Highly efficient one-pot amination of carboxylate-substituted nitrogen-containing heteroaryl chlorides via Staudinger reaction

Article abstract of DOI:10.1016/j.tetlet.2012.11.027

An efficient one-pot method for the synthesis of tert-butyl 6-aminonicotinate (5) is described. The key transformation involves displacement of the chloro group in tert-butyl 6-chloronicotinate (2) with azide followed by a Staudinger reaction. The scope of this methodology is further extended for the synthesis of a series of carboxylate-substituted heteroaryl amines. In particular, we synthesized tert-butyl carboxylate-substituted amino-pyridine, -pyridazine, and -pyrazine. In addition to one-pot conversion, short reaction time, simplicity of operation, ease of purification, and good yields are the key advantages of this methodology.

Full text of DOI:10.1016/j.tetlet.2012.11.027

Tetrahedron Letters 54 (2013) 414–418
Contents lists available at SciVerse ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Highly efficient one-pot amination of carboxylate-substituted
nitrogen-containing heteroaryl chlorides via Staudinger reaction
Sachin R. Kandalkar a,b, Rahul D. Kaduskar a, Parimi Atchuta Ramaiah b, Dinesh A. Barawkar a,
Debnath Bhuniya a, Anil M. Deshpande a,
⇑
a Drug Discovery Facility, Advinus Therapeutics Ltd, Quantum Towers, Plot-9, Rajiv Gandhi Infotech Park, Phase-I, Hinjewadi, Pune 411057, India
b Department of Organic Chemistry, Andhra University, Visakhapatnam 530003, India
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient one-pot method for the synthesis of tert-butyl 6-aminonicotinate (5) is described. The key
transformation involves displacement of the chloro group in tert-butyl 6-chloronicotinate (2) with azide
followed by a Staudinger reaction. The scope of this methodology is further extended for the synthesis of
a series of carboxylate-substituted heteroaryl amines. In particular, we synthesized tert-butyl carboxyl-
ate-substituted amino-pyridine, -pyridazine, and -pyrazine. In addition to one-pot conversion, short reac-
tion time, simplicity of operation, ease of purification, and good yields are the key advantages of this
methodology.
Received 18 September 2012
Revised 5 November 2012
Accepted 7 November 2012
Available online 20 November 2012
Keywords:
Carboxylate-substituted heteroaryl amine
tert-Butyl 6-aminonicotinate
Staudinger reaction
Ó 2012 Elsevier Ltd. All rights reserved.
Tetrazolo-pyridine
Aminonicotinic acid is a commonly used building block in the
synthesis of many bioactive molecules,1 providing access to chem-
ical diversity with amine and carboxylate functionality. In particu-
lar, 6-aminonicotinic acid is an important building block toward
many pharmacologically active compounds which exhibit antidia-
betic,2 anticancer,3 and antiinflammatory4 activity (Fig. 1). Some of
these compounds act as a modulator for kinases wherein the amine
is derivatized to an amide and is involved in hydrogen bond donor
and acceptor interactions via the NH in amide and the nitrogen in
pyridine.2a,5 Recently, in one of our ongoing programs methyl 6-
aminonicotinate was coupled with a carboxylic acid to obtain the
amide scaffold (1a, Fig. 2).6 Subsequent hydrolysis of the methyl
O
HN
N
O
O
Cl
O
N
H
O
O
O
OH
N
N
N
S
HN
N
N
H
N
N
O
N
N
H
O
Bradykinin B1 Receptor Antagonist
RXR Agonist
Ref 2c
p38 MAP Kinase Inhibitor
O
Ref 1a
Ref 4
S
O
O
H
O
S
O
N
N
Ref 2a
Ref 3
N
N
N
OH
CF3
H
O
OH
N
N
O
H2N
N
O
Glucokinase Activator
6-Aminonicotinic Acid
Histone Deacetylase Inhibitor-KD5170
Figure 1. Representative bioactive compounds bearing 6-aminonicotinic acid as a structural fragment.
⇑
Corresponding author. Tel.: +91 20 66539637; fax: +91 20 66539620.
E-mail address: anil.deshpande@advinus.com (A.M. Deshpande).
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.11.027

S. R. Kandalkar et al. / Tetrahedron Letters 54 (2013) 414–418
415
O
O
O
R2
1a: R = Me
O
OH
OH
OR
+
+
Basic condition
R2
R1
N
H
N
H
N
N
2
R1
O
Amide hydrolysis: Major
Target product: Minor
O
OR
R2
O
N
H
N
R1
O
OH
R2
N
H
N
R1
1b: R = tert-Bu
Acidic condition
Target product
Figure 2. Hydrolysis of nicotinate derivative.
under basic conditions. To circumvent this issue we sought to em-
ploy tert-butyl 6-aminonicotinate in place of methyl 6-aminonico-
tinate to synthesize the hydrolytically-labile amide scaffold 1b,
which would allow for exclusive hydrolysis of the tert-butyl ester
under acidic conditions. While this manuscript was under prepara-
tion, an article appeared describing the synthesis of 2, 4-, 5-, and 6-
aminonicotinic acid tert-butyl esters from the corresponding
chloro derivative via aminolysis with hydrazine hydrate as a key
step.7 Herein, we report a facile, one-pot methodology for the syn-
thesis of tert-butyl 6-aminonicotinate and various carboxylate-
substituted heteroaryl amines.
Our initial attempt to access the target product involved the
nucleophilic displacement of the chloro group in tert-butyl 6-chlo-
ronicotinate (2)8 employing either ammonium hydroxide or neat
ammonia.9 Reactions were found to be inefficient even though car-
ried out in sealed tube with heating for several hours. Next, we
tried the copper-catalyzed direct amination of tert-butyl 6-chloro-
nicotinate (2) with sodium azide10a and trimethylsilylazide10b as
amine source.
However, these reactions gave the desired product in low yield
along with side products.10 Alternatively, we sought to obtain the
desired amine from 2 by displacement of chlorine with azide fol-
lowed by a Staudinger reaction. Under typical Staudinger condi-
tions, azide derivatives are reduced by triphenylphosphine (PPh3)
to access iminophosphoranes, which generate amine products
upon hydrolysis under acidic conditions.11 However, it has been re-
ported in the literature that 2-chloropyridine reacts with sodium
azide to give the corresponding azido-pyridine and tetrazolo[1,5-
a]pyridine (Fig. 3).12 The equilibrium of these products is governed
by several factors such as the nature of substituents (R), solvent,
and reaction temperature.12c,12d
NaN3
R
R
R
N
N
N
N
Cl
N
N3
N
Substituted
tetrazolopyridine
Substituted
2-chloropyridine
Substituted
azidopyridine
Figure 3. Reaction of sodium azide with substituted 2-chloropyridin.
O
O
O
O
a
b
N
N
N
Cl
N
N
2
3
O
O
c
O
O
Ph3P
H2N
N
N
N
4
5
Scheme 1. Reagents and conditions: (a) NaN3 (2 equiv), DMSO, 120 °C, 10 h, 97%;
(b) triphenylphosphine (2 equiv), DMSO, 120 °C, 2 h, 93%; (c) DMSO, 1 N HCl, 90 °C,
2 h, 90%.
ester functionality in 1a using sodium or lithium hydroxide at
room temperature afforded the nicotinic acid derivative as a target
product, unfortunately in very low yield (15–20% yield). It was ob-
served that the amide hydrolysis was a major side reaction for 1a
Path A
O
O
O
O
O
O
Ph
Ph
Ph
Ph
Ph
P+
··
N
N
N
Ph
N
N
Ph
P
P
N
N
N
N
Ph
Ph
N
4
3
N2
Path B
N2
O
O
O
O
O
O
O
O
Ph
N
N
N
Ph
Ph
N
N
N
P
N
Ph
N
N
N
N
P+ Ph
Ph
··
P+ Ph
Ph
N
N
N
Ph
Ph
N
N
P
Ph
3
Ph
Figure 4. Putative mechanism for the formation of iminophosphorane 4.

416
S. R. Kandalkar et al. / Tetrahedron Letters 54 (2013) 414–418
Table 1
We initiated our efforts by reacting 2 (1 equiv) with sodium
Optimization of solvent for one-pot reaction
azide (2 equiv) in DMSO which on heating at 120 °C for 10 h affor-
ded a new product (Scheme 1). Characterization using IR and NMR
confirmed that the product formed is tert-butyl tetrazolo[1,5-
a]pyridine-6-carboxylate (3, 97% yield). Tetrazolopyridine 3 was
exclusively formed and equilibration to its azide isomer was not
observed. The next reaction was performed using tetrazolo-pyri-
dine 3 (1 equiv) and PPh3 (2 equiv) in DMSO at 120 °C for 2 h. It
provided iminophosphorane 4 in 93% yield, which was found to
be very stable. Subsequent hydrolysis of 4 using 1 N HCl went
smoothly in DMSO at 120 °C for 2 h to provide the desired amine
5 in 90% yield (Scheme 1).
O
O
NaN3 (2 equiv), PPh3 (2 equiv)
O
O
Ph3P
Solvent
N
Cl
N
N
2
4
1 N HCl
The putative mechanism for the conversion of 3 to 4 proposed
in Figure 4 is consistent with a literature report.13 It involves the
initial attack of PPh3 to open the tetrazole ring in 3 by either path
A or path B, both of which undergoes elimination of nitrogen to
provide 4.
O
O
H2N
N
5
We investigated the possibility for the synthesis of 5 by
employing a one-pot reaction of 2 with sodium azide and PPh3. A
one-pot conversion would offer operational simplicity and reduc-
tion in overall reaction time. Our present investigations were initi-
ated by treating 2 (1 equiv) with sodium azide (2 equiv) and PPh3
(2 equiv) in DMSO/1 N HCl (4:1) at 120 °C. The reaction was very
sluggish and even after 24 h did not go to completion.
Solvent
Temperature (°C)
Time (h)
Isolated yield (%)
Toluene
EtOH
THF
Acetonitrile
DMSO
110
80
65
85
120
120
24
24
24
24
4
No reactiona
No reactiona
No reactiona
No reactiona
90
DMF
6
72
To optimize the reaction conditions for complete conversion of
2 to 5, we thought of adding 1 N HCl to the reaction mixture after
a
Formation of iminophosphorane 4 was not observed.
Table 2
Synthesis of substituted heteroaryl amine
i. NaN3, PPh3
Z
Z
Y
X
DMSO, 120 °C, 3 5 h
Y
X
−
Cl
R
H2N
R
N
N
ii. 1 N HCl, 120 °C, 2 h
iii. NaHCO 3
Substituted heteroaryl chloride
Substituted heteroaryl amine
Entry
1
Substrate
Product
Timea (h)
Yieldb (%)
95
O
O
OEt
OEt
5
N
Cl
H2N
H2N
H2N
H2N
N
6
CF3
CN
CF3
2
3
4
5
4
5
91
95
88
N
Cl
Cl
Cl
N
7
CN
NO2
O
N
N
N
N
8
NO2
9
O
OEt
OEt
5
8
76
N
N
N
Cl
H2N
H2N
10
NO2
NO2
N
6
7
5
5
84
61
Cl
11
O
O
EtO
EtO
N
H2N
12
Cl
N

S. R. Kandalkar et al. / Tetrahedron Letters 54 (2013) 414–418
417
Table 2 (continued)
Entry
Substrate
Product
Timea (h)
Yieldb (%)
O
O
tBuO
tBuO
8
9
5
64
37
H2N
N
N
Cl
13
14
O
O
O
Cl
N
H2N
OEt
OEt
7
N
O
Cl
N
H2N
OtBu
OtBu
10
11
7
41
10
N
15
24
H2N
Cl
N
N
16
12
13
No reaction
No reaction
24
24
—
—
N
Cl
Cl
N
O
O
OEt
OEt
N
N
14
15
16
3
3
3
95
91
99
H2N
N
Cl
Cl
N
17
18
O
O
N
N
N
OtBu
OtBu
N
H2N
O
O
N
N
N
N
OMe
OMe
Cl
H2N
19
O
O
O
OtBu
OtBu
17
18
6
4
81
83
N
N
N
H2N
N
Cl
Cl
N
N
20
21
O
OEt
OEt
N
H2N
N
a
Total reaction time.
Isolated yields.
b
the formation of iminophosphorane 4. With this modified condi-
tion, initial treatment of 2 with sodium azide and PPh3 in DMSO
at 120 °C for 3 h gave iminophosphorane 4 (monitored by TLC).
Subsequent addition of 1 N HCl to the same pot and stirring at
120 °C for an additional 1 h provided 5 in excellent yield (90%).
The reaction was studied in various organic solvents (results are
provided in Table 1). Among all solvents, the reaction progressed
well in high boiling polar-aprotic solvents like DMSO and DMF.
The most efficient solvent was found to be DMSO. Moreover, this
process involves easy work-up to isolate the product which does
not require further purification. The reaction was performed very
efficiently on a 6 gram scale and can therefore be readily adopted
for the large scale syntheses.14
With optimized conditions in hand, we tested the generality of
this methodology (Table 2). The reactions provided excellent yields
for chloropyridines when the electron withdrawing groups are
placed ortho- or para- to the leaving chloro group (entries 1–8) rel-
ative to the meta-position (entries 9 and 10). But the non-substi-
tuted (entries 11 and 12) and electron donating group
substituted chloropyridine (entry 13) showed very poor or no con-
version to the respective aminopyridines. A series of heteroaryl
chloride-substituted compounds with carboxylate functionality at
para-position with respect to chloro group showed excellent con-
versions (entries 14–18). Particularly, this method is very efficient
to access tert-butoxycarbonyl substituted heteroaryl amines com-
pared to literature methods.7,15
In conclusion, we have developed an efficient one-pot method for
the synthesis of tert-butyl 6-aminonicotinate (5) employing azida-
tion followed by Staudinger reaction. A variety of carboxy-substi-
tuted heteroaryl amine derivatives, have been synthesized in good
to excellent yield using this methodology. In addition to one-pot con-
version, short reaction time, simplicity of operation, ease of purifica-
tion, and good yields are the key advantages of this methodology.
Acknowledgments
We are grateful to Dr. Rashmi Barbhaiya and Dr. Kasim A. Moo-
khtiar for their support and encouragement. S.K. would like to

418
S. R. Kandalkar et al. / Tetrahedron Letters 54 (2013) 414–418
W.; Balimane, P.; Patel, K.; Yang, Z.; Marathe, P.; Kadiyala, P.; Tebben, A. J.;
Sheriff, S.; Chang, Y.; Ziemba, T.; Zhang, H.; Chen, B.-C.; DelMonte, A. J.;
Aranibar, N.; McKinnon, M.; Barrish, J. C.; Suchard, S. J.; Murali Dhar, T. G. J.
Med. Chem. 2010, 53, 3814–3830.
thank Professor Y.L.N. Murthy (Andhra University), Dr. Vinod Vyav-
ahare, Dr. Anup Ranade, Santosh Kurhade for their help and Dr.
Mahesh Mone for the analytical support.
9. Thomas, A. A.; Huerou, Y. L.; Meese, J. D.; Gunawardana, I.; Kaplan, T.; Romoff,
T. T.; Gonzales, S. S.; Condroski, K.; Boyd, S. A.; Ballard, J.; Bernat, B.; DeWolf,
W.; Han, M.; Lee, P.; Lemieux, C.; Pedersen, R.; Pheneger, J.; Poch, G.; Smith, D.;
Sullivan, F.; Weiler, S.; Wright, S. K.; Lin, J.; Brandhuber, B.; Vigers, G. Bioorg.
Med. Chem. Lett. 2008, 18, 2206–2210.
Advinus publication no. ADV–A–019.
Supplementary data
10. (a) Goriya, Y.; Ramana, C. V. Tetrahedron 2010, 66, 7642–7650 [traces of the
desired product (<5%) was obtained along with tetrazolopyridine (21%) and
recovered starting material (69%).by HPLC]; (b) Maejima, T.; Shimoda, Y.;
Nozaki, K.; Mori, S.; Sawama, Y.; Monguchi, Y.; Sajiki, H. Tetrahedron 2012, 68,
1712–1722 [starting material was consumed to provide ꢀ40% of the desired
product along with side products].
11. (a) Staudinger, H.; Meyer, J. Helv. Chim. Acta 1919, 2, 635–646; (b) Gololobov, Y.
G.; Zhmurova, I. N.; Kasukhin, L. F. Tetrahedron 1981, 37, 437–472; (c) Vaultier,
M.; Knouzi, N.; Carrie, R. Tetrahedron Lett. 1983, 24, 763–764.
12. (a) Chattopadhyay, B.; Vera, C. I. R.; Chuprakov, S.; Gevorgyan, V. Org. Lett.
2010, 12, 2166–2169; (b) Chan, J.; Faul, M. Tetrahedron Lett. 2006, 47, 3361–
3363; (c) Lowe-Ma, C. K.; Nissan, R. A.; Wilson, W. S. J. Org. Chem. 1990, 55,
3755–3761; (d) Pochinok, V. V.; Averamenko, L. F.; Grigorenko, P. S.; Skopenko,
V. N. Russ. Chem. Rev. 1975, 44, 481.
13. Sasaki, T.; Kanematsu, K.; Murata, M. Tetrahedron 1971, 27, 5359–5366.
14. Typical procedure for the preparation of tert-butyl 6-amino nicotinate (5): a
round-bottom flask equipped with a reflux condensor and magnetic stirring
bar was charged with tert-butyl 6-chloropyridine-3-carboxylate (2, 6.0 g,
28.17 mmol), sodium azide (3.66 g, 56.3 mmol), triphenylphosphine (14.77 g,
56.3 mmol), and DMSO (160 mL). The reaction mixture was stirred at 120 °C.
Reaction progress was monitored by TLC. After full conversion of the starting
material, 1 N HCl (40 mL) was added to the reaction mixture and stirring was
continued at 120 °C for an additional 1 h. The reaction mixture was cooled to
room temperature and diluted with 1 N HCl (40 mL). The resulting mixture
was poured into distilled water (500 mL) and the aqueous layer was washed
with EtOAc (2 Â 100 mL) to remove triphenylphosphine oxide and the majority
of DMSO thus allowing easy removal of solvent at the end of work-up. The
aqueous layer was slowly neutralized with saturated aqueous NaHCO3. The
aqueous layer was extracted with EtOAc (2 Â 200 mL). The combined organic
layers were washed with water (100 mL), brine (50 mL), dried over sodium
sulfate, filtered and concentrated under reduced pressure to afford the desired
Supplementary data (synthetic procedure, analytical data and
spectra) associated with this article can be found, in the online ver-
sion, at http://dx.doi.org/10.1016/j.tetlet.2012.11.027.
References and notes
1. (a) Biswas, K.; Peterkin, T. A. N.; Bryan, M. C.; Arik, L.; Lehto, S. G.; Sun, H.;
Hsieh, F.-Y.; Xu, C.; Fremeau, R. T.; Allen, J. R. J. Med. Chem. 2011, 54, 7232–
7246; (b) Takamatsu, K.; Takano, A.; Yakushiji, N.; Morohashi, K.; Morishita, K.;
Matsuura, N.; Makishima, M.; Tai, A.; Sasaki, K.; Kakuta, H. ChemMedChem
2008, 3, 780–787; (c) Dominguez, C.; Smith, L.; Huang, Q.; Yuan, C.; Ouyang, X.;
Cai, L.; Chen, P.; Kim, J.; Harvey, T.; Syed, R.; Kim, T.-S.; Tasker, A.; Wang, L.;
Zhang, M.; Coxon, A.; Bready, J.; Starnes, C.; Chen, D.; Gan, Y.; Neervannan, S.;
Kumar, G.; Polverino, A.; Kendall, R. Bioorg. Med. Chem. Lett. 2007, 17, 6003–
6008.
2. (a) Pfefferkorn, J. A.; Guzman-Perez, A.; Litchfield, J.; Aiello, R.; Treadway, J. L.;
Pettersen, J.; Minich, M. L.; Filipski, K. J.; Jones, C. S.; Tu, M.; Aspnes, G.; Risley,
H.; Bian, J.; Stevens, B. D.; Bourassa, P.; D’Aquila, T.; Baker, L.; Barucci, N.;
Robertson, A. S.; Bourbonais, F.; Derksen, D. R.; MacDougall, M.; Cabrera, O.;
Chen, J.; Lapworth, A. L.; Landro, J. A.; Zavadoski, W. J.; Atkinson, K.; Haddish-
Berhane, N.; Tan, B.; Yao, L.; Kosa, R. E.; Varma, M. V.; Feng, B.; Duignan, D. B.;
El-Kattan, A.; Murdande, S.; Liu, S.; Ammirati, M.; Knafels, J.; DaSilva-Jardine,
P.; Sweet, L.; Liras, S.; Rolph, T. P. J. Med. Chem. 2012, 55, 1318–1333; (b) Pike, K.
G.; Allen, J. V.; Caulkett, P. W. R.; Clarke, D. S.; Donald, C. S.; Fenwick, M. L.;
Johnson, K. M.; Johnstone, C.; McKerrecher, D.; Rayner, J. W.; Walker, R. P.;
Wilson, I. Bioorg. Med. Chem. Lett. 2011, 21, 3467–3470; (c) Ohsawa, F.;
Morishita, K.-I.; Yamada, S.; Makishima, M.; Kakuta, H. ACS Med. Chem. Lett.
2010, 1, 521–525.
3. Hassig, C. A.; Symons, K. T.; Guo, X.; Nguyen, P.-M.; Annable, T.; Wash, P. L.;
Payne, J. E.; Jenkins, D. A.; Bonnefous, C.; Trotter, C.; Wang, Y.; Anzola, J. V.;
Milkova, E. L.; Hoffman, T. Z.; Dozier, S. J.; Wiley, B. M.; Saven, A.; Malecha, J.
W.; Davis, R. L.; Muhammad, J.; Shiau, A. K.; Noble, S. A.; Rao, T. S.; Smith, N. D.;
Hager, J. H. Mol. Cancer Ther. 2008, 7, 1054–1065.
4. Goldberg, D. R.; Hao, M.-H.; Qian, K. C.; Swinamer, A. D.; Gao, D. A.; Xiong, Z.;
Sarko, C.; Berry, A.; Lord, J.; Magolda, R. L.; Fadra, T.; Kroe, R. R.; Kukulka, A.;
Madwed, J. B.; Martin, L.; Pargellis, C.; Skow, D.; Song, J. J.; Tan, Z.; Torcellini, C.
A.; Zimmitti, C. S.; Yee, N. K.; Moss, N. J. Med. Chem. 2007, 50, 4016–4026.
5. Hilton, S.; Naud, S.; Caldwell, J. J.; Boxall, K.; Burns, S.; Anderson, V. E.; Antoni,
L.; Allen, C. E.; Pearl, L. H.; Oliver, A. W.; Aherne, G. W.; Garrett, M. D.; Collins, I.
Bioorg. Med. Chem. Lett. 2010, 18, 707–718.
product
5
with high purity without column purification and/or
recrystallization (4.95 g, 90%).
1H NMR and 13C NMR spectra were recorded on a Varian 400 spectrometer
using TMS as an internal standard.
1H NMR (400 MHz; DMSO-d6) d 1.50 (s, 9H), 6.42 (d, J = 8.8 Hz, 1H), 6.75 (br s,
2H), 7.76 (d, J = 8.6 Hz, 1H), 8.44 (s, 1H).
13C NMR (100 MHz; DMSO-d6): d 28.41 (3C), 80.08, 107.35, 115.42, 137.95,
151.29, 162.76, 165.05.
LC–MS (m/z): 195.3 [M+1].
15. (a) For the synthesis of tert-butyl 5-aminopyrazine-2-carboxylate: Chen, S.;
Corbett, W. L.; Guertin, K. R.; Haynes, N. E.; Kester, R. F.; Mennona, F. A.;
Mischke, S. G.; Qian, Y.; Sarabu, R.; Scott, N. R.; Thakkar, K. C. WO2004/052869,
2004.; (b) Tamura, Y.; Suzuki, S.; Tada, Y.; Yonezawa, S.; Fujikoshi, C.;
Matsumoto, S.; Kooriyama, Y.; Ueno, T. WO2008/133274, 2008.
6. Bhuniya, D.; Bhosale, S. B.; Kapkoti, G. S.; Palle, V. P.; De, S.; Mookhtiar, K. A.;
Dave, B.; Deshpande, A.; Kurhade, S.; Kobal, B.; Naik, K.; Kandalkar, S. U.S.
Patent 2010/0310493A1, 2010.
7. Wright, S. W. J. Heterocycl. Chem. 2012, 49, 442–445.
8. Watterson, S. H.; Xiao, Z.; Dodd, D. S.; Tortolani, D. R.; Vaccaro, W.; Potin, D.;
Launay, M.; Stetsko, D. K.; Skala, S.; Davis, P. M.; Lee, D.; Yang, X.; McIntyre, K.