Transition-Metal-Free Conversion of Trifluoropropanamides into Cyanoformamides through C-CF3 Bond Cleavage and Nitrogenation

Article abstract of DOI:10.1021/acs.joc.7b00626

A new transition-metal-free transformation of trifluoropropanamides into cyanoformamides through a sequence of C-CF₃ bond cleavage and nitrogenation using tert-butyl nitrite as the nitrogen source is described. The method features direct detrifluoromethylation, broad substrate scopes, and excellent selectivity control, representing a new shortcut for constructing the nitrile group involving C-CF₃ σ-bond cleavage.

Full text of DOI:10.1021/acs.joc.7b00626

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Note
Transition-Metal-Free Conversion of Trifluoropropanamides into
Cyanoformamides through C-CF3 Bond Cleavage and Nitrogenation
Fang Wang, Tao Zhang, Hai-Yong Tu, and Xing-Guo Zhang
J. Org. Chem., Just Accepted Manuscript • Publication Date (Web): 03 May 2017
Downloaded from http://pubs.acs.org on May 3, 2017
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The Journal of Organic Chemistry
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Transition-Metal-Free Conversion of
Trifluoropropanamides into Cyanoformamides
through C-CF3 Bond Cleavage and Nitrogenation
Fang Wang, Tao Zhang, HaiꢀYong Tu and XingꢀGuo Zhang*
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College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
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zxg@wzu.edu.cn
RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required
according to the journal that you are submitting your paper to)
Abstract
A new transitionꢀmetalꢀfree transformation of trifluoropropanamides into cyanoformamides through a
sequence of CꢀCF3 bond cleavage and nitrogenation using tertꢀbutyl nitrite (TBN) as the nitrogen source
is described. The method features direct detrifluoromethylation, broad substrate scopes and excellent
selectivity control, representing a new shortcut for constructing the nitrile group involving CꢀCF3 σꢀ
bond cleavage.
With the increased awareness of degrading the environmentally persistent nature of fluorinated
molecules and improvement of fluorineꢀcontaining compounds in synthesis,1 development of
fluorocarbon disposal methods for such purposes is of increasing importance.2 In the field, common and
attractive strategies include the defluorination reaction, which has received much attention in the past
decades. Typically, the elimination of fluorine atoms from fluorinated molecules, particularly
trifluoromethylated compounds, is achieved via hydrodefluorination; however, these transformations are
restricted to the requirement of strong reductive reagent and/or transitionꢀmetal catalysts because the
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fluorocarbon group is one of the most chemically and thermally stable functional groups.3 Although
approaches via direct cleavage of CꢀCF3 bond are especially fascinating for fluorocarbon degradation,
such available examples are much less abundant.4 Thus, the establishment of new efficient and practical
methods for achieving the detrifluoromethylation, especially avoiding the use of strong reducing agents
and transitionꢀmetal catalysts, is worthy of investigation.
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Nitriles, including cyanoformamides (Scheme 1),5 are prevalent as key structures in numerous
pharmaceuticals, agricultural chemicals and materials, as well as versatile building blocks in chemical
synthesis.6 Accordingly, considerable efforts have been devoted to development of new efficient and
reliable synthetic processes that allow the preparation of diverse functionalized nitriles. Classical
methods focus on transitionꢀmetalꢀcatalyzed cyanation of aryl halides7 and transitionꢀmetalꢀcatalyzed Cꢀ
H cyanation;8 however, both suffer from the use of highly toxic metal cyanide as the nitrile group
resources. Alternatively, attractive access to nitriles has been developed by direct transformations of
functional groups into the nitrile group in recent years. Generally, the nitrile group is formed by the
dehydration of the corresponding amides, oximes or their precursors.9 Recently, Jiao and coꢀworkers
reported a conceptuallyꢀnew CꢀC unsaturated bond cleavage and nitrogenation cascade for assembling
the nitrile group using TMSN3 as the nitrogen source (Scheme 2a).10 Maiti and coꢀworkers have
subsequently developed a metalꢀfree nitrogenation of terminal arylalkynes with TBN (the nitrogen
source) in the presence of 2ꢀpicolineꢀNꢀoxide, which delivered aryl nitriles via CꢀC triple bond
cleavage.11 Despite recent advances in direct transformations of functional groups into the nitrile group,
similar versions for the preparation of cyanoformamides are quite rare.12 We envisioned that a
combination of detrifluoromethylation and nitrogenation might be applicable to the construction of the
nitrile group. Herein, we report a new design cascade strategy for producing a wide range of
cyanoformamides in moderate to high yields via transitionꢀmetalꢀfree conversion of
trifluoropropanamides into cyanoformamides using tertꢀbutyl nitrite as the nitrogen source, which
represents the first example of direct construction of the nitrile group via the CꢀCF3 single bond
cleavage and nitrogenation cascades.
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Scheme 1. Examples of CyanoformamideꢀContaining Natural Products.
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The Journal of Organic Chemistry
Scheme 2. Construction of the Nitrile Group by CꢀC Bond Cleavage.
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Table 1. Screening of Optimal Reaction Conditionsa
Entry
Base
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
CsOAc
K2CO3
K3PO4
tꢀBuOK
Cs2CO3
Cs2CO3
ꢀ
Additive
Solvent
MeCN
dioxane
DMF
Yield (%)
1
2
ꢀ
55
29
47
38
34
27
11
27
78
trace
0
ꢀ
3
ꢀ
4
ꢀ
toluene
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
5
ꢀ
6
ꢀ
7
ꢀ
ꢀ
8
9
HOAc
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13b
CF3CO2H
HOAc
Cs2CO3
Cs2CO3
HOAc and 4Å MS
HOAc and 4Å MS
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39
a
Reaction conditions: 1a (0.2 mmol), tBuONO (0.8 mmol), base (2 equiv), acid (2 equiv), 4Å MS
(100 mg), dry solvent (2 mL), 100 oC, air and 24 h. b At 80 oC.
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We began our studies by evaluating the reaction between 3,3,3ꢀtrifluoroꢀNꢀmethylꢀNꢀ
phenylpropanamide (1a) and tertꢀbutyl nitrite to optimize the reaction condition (Table 1). Initially,
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substrate 1a was reacted with TBN and Cs2CO3 in MeCN at 100 C for 24 h, giving the target product
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2a in 55% yield (entry 1). A rotamerization of amide 2a was observed in NMR spectra (see SI).
Encouraged by the results, three other solvents, including dioxane, DMF and toluene, were examined to
enhance the yield, (entries 2ꢀ4), which supported MeCN as the preferred solvent. A screen of the base
effect revealed that other bases, such as CsOAc,K2CO3, K3PO4 and tꢀBuOK, were less effective than
Cs2CO3 (entries 5ꢀ8). Gratifyingly, the yield increased from 55% (entry 1) to 78% when using 2 equiv
of HOAc (entry 9). However, the reaction could not take place using CF3CO2H instead of HOAc (entry
10) or in the absence of Cs2CO3 (entry 11). We were pleased to find that molecular sieves (MS)
improved the reaction: in the presence of 100 mg 4Å MS, a 91% yield of 2a was obtained (entry 12).
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o
Notably, a lower reaction temperature (80 C) had a negative effect on the reaction by comparison with
the result at 100 oC (entry 13).
With the optimal reaction conditions in hand, we set out to investigate the substrate scope (Schemes 3
and 4). First, the substitution effect on the aromatic ring of the Nꢀaryl moiety was examined: an array of
substituents, including Me, MeO, F, Cl, Br, CF3, CO2Me, CH3CO and Ph, were well tolerated, and the
electronic nature of the substrates had a fundamental influence on the reactivity (2b-j). While
trifluoropropanamides 1b-c, bearing an electronꢀdonating group (Me or MeO) on the Nꢀaryl ring,
afforded 2b-c in good yields, substrates 1g-i with a strong electronꢀwithdrawing group, namely CF3,
CO2Me and CH3CO, furnished 2g-i with lower yields. Importantly, halide substituents (F, Cl and Br)
were consistent with the optimal conditions (2d-f), thus providing potential handles for further
modification, and the structure of product 2f was confirmed by Xꢀray singleꢀcrystal diffraction analysis
(see SI). Using 4ꢀPhꢀsubstituted amide 1j, the reaction gave Nꢀ(4ꢀbiphenyl)ꢀcyanoformamide (2j) in
51% yield. The results showed that the steric hindrance effect slightly affected the reaction. Both meltaꢀ
substituted and orthoꢀsubstituted trifluoropropanamides 1k-q delivered 2k-q in 65ꢀ86% yields.
Moreover, NꢀmethylꢀNꢀ(naphthalenꢀ1ꢀyl)trifluoropropanamide 1r was compatible with the optimal
conditions, affording 2r in 67% yield. Subsequently, the substitution effect on the nitrogen atom was
examined. Gratifyingly, symmetrical and unsymmetrical disubstituted amines 1s-y, either N,Nꢀdiaryl,
N,Nꢀdialkyl or NꢀarylꢀNꢀalkyl variations, were viable for the assembly of 2s-y in moderate to good
yields. For example, N,Nꢀdihexyltrifluoropropanamide 1w was successfully converted into 2w, albeit
giving a lower yield. For N,Nꢀdibenzyltrifluoropropanamide 1x and N,Nꢀdiphenyltrifluoropropanamide
1y, the corresponding products 2x-y were obtained in 53% and 42% yields, respectively.
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The Journal of Organic Chemistry
Scheme 3. Variation of the Trifluoropropanamides 1a
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Me
Me
N
Me
N
Me
N
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N
CN
CN
CN
CN
CN
O
O
O
O
MeO
Cl
F
2c
, 81%
2d
, 80%
2e
2b
2f
, 83%
, 79%
Me
N
Me
N
Me
Me
N
CN
N
CN
CN
O
O
O
O
O
MeO2C
CN
Ac
Br
F3C
2g
, 41%
2i
2h, 45%
, 54%
2n
, 77%
Me
Me
R
Me
R = Me, , 71%
R
N
N
CN
2o
R = MeO, , 77%
CN
N
2p
R = F, , 86%
O
2q
R = Cl, , 76%
O
Ph
2k
R = Me, , 68%
2l
R = MeO, , 65%
2j
, 51%
2m
R = Cl,
, 75%
N
CN
Me
N
Et
N
CN
N
CN
O
CN
2u
, 71%
O
O
O
2r
2s
2t
, 47%
, 67%
, 62%
Bn
Bn
N
N
CN
N
CN
CN
N
CN
Bn
O
O
O
O
2y
, 42%
2x
, 53%
2v
, 66%
2w
, 38%
a Reaction conditions: 1 (0.2 mmol) and TBN (0.8 mmol), Cs2CO3 (2 equiv), AcOH (2 equiv), 100 mg
4Å MS and MeCN (dry 2 mL) under air atmosphere at 100 °C for 24 h.
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However, using Nꢀmonoꢀsubstituted trifluoropropanamide (1z) resulted in no occurrence of the
cyanation reaction under the optimal conditions, and furnished the Nꢀacetylaniline 3z in 68% yield
[Scheme 4, eq (1)]. The reaction could be performed in the absence of TBN and/or HOAc, albeit with
diminished yields (52%). These results suggest that product 3z is formed from a sequence of
detrifluoromethylation and workup hydrolyzation. The experiment was also confirmed by 19F NMR
experiments of the reaction mixture of 1z under the standard conditions after 24 h, in which the
generation of the volatile trifluoromethanol resulted in observation of no signal.13
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Scheme 4. Reaction with Other Propanamides 1 and Control Experiments.
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To probe the mechanism of this detrifluoromethylative cyanation, some control experiments were
conducted (Scheme 4). The reaction of NꢀmethylꢀNꢀphenylacetamide 1aa with TBN was carried out
under the optimal conditions. However, neither nitrosative product nor the target product 2a could be
observed [eq (2)], suggesting that the elimination of trifluoromethyl group occurred after the nitrosation.
Furthermore, the reaction of substrate 1a with TBN was completely inhibited by adding 4.5 equiv of
2,2,6,6ꢀtetramethylpiperidine oxide (TEMPO), a radical scavenger [eq (3)]. These results indicated that
the reaction might involve a radical process.
Scheme 5. Possible mechanism.
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A plausible mechanism for this cascade reaction is proposed (Scheme 5).14 Decomposition of
tertꢀbutyl nitrite readily takes place and gives the tertꢀbutoxy radical and NO radical.9d, 14 Hydrogen
abstraction of substrate 1a by the tertꢀbutoxy radical generates the alkyl radical intermediate D,14a,
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14e
which sequentially reacts with the NO radical to afford the intermediate E. The tautomerization
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of intermediate E delivers the corresponding oxime F. Finally, βꢀelimination of intermediate F with
the aid of Cs2CO3 furnishes the desired detrifluoromethylative product 2a.4a
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In summary, we have developed a new convenient and efficient method for conversion of
trifluoropropanamides into cyanoformamides via CꢀCF3 bond cleavage and nitrogenation cascades,
which exhibits a broad scope with regard to a wide range of trifluoropropanamides and excellent
tolerance of functional groups. Most importantly, new CꢀC single bond cleavage and nitrogenation
cascades to construct the nitrile group are established.
Experimental Section
General Information:
1
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Chemicals were either purchased or purified by standard techniques. H NMR and C NMR spectra
were measured on a 500 MHz spectrometer (1H: 500 MHz, 13C: 125 MHz), using CDCl3 as the solvent
with tetramethylsilane (TMS) as an internal standard at room temperature. Chemical shifts are given in
δ relative to TMS, the coupling constants J are given in Hz. High resolution mass spectra were recorded
on an ESIꢀQꢀTOF mass spectrometry. All reactions under air atmosphere were conducted using standard
Schlenk techniques. Melting points were measured on X4 melting point apparatus and uncorrected.
Column chromatography was performed using EM Silica gel 60 (300ꢀ400 mesh).
General Procedure for the Synthesis of Trifiuoromethylacetanilides 1:
To a stirred suspension of 3,3,3ꢀtrifluoropropionic acid (0.58 mL, 6.5 mmol) in dichloromethane (20
mL) was added oxalyl chloride (0.52 mL, 6 mmol) followed by three drops of DMF at 0 °C. The
reaction mixture was stirred at rt for 3 h. To this solution was added a solution of anilines (5 mmol) in
dichloromethane (10 mL) followed by triethylamine (1.74 mL, 12.5 mmol) at 0 °C. The reaction
mixture was stirred for 12–24 hours and then washed with water (15 mL) and 1N HCl (15 mL). The
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organic layer was dried over Na2SO4 and evaporated to afford residue, which was purified by flash
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column chromatography (hexane/ethyl acetate) to afford trifiuoromethylacetanilides 1.15
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General Procedure for the Synthesis of Cyanoformamides 2:
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To a flameꢀdried Schlenk tube with a magnetic stirring bar was charged with 1 (0.2 mmol), TBN (0.8
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mmol), Cs2CO3 (130.4 mg, 0.4 mmol), HOAc (24 mg, 0.4 mmol), 4Å MS (100 mg) in dry MeCN (2
mL) under air atmosphere. The reaction mixture was stirred at 100 °C until complete consumption of
the starting material as detected by TLC or GCꢀMS analysis. After the reaction equilibrium, the mixture
was poured into ethyl acetate, which was washed with saturated NaHCO3 (2 x 10 mL) and then brine (1
x 10 mL). After the aqueous layer was extracted with ethyl acetate, the combined organic layers were
dried over anhydrous MgSO4 and evaporated under vacuum. The residue was purified by flash column
chromatography (hexane/ethyl acetate) to afford the desired products. A rotamerization of amide 2 was
observed in NMR spectra.
methyl(phenyl)carbamoyl cyanide (2a, 1:14)12c: White solid (29.1 mg, 91% yield), mp 61ꢀ62 °C
(uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.45ꢀ7.40 (m, 3H), 7.25ꢀ7.23 (m, 2H), 3.57 (s, 0.2H), 3.29
(s, 2.8H); 13C NMR (125 MHz, CDCl3) δ 144.6, 139.8, 130.1, 129.8, 127.0, 110.6, 36.8; LRMS (EI, 70
eV) m/z (%): 160 (M+, 100), 132 (38), 106 (16), 91 (48).
methyl(pꢀtolyl)carbamoyl cyanide (2b, 1:14)12c: Yellow solid (27.5 mg, 79% yield), mp 80ꢀ82 °C
(uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.29 (d, J = 8.5 Hz, 2H), 7.19 (d, J = 8.5 Hz, 2H), 3.63 (s,
0.2H), 3.34 (s, 2.8H), 2.41 (s, 2.8H), 2.37 (s, 0.2H). 13C NMR (125 MHz, CDCl3) δ 144.7, 140.0, 137.3,
130.7, 126.8, 110.7, 36.8, 21.2; LRMS (EI, 70 eV) m/z (%): 174 (M+, 100), 146 (17), 105 (58).
1
(4ꢀmethoxyphenyl)(methyl)carbamoyl cyanide (2c, 1:14)12c: Brown oil (30.8 mg, 81% yield); H NMR
(500 MHz, CDCl3) δ 7.22 (d, J = 9.0 Hz, 2H), 6.98 (d, J = 9.0 Hz, 2H), 3.84 (s, 2.8H), 3.82 (s, 0.2H),
13
3.61 (s, 0.2H), 3.32 (s, 2.8H); C NMR (125 MHz, CDCl3) δ 160.3, 144.8, 132.4, 128.3, 115.2, 110.7,
55.5, 36.9; LRMS (EI, 70 eV) m/z (%): 190 (M+, 100), 159 (8), 120 (25).
(4ꢀfluorophenyl)(methyl)carbamoyl cyanide (2d, 1:14): Yellow solid (28.5 mg, 80% yield), mp 85ꢀ87
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°C (uncorrected); H NMR (500 MHz, CDCl3) δ 7.34ꢀ7.30 (m, 2H), 7.22ꢀ7.18 (m, 2H), 3.63 (s, 0.2H),
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3.34 (s, 2.8H); 13C NMR (125 MHz, CDCl3) δ 162.9 (d, J = 254.0 Hz), 144.6, 135.9, 129.2, 117.3 (d, J
= 23.0 Hz), 110.4, 36.8; LRMS (EI, 70 eV) m/z (%): 178 (M+, 100), 150 (11), 124 (39), 109 (27);
HRMS (ESI) calcd for C9H7FN2ONa+ ([M + Na]+) 201.0435, found 201.0431.
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(4ꢀchlorophenyl)(methyl)carbamoyl cyanide (2e, 1:14)12c: Yellow oil (32.2 mg, 83% yield); H NMR
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(500 MHz, CDCl3) δ 7.49 (d, J = 9.0 Hz, 2H), 7.27 (d, J = 9.0 Hz, 2H), 3.65 (s, 0.2H), 3.35 (s, 2.8H);
13C NMR (125 MHz, CDCl3) δ 144.4, 138.3, 135.9, 130.4, 128.4, 110.4, 36.8; LRMS (EI, 70 eV) m/z
(%): 194 (M+, 100), 166 (12), 131 (23), 125 (21).
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(4ꢀbromophenyl)(methyl)carbamoyl cyanide (2f, 1:14)12c: Yellow solid (36.7 mg, 77% yield), mp 105ꢀ
107 °C (uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.64 (d, J = 9.0 Hz, 2H), 7.21 (d, J = 9.0 Hz, 2H),
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3.64 (s, 0.2H), 3.35 (s, 2.8H); C NMR (125 MHz, CDCl3) δ 144.3, 138.9, 133.5, 128.6, 123.9, 110.4,
36.7; LRMS (EI, 70 eV) m/z (%): 240/238 (M+, 48), 184 (13), 131 (14), 105 (28), 67(100).
methyl(4ꢀ(trifluoromethyl)phenyl)carbamoyl cyanide (2g, 1:14): Yellow solid (18.7 mg, 41% yield), mp
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81ꢀ83 °C (uncorrected); H NMR (500 MHz, CDCl3) δ 7.70 (d, J = 8.5 Hz, 2H), 7.40 (d, J = 8.5 Hz,
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2H), 3.60 (s, 0.2H), 3.30 (s, 2.8H); C NMR (125 MHz, CDCl3) δ 144.1, 142.9, 131.7 (q, JCꢀF = 33.0
Hz), 127.5, 127.4, 123.4 (q, JCꢀF = 270.1 Hz), 110.4, 36.6; LRMS (EI, 70 eV) m/z (%): 228 (M+, 100),
200 (28), 174 (15), 159 (24), 145 (44); HRMS (ESI) calcd for C10H8F3N2O+ ([M + H]+) 229.0583, found
229.0580.
(4ꢀ(methoxycarbonyl)phenyl)(methyl)carbamoyl cyanide (2h, 1:14): White solid (19.6 mg, 45% yield),
mp 75ꢀ76 °C (uncorrected); 1H NMR (500 MHz, CDCl3) δ 8.18 (d, J = 8.5 Hz, 2H), 7.42 (d, J = 8.5 Hz,
13
2H), 3.96 (s, 2.8H), 3.93 (s, 0.2H), 3.70 (s, 0.2H), 3.40 (s, 2.8H); C NMR (125 MHz, CDCl3) δ 165.7,
144.2, 143.5, 131.5, 126.9, 124.5, 110.4, 52.5, 36.6; LRMS (EI, 70 eV) m/z (%): 218 (M+, 100), 187
+
(94), 121 (56); HRMS (ESI) calcd for C11H11N2O3 ([M + H]+) 219.0764, found 219.0772.
(4ꢀacetylphenyl)(methyl)carbamoyl cyanide (2i, 1:14): Yellow solid (21.8 mg, 54% yield), mp 121ꢀ123
°C (uncorrected); 1H NMR (500 MHz, CDCl3) δ 8.09 (d, J = 8.5 Hz, 2H), 7.45 (d, J = 8.5 Hz, 2H), 3.70
13
(s, 0.2H), 3.40 (s, 2.8H), 2.65(s, 2.8H), 2.61(s, 0.2H); C NMR (125 MHz, CDCl3) δ 196.5, 144.1,
143.6, 137.8, 130.1, 127.0, 110.4, 36.6, 26.7; LRMS (EI, 70 eV) m/z (%): 202 (M+, 48), 187 (100), 121
(33); HRMS (ESI) calcd for C11H10N2O2Na+ ([M + Na]+) 225.0634, found 225.0638.
[1,1'ꢀbiphenyl]ꢀ4ꢀyl(methyl)carbamoyl cyanide (2j, 1:14)12c: White solid (24.1 mg, 51% yield), mp 151ꢀ
153 °C (uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.63 (d, J = 8.5 Hz, 2H), 7.52 (d, J = 8.5 Hz, 2H),
13
7.41ꢀ7.38 (m, 2H), 7.32ꢀ7.29(m, 3H), 3.62 (s, 0.2H) 3.32 (s, 2.8H); C NMR (125 MHz, CDCl3) δ
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144.6, 142.8, 139.5, 138.9, 129.0, 128.8, 128.1, 127.3, 127.2 110.7, 36.8; LRMS (EI, 70 eV) m/z (%):
236 (M+, 100), 207 (20), 182 (21), 170 (29), 167 (29), 154 (21), 152(48), 67(60).
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methyl(mꢀtolyl)carbamoyl cyanide (2k, 1:14)12c: Yellow oil (23.7 mg, 68% yield); H NMR (500 MHz,
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CDCl3) δ 7.39ꢀ7.36 (m, 1H), 7.28ꢀ7.26(m, 1H), 7.11ꢀ7.10 (m, 2H), 3.63 (s, 0.2H), 3.34 (s, 2.8H), 2.41
13
(s, 2.8H), 2.37 (s, 0.2H),. C NMR (125 MHz, CDCl3) δ 144.6, 140.4, 139.8, 130.5, 129.8, 127.5,
124.0, 110.7, 36.7, 21.2; LRMS (EI, 70 eV) m/z (%): 174 (M+, 100), 146 (36), 105 (96).
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(3ꢀmethoxyphenyl)(methyl)carbamoyl cyanide (2l, 1:14): Yellow solid (24.7 mg, 65% yield), mp 77ꢀ78
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°C (uncorrected); H NMR (500 MHz, CDCl3) δ 7.41ꢀ7.38 (m, 1H), 7.01ꢀ7.00 (m, 1H), 6.91ꢀ6.89 (m,
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1H), 6.83 (s, 1H), 3.84 (s, 2.8H), 3.80 (s, 0.2H), 3.63 (s, 0.2H), 3.35 (s, 2.8H); C NMR (125 MHz,
CDCl3) δ 160.7, 144.5, 140.8, 130.9, 119.1, 115.3, 112.9, 110.7, 55.6, 36.7; LRMS (EI, 70 eV) m/z (%):
+
190 (M+, 100), 159 (72), 120 (56); HRMS (ESI) calcd for C10H11N2O2 ([M + H]+) 191.0815, found
191.0814.
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(3ꢀchlorophenyl)(methyl)carbamoyl cyanide (2m, 1:14)12c: Yellow oil (29.1 mg, 75% yield); H NMR
(500 MHz, CDCl3) δ 7.49ꢀ7.44 (m, 2H), 7.34 (s, 1H), 7.25ꢀ7.23 (m, 1H), 3.65 (s, 0.2H), 3.36 (s, 2.8H);
13C NMR (125 MHz, CDCl3) δ 144.3, 140.9, 135.7, 131.2, 130.1, 127.4, 125.5, 110.4, 36.8; LRMS (EI,
70 eV) m/z (%): 194 (M+, 100), 166 (46), 131 (32), 125 (50).
methyl(oꢀtolyl)carbamoyl cyanide (2n, 1:14)12c: Yellow solid (24.7 mg, 71% yield), mp 75ꢀ76 °C
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(uncorrected); H NMR (500 MHz, CDCl3) δ 7.41ꢀ7.32 (m, 3H), 7.22 (d, J = 7.0 Hz, 1H), 3.55 (s,
0.2H), 3.28 (s, 2.8H), 2.30 (s, 2.8H), 2.20 (s, 0.2H); 13C NMR (125 MHz, CDCl3) δ 145.1, 138.6, 136.1,
131.9, 130.4, 128.4, 127.9, 110.6, 35.8, 17.2; LRMS (EI, 70 eV) m/z (%): 174 (M+, 100), 157 (88), 146
(33), 118 (50).
(2ꢀmethoxyphenyl)(methyl)carbamoyl cyanide (2o, 1:29): Yellow solid (29.3 mg, 77% yield), mp 74ꢀ76
°C (uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.46ꢀ7.43 (m, 1H), 7.26ꢀ7.24 (m, 1H), 7.06ꢀ7.03 (m,
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2H), 3.89 (s, 2.9H), 3.85 (s, 0.1H), 3.53 (s, 0.1H), 3.26 (s, 2.9H); C NMR (125 MHz, CDCl3) δ 155.5,
145.8, 131.4, 129.0, 128.4, 121.3, 112.4, 110.9, 55.7, 35.7; LRMS (EI, 70 eV) m/z (%): 190 (M+, 100),
+
159 (90), 120 (88); HRMS (ESI) calcd for C10H11N2O2 ([M + H]+) 191.0815, found 191.0810.
(2ꢀfluorophenyl)(methyl)carbamoyl cyanide (2p, 1:14): Yellow solid (30.6 mg, 86% yield), mp 81ꢀ83
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°C (uncorrected); H NMR (500 MHz, CDCl3) δ 7.52ꢀ7.47 (m, 1H), 7.38ꢀ7.35 (m, 1H), 7.30ꢀ7.26 (m,
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2H), 3.61 (s, 0.2H), 3.34 (s, 2.8H); C NMR (125 MHz, CDCl3) δ 158.2 (d, J = 250.6 Hz), 144.9,
131.9, 129.6, 127.5 (d, J = 12.8 Hz), 125.1, 117.4 (d, J = 19.5 Hz), 110.3, 36.2; LRMS (EI, 70 eV) m/z
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(%): 178 (M+, 100), 159 (24), 124 (25), 109 (30); HRMS (ESI) calcd for C9H7FN2ONa+ ([M + Na]+)
201.0435, found 201.0443.
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(2ꢀchlorophenyl)(methyl)carbamoyl cyanide (2q, 1:14): Yellow oil (29.5 mg, 76% yield); 1H NMR (500
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MHz, CDCl3) δ 7.50ꢀ7.48 (m, 1H), 7.40ꢀ7.30 (m, 3H), 3.48 (s, 0.2H), 3.21 (s, 2.8H); C NMR (125
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MHz, CDCl3) δ 145.0, 137.2, 133.3, 131.6, 131.1, 130.1, 128.7, 110.3, 36.6; LRMS (EI, 70 eV) m/z
(%): 194 (M+, 100), 166 (68), 131 (43), 125 (63); HRMS (ESI) calcd for C9H7ClN2ONa+ ([M + Na]+)
217.0139, found 217.0131.
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methyl(naphthalenꢀ1ꢀyl)carbamoyl cyanide (2r, 1:29): Yellow oil (28.1 mg, 67% yield); H NMR (500
MHz, CDCl3) δ 7.94ꢀ7.89 (m, 2H), 7.65 (d, J = 8.0 Hz, 1H), 7.60ꢀ7.52 (m, 2H), 7.50ꢀ7.47 (m, 1H), 7.42
13
(d, J = 7.5 Hz, 1H), 3.65 (s, 0.1H), 3.39 (s, 2.9H); C NMR (125 MHz, CDCl3) δ 145.6, 136.0, 134.8,
130.8, 130.0, 129.0, 128.3, 127.3, 126.6, 125.6, 121.3, 110.6, 36.8; LRMS (EI, 70 eV) m/z (%): 210
(M+, 97), 182 (20), 154 (38), 141 (21), 128 (54), 115 (37), 67 (100); HRMS (ESI) calcd for
C13H10N2ONa+ ([M + Na]+) 233.0685, found 233.0692.
ethyl(phenyl)carbamoyl cyanide (2s, 1:9)12c: Yellow solid (21.6 mg, 62% yield) , mp 94ꢀ95 °C
(uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.53ꢀ7.45 (m, 3H), 7.31ꢀ7.26 (m, 2H), 4.04 (q, J = 7.0 Hz,
0.2H), 3.83 (q, J = 7.0 Hz, 1.8H), 1.29 (t, J = 7.0 Hz, 0.3H), 1.18 (t, J = 7.0 Hz, 2.7H); 13C NMR (125
MHz, CDCl3) δ 144.3, 138.3, 130.1, 129.9, 128.2, 110.6, 44.4, 12.4; LRMS (EI, 70 eV) m/z (%): 174
(M+, 100), 159 (71), 146 (28), 118 (55), 105 (69).
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hexyl(phenyl)carbamoyl cyanide (2t, 1:9): Yellow oil (21.6 mg, 47% yield); H NMR (500 MHz,
CDCl3) δ 7.46ꢀ7.39 (m, 3H), 7.21 (d, J = 7.5 Hz, 2H), 3.90 (t, J = 7.5 Hz, 0.2H) 3.69 (t, J = 7.5 Hz,
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1.8H), 1.49ꢀ1.43 (m, 2H), 1.24ꢀ1.19 (m, 6H), 0.80ꢀ0.78 (m, 3H); C NMR (125 MHz, CDCl3) δ 144.6,
138.6, 130.1, 129.8, 128.1, 110.7, 49.4, 31.3, 27.1, 26.2, 22.4, 13.9; LRMS (EI, 70 eV) m/z (%): 230
(M+, 26), 188 (20), 159 (100), 146 (51), 132 (33), 119 (28), 105 (66); HRMS (ESI) calcd for
C14H18N2ONa+ ([M + Na]+) 253.1311, found 253.1311.
isopropyl(phenyl)carbamoyl cyanide (2u): Yellow solid (26.7 mg, 71% yield), mp 92ꢀ94 °C
(uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.47ꢀ7.40 (m, 3H), 7.20ꢀ7.16 (m, 2H), 4.73 (hept, J = 7.0
13
Hz, 1H), 1.09 (d, J = 7.0 Hz, 6H); C NMR (125 MHz, CDCl3) δ 144.7, 135.3, 130.3, 130.2, 129.8,
110.7, 48.6, 20.4; LRMS (EI, 70 eV) m/z (%): 188 (M+, 100), 173 (52), 146 (59), 119 (67); HRMS
(ESI) calcd for C11H13N2O+ ([M + H]+) 189.1022, found 189.1029.
benzyl(phenyl)carbamoyl cyanide(2v, 1:19): Yellow solid (31.2 mg, 66% yield), mp 119ꢀ
121 °C(uncorrected); 1H NMR (500 MHz, CDCl3) δ 7.45ꢀ7.39 (m, 3H), 7.30ꢀ7.29 (m, 3H), 7.17ꢀ7.15 (m,
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2H), 7.10ꢀ7.08 (m, 2H), 5.14 (s, 0.1H), 4.91 (s, 1.9H); C NMR (125 MHz, CDCl3) δ 144.9, 138.3,
134.6, 130.0, 129.98, 129.1, 128.8, 128.43, 128.35, 110.6, 53.1; LRMS (EI, 70 eV) m/z (%): 236 (M+,
91), 119 (100), 91 (97); HRMS (ESI) calcd for C15H13N2O+ ([M + H]+) 237.1022, found 237.1025.
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dihexylcarbamoyl cyanide (2w): Colourless oil (18.1 mg, 38% yield); H NMR (500 MHz, CDCl3) δ
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3.47 (t, J = 7.0 Hz, 2H), 3.29 (t, J = 7.0 Hz, 2H), 1.58ꢀ1.48 (m, 4H), 1.26ꢀ1.19 (m, 12H), 0.83ꢀ0.81 (m,
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6H); C NMR (125 MHz, CDCl3) δ 144.8, 110.9, 49.1, 45.4, 31.3, 31.2, 28.8, 27.0, 26.4, 26.1, 22.44,
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22.43, 13.89, 13.86; LRMS (EI, 70 eV) m/z (%): 238 (M+, 1), 166 (51), 96 (100), 83 (50), 55 (28);
HRMS (ESI) calcd for C14H27N2O+ ([M +H]+) 239.2118, found 239.2125.
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dibenzylcarbamoyl cyanide (2x)12c: Yellow oil (26.5 mg, 53% yield); H NMR (500 MHz, CDCl3) δ
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7.30ꢀ7.20 (m, 6H), 7.13ꢀ7.07 (m, 4H), 4.52 (s, 2H), 4.36 (s, 2H); C NMR (125 MHz, CDCl3) δ 145.3,
134.4, 133.8, 129.3, 129.1, 128.9, 128.7, 128.5, 127.9, 110.9, 51.4, 47.1; LRMS (EI, 70 eV) m/z (%):
250 (M+, 10), 159 (52), 109 (38), 92 (89), 91 (100), 79 (34), 65 (27).
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diphenylcarbamoyl cyanide(2y): Yellow oil (18.7 mg, 42% yield); H NMR (500 MHz, CDCl3) δ 7.44ꢀ
7.41 (m, 3H), 7.33ꢀ7.29 (m, 4H), 7.22ꢀ7.20 (m, 3H); 13C NMR (125 MHz, CDCl3) δ 143.9, 139.4, 139.1,
130.3, 130.0, 129.4, 128.7, 127.8, 125.1, 110.9; LRMS (EI, 70 eV) m/z (%): 222 (M+,95), 193 (28), 167
(45), 128 (100), 77 (47); HRMS (ESI) calcd for C14H11N2O+ ([M + H]+) 223.0866, found 223.0856.
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dibenzylcarbamoyl cyanide (3z)16: Yellow solid (18.5 mg, 68% yield), mp 161ꢀ164 °C; H NMR (500
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MHz, CDCl3) δ 7.94 (s, 1H), 7.42 (d, J = 7.8 Hz, 2H), 7.20 (m, 2H), 7.00 (m, 1H), 2.06 (s, 3H); C
NMR (125 MHz, CDCl3) δ 168.9, 138.0, 128.9, 124.3, 120.1, 24.4; LRMS (EI, 70 eV) m/z (%): 135
(M+, 58), 93 (100), 77 (7), 65 (5).
Acknowledgment. We thank the National Natural Science Foundation of China (No. 21272177) and
Natural Science Foundation of Zhejiang Province (No. LR15B020002) for financial support.
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Supporting Information Available: Copies of H and C NMR spectra for product 2aꢀ2y and 3z.
This material is available free of charge via the Internet at http://pubs.acs.org.
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