Cobalt(II)-catalyzed intermolecular benzylic C-H amination with 2,2,2-trichloroethoxycarbonyl azide (TrocN3)

Article abstract of DOI:10.1021/om900916g

2,2,2-Trichloroethoxycarbonyl azide (TrocN₃) is an effective nitrene source for cobalt(II)-catalyzed intermolecular nitrene insertion of C-H bonds. Among different metalloporphyrins studied, Co(II)(TPP) was shown to be a competent catalyst for the selective amination of various benzylic C-H bonds under mild conditions without the need of other reagents or additives, forming the desired Trocprotected amines in moderate to high yields with nitrogen gas as the only byproduct.

Full text of DOI:10.1021/om900916g

Organometallics 2010, 29, 389–393 389
DOI: 10.1021/om900916g
Cobalt(II)-Catalyzed Intermolecular Benzylic C-H Amination with
2,2,2-Trichloroethoxycarbonyl Azide (TrocN3)
Hongjian Lu, Velusamy Subbarayan, Jingran Tao, and X. Peter Zhang*
Department of Chemistry, University of South Florida, Tampa, Florida 33620-5250
Received October 19, 2009
2,2,2-Trichloroethoxycarbonyl azide (TrocN3) is an effective nitrene source for cobalt(II)-catalyzed
intermolecular nitrene insertion of C-H bonds. Among different metalloporphyrins studied, Co(II)-
(TPP) was shown to be a competent catalyst for the selective amination of various benzylic C-H bonds
under mild conditions without the need of other reagents or additives, forming the desired Troc-
protected amines in moderate to high yields with nitrogen gas as the only byproduct.
Introduction
the field that validate the need to identify more effective
nitrene sources in conjunction with the development of more
selective metal catalysts. To this end, recent efforts have been
made to employ alternative nitrene sources for catalytic
C-H amination processes, including haloamine-T,4g,6 tosyl-
oxycarbamates,7 and azides.8
Employing porphyrins as supporting ligands, we have
recently developed several Co(II)-catalyzed nitrene tran-
sfer processes, including olefin aziridination and C-H
amination, with the use of bromamine-T9 and azides10 as
alternative nitrene sources. We demonstrated previously the
capability of cobalt(II) porphyrins ([Co(Por)]) in catalyzing
intermolecular nitrene insertion of C-H bonds with brom-
amine-T.9a While the desired amination products could be
formed under milder conditions with NaBr as the byproduct,
the catalytic system suffered from low yields and narrow
substrate scope. Encouraged by our recent work on intra-
molecular C-H amination with azides,10a we hoped to
improve the Co(II)-catalyzed intermolecular nitrene C-H
The biological and medicinal importance of the prevalent
amine functionalities in natural and synthetic products has
prompted vast efforts to develop effective and selective
amination methodologies.1 Metal-catalyzed nitrene inser-
tion into ubiquitous C-H bonds with suitable nitrene
sources has emerged as one of the most promising appro-
aches for general synthesis of amine derivatives in a direct
and controlled manner.2 While enormous progress has been
achieved for intermolecular C-H amination with the widely
used reagent PhIdNTs and related iminoiodane derivatives
as nitrene sources,3-5 significant challenges have remained in
*Corresponding author. E-mail: pzhang@cas.usf.edu. Fax: 813-974-
1733.
(1) (a) Modern Amination Methods; Racci, A., Ed.; Willey-VCH:
Weinheim, 2000. (b) Salvatore, R. N.; Yoon, C. H.; Jung, K. W. Tetrahedron
2001, 57, 7785. (c) Johannsen, M.; Jorgensen, A. Chem. Rev. 1998, 98, 1689.
(d) Muller, T. E.; Beller, M. Chem. Rev. 1998, 98, 675.
(2) (a) Muller, P.; Fruit, V. Chem. Rev. 2003, 103, 2905. (b) Dauban, P.;
Dodd, R. H. Synlett 2003, 1571. (c) Koser, G. F. Top. Curr. Chem. 2003,
224, 137. (d) Halfen, J. A. Curr. Org. Chem. 2005, 9, 657.
(6) (a) Chanda, B. M.; Vyas, R.; Bedekar, A. V. J. Org. Chem. 2001,
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J. V.; Gao, G.-Y.; Moore, T. M.; Zhang, X. P. J. Org. Chem. 2008, 73, 7260.
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Commun. 2009, 4266.
(3) For recent reviews, see: (a) Espino, C. G.; Du Bois, J. In Modern
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(4) For select recent examples of intermolecular C-H amination with
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J. Chem. 1989, 13, 651. (b) Nageli, I.; Baud, C.; Bernardinelli, G.; Jacquier,
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2007, 46, 5184. (i) Chang, J. W. W.; Chan, P. W. H. Angew. Chem., Int. Ed.
2008, 47, 1138.
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X.-G.; Che, C.-M. Org. Lett. 2000, 2, 2233. (b) Reddy, R. P.; Davies, H. M.
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r
2009 American Chemical Society
Published on Web 12/22/2009
pubs.acs.org/Organometallics

390 Organometallics, Vol. 29, No. 2, 2010
Lu et al.
Table 1. Intermolecular C-H Amination of Tetralin with
Different Azidesa
Figure 1. Structures of metalloporphyrin catalysts.
Scheme 1. Cobalt(II)-Catalyzed C-H Amination with TrocN3
a
˚
Performed under N2 in the presence of 5 A molecular sieves: [1a] =
2.0 mmol/2 mL; 1a:TrocN3 = 10:1. bIsolated yields.
insertion process by further utilizing azides as nitrene sources.
Herein, we report that 2,2,2-trichloroethoxycarbonyl azide
(TrocN3) is an effective nitrene source for Co(II)-catalyzed
intermolecular nitrene insertion of C-H bonds (Scheme 1).11
Among different metalloporphyrins studied (Figure 1), Co-
(TPP) was shown to be a competent catalyst for the selective
amination of various benzylic C-H bonds, forming the
desired Troc-protected amines in moderate to high yields.
The Co(II)-based catalytic system can be operated under mild
conditions without the need for other reagents or additives
while generating nitrogen gas as the only byproduct.
Table 2. Intermolecular C-H Amination of Tetralin with TrocN3
by Metalloporphyrinsa
entry
[M(Por)]b
mol (%) solvent temp (°C) time (h) yield (%)c
1
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
5
10
10
5
ClC6H5
ClC6H5
ClC6H5
ClC6H5
CF3C6H5
CH3C6H5
C6H14
60
60
60
60
60
60
60
60
40
80
60
60
40
40
RT
40
40
40
40
40
40
24
24
42
48
48
48
48
48
32
48
48
48
48
48
48
48
48
48
48
48
48
50
52
58
69
71
50
73
0
Results and Discussion
2
3
4d
5d
6d
7d
8d
9d
10d
At the outset of the project, tetralin was selected as a
model substrate to identify a suitable azide for the catalytic
amination reaction. Different kinds of azides, including
sulfonyl, phosphoryl, and carbonyl azides, were evaluated
as potential nitrene sources. While most of the azides were
found to be ineffective for the process (Table 1), the use of
TrocN3, a carbonyl azide that is relatively small in size and
contains an electron-withdrawing group, allowed for the
amination of tetralin (1a) by [Co(Por)] under proper con-
ditions (Table 2). For example, the amination of 1a with
TrocN3 (1a:TrocN3 = 10:1) could be successfully catalyzed
using 5 mol % Co(TPP) at 60 °C in chlorobenzene, forming
the corresponding Troc-protected amine 2a in 50% yield
via selective nitrene insertion into one of the benzylic C-H
bonds (Table 2, entry 1). While no noticeable improvement
was realized using higher catalyst loading, a longer reaction
time gave a better result (Table 2, entries 2 and 3). More
significant increase in yield was attained when the reaction
was conducted at a higher concentration (Table 2, entry 4).
Other solvents such as trifluorotoluene, toluene, and
n-hexane could also be effectively utilized for the reaction,
5
5
5
5
CH3CN
ClC6H5
ClC6H5
ClC6H5
5
70
68
34
79
85
79
66
26
10
<5
0
5
11d,e Co(TPP)
5
f
12
13
14
15
16
17
18
19
20
21
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPP)
Co(TPFPP)
Co(TDClPP)
Co(Pc)
5
-
-
-
-
-
-
-
-
f
5
f
2
f
5
f
5
f
5
f
5
f
Fe(TPP)Cl
Ni(TPP)
Cu(TPP)
5
f
5
-
-
0
f
5
0
a
˚
Performed under N2 in the presence of 5 A molecular sieves: [1a] =
2.0 mmol/2 mL; 1a:TrocN3 = 10:1. b See Figure 1 for structures.
c Isolated yields. d [1a] = 2.0 mmol/0.5 mL. e 1a:TrocN3 = 3:1. f Neat
reaction.
producing 2a in 71%, 50%, and 73% yields, respectively
(Table 2, entries 5-7). However, no desired product was
observed when the reaction was performed in acetonitrile
(Table 2, entry 8). When using chlorobenzene as solvent, it
was noticed that temperature had no obvious effect on the
amination, as the reactions at 40, 60, and 80 °C gave
(11) TrocN3 was readily synthesized from the commercially available
CCl3CH2OC(O)Cl in high yield and on a multiple-gram scale; DSC
showed it decomposed at 157 °C (see Supporting Information). TrocN3
was previously used for a Ru-catalyzed sulfimidation process; see:
Tamura, Y.; Uchida, T.; Katsuki, T. Tetrahedron Lett. 2003, 44, 3301.

Article
Organometallics, Vol. 29, No. 2, 2010 391
practically the same isolated yield of 2a (Table 2, entries 4,
9, and 10). While a decrease in the ratio of 1a to TrocN3
reduced the yield (only a trace amount of product was
observed when 1a was used as a limiting reagent), a sig-
nificantly higher yield was achieved for a reaction carried
out in neat form (Table 2, entries 11 and 12). It is worthy of
note that the yield was raised further to 85% when the
reaction temperature was changed from 60 to 40 °C, due to
decreased formation of the corresponding TrocNH2
(Table 2, entry 13). Further experiments showed that the
neat reaction could be productively carried out with 2 mol
% catalyst loading or at room temperature (Table 2, entries
14 and 15).
Table 3. Co(TPP)-Catalyzed Intermolecular C-H Amination
Reactions with TrocN3
a
Changing Co(TPP) to sterically hindered and/or electro-
nically deficient catalysts such as Co(TDClPP) and Co-
(TPFPP) (Figure 1), which were shown to be more effective
for C-H amination with bromamine-T,9a produced the
desired 2a in greatly reduced yields (Table 2, entries 16 and
17). This result reveals the difference in reactivity between
TrocN3 and bromamine-T as nitrene sources. Only a trace
amount of the desired amination product could be detected
when the cobalt complex of phthalocyanine [Co(Pc)]
(Figure 1) was used as the catalyst (Table 2, entry 18). As
observed previously in other azide-based nitrene transfer
reactions by metalloporphyrins,10 the cobalt ion seems cru-
cial to the successful C-H amination with TrocN3. While
Co(TPP) could effectively catalyze the amination of 1a
(Table 2, entries 1-15), the employment of other metallo-
porphyrins, including Fe(TPP)Cl, Ni(TPP), and Cu(TPP)
(Figure 1), led to no formation of the desired product 2a
(Table 2, entries 19-21).12
On the basis of the catalytic conditions optimized for the
amination of 1a, the scope of the Co(TPP)/TrocN3-based
catalytic system toward nitrene insertion of other benzylic
C-H bonds was then investigated using different sub-
strates (Table 3).13 Like the cyclic 1a (Table 3, entry 1),
the benzylic C-H bonds of ethyl benzene (1b) and its para-
brominated derivative (1c) could also be selectively ami-
nated to provide the corresponding amine products 2b and
2c in 69% and 79% yields, respectively (Table 3, entries 2
and 3). Ethyl benzene derivatives substituted with alkyl
groups such as 1d could be properly aminated with TrocN3,
producing the C-H insertion product 2d in 74% yield
(Table 3, entry 4). While diphenylmethane 1e is a good
substrate for the catalytic amination (Table 3, entry 5), the
best results were achieved for the reactions of 1-ethyl- and
2-ethylnaphthalene 1f and 1g, forming the desired amines
2f and 2g in 87% and 92% yields, respectively (Table 3,
entries 6 and 7). It is noteworthy that the Co(TPP)/TrocN3-
based catalytic system was also capable of aminating
challenging substrates such as ethyl phenylacetate 1p to
produce the R-amino acid derivative 2h albeit in a low yield
(Table 3, entry 8). This notable reaction presents an
encouraging prospect for catalytic synthesis of R-amino
acids via selective C-H amination directly from the corre-
sponding carboxylic acids. It was noted that the corre-
sponding TrocNH2 of TrocN3 was the common side
a Performed in neat at 40 °C for 48 h under N2 with 5 mol % Co(TPP)
in the presence of 5 A MS: substrate:TrocN3 = 10:1. b Isolated yields.
˚
product of the Co(II)-catalyzed amination process. In most
cases, TrocN3 was completely consumed; the formation of
TrocNH2 was primarily responsible for the lower yielding
reactions (Table 3). Control experiments showed that
addition of a small amount of water resulted in a significant
decrease in the yield of desired amination product with a
concomitant increase of TrocNH2.
On the basis of the previously proposed mechanism for
Co(II)-catalyzed aziridination with DPPA,10b one possible
mechanism for the Co(TPP)/TrocN3-based amination is
outlined in Scheme 2 to provide a means to better understand
the catalytic process. As a 15e metalloradical, the initial
Co(II) catalyst A reacts with TrocN3 to generate the cobalt-
nitrene intermediate B with simultaneous release of nitrogen.
The intermediate B, which is assumed to be a Co(III) 16e
complex having a Co-N single bond with nitrogen-based
radical character, reacts with substrate R-H via hydrogen
abstraction to form intermediate C with a caged R• radical
nearby. Formation of the C-N bond produces the amine
product and regenerates the catalyst A to turn over the
catalytic cycle. Due to its weak Co-N bond, homolysis of
intermediate C may generate an aminyl free radical that
results in the formation of the observed side product
TrocNH2. While the proposed mechanism may allow com-
prehension of the results summarized in Tables 2 and 3, it
should be emphasized that no experimental evidence have
been obtained to support the intermediates presented
in Scheme 2.
(12) Under similar conditions, use of a porphyrin complex of the
second-row transition metal ruthenium, Ru(TPP)(CO), could produce
2a in 79% yield.
(13) The current catalytic system appeared to be ineffective for
primary benzylic C-H bonds (such as toluene) and non-benzylic
C-H bonds (such as cyclohexane). Reactions with tertiary benzylic
C-H bonds gave the desired products in much lower yields.

392 Organometallics, Vol. 29, No. 2, 2010
Lu et al.
Scheme 2. Possible Mechanism for Cobalt(II)-Catalyzed
Nitrene Insertion of Benzylic C-H Bonds with TrocN3
4-Methylbenzenesulfonyl azide10c,14 (Table 1, entry 2) was
prepared using the general procedure as a colorless liquid in
75% yield. 1H NMR (250 MHz, CDCl3): δ 7.82 (d, J = 8.5 Hz,
2H), 7.39 (d, J = 8.5 Hz, 2H), 2.46 (s, 3H). 13C NMR (CDCl3,
62.9 MHz): δ 146.2, 135.3, 130.2, 127.4, 21.6. IR (neat, cm-1):
2123, 1368, 1163, 1085, 813, 745, 657.
Diethylphosphoroazidate15 (Table 1, entry 3) was prepared by
following the literature procedure.2 1H NMR (250 MHz,
CDCl3): δ 4.24-4.12 (m, 4H), 1.36 (t, J = 7.0 Hz, 6H). 13C
NMR (62.9 MHz, CDCl3): δ 64.9, 64.8, 16.0, 15.9. IR (neat,
cm-1): 2158, 1275, 1014, 983, 780. IR (neat, cm-1): 2161, 1266,
1016, 983, 782.
Benzoyl azide16 (Table 1, entry 5) was prepared by following
the literature procedure.3 1H NMR (250 MHz, CDCl3): δ
8.04-8.00 (m, 2H), 7.65-7.57 (m, 1H), 7.48-7.41 (m, 2H).
13C NMR (62.9 MHz, CDCl3): δ 172.4, 134.3, 130.5, 129.4,
128.6. IR (neat, cm-1): 2132, 1692, 1234, 1175, 985, 694, 684.
2-Phenylethyl azidocarbonate17 (Table 1, entry 6) was pre-
pared by following the literature procedure.4 1H NMR (CDCl3,
250 MHz): δ 7.26-7.13 (m, 5H), 4.34 (t, J = 7.0 Hz, 2H), 2.93 (t,
J = 7.0 Hz, 2H). 13C NMR (CDCl3, 62.9 MHz): δ 157.3, 136.7,
128.8, 128.6, 126.8, 68.8, 34.8.
Conclusions
In summary, we have demonstrated a Co(II)-catalyzed
intermolecular C-H amination process with TrocN3 as a
nitrene source. This represents the first example of a carbo-
nyl azide being utilized for the metal-catalyzed nitrene
insertion of sp3 C-H bonds. The Co(TPP)/TrocN3-based
catalytic system can selectively aminate benzylic C-H bonds
in a range of substrates to form the desired Troc-protected
amines in moderate to high yields while generating nitrogen
gas as the byproduct. Efforts are underway in our laboratory
to develop new porphyrins as supporting ligands for the Co-
based catalytic amination system with a goal to improve its
reactivity and selectivity.
2,2,2-Trichloro-1,1-dimethylethyloxycarbonyl azide11,18 (Table 1,
entry 7) was prepared using the general procedure as a colorless
solid in 90% yield. 1H NMR (250 MHz, CDCl3): δ 1.97 (s, 6H).
13C NMR (CDCl3, 62.9 MHz): δ 154.4, 104.9, 91.4, 21.1. IR
(neat, cm-1): 2201, 2144, 1717, 1261, 1240, 1209, 1139, 831, 789,
759.
2,2,2,-Trichloroethoxycarbonyl azide11 (Table 1, entry 8) was
prepared using the general procedure as a colorless liquid in
1
92% yield. H NMR (250 MHz, CDCl3): δ 4.83 (s, 2H). 13C
NMR (62.9 MHz, CDCl3): δ 156.5, 93.8, 76.5. IR (neat, cm-1):
2179, 2143, 1769, 1734, 1223, 712.
Experimental Section
˚
General Procedure for Amination. Molecular sieves (5 A,
General Considerations. All reactions were carried out under a
nitrogen atmosphere in oven-dried glassware following stan-
dard Schlenk techniques. Diphenylphosphoryl azide was pur-
chased from Sigma-Aldrich Company. Chlorobenzene was
distilled under nitrogen from calcium hydride. Thin-layer
chromatography was performed on Merck TLC plates (silica
gel 60 F254). Flash column chromatography was performed
100 mg) were placed in a resealable Schlenk tube and dried in
an oven for 24 h. Catalyst (5 mol %) was added to the tube,
which was then capped with a Teflon screwcap, evacuated, and
backfilled with nitrogen. The screwcap was replaced with a
rubber septum, and TrocN3 (0.4 mmol) was added via syringe,
followed by 10 equiv of substrate. After the Schlenk tube was
purged with nitrogen for 1 min, the rubber septum was replaced
with the screwcap. The reaction content was stirred at a specified
temperature for a certain period of time. After completion of the
reaction, the resulting mixture was purified directly by flash
chromatography (silica gel) to afford the pure product.
˚
with ICN silica gel (60 A, 230-400 mesh, 32-63 μm). Proton
and carbon nuclear magnetic resonance spectra (1H NMR and
13C NMR) were recorded on a Bruker 250-MHz instrument and
referenced with respect to internal TMS standard. Infrared
spectra were measured with a Nicolet Avatar 320 spectrometer
with a Smart Miracle accessory. HRMS data were obtained on
an Agilent 1100 LC/MS ESI/TOF mass spectrometer with
electrospray ionization.
2,2,2-Trichloroethyl-1,2,3,4-tetrahydronaphthalen-1-ylcarba-
1
mate (2a, Table 3, entry 1). H NMR (250 MHz, CDCl3): δ
7.35-7.31 (m, 1H), 7.21-7.08 (m, 3H), 5.22 (br, 1H), 4.98-4.72
(m, 3H), 2.83-2.75 (m, 2H), 2.10-2.05 (m, 1H), 1.93-1.82 (m,
3H). 13C NMR (62.9 MHz, CDCl3): δ 154.0, 137.4, 136.0, 129.2,
128.6, 127.5, 126.3, 95.7, 74.4, 49.6, 30.2, 29.1, 20.0. IR (neat,
cm-1): 3320, 2930, 2359, 1704, 1527, 1235, 1082, 1034, 711.
HRMS (ESI) ([M þ H]þ): calcd for C13H15Cl3NO2 322.0163,
found 322.0161.
General Procedure for Synthesis of Azides. To a well-stirred
suspension of NaN3 (1.95 g, 30 mmol) in acetone (40 mL)
protected from light by aluminum foil was added acyl chloride
(20 mmol) at room temperature. The reaction was monitored by
TLC. After the reaction finished, the mixture was then poured
into a flash chromatography column filled with Celite (dry) and
was washed with methylene chloride until all the product was
washed out. The filtrate was collected and concentrated by
rotary evaporation at room temperature to give the product,
which was further purified by flash chromatography column
(silica gel).
2,2,2-Trichloroethyl-1-phenylethylcarbamate7c (2b, Table 3,
1
entry 2). H NMR (250 MHz, CDCl3): δ 7.37-7.25 (m, 5H),
5.30 (br, 1H), 4.92-4.85 (m, 1H), 4.79-4.65 (m, 2H), 1.53 (d,
J = 7.0 Hz, 3H). 13C NMR (62.9 MHz, CDCl3): δ 153.7, 142.7,
128.7, 127.5, 125.9, 95.5, 74.4, 51.0, 22.2. IR (neat, cm-1): 3327,
2361, 1716, 1522, 1234, 1117, 1088. HRMS (ESI) ([M þ H]þ):
calcd for C11H13Cl3NO2 296.0006, found 296.0005.
4-Nitrobenzenesulfonyl azide10c,14 (Table 1, entry 1) was
prepared using the general procedure as a solid in 75% yield.
1H NMR (250 MHz, CDCl3): δ 8.46 (d, J = 9.0 Hz, 2H), 8.17 (d,
J = 9.0 Hz, 2H). 13C NMR (62.9 MHz, CDCl3): δ 151.2, 143.6,
128.9, 124.9. IR (neat, cm-1): 2141, 1529, 1375, 1349, 1176,
1157, 1085, 854, 769.
2,2,2-Trichloroethyl-1-(4-bromophenyl)ethylcarbamate (2c,
Table 3, entry 3). 1H NMR (250 MHz, CDCl3): δ 7.47 (d, J =
8.5 Hz, 2H), 7.20 (d, J = 8.5 Hz, 2H), 5.25 (br, 1H), 4.86-4.64
(16) Liu, J.; Mandel, S.; Hadad, C. M.; Platz, M. S. J. Org. Chem.
2004, 69, 8583.
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Hennrich, F.; Kappes, M.; Hirsch, A. J. Am. Chem. Soc. 2003, 125, 8566.
(18) Uchida, T.; Tamura, Y.; Ohba, M.; Katsuki, T. Tetrahedron
Lett. 2003, 44, 7965.
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Article
Organometallics, Vol. 29, No. 2, 2010 393
(m, 3H), 1.50 (d, J = 6.8 Hz, 3H). 13C NMR (62.9 MHz,
CDCl3): δ 153.6, 141.9, 131.7, 127.6, 121.2, 95.4, 74.4, 50.5, 22.1.
IR (neat, cm-1): 3397, 2982, 2929, 1712, 1513, 1232, 1058, 1008,
824, 710. HRMS (ESI) ([M þ H]þ): calcd for C11H12BrCl3NO2
375.9079, found 375.9017.
2,2,2-Trichloroethyl-1-(3,5-diethylphenyl)ethylcarbamate (2d,
Table 3, entry 4). 1H NMR (250 MHz, CDCl3): δ 6.98 (s, 3H),
5.27 (br, 1H), 4.91-4.67 (m, 3H), 2.63 (q, J = 7.5 Hz, 4H), 1.53
(d, J = 6.8 Hz, 3H), 1.24 (t, J = 7.5 Hz, 6H). 13C NMR (62.9
MHz, CDCl3): δ 153.7, 144.7, 142.7, 126.7, 122.8, 95.6, 74.4,
51.1, 28.8, 22.3, 15.6. IR (neat, cm-1): 3333, 2965, 2929, 2360,
1719, 1523, 1234, 1116, 1087. HRMS (ESI) ([M þ H]þ): calcd for
C15H21Cl3NO2 352.0632, found 352.0623.
2,2,2-Trichloroethylbenzhydrylcarbamate (2e, Table 3, entry
5). 1H NMR (250 MHz, CDCl3): δ 7.24-7.13 (m, 10H), 5.90 (d,
J = 8.0 Hz, 1H), 5.61 (d, J = 7.3 Hz, 1H), 4.64 (s, 2H). 13C
NMR (62.9 MHz, CDCl3): δ 153.8, 140.9, 128.7, 127.7, 127.2,
95.4, 74.6, 59.0. IR (neat, cm-1): 3301, 2921, 2360, 1709, 1528,
1134, 1024, 761. HRMS (ESI) ([M þ H]þ): calcd for
C16H14Cl3NO2 358.0163, found 358.0156.
J1 = J2 = 7.0 Hz, 1H), 4.74 (q, J = 7.0 Hz, 2H), 1.62 (t, J = 6.8
Hz, 3H). 13C NMR (62.9 MHz, CDCl3): δ 153.7, 140.1, 133.3,
132.8, 128.6, 127.9, 127.6, 126.3, 126.0, 124.4, 124.2, 95.5, 74.5,
51.1, 22.2. IR (neat, cm-1): 3312, 2359, 1708, 1522, 1239, 1086,
803, 746. HRMS (ESI) ([M þ H]þ): calcd for C15H15Cl3NO2
346.0163, found 346.0156.
Ethyl 2-phenyl-2-((2,2,2-trichloroethoxy)carbonylamino)acetate
(2h, Table 3, entry 8). 1H NMR (250 MHz, CDCl3): δ 7.45-7.29
(m, 5H), 6.01 (d, J = 8.0 Hz, 1H), 5.36 (d, J = 7.3 Hz, 1H),
4.77-4.65 (m, 2H), 4.30-4.12 (m, 2H), 1.22 (t, J = 7.3 Hz, 3H).
13C NMR (62.9 MHz, CDCl3): δ 170.3, 153.5, 136.2, 129.0,
128.8, 127.1, 95.2, 74.7, 62.1, 58.1, 14.0. IR (neat, cm-1): 3355,
2979, 2360, 1724, 1498, 1208, 1092, 1043, 698. HRMS (ESI)
([M þ H]þ): calcd for C13H15Cl3NO4 354.0061, found 354.0057.
1-p-Tolylsulfonylaminotetralin6a (Table 1, entry 2). 1H NMR
(250 MHz, CDCl3): 7.84 (d, J = 8.3 Hz, 2H), 7.35 (d, J = 8.3 Hz,
2H), 7.18-6.91 (m, 4H), 4.61(d, J = 7.8 Hz, 1H), 4.47-4.43 (m,
1H), 2.81-2.62 (m, 2H), 2.47 (s, 3H), 1.87-1.71 (m, 4H). 13C
NMR (62.9 MHz, CDCl3): δ 143.5, 138.1, 137.6, 135.6, 129.8,
129.3, 128.8, 127.7, 127.2, 126.3, 51.9, 30.8, 28.9, 21.6, 19.1.
2,2,2-Trichloroethyl-1-(naphthalen-1-yl)ethylcarbamate (2f,
Table 3, entry 6). 1H NMR (250 MHz, CDCl3): δ 8.13 (d, J =
7.5 Hz, 1H), 7.92-7.87 (m, 1H), 7.82 (d, J = 7.8 Hz, 1H),
7.60-7.43 (m, 4H), 5.71 (dt, J1 = J2 = 7.0 Hz, 1H), 5.44 (d, J =
7.3 Hz, 1H), 4.77 (s, 2H), 1.70 (t, J = 6.8 Hz, 3H). 13C NMR
(62.9 MHz, CDCl3): δ 153.6, 137.9, 133.9, 130.7, 128.8, 128.4,
126.5, 125.8, 125.2, 123.1, 122.2, 95.6, 74.4, 46.9, 21.3. IR (neat,
cm-1): 3321, 2924, 2360, 1716, 1509, 1232, 1113, 1050, 799, 775,
715. HRMS (ESI) ([M þ H]þ): calcd for C15H15Cl3NO2
346.0163, found 346.0167.
Acknowledgment. We are grateful for financial sup-
port of this work from USF for Startup Funds, American
Chemical Society for a PRF-AC grant, and National
Science Foundation for a CAREER Award. Funding
for the USF Department of Chemistry Mass Spectro-
metry Facility has been furnished in part by NSF (CRIF:
MU-0443611).
Supporting Information Available: 1H NMR and 13C NMR
spectra for all products and DSC for TrocN3. This material is
available free of charge via the Internet at http://pubs.acs.org.
2,2,2-Trichloroethyl-1-(naphthalen-2-yl)ethylcarbamate (2g,
1
Table 3, entry 7). H NMR (250 MHz, CDCl3): δ 7.86-7.77
(m, 4H), 7.53-7.42 (m, 3H), 5.39 (d, J = 7.3 Hz, 1H), 5.05 (dt,