protein Res. 1972, 4, 109–115; (c) Boyd, H.; Leach, S. H.; Milligan,
B. Int. J. Peptide Protein Res. 1972, 4, 117–122; (d) McAlees, A. J.; McCrindle, R.
J. Chem. Soc. C 1969, 2425–2435; (e) Djerassi, C.; Lenk, C. T. J. Am. Chem. Soc. 1953,
75, 3493–3495; (f) Heller, G.; Jacobsohn, P. Chem. Ber. 1921, 54, 1107–1117; (g) Titherley,
A. W. J. Chem. Soc., Trans. 1904, 85, 1673–1691; (h) Tafel, J.; Stern, M. Chem. Ber. 1900,
33, 2224–2236.
13. Macrae, C. F.; Bruno, I. J.; Chisholm, J. A.; Edgington, P. R.; McCabe, P.; Pidcock, E.;
Rodriguez-Monge, L.; Taylor, R.; van de Streek, J.; Wood, P. A. J. Appl. Cryst. 2008,
41, 466.
14. Yokomatsu, T.; Arakawa, A.; Shibuya, S. J. Org. Chem. 1994, 59, 3506–3508.
15. CAD4Express Software; Enraf-Nonius, Delft, the Netherlands, 1994.
16. Harms, K.; Wocadlo, S. XCAD-4 program for processing CAD-4 diffractometer data;
University of Marburg, Germany, 1995.
17. Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl. Crystallogr. 1993,
26, 343.
18. Sheldrick, G. M. SHELX 97, program for crystal structure refinement; University of
Go¨ttingen, Germany, 1997.
19. Lee, S. Y.; Lee, C. W.; Oh, D. Y. J. Org. Chem. 1999, 64, 7017–7022.