Silver-catalyzed 2-isocyanobiaryls insertion/cyclization with phosphine oxides: Synthesis of 6-phosphorylated phenanthridines

Article abstract of DOI:10.1016/j.tet.2014.07.078

A silver-catalyzed 2-isocyanobiaryls insertion/cyclization with phosphine oxides was described for the construction of the 6-phosphorylated phenanthridines through radical addition of in situ formed P-centered radical to 2-isocyanobiphenyls and homolytic

Full text of DOI:10.1016/j.tet.2014.07.078

Tetrahedron 70 (2014) 6985e6990
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Silver-catalyzed 2-isocyanobiaryls insertion/cyclization with
phosphine oxides: synthesis of 6-phosphorylated phenanthridines
*
*
Jia-Jia Cao, Tong-Hao Zhu, Zheng-Yang Gu, Wen-Juan Hao, Shun-Yi Wang , Shun-Jun Ji
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University,
Suzhou 215123, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 May 2014
Received in revised form 14 July 2014
Accepted 21 July 2014
Available online 24 July 2014
A silver-catalyzed 2-isocyanobiaryls insertion/cyclization with phosphine oxides was described for the
construction of the 6-phosphorylated phenanthridines through radical addition of in situ formed P-
centered radical to 2-isocyanobiphenyls and homolytic aromatic substitution process. The reactions
could proceed smoothly to give the desired 6-phosphorylated phenanthridines promoted by AgOAc
(20 mol %) with PhI(OAc)2 (3.0 equiv).
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Silver-catalyzed
Isocyanobiaryls insertion
Phosphine oxides
6-Phosphorylated phenanthridines
1. Introduction
Isocyanides have been used as useful building blocks for the
synthesis of broad varieties of peptides and peptide mimetics based
on the pioneer Ugi reaction.1 With the new development of iso-
cyanide chemistry, it got a renaissance during the past 15 years.2
New isocyanide-based multicomponent reactions, transition-
metal-catalyzed isocyanide insertion reaction, and somophiliciso-
cyanide insertion reaction have become increasingly popular.3e5
Phenanthridine derivatives are very important core scaffolds with
versatile biological activities such as anti-bacterial, cytotoxic, DNA
intercalator, and antitumoral (Fig.1). The remarkable biological
profiles stimulated people to explore efficient methods for the
synthesis of these compounds.6 Recently, Chatani’s group has re-
ported the synthesis of phenanthridine derivatives by Mn(acac)3
mediated annulation of 2-isocyanobiphenyls with arylboronic
acid.7 Studer’s group8 and Zhou’s group9 have independently re-
ported the formation of 6-trifluoromethyl-phenanthridines
through radical trifluoromethylation of 2-isocyanobiphenyls. It’s
interesting that Yu and co-workers have reported the synthesis of
6-alkylated phenanthridines through photoredox neutral iso-
cyanide insertions almost at the same time.10
Fig. 1. Selected phenanthridine derivatives.
phosphorylated oxindoles through the in situ generated Ph2P(O)Ag
from Ph2P(O)H.11 Almost at the same time, Duan group has re-
ported the silver-promoted oxidative CeH/PeH functionalization of
arylphosphine oxides with internal alkynes.12 More recently,
Studer’s group and Yang’s group have reported excess Ag-mediated
2-isocyanobiaryls insertion reactions with phosphine oxides, in-
dependently.13 However, these conditions utilizing stoichiometric
amounts of silver salts as the radical initiator and oxidant limited
their applications. As a continuation of our works on the con-
struction of 6-alkyl phenanthridines by tert-butyl benzoperoxoate
Yang’s group has reported that silver salt could catalyze car-
bonephosphorus functionalization of alkenes to synthesis of
* Corresponding authors. E-mail addresses: shunjun@suda.edu.cn, chemjsj@
suda.edu.cn (S.-J. Ji).
http://dx.doi.org/10.1016/j.tet.2014.07.078
0040-4020/Ó 2014 Elsevier Ltd. All rights reserved.

6986
J.-J. Cao et al. / Tetrahedron 70 (2014) 6985e6990
(TBPB) mediated 2-isocyanobiaryls insertion with 1,4-dioxane14
and a novel phosphinylation of -diarylallylic alcohols via 1,2-
aryl migration of an aryl group,15 herein, we disclose the con-
struction of 6-phosphorylated phenanthridines by 2-
a,a
isocyanobiaryls insertion/cyclization with phosphine oxides uti-
lizing a catalytic amount of AgOAc in the presence of PhI(OAc)2
(Scheme 1).
Fig. 2. Crystal structure of 3a.
promising results push us to try the reaction utilizing other dif-
ferent oxidants such as PhI(OAc)2, O2, BQ, TEMPO, as well as
Cu(OAc)2$H2O (Table 2, entries 1e15). The screening results in-
dicated that PhI(OAc)2 (2.0 equiv) was the best oxidant, which
leading to 3a in 57% LC yield (Table 1, entry 2). Further screening of
the amount of AgOAc and PhI(OAc)2 established the competitive
optimized condition (Table 1, entries 16e21). Compound 3a could
be formed in 73% LC yield catalyzed by 20 mol % AgOAc in the
presence of 3.0 equiv PhI(OAc)2 (Table 1, entry 17). When the re-
action was conducted under O2 atmosphere, it was found that 3a
could be produced in only 52% LC yield (Table 1, entry 22). Notably,
when the reaction was carried out in an increased time, 83% LC
yield of 3a could be obtained (61% isolated yield) (Table 1, entry 24).
Scheme 1. Phenanthridines synthesis via somophilicisocyanide insertion.
2. Results and discussion
Our initial efforts were focused on using a catalytic amount of
AgOAc in the presence of different simple oxidants (Table 1). Ex-
citingly, when the model reaction of 1a with 2a catalyzed by
20 mol % AgOAc in the presence of 2.0 equiv K2S2O8, the desired
product 3a could be obtained in 34% LC yield (Table 1, entry 1),
which was further confirmed by X-ray analysis (Fig. 2). This
Table 2
Screening of reaction conditions (in situ oxidation of iodo(I)arenes to iodine(III)
species)a
Table 1
Screening of reaction conditions in the presence of a catalytic amount of AgOAca
Entry
Cat. (mol %)
RI (equiv)
Oxidant (equiv)
Yieldb (%)
Entry
Cat. (mol %)
Oxidant (equiv)
Time (h)
Yieldb (%)
1
2
3
4
5
6
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
d
AcOOH (3)
AcOOH (3)
m-CPBA (3)
AcOOH (3)
AcOOH (2)
AcOOH (6)
AcOOH (3)
AcOOH (3)
AcOOH (3)
34
45
Trace
44
39
29
48
41
37
PhI (1)
PhI (1)
DIBP (1)
PhI (1)
PhI (1)
PhI (1)
PhI (1)
PhI (0.1)
1
2
3
4
5
6
7
8
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (20)
AgOAc (15)
AgOAc (10)
AgOAc (5)
K2S2O8 (2)
PhI(OAc)2 (2)
O2 (1 atm)
TBHP (2)
TBPB (2)
DTBP (2)
CHP (2)
BQ (2)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3.5
34
57
29
51
47
33
38
7
7c
8d
9c
9
TEMPO (2)
23
47
36
40
42
33
30
56
73
66
54
49
41
52
25
83(61e)
a
Reaction conditions: 1a (1.0 equiv), 2a (2.5 equiv), AgOAc (20 mol %), RI, and
oxidant in DMF (2 mL) with stirring at 100 ꢀ C under argon for 3.5 h.
10
11
12
13
14
15
16
17
18
19
20
21
22c
23d
24
Zn(NO3)2$6H2O (2)
Zn(OAc)2$H2O (2)
ZnCl2 (2)
b
Yields were determined by LC with an internal standard (benzophenone) as the
ratio between the formed products and the initial amount of limiting reactant.
ZnO (2)
c
The mixture of PhI and AcOOH was stirred for 10 min, then the others were
Cu(OAc)2$H2O (2)
Cu(NO3)2$H2O (2)
PhI(OAc)2 (1)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
PhI(OAc)2 (3)
added.
d
The mixture of PhI and AcOOH was stirred for 30 min, then the others were
added. DIBP¼2,20-diiodo-1,10-biphenyl.
In the light of literature, (diacetoxy)iodobenzene can be ach-
ieved by in situ oxidation of iodo(I)arenes to iodine(III) species. We
have also tried the reaction in the presence of 1 equiv PhI and
3 equiv peracetic acid instead of 3.0 equiv PhI(OAc)2 (Table 2). To
our delight, the desired product 3a could be formed in up to 48% LC
yield (Table 2, entry 7), even the yield is lower than the yield of the
reaction utilizing PhI(OAc)2.
With the optimal conditions in hand, we investigated the scope
of various substrates. The results are listed in Table 3. Firstly, the 2-
isocyanobiaryl substrates
AgOAc (0)
AgOAc (20)
AgOAc (20)
AgOAc (20)
a
Reaction conditions: 1a (1.0 equiv), 2a (2.5 equiv), catalyst, and oxidant in DMF
(2 mL) with stirring at 100 ꢀ C under argon.
b
Yields were determined by LC with an internal standard (benzophenone) as the
ratio between the formed products and the initial amount of limiting reactant.
c
Under O2 atmosphere.
Et3N as solvent.
Isolated yield.
d
e
1 bearing electron-withdrawing or

J.-J. Cao et al. / Tetrahedron 70 (2014) 6985e6990
6987
Table 3
The reaction of 1with 2a
Scheme 2. The reaction of 1a with 2bed.
benzo[c][1,5]naphthyridin-6-yldiphenylphosphine oxide 6 in 68%
yield (Scheme 3).
Scheme 3. The reaction of 5 with 2a.
Based on the literature and the above results, we supposed that
catalytic amount of Ag(I) can be reformed in the presence of excess
PhI(OAc)2.
3. Conclusion
In summary, we have described a simple and efficient silver-
catalyzed 2-isocyanobiaryls insertion/cyclization with phos-
phine oxides, furnishing the 6-phosphorylated phenanthridines
in moderate to good yields. This method avoided using stoi-
chiometric amounts of silver. In the light of important biological
properties of phenanthridine derivatives and aromatic organo-
phosphorus compounds, 6-phosphorylatedphenanthridine de-
rivatives have the potential biological properties and to be used
as N,P,O-ligand.
electron-donating substituents at the arene without the isonitrile
function group were applied to the reaction and reacted with
diphenylphosphine 2a well to form the desired products 3aeg in
45e75% yield. The reaction of 2-isocyano-30-methyl-1,10-biphenyl
1g with 2a leaded to the corresponding regioselective products 3g
and 3g0 (2:1) with 72% total yield. Then, 2-isocyanobiaryls 2-(2-
isocyanophenyl)naphthalene 1h and 9-(2-isocyanophenyl)phen-
anthrene 1i were applied to the reactions with 2a, the desired
products 3h and 3i could be isolated in 40% and 49% yields, re-
spectively. Finally, we investigated the electron effects on the arene
with isonitrile function group. It was found that 5-methyl
substituted 2-isocyanobiaryl 1j reacted well with 2a to afford 3j
in the highest yield (70%). The substrates bearing F, Cl or OMe could
also couple with 2a to afford the desired products in moderate
yields (56e65%). To our delight, the reaction of 2-isocyano-5-nitro-
1,10-biphenyl 1n with strong electron-withdrawing group could
also afford the desired product in 30% yield (only trace amount of
3n was formed when 4 equiv AgOAc was employed as the oxidant).
The reactions of 1a with other phosphine oxides such as
monophenylphosphine oxide 2b could also undergo well to afford
4a in 80% yield. When diethyl phosphonate 2c and dimethyl
phosphonate 2d were applied to the reaction, the yields of 4b and
4c were decreased to 32% and 33%, respectively. It might be due to
the poor stability the corresponding phosphorus radical in-
termediate (Scheme 2).
4. Experimental section
4.1. General
Melting points were recorded on an Electrothermal digital
melting point apparatus and were uncorrected. IR spectra were
recorded on a Varian FT-1000 spectrophotometer using KBr optics.
1H NMR and 13C NMR spectra were recorded on a Varian INOVA 400
or 600 MHz (1H NMR), 101 or 151 MHz (13C NMR) and 162 or
243 MHz (31P NMR) spectrometer using CDCl3 as solvent and TMS
as internal standard. High-resolution mass spectra were obtained
using GCT-TOF instrument with CI source.
4.2. Typical procedure for carbon phosphorylation of
isocyanides
To a mixture of isocyanide 1 (0.5 mmol) and disubstituted
phosphine oxide 2a (2.5 equiv), AgOAc (20 mol %), PhI(OAc)2
(3.0 equiv), and DMF (3 mL) were added into a Schlenk tube under
argon atmosphere. Then the mixture was vigorously stirred under
at 100 ꢀC for 3 h (monitored by TLC). After removing the solvents in
vacuo, the residue was directly purified by flash column
It’s interesting to note that the reaction of 3-isocyano-2-
phenylpyridine 5 with 2a could also furnish the desired product

6988
J.-J. Cao et al. / Tetrahedron 70 (2014) 6985e6990
chromatography by using ethyl acetate and petroleum ether as
eluents to afford pure product.
132.87 (s), 132.3 (d, JCeP¼9.2 Hz), 132.2 (s), 131.8 (d, JCeP¼1.8 Hz),
131.2 (s), 129.2 (s), 128.6 (s), 128.2 (d, JCeP¼12.2 Hz), 124.6 (d,
JCeP¼8.4 Hz, 3H), 124.0 (s), 121.9 (s), 120.5 (d, JCeF¼24.4 Hz), 113.2
4.2.1. 6-(Diphenylphosphoryl)phenanthridine (3a). Yield 116 mg,
(d, JCeF¼23.2 Hz). 31P NMR (243 MHz, CDCl3) (
d, ppm): 27.63; IR
61%. White solid. Mp 190e192 ꢀC; 1H NMR (400 MHz, CDCl3) (
d
,
(neat, n
, cmꢁ1) 1583, 1479, 1188, 844, 760, 694; HRMS calcd for
ppm): 9.42 (d, J¼8.3 Hz, 1H), 8.56 (d, J¼8.4 Hz, 1H), 8.53e8.48 (m,
1H), 7.97 (dd, J¼7.3, 2.1 Hz, 1H), 7.92e7.81 (m, 4H), 7.81e7.71 (m,
1H), 7.61 (tdd, J¼8.1, 6.6, 1.6 Hz, 3H), 7.48e7.40 (m, 2H), 7.40e7.32
C
25H18FNOPþ (CIþ, MþHþ): 398.1110; found: 398.1107.
4.2.5. 1-(6-(Diphenylphosphoryl)phenanthridin-8-yl)ethanone
(m, 4H); 13C NMR (101 MHz, CDCl3)
(d
,
ppm): 156.9 (d,
(3e). Yield 124 mg, 59%. White solid. Mp 215e216 ꢀC; 1H NMR
JCeP¼128.3 Hz), 142.7 (d, JCeP¼23.3 Hz, 0H), 133.4 (s), 132.6 (d,
JCeP¼6.9 Hz), 132.3 (d, JCeP¼9.2 Hz), 131.7 (d, JCeP¼2.8 Hz), 131.2
(d, JCeP, J¼1.3 Hz), 131.1 (s, 1H), 128.8 (d, JCeP¼12.0 Hz), 128.6 (s, 1H),
128.2 (dCeP, J¼12.2 Hz), 128.0 (s), 127.9 (s), 127.7 (s), 124.4 (d,
(400 MHz, CDCl3) (
d
, ppm): 10.22 (d, J¼1.6 Hz, 1H), 8.64 (dd, J¼8.8,
1.5 Hz, 1H), 8.56 (dd, J¼7.5, 2.1 Hz, 1H), 8.37 (dd, J¼8.7, 1.7 Hz, 1H),
8.13e8.03 (m, 1H), 7.95e7.85 (m, 4H), 7.84e7.68 (m, 2H), 7.48 (ddd,
J¼7.3, 4.9, 1.4 Hz, 2H), 7.44e7.37 (m, 4H), 2.68 (s, 3H); 13C NMR
JCeP¼2.4 Hz), 122.1 (d, JCeP¼2.9 Hz). 31P NMR (162 MHz, CDCl3) (
d
,
(101 MHz, CDCl3) (
d
, ppm): 197.9 (s), 157.3 (d, JCeP¼127.6 Hz), 143.6
ppm): 28.37; IR (neat,
n
, cmꢁ1) 1578, 1432, 1197, 1103, 760, 699;
(d, JCeP¼22.7 Hz), 135.7 (s), 135.7 (s), 133.1 (s), 132.3 (d,
JCeP¼9.3 Hz), 132.1 (s), 132.0 (d, JCeP¼2.7 Hz), 131.3 (d, JCeP¼1.0 Hz),
130.5 (s), 130.0 (s), 128.4 (d, JCeP¼12.2 Hz), 127.5 (d, JCeP¼23.1 Hz),
123.7 (d, JCeP¼2.4 Hz), 122.8 (s), 26.7 (s). 31P NMR (162 MHz, CDCl3)
HRMS calcd for C25H19NOPþ (CIþ, MþHþ): 380.1204; found:
380.1202. Crystal data for 3a,which have been deposited at the
Cambridge Crystallographic Data Centre as supplementary publi-
cation with no. CCDC 1002773. Copies of this information may be
obtained free of charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (e-mail: linstead@ccdc.cam.ac.uk or
deposit@ccdc.cam.ac.uk; fax: þ44 (0)1223 336033). Structural pa-
rameters for product 3a: data collection: Rigaku Mercury CCD area
detector; crystal size: 0.35ꢂ0.30ꢂ0.25 mm3; C25H18NOP,
Mr¼379.37, monoclinic, space group P21/c, a¼13.2043(19),
(d, ppm): 27.34; IR (neat, n
, cmꢁ1) 2932, 2853, 1726, 1442, 1113, 614,
684; HRMS calcd for C27H21NO2Pþ (CIþ, MþHþ): 422.1310; found:
422.1317.
4.2.6. 6-(Diphenylphosphoryl)-8-methylphenanthridine (3f). Yield
143 mg, 73%. White solid. Mp 206e208 ꢀC; 1H NMR (600 MHz,
CDCl3) (
d
, ppm): 9.23 (s, 1H), 8.52e8.40 (m, 2H), 7.96 (d, J¼8.1 Hz,
ꢀ
b¼8.39940(10), c¼17.2912(3) A, a¼90.00, b¼90.020(2), g¼90.00,
1H), 7.92e7.82 (m, 4H), 7.69e7.54 (m, 3H), 7.44 (dd, J¼10.7, 4.1 Hz,
3
V¼1917.74(5) A , Z¼4, Dc¼1.314 g cmꢁ3, R[I>2
s(I)]¼0.0278, wR
2H), 7.37 (td, J¼7.6, 2.7 Hz, 4H), 2.49 (s, 3H); 13C NMR (151 MHz,
ꢀ
[I>2s(I)]¼0.0188.
CDCl3) (
d
, ppm): 158.8 (s), 155.4 (d, JCeP¼129.4 Hz), 142.0 (d,
JCeP¼23.1 Hz), 133.0 (d, JCeP¼104.6 Hz), 132.3 (d, JCeP¼9.1 Hz), 131.7
(d, JCeP¼2.6 Hz), 131.1 (s), 129.4 (d, JCeP¼23.0 Hz), 128.8 (s), 128.2 (d,
JCeP¼12.1 Hz), 127.6 (s), 127.0 (d, JCeP¼6.8 Hz), 124.5 (d,
JCeP¼2.4 Hz),123.6 (s),122.6 (s),121.6 (s),107.5 (s), 55.6 (s). 31P NMR
4.2.2. 6-(Diphenylphosphoryl)-8-methoxyphenanthridine
(3b). Yield 154 mg, 75%. Light yellow solid. Mp 180e183 ꢀC; 1H
NMR (600 MHz, CDCl3) (
d
, ppm): 8.93 (s, 1H), 8.47 (d, J¼9.1 Hz, 1H),
8.43 (d, J¼8.1 Hz, 1H), 7.97 (d, J¼8.1 Hz, 1H), 7.89 (dd, J¼11.2, 7.9 Hz,
(243 MHz, CDCl3) (d, ppm): 28.25; IR (neat, n
, cmꢁ1) 3064, 2920,
4H), 7.62 (t, J¼7.5 Hz, 1H), 7.57 (t, J¼7.5 Hz, 1H), 7.44 (t, J¼7.4 Hz,
1574, 1442, 1192, 1108, 779, 694; HRMS calcd for C26H21NOPþ (CIþ,
2H), 7.41e7.33 (m, 5H), 3.86 (s, 3H); 13C NMR (151 MHz, CDCl3) (
d
,
MþHþ): 394.1361; found: 394.1359.
ppm): 158.8 (s), 155.4 (d, JCeP¼129.4 Hz), 142.0 (d, JCeP¼23.1 Hz),
133.0 (d, JCeP¼104.6 Hz), 132.3 (d, JCeP¼9.1 Hz), 131.7 (d,
JCeP¼2.6 Hz), 131.1 (s), 129.4 (d, JCeP¼23.0 Hz), 128.8 (s), 128.2 (d,
JCeP¼12.1 Hz), 127.6 (s), 127.0 (d, JCeP¼6.8 Hz), 124.5 (d,
JCeP¼2.4 Hz),123.6 (s),122.6 (s),121.6 (s),107.5 (s), 55.6 (s). 31P NMR
4.2.7. 6-(Diphenylphosphoryl)-9-methylphenanthridine
3g0). Yield 141 mg, 72%. White solid. Mp 182e184 ꢀC; 1H NMR
(600 MHz, CDCl3) (
(3g,
d
, ppm): 9.30 (d, J¼8.4 Hz, 1H), 8.52e8.43 (m,
2H), 8.34 (s, 1H), 7.95 (d, J¼8.9 Hz, 1H), 7.85 (dd, J¼11.5, 7.6 Hz, 4H),
7.72 (dd, J¼10.9, 8.0 Hz, 2H), 7.67 (d, J¼7.9 Hz, 0.48H), 7.64e7.57
(m, 3H), 7.54 (d, J¼7.2 Hz, 0.47H), 7.47e7.39 (m, 4H), 7.36 (dd,
J¼6.8, 5.2 Hz, 6H), 2.90 (s, 1H), 2.53 (s, 3H); 13C NMR (151 MHz,
(243 MHz, CDCl3) (d, ppm): 27.67; IR (neat, n
, cmꢁ1) 3093, 2924,
2858, 1621, 1527, 1465, 1225, 760, 689; HRMS calcd for
C
26H21NO2Pþ (CIþ, MþHþ): 410.1310; found: 410.1306.
CDCl3) (
d
, ppm): 156.8 (d, JCeP¼129.1 Hz), 156.5 (d, JCeP¼128.7 Hz),
4.2.3. 6-(Diphenylphosphoryl)-8,9-dimethoxyphenanthridine
142.9 (d, JCeP¼23.4 Hz), 141.56 (s), 141.1 (d, JCeP¼23.9 Hz), 137.8 (s),
134.8 (d, JCeP¼107.7 Hz), 134.1 (d, JCeP¼6.6 Hz), 133.3 (s), 132.8 (d,
JCeP¼6.9 Hz), 132.6 (s), 132.3 (d, JCeP¼9.2 Hz), 132.0 (d,
JCeP¼8.9 Hz), 131.6 (d, JCeP¼2.6 Hz), 131.6 (s), 131.2 (d,
JCeP¼2.5 Hz), 131.1 (s), 130.5 (s), 130.5 (s), 129.6 (s), 128.9 (s), 128.5
(s), 128.3 (s), 128.1 (d, JCeP¼12.2 Hz), 128.0 (d, JCeP¼12.3 Hz), 127.3
(d, JCeP¼23.4 Hz), 126.1 (d, JCeP¼23.3 Hz), 124.3 (d, JCeP¼2.5 Hz),
124.2 (d, JCeP¼2.3 Hz), 122.2 (s), 122.1 (s), 121.7 (d, JCeP¼0.9 Hz),
120.2 (d, JCeP¼1.6 Hz), 25.1 (s), 22.44 (s). 31P NMR (243 MHz,
(3c). Yield 136 mg, 62%. Yellow solid. Mp 222e224 ꢀC; 1H NMR
(600 MHz, CDCl3) (d, ppm): 9.01 (s, 1H), 8.37 (s, 1H), 7.97 (d,
J¼7.5 Hz, 1H), 7.92e7.86 (m, 4H), 7.82 (d, J¼4.3 Hz, 1H), 7.65e7.53
(m, 2H), 7.43 (dd, J¼10.4, 4.3 Hz, 2H), 7.37 (td, J¼7.5, 2.9 Hz, 4H),
4.04 (d, J¼2.8 Hz, 3H), 3.95 (s, 3H); 13C NMR (151 MHz, CDCl3) (
d,
ppm): 149.4 (d, JCeP¼129.9 Hz), 147.9 (s), 144.9 (s), 137.7 (d,
JCeP¼23.4 Hz),128.3 (d, JCeP¼104.3 Hz),127.6 (d, JCeP¼9.2 Hz),126.9
(d, JCeP¼2.7 Hz),126.8 (s),124.0 (d, JCeP¼7.2 Hz),123.5 (s),123.4 (dd,
JCeP¼8.9, 6.1 Hz), 123.0 (s), 119.3 (d, JCeP¼3.4 Hz), 119.1 (s), 116.9 (s),
103.0 (s), 96.9 (d, JCeP¼1.6 Hz), 51.4 (d, JCeP¼23.7 Hz). 31P NMR
CDCl3) (d, ppm): 36.18, 28.22; IR (neat, n
, cmꢁ1) 3083, 2933, 1621,
1437, 1202, 1103, 779, 694; HRMS calcd for C26H21NOPþ (CIþ,
(243 MHz, CDCl3) (
d
, ppm): 27.44; IR (neat,
n
, cmꢁ1) 3066, 3032,
MþHþ): 394.1361; found: 394.1362.
2934, 1621, 1527, 1437, 764; HRMS calcd for C27H23NO3Pþ (CIþ,
MþHþ): 440.1416; found: 440.1414.
4.2.8. 5-(Diphenylphosphoryl)benzo[i]phenanthridine
86 mg, 40%. White solid. Mp 221e223 ꢀC; 1H NMR (600 MHz,
CDCl3) (
(3h). Yield
4.2.4. 6-(Diphenylphosphoryl)-8-fluorophenanthridine (3d). Yield
89 mg, 45%. White solid. Mp 221e224 ꢀC; 1H NMR (600 MHz,
d
, ppm): 9.52 (d, J¼8.3 Hz, 1H), 8.57 (dd, J¼22.2, 8.5 Hz, 2H),
8.10 (d, J¼8.9 Hz, 1H), 7.89 (d, J¼8.1 Hz, 1H), 7.81 (d, J¼7.7 Hz, 1H),
7.75 (dd, J¼11.1, 7.8 Hz, 4H), 7.67 (ddd, J¼21.3, 14.3, 7.2 Hz, 2H), 7.46
(dt, J¼24.4, 7.5 Hz, 2H), 7.37 (t, J¼7.4 Hz, 2H), 7.30 (td, J¼7.6, 2.8 Hz,
CDCl3) (
d
, ppm): 9.24 (dd, J¼10.1, 2.4 Hz, 1H), 8.59 (dd, J¼9.0, 5.3 Hz,
1H), 8.47 (d, J¼7.9 Hz, 1H), 8.08e7.94 (m, 1H), 7.95e7.82 (m, 4H),
7.79e7.58 (m, 2H), 7.58e7.50 (m, 1H), 7.46 (td, J¼7.4, 1.3 Hz, 2H),
4H); 13C NMR (151 MHz, CDCl3) (
d, ppm): 154.9 (d, JCeP¼129.4 Hz),
7.42e7.35 (m, 4H); 13C NMR (151 MHz, CDCl3) (
d
, ppm): 161.2 (d,
142.8 (d, JCeP¼23.1 Hz), 134.0 (d, JCeP¼107.4 Hz), 133.4 (d,
JCeP¼6.7 Hz), 132.7 (s), 132.54 (s), 132.0 (d, JCeP¼8.9 Hz), 131.2 (d,
JCeF¼249.4 Hz), 155.9 (d, JCeP¼132.4 Hz), 142.4 (d, JCeP¼22.8 Hz),

J.-J. Cao et al. / Tetrahedron 70 (2014) 6985e6990
6989
JCeP¼2.7 Hz), 130.5 (s), 130.25 (s), 128.9 (d, JCeP¼17.3 Hz), 128.8 (s),
127.9 (d, JCeP¼12.2 Hz), 127.5 (d, JCeP¼41.7 Hz), 126.6 (s), 125.4 (d,
JCeP¼22.7 Hz), 123.9 (d, JCeP¼2.6 Hz), 122.5 (s), 119.6 (d,
cmꢁ1) 1630, 1503, 1451, 1183, 835, 769, 717; HRMS calcd for
C
25H18FNOPþ (CIþ, MþHþ): 398.1110; found: 398.1111.
JCeP¼1.6 Hz). 31P NMR (243 MHz, CDCl3) (
d
, ppm): 33.58; IR (neat,
n
,
4.2.13. 2-Chloro-6-(diphenylphosphoryl)phenanthridine (3m). Yield
118 mg, 57%. White solid. Mp 243e244 ꢀC; 1H NMR (600 MHz,
cmꢁ1)1437, 1192, 1108, 760, 699; HRMS calcd for C29H21NOPþ (CIþ,
MþHþ): 430.1361; found: 430.1361.
CDCl3) (
d
, ppm): 9.41 (d, J¼8.3 Hz, 1H), 8.52e8.43 (m, 2H), 7.90 (d,
J¼8.7 Hz,1H), 7.86e7.80 (m, 4H), 7.80e7.76 (m,1H), 7.64 (dd, J¼11.3,
4.0 Hz, 1H), 7.56 (dd, J¼8.7, 2.1 Hz, 1H), 7.48e7.42 (m, 2H), 7.38 (td,
4.2.9. 9-(Diphenylphosphoryl)dibenzo[i,k]phenanthridine (3i). Yield
117 mg, 49%. Yellow solid. Mp 266e269 ꢀC; 1H NMR (600 MHz,
J¼7.6, 3.0 Hz, 4H); 13C NMR (151 MHz, CDCl3) (
d, ppm): 157.2 (d,
CDCl3) (
d
, ppm): 8.75 (d, J¼8.1 Hz,1H), 8.65 (t, J¼8.8 Hz, 2H), 8.58 (d,
JCeP¼127.6 Hz), 141.1 (d, JCeP¼23.4 Hz), 134.9 (s), 132.9 (s), 132.6 (s),
132.3 (d, JCeP¼9.3 Hz), 131.8 (d, JCeP¼2.7 Hz), 131.6 (d, JCeP¼6.7 Hz),
131.3 (s), 129.3 (s), 128.6 (d, JCeP¼14.9 Hz), 128.2 (d, JCeP¼12.2 Hz),
127.9 (d, JCeP¼22.9 Hz), 125.4 (d, JCeP¼2.3 Hz), 122.2 (s), 121.8 (s).
J¼8.0 Hz, 1H), 8.42 (d, J¼8.1 Hz, 1H), 8.05 (d, J¼8.1 Hz, 1H),
7.92e7.83 (m, 4H), 7.72e7.67 (m, 1H), 7.65e7.61 (m, 1H), 7.59 (tdd,
J¼7.1, 2.7, 1.2 Hz, 2H), 7.54e7.48 (m, 1H), 7.41e7.34 (m, 3H), 7.30 (td,
J¼7.6, 3.0 Hz, 4H); 13C NMR (151 MHz, CDCl3) (
d
, ppm): 153.4 (d,
31P NMR (243 MHz, CDCl3) ( , cmꢁ1)1583,
d, ppm): 28.51; IR (neat, n
JCeP¼128.6 Hz),144.8 (d, JCeP¼23.1 Hz),134.5 (d, JCeP¼6.5 Hz), 134.4
(s), 133.3 (d, JCeP¼116.8 Hz), 132.2 (d, JCeP¼8.8 Hz), 131.3 (s), 130.0
(s), 129.6 (d, JCeP¼32.3 Hz), 128.8 (d, JCeP¼68.4 Hz), 128.1 (s), 128.0
(d, JCeP¼12.1 Hz), 128.0 (s), 127.8 (d, JCeP¼23.1 Hz), 127.3 (s), 126.7
(d, JCeP¼64.6 Hz), 126.0 (d, JCeP¼21.3 Hz), 124.0 (s), 123.2 (s), 122.5
1489, 1432, 1207, 1112, 774, 703; HRMS calcd for C25H17ClNOP (CIþ,
M): 413.0736; found: 413.0730.
4.2.14. 6-(Diphenylphosphoryl)-2-nitrophenanthridine (3n). Yield
64 mg, 30%. Yellow solid. Mp 225e227 ꢀC; 1H NMR (400 MHz,
(s). 31P NMR (243 MHz, CDCl3) (
d
, ppm): 28.58; IR (neat,
n
, cmꢁ1
)
CDCl3) (
d
, ppm): 9.41 (d, J¼8.3 Hz, 1H), 9.20 (d, J¼8.3 Hz, 1H), 8.97
1437, 1178, 1117, 732, 755, 699; HRMS calcd for C33H23NOPþ (CIþ,
(dd, J¼4.2, 1.3 Hz, 1H), 8.25 (dd, J¼8.2, 1.3 Hz, 1H), 7.93e7.78 (m,
5H), 7.78e7.68 (m, 1H), 7.58 (dd, J¼8.3, 4.3 Hz, 1H), 7.46 (td, J¼7.3,
1.2 Hz, 2H), 7.38 (ddd, J¼7.2, 5.4, 2.4 Hz, 4H); 13C NMR (101 MHz,
MþHþ): 480.1517; found: 480.1512.
4.2.10. 6-(Diphenylphosphoryl)-2-methylphenanthridine (3j). Yield
138 mg, 70%. White solid. Mp 222e223 ꢀC; 1H NMR (400 MHz,
CDCl3) (
d
, ppm): 158.5 (d, JCeP¼125.7 Hz),151.1 (s),141.0 (s),138.2 (s,
3H), 137.6 (d, JCeP¼23.6 Hz), 133.5 (d, JCeP¼7.4 Hz), 133.1 (s), 132.3
(d, JCeP¼9.3 Hz), 132.0 (s), 131.9 (d, JCeP¼2.7 Hz), 131.6 (s), 123.0 (d,
JCeP¼23.2 Hz), 129.6 (s), 128.3 (d, JCeP¼12.2 Hz), 128.0 (s), 123.9 (s),
CDCl3) (
d
, ppm): 9.39 (d, J¼8.3 Hz, 1H), 8.56 (d, J¼8.3 Hz, 1H), 8.29
(s, 1H), 7.85 (dd, J¼12.0, 7.5 Hz, 5H), 7.74 (t, J¼7.7 Hz, 1H), 7.59 (t,
J¼7.7 Hz,1H), 7.50e7.40 (m, 3H), 7.40e7.32 (m, 4H), 2.55 (s, 3H); 13
C
123.7 (s). 31P NMR (162 MHz, CDCl3) (
d, ppm): 28.63; IR (neat, n,
NMR (101 MHz, CDCl3) (
d, ppm): 155.6 (d, JCeP¼129.5 Hz), 141.2 (d,
cmꢁ1
)
1700, 1510, 1342, 1199, 702; HRMS calcd for
JCeP¼23.4 Hz), 139.1 (s), 133.1 (d, JCeP¼104.6 Hz), 132.3 (d,
JCeP¼9.2 Hz), 131.6 (d, JCeP¼2.8 Hz), 130.9 (d, JCeP¼1.0 Hz), 130.8 (s),
130.56 (s),128.5 (s),128.2 (d, JCeP¼12.2 Hz),127.9 (s),127.8 (s), 124.2
(d, JCeP¼2.5 Hz), 122.1 (d, JCeP¼1.5 Hz), 121.7 (d, JCeP¼0.7 Hz), 22.2
C
25H18N2O3Pþ (CIþ, MþHþ): 425.1055; found: 425.1011.
4.2.15. Ethyl phenanthridin-6-yl(phenyl)phosphinate (4a). Yield
139 mg, 80%. Yellow oil. 1H NMR (600 MHz, CDCl3) (
, ppm): 9.21 (d,
d
(s). 31P NMR (162 MHz, CDCl3) (
d, ppm): 28.26; IR (neat,
n
, cmꢁ1
)
J¼8.3 Hz, 1H), 8.51 (d, J¼8.2 Hz, 1H), 8.45 (d, J¼7.6 Hz, 1H), 8.09 (d,
J¼7.4 Hz, 1H), 7.96 (t, J¼9.7 Hz, 2H), 7.76e7.65 (m, 2H), 7.61 (t,
J¼7.3 Hz, 3H), 7.35 (d, J¼2.3 Hz, 2H), 4.55e4.15 (m, 2H), 1.38 (t,
3058, 1611, 1484, 1442, 1202, 1113, 764, 703; HRMS calcd for
C
26H21NOPþ (CIþ, MþHþ): 394.1361; found: 394.1360.
J¼7.0 Hz, 3H); 13C NMR (151 MHz, CDCl3) (
d, ppm): 155.7 (d,
4.2.11. 6-(Diphenylphosphoryl)-3-methoxyphenanthridine
JCeP¼161.5 Hz), 143.0 (d, JCeP¼24.0 Hz), 133.1 (d, JCeP¼2.9 Hz), 132.6
(d, JCeP¼8.2 Hz), 132.4 (d, JCeP¼9.9 Hz), 132.3 (d, JCeP¼2.8 Hz), 131.2
(d, JCeP¼0.8 Hz),130.9 (s),130.9 (d, JCeP¼9.9 Hz),130.32 (s),128.8 (d,
JCeP¼5.1 Hz), 128.7 (d, JCeP¼2.5 Hz),128.3 (d, JCeP¼3.9 Hz),128.2 (s),
127.8 (s), 126.9 (d, JCeP¼26.9 Hz), 124.5 (d, JCeP¼2.8 Hz), 122.1 (d,
JCeP¼1.7 Hz), 122.0 (s), 62.4 (d, JCeP¼6.6 Hz), 16.6 (d, JCeP¼6.6 Hz).
(3k). Yield 133 mg, 65%. White solid. Mp 182e184 ꢀC; 1H NMR
(400 MHz, CDCl3) (
d
, ppm): 9.40 (d, J¼8.4 Hz, 1H), 8.48 (d, J¼8.4 Hz,
1H), 8.41 (d, J¼9.0 Hz, 1H), 7.85 (dd, J¼11.7, 7.3 Hz, 4H), 7.73 (t,
J¼7.6 Hz, 1H), 7.54 (t, J¼7.6 Hz, 1H), 7.45 (t, J¼7.2 Hz, 2H), 7.38 (td,
J¼7.4, 2.7 Hz, 4H), 7.35e7.25 (m, 2H), 3.87 (s, 3H); 13C NMR
(101 MHz, CDCl3) (
d
, ppm): 160.1 (s), 157.1 (d, JCeP¼128.5 Hz), 144.4
31P NMR (243 MHz, CDCl3) ( , cmꢁ1) 2994,
d, ppm): 28.65; IR (neat, n
(d, JCeP¼23.5 Hz), 133.6 (s), 132.9 (s), 132.51 (s), 132.3 (d,
JCeP¼9.3 Hz), 131.7 (d, JCeP¼2.7 Hz), 131.1 (s), 128.6 (s), 128.2 (d,
JCeP¼12.2 Hz), 127.2 (d, JCeP¼23.1 Hz), 126.8 (s), 123.3 (s), 121.6 (s),
120.1 (s), 118.6 (d, JCeP¼2.4 Hz), 110.6 (s), 55.7 (s). 31P NMR
1451, 1216, 1042, 920; HRMS calcd for C21H19NO2Pþ (CIþ, MþHþ):
348.1153; found: 348.1165.
4.2.16. Diethyl phenanthridin-6-ylphosphonate (4b). Yield 50 mg,
(162 MHz, CDCl3) (
d
, ppm): 28.46; IR (neat,
n
, cmꢁ1) 3060, 3000,
32%. Yellow oil. 1H NMR (600 MHz, CDCl3) (
d, ppm): 8.96 (d,
2951, 1621, 1475, 1442, 1183, 844, 750, 703; HRMS calcd for
C
J¼8.3 Hz, 1H), 8.68 (d, J¼8.3 Hz, 1H), 8.61 (d, J¼8.2 Hz, 1H), 8.30 (d,
26H21NO2Pþ (CIþ, MþHþ): 410.1310; found: 410.1316.
J¼7.4 Hz, 1H), 7.89 (t, J¼7.6 Hz, 1H), 7.81e7.72 (m, 3H), 4.48e4.34
(m, 4H), 1.43 (t, J¼7.0 Hz, 6H, CH3); 13C NMR (151 MHz, CDCl3) (
d,
4.2.12. 6-(Diphenylphosphoryl)-2-fluorophenanthridine (3l). Yield
111 mg, 56%. White solid. Mp 235e237 ꢀC; 1H NMR (600 MHz,
ppm): 174.9 (s, 1H), 162.7 (s), 153.5 (d, JCeP¼221.5 Hz), 143.0 (d,
JCeP¼27.2 Hz), 138.8 (s), 137.0 (s), 132.6 (d, JCeP¼9.8 Hz), 131.3 (s),
131.0 (s), 130.5 (s), 129.5 (s), 128.9 (d, JCeP¼2.4 Hz), 128.8 (s), 128.5
(s), 128.3 (d, JCeP¼8.6 Hz), 128.1 (s), 127.8 (d, JCeP¼6.7 Hz), 126.2 (d,
JCeP¼30.0 Hz), 124.7 (d, JCeP¼3.4 Hz), 122.2 (d, JCeP¼2.3 Hz), 122.0
(d, JCeP¼0.9 Hz), 63.6 (d, JCeP¼6.4 Hz), 58.4 (s). 31P NMR (243 MHz,
CDCl3) (
d
, ppm): 9.41 (d, J¼8.3 Hz, 1H), 8.44 (d, J¼8.2 Hz, 1H), 8.10
(dd, J¼9.9, 1.9 Hz, 1H), 7.96 (dd, J¼8.8, 5.8 Hz, 1H), 7.83 (dd, J¼11.4,
7.9 Hz, 4H), 7.78 (t, J¼7.6 Hz, 1H), 7.64 (t, J¼7.6 Hz, 1H), 7.45 (t,
J¼7.2 Hz, 2H), 7.37 (dt, J¼10.2, 3.9 Hz, 6H); 13C NMR (151 MHz,
CDCl3) (
d
, ppm): 162.4 (d, JCeF¼250.0 Hz), 156.5 (d, JCeP¼3.0 Hz),
CDCl3) (d, ppm): 10.05; IR (neat, n
, cmꢁ1) 2983, 1440, 1381, 1249,
155.6 (d, JCeP¼2.9 Hz), 139.6 (d, JCeP¼22.1 Hz), 133.6 (d,
JCeP¼1.1 Hz), 133.5 (d, JCeP¼1.1 Hz), 133.0 (s), 132.3 (s), 132.3 (d,
JCeP¼9.3 Hz), 132.0 (d, JCeP¼4.3 Hz), 132.0 (d, JCeP¼4.4 Hz), 131.8 (d,
JCeP¼2.8 Hz), 131.1 (s), 128.6 (d, JCeP¼13.7 Hz), 128.2 (d,
JCeP¼12.2 Hz), 127.7 (d, JCeP¼23.1 Hz), 126.0 (dd, JCeP¼9.6, 2.4 Hz),
122.3 (s), 117.8 (d, JCeP¼24.5 Hz), 107.2 (d, JCeP¼1.2 Hz), 107.0 (d,
1047, 910, 736; HRMS calcd for
316.1103; found: 316.1097.
C
17H19NO3Pþ (CIþ, MþHþ):
4.2.17. Dimethyl phenanthridin-6-ylphosphonate (4c). Yield 47 mg,
33%. Yellow oil. 1H NMR (400 MHz, CDCl3) (
, ppm): 9.52 (d,
d
J¼8.3 Hz,1H, ArH), 9.30 (d, J¼8.3 Hz,1H), 9.07 (dd, J¼4.3,1.6 Hz,1H),
JCeP¼1.0 Hz). 31P NMR (243 MHz, CDCl3) (
d, ppm): 28.53; IR (neat, n,
8.35 (dd, J¼8.3, 1.6 Hz, 1H), 7.95 (ddd, J¼11.8, 9.1, 1.2 Hz, 5H),

6990
J.-J. Cao et al. / Tetrahedron 70 (2014) 6985e6990
7.87e7.79 (m, 1H), 7.68 (dd, J¼8.3, 4.3 Hz, 1H), 7.60e7.52 (m, 2H),
References and notes
7.48 (ddd, J¼7.1, 5.4, 2.4 Hz, 4H); 13C NMR (151 MHz, CDCl3) (
d,
1. Isocyanide Chemistry: Applications in Synthesis and Material Science; Ne-
najdenko, V. G., Ed.; John Wiley & Sons: Weinheim, 2012.
ppm): 167.7 (s), 152.9 (d, JCeP¼222.3 Hz), 143.0 (d, JCeP¼27.4 Hz),
132.7 (d, JCeP¼10.1 Hz), 132.3 (s), 131.3 (s), 131.2 (s), 130.9 (s), 130.5
(s), 129.3 (d, JCeP¼50.6 Hz), 129.0 (d, JCeP¼24.7 Hz), 128.7 (d,
JCeP¼43.8 Hz), 128.1 (d, JCeP¼27.8 Hz), 126.3 (d, JCeP¼30.1 Hz), 124.7
(d, JCeP¼3.5 Hz), 122.1 (d, JCeP¼19.3 Hz), 65.6 (s). 31P NMR
2. For selected reviews on the Ugi reaction and related multi component re-
}
actions, see: (a) Domling, A.; Ugi, I. Angew. Chem., Int. Ed. 2000, 39, 3168; (b)
}
Zhu, J. Eur. J. Org. Chem. 2003, 1133; (c) Domling, A. Chem. Rev. 2006, 106, 17; (d)
}
van Berkel, S. S.; Bogels, B. G. M.; Wijdeven, M. A.; Westermann, B.; Rutjes, F. P.
J. T. Eur. J. Org. Chem. 2012, 3543.
(162 MHz, CDCl3) (d, ppm): 12.27; IR (neat, n
, cmꢁ1) 2957, 2834,
3. (a) Wang, X.; Xu, X.-P.; Wang, S.-Y.; Ji, S.-J. Org. Lett. 2013, 15, 4246; (b) Wang, X.;
Wang, S.-Y.; Ji, S.-J. Org. Lett. 2013, 15, 1954; (c) Zhu, T.-H.; Wang, S.-Y.; Wang, G.-
N.; Ji, S.-J. Chem.dEur. J. 2013, 19, 5850; (d) Zhao, L.-L.; Wang, S.-Y.; Xu, X.-P.; Ji,
S.-J. Chem. Commun. 2013, 2569; (e) Wang, R.; Xu, X.-P.; Meng, H.; Wang, S.-Y.;
Ji, S.-J. Tetrahedron 2013, 69, 1761; (f) Wang, R.; Wang, S.-Y.; Ji, S.-J. Tetrahedron
2013, 69, 10836; (g) Gu, Z.-Y.; Zhu, T.-H.; Cao, J.-J.; Wang, S.-Y.; Wang, G.-N.; Ji,
S.-J. ACS Catal. 2014, 4, 49.
4. (a) Vlaar, T.; Maes, B. U. W.; Ruijter, E.; Orru, R. V. A. Angew. Chem., Int. Ed. 2013,
52, 7084; (b) Qiu, G.; Ding, Q.; Wu, J. Chem. Soc. Rev. 2013, 42, 5257; (c) Lang, S.
Chem. Soc. Rev. 2013, 42, 4867.
5. (a) Ryu, I.; Sonoda, N.; Curran, D. P. Chem. Rev. 1996, 96, 177; (b) Spagnolo, D.;
Nanni, D. In Encyclopedia of Radicals in Chemistry, Biology and Materials; Chat-
gilialoglu, C., Studer, A., Eds.; John Wiley & Sons: Chichester, UK, 2012; Vol. 2;
(c) Cheng, Y.; Jiang, H.; Zhang, Y.; Yu, S. Org. Lett. 2013, 15, 5520; (d) Leifert, D.;
Daniliuc, C. G.; Studer, A. Org. Lett. 2013, 15, 6286; (e) Liu, J.; Fan, C.; Yin, H.; Qin,
C.; Zhang, G.; Zhang, X.; Yi, H.; Lei, A. Chem. Commun. 2014, 2145; (f) Xiao, T.; Li,
L.; Lin, G.; Wang, Q.; Zhang, P.; Mao, Z.-W.; Zhou, L. Green Chem. 2014, 16, 2418;
(g) Wang, L.; Sha, W.; Dai, Q.; Feng, X.; Wu, W.; Peng, H.; Chen, B.; Cheng, J. Org.
Lett. 2014, 16, 2088; (h) Gu, L.; Jin, C.; Liu, J.; Ding, H.; Fan, B. Chem. Commun.
2014, 4643; (i) Xia, Z.; Huang, J.; He, Y.; Zhao, J.; Lei, J.; Zhu, Q. Org. Lett. 2014, 16,
2546; (j) Li, X.; Fang, M.; Hu, P.; Hong, G.; Tang, Y.; Xu, X. Adv. Synth. Catal. 2014,
356, 2103; (k) Jiang, H.; Cheng, Y.; Wang, R.; Zhang, Y.; Yu, S. Chem. Commun.
2014, 6164.
1446, 1240, 1028, 915; HRMS calcd for C15H15NO3Pþ (CIþ, MþHþ):
288.0790; found: 288.0794.
4.2.18. 6-(Diphenylphosphoryl)benzo[c][1,5]naphthyridine (6). Yield
129 mg, 68%. White solid. Mp 192e195 ꢀC; 1H NMR (400 MHz,
CDCl3) (
d
, ppm): 9.49 (d, J¼8.3 Hz, 1H), 9.29 (d, J¼8.3 Hz, 1H), 9.07
(dd, J¼4.3, 1.6 Hz, 1H), 8.35 (dd, J¼8.3, 1.6 Hz, 1H), 8.00e7.90 (m,
5H), 7.82 (ddd, J¼8.3, 7.1, 1.3 Hz, 1H), 7.68 (dd, J¼8.3, 4.3 Hz, 1H),
7.55 (ddd, J¼5.2, 4.2, 3.7 Hz, 2H), 7.51e7.42 (m, 4H); 13C NMR
(101 MHz, CDCl3) (
d, ppm): 158.4 (d, JCeP¼126.0 Hz), 151.2 (s), 141.0
(s),138.2 (s),137.6 (d, JCeP¼23.7 Hz),133.5 (d, JCeP¼7.4 Hz),133.0 (s),
132.3 (d, JCeP¼9.4 Hz), 131.9 (d, JCeP¼2.8 Hz), 131.6 (s), 123.0 (d,
JCeP¼23.2 Hz), 129.6 (s), 128.3 (d, JCeP¼12.3 Hz), 128.0 (s), 124.0 (s),
123.7 (s). 31P NMR (162 MHz, CDCl3) (
d, ppm): 28.50; IR (neat, n,
cmꢁ1) 1676, 1447, 1182, 1352, 763, 694, 659; HRMS calcd for
C
24H18N2OPþ (CIþ, MþHþ): 381.1157; found: 381.1162.
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Acknowledgements
We gratefully acknowledge the National Natural Science Foun-
dation of China (21172162, 21372174), the Young National Natural
Science Foundation of China (No. 21202111), the Ph.D. Programs
Foundation of Ministry of Education of the People’s Republic of
China (2013201130004), the Young Natural Science Foundation of
Jiangsu Province (BK2012174), PAPD, Key Laboratory of Organic
Synthesis of Jiangsu Province (KJS1211), and Soochow University
for financial support.
€
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Supplementary data
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2014.07.078.
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