Synthesis of 6-Phosphorylated Phenanthridines by Mn(II)-Promoted Tandem Reactions of 2-Biaryl Isothiocyanates with Phosphine Oxides

Article abstract of DOI:10.1021/acs.joc.7b00907

A novel Mn(II)-promoted tandem phosphorylation/cyclization reaction of 2-biaryl isothiocyanates with phosphine oxides is described. This is the first general method to synthesize 6-phosporylated phenanthridines from 2-biaryl isothiocyanates. The approach is featured by oxidant-free, low loading of P-reagent, easy operation, and high functional group tolerance.

Full text of DOI:10.1021/acs.joc.7b00907

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Note
Synthesis of 6-Phosphorylated Phenanthridines by Mn(II)-Promoted
Tandem Reactions of 2-Biaryl Isothiocyanates with Phosphine Oxides
Wei-Si Guo, Qian Dou, Jian Hou, Li-Rong Wen, and Ming Li
J. Org. Chem., Just Accepted Manuscript • Publication Date (Web): 13 Jun 2017
Downloaded from http://pubs.acs.org on June 13, 2017
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Synthesis of 6ꢀPhosphorylated Phenanthridines by Mn(II)ꢀPromoted
Tandem Reactions of 2ꢀBiaryl Isothiocyanates with Phosphine
Oxides
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WeiꢀSi Guo,†,‡ Qian Dou,† Jian Hou,‡ LiꢀRong Wen,*,† Ming Li*,†
†State Key Laboratory Base of EcoꢀChemical Engineering, College of Chemistry and Molecular
Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
‡State Key Laboratory for Marine Corrosion and Protection, Luoyang Ship Material Research
Institute (LSMRI), Qingdao 266101, P. R. China
Eꢀmail: wenlirong@qust.edu.cn, liming928@qust.edu.cn.
A novel Mn(II)ꢀpromoted tandem phosphorylation/cyclization reaction of 2ꢀbiaryl
isothiocyanates with phosphine oxides was described. This is the first general method
to synthesize 6ꢀphosporylated phenanthridines from 2ꢀbiaryl isothiocyanates. The
approach is featured by oxidantꢀfree, low loading of Pꢀreagent, easy operation, and
high functional group tolerance.
TOC Graphic
Organic phosphorus compounds are broadly applied in organic synthesis,1
medicinal chemistry,2 materials science,3 and as phosphorus ligands.4 Many
Pꢀsubstituted heterocycles show excellent biologic activities.5 Therefore, the
development of new and efficient methods to synthesize heterocycles containing
Pꢀsubstituents are always highly desirable.6 Among them, the phenanthridine nucleus
is a representative scaffold.7 The established synthetic methods for 6ꢀphosphorylated
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phenanthridines involve 2ꢀisocyanobiarylsꢀinitiated radical cascade reactions (Scheme
1).8,9 In 2014, Studer reported a pioneering work using 3 equiv of AgOAc as the
oxidant and 2 equiv of Pꢀreagent.9a In the same year, Ji described a similar radical
process with excess of PhI(OAc)2 as the oxidant (3 equiv).9b Very recently, Lu
reported an efficient photoredoxꢀmediated reaction,9c however, this method also
required 3 equiv of K2S2O8 as the oxidant and 3 equiv of Pꢀreagent as the starting
materials. Despite the robustness of these methods, all of them are using excess
amount of oxidants and Pꢀreagents. Therefore, from a sustainable perspective,
developing a more environmentally friendly and convenient procedure for the
synthesis of 6ꢀphosphorylated phenanthridines has remained a great challenge.
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Scheme 1. Synthetic Strategies toward 6ꢀPhosporylated Phenanthridine
Derivatives
Isothiocyanates are easilyꢀprepared synthetic intermediates with versatile chemical
reactivity,10 they could be used as electrophiles,11 nucleophiles,12 and radical
receptors.13 Recently, we have developed a tandem arylation/cyclization process for
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the synthesis of 6ꢀarylthio phenanthridines from 2ꢀbiaryl isothiocyanates.14 As part of
our ongoing endeavors to develop new protocols for the construction of
phenanthridine derivatives, we describe herein a novel Mn(II)ꢀpromoted tandem
reaction to synthesize 6ꢀphosphorylated phenanthridines from 2ꢀbiaryl isothiocyanates
and phosphine oxides under oxidantꢀfree conditions is described. There are a number
of advantages of this present method: (1) the reactions are promoted by stoichiometric
lowꢀcost Lewis acid. (2) The amount of Pꢀreagents is decreased to 1.2 equiv, which
make the reactions more environmentally benign. (3) In contrast to the
2ꢀisocyanobiarylsꢀinitiated radical reactions, our approach starts from more readily
prepared 2ꢀbiaryl isothiocyanates. (4) The reactions are performed in air atmosphere
and do not need anhydrous conditions, water brought into the system by
Mn(OAc)2·4H2O exhibits no impact on the yields.
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Initially, easily accessible 2ꢀbiphenyl isothiocyanate 1a and diphenylphosphine
oxide 2a were selected as model substrates for reaction conditions optimization.
Product 3a was obtained in 27% yield in the presence of Cu(OAc)2·H2O as Lewis
acid in DMF at 110 °C (Table 1, entry 1). This finding encouraged us to examine
other lowꢀcost Lewis acids, the results revealed that Mn(OAc)2·4H2O was the best
choice, and the yield of 3a increased to 76%, others such as Fe(OAc)2,
Co(OAc)2·4H2O, Ni(OAc)2·4H2O, MnCO3, and MnSO4 were all less effective
(entries 2ꢀ7). It is noteworthy that the Lewis acid was indispensable in this
transformation (entry 8). Solvent screening indicated that DMF was the most efficient
one, and DMSO also gave a comparable yield (70%, entry 9), while other solvents
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such as 1,4ꢀdioxane, toluene, and CH3NO2 were all inferior (entries 10ꢀ12). The yield
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o
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of 3a dropped with decreasing the temperature to 100 C or elevating to 120 C
(entries 13 and 14). Increasing the Lewis acid loading to 1.5 equiv did not affect the
yield of the reaction (entry 15), however, reducing the loading from 1.0 to 0.5 equiv
had a detrimental effect on the yield (entry 16). Finally, an optimized procedure
involved stirring a 0.2 M solution of 1a and 2a (1.2 equiv) in DMF in the presence of
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1.0 equiv Mn(OAc)2·4H2O at 110 oC for 6 h.
Table 1. Optimization of the reaction conditionsa
Entry
1
Catalyst (equiv)
Solvent
DMF
T [oC]
110
110
110
110
110
110
110
110
110
110
110
110
100
120
Yield [%]b
.
Cu(OAc)2 H2O (1.0)
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44
76
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8
2
Fe(OAc)2 (1.0)
DMF
.
3
Co(OAc)2 4H2O (1.0)
DMF
.
4
Ni(OAc)2 4H2O (1.0)
DMF
.
5
Mn(OAc)2 4H2O (1.0)
DMF
6
MnSO4 (1.0)
MnCO3 (1.0)
DMF
7
DMF
8
DMF
.
9
Mn(OAc)2 4H2O (1.0)
DMSO
1,4ꢀdioxane
toluene
CH3NO2
DMF
70
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47
54
48
70
.
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Mn(OAc)2 4H2O (1.0)
.
Mn(OAc)2 4H2O (1.0)
.
Mn(OAc)2 4H2O (1.0)
.
Mn(OAc)2 4H2O (1.0)
.
Mn(OAc)2 4H2O (1.0)
DMF
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.
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110
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Mn(OAc)2 4H2O (1.5)
DMF
DMF
78
35
.
Mn(OAc)2 4H2O (0.5)
6
aReaction conditions: 1a (0.2 mmol), 2a (0.24 mmol), solvent (1.0 mL), 6 h. bIsolated yield based
on 1a.
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By following the optimized conditions, the scope of 2ꢀbiaryl isothiocyanates was
explored first (Table 2). Isothiocyanates bearing electronꢀdonating substituents (ꢀMe,
ꢀOMe, ꢀPh) on the para position of phenyl ring A performed the reaction smoothly to
provide the corresponding products 3bꢀd in good yields. Excellent yields were
obtained with very electron rich dimethoxy, methylenedioxy substrates used for the
synthesis of compounds 3e and 3f, whereas when substrates bearing
electronꢀwithdrawing groups (ꢀF, ꢀCl, ꢀCF3, ꢀCOOMe) were used, moderate yields
(53ꢀ62%) were observed for products 3gꢀj. Compounds 3kꢀn were obtained in
moderate to good yields regardless of positions of the methyl group on the phenyl ring.
It is worth mentioning that two unseparated regioisomers 3k and 3k′ (7.8:1) were
provided in 78% total yield with the reaction of 3ꢀmethylsubstituted isothiocyanate 1k
and 2a. Similarly, unseparated isomers 3o and 3o′ (1.2:1) were isolated in 31% total
yield when electronꢀwithdrawing 3ꢀtrifluoromethyl substituted isothiocyanate 1o was
reacted with 2a. Notably, product 3p with an electronꢀwithdrawing fluoro group on
the meta position of phenyl ring B, which could not obtain in the previous report,9c
was generated in 58% yield under our conditions. Subsequently, isothiocyanates with
two substituents were assessed and found that these substrates were compatible for the
transformation, compounds 3rꢀt were afforded in moderate yields. Heterocycles such
as thiophene and dibenzofuran were also tolerated for the reactions, products 3u and
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3v were isolated in 54% and 68% yields, respectively. The structures of 3 were
undoubtedly confirmed by Xꢀray crystallographic analysis of 3a (See Figure S1).
Table 2. Substrate Scope of 2ꢀBiary Isothiolyanates 1a,b
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aReaction conditions: 1 (0.4 mmol), 2 (0.48 mmol), DMF (2.0 mL). bIsolated yield.
Having established the scope of isothiocyanates 1, we moved on to examine the
Pꢀreagents under the optimal conditions (Table 3). The electronic effect was not an
important factor for the reactions. Both electronꢀdonating groups (ꢀMe, OMe) and
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electronꢀwithdrawing groups (ꢀF, ꢀCl) on the phenyl ring were tolerated, the desired
products 3wꢀz were generated in moderate yields. The reaction also proceeded
smoothly with cyclohexyl phenylphosphine oxide, providing the phenanthridine 3aa
in 46% yield. In addition, ethyl phenylphosphine oxide was a suitable Pꢀreagent for
the reaction and product 3ab was isolated in 42% yield. However, no desired products
3ac or 3ad were generated for the reaction of dibutylphosphine oxide or dimethyl
phosphonate with 1a.
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Table 3. Substrate Scope of Pꢀreagents 2a,b
O
P
O
P
O
O
P
N
N
N
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N
Cl
F
Me
OMe
Cl
3z
F
Me
3w, 65%
MeO
3x, 53%
3y, 67%
, 70%
O
O
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O
P
O
P
N
P
N
Me
N
N
OMe
MeO
3ad, 0%
3ac, 0%
3aa, 46%
3ab, 42%
aReaction conditions: 1 (0.4 mmol), 2 (0.48 mmol), DMF (2.0 mL). bIsolated yield.
Control experiments were performed to obtain some mechanism insight into the
reaction. Initially, 4 equiv 2,2,6,6 tetramethylpiperidine Nꢀoxide (TEMPO) was added
in the reaction of 1a with 2a, product 3a could be isolated in 65% yield (Scheme 2, eq
1). Similarly, the reaction was not influenced with the addition of 4 equiv
2,6ꢀdiꢀtertꢀbutylꢀ4ꢀmethylphenol (BHT). These results indicated that the reaction
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might not proceed in a radical pathway. When the reaction of 1a and 2a was
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performed in DMF at 40 C, the thioamide 4 was obtained in 86% yield (eq 2). The
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structure of 4 was confirmed by Xꢀray crystallographic analysis (See Figure S2).
Considering 4 was probably an intermediate in the transformation, the reaction of 4
under the standard conditions was evaluated. To our delight, the desired product 3a
was isolated in 82% yield, which confirmed our hypothesis (eq 3).
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Scheme 2. Control Experiments for Mechanism
Based on the above results and previous reports,15 a general mechanism is proposed
for this reaction (Scheme 3). Initially, the diphenylphosphine oxide 2a can
tautomerize to the PꢀOH form 2a′.16 Next, the NCS group in 1a would be attacked by
2a′ to give thioamide 4. The unusual intramolecular cyclization of intermediate 4 in
the presence of Mn(II) is the key process for this synthesis,17 affording the
intermediate B, which rapidly eliminates H2S to provide the final product 3a. The
reason that cyclization could take place probably due to the high electronꢀnegative
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property of the Pꢀsubstituted thioamide.
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Scheme 3. Proposed Reaction Mechanism
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CONCLUSION
In summary, we have developed an efficient tandem phosphorylation/cyclization
process to synthesize 6ꢀphosphorylated phenanthridines from 2ꢀbiaryl isothiocyanates
with diarylphosphine oxide. Remarkably, the reaction was proceeded only in the
presence of inexpensive Lewis acid Mn(OAc)2·4H2O. Most attractively, compared to
classical radical isocyanide insertion reactions, this approach not only avoids the use
of excess expensive oxidants and Pꢀreagents, but also uses readily available
isothiocyanates as starting materials instead of isocyanides. This environmentally
benign strategy is expected to become a useful alternative for the synthesis of
6ꢀphosphorylated phenanthridine derivatives.
EXPERIMENTAL SECTION
General information. All airꢀ or moistureꢀsensitive reactions were conducted
under a nitrogen atmosphere. Unless noted, all commercial reagents were used
without further purification. Melting points were recorded on a microscopic melting
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apparatus and uncorrected. H NMR spectra were recorded at 500 MHz, and 13C
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NMR spectra were recorded at 125 MHz in CDCl3 or DMSOꢀd6. Chemical shifts were
reported in parts per million (δ) relative to tetramethylsilane (TMS). HRMS was
obtained on a spectrometer with an ESI source. The Xꢀray singleꢀcrystal diffraction
was performed on a CCD area detector. Silica gel (200−300 mesh) was used for
column chromatography and silica GF254 for TLC.
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Preparation of starting materials. 2ꢀIsothiocyanatoꢀ1,1'ꢀbiaryl14 and phosphine
oxides18 were prepared according to the literatures.
General procedure for the synthesis of 6ꢀphosphorylated phenanthridines 3
(3a for example). To a 15 mL sealed tube was charged with a mixture of
2ꢀisothiocyanatoꢀ1,1'ꢀbiphenyl 1a (84.5 mg, 0.4 mmol), diphenylphosphine oxide 2a
(97 mg, 0.48 mmol), Mn(OAc)2·4H2O (98 mg, 0.4 mmol) and DMF (2.0 mL). The
o
reaction mixture was allowed to stir at 110 C for 6 h. After completion, the mixture
was cooled to room temperature, diluted with EtOAc (20 mL), and washed by
saturated NaCl (5 x 5.0 mL). The organic layer was dried over anhydrous MgSO4,
filtered, and concentrated in vacuum. The residue was purified by flash column
chromatography on silica gel to afford the product 3a as a white solid (115 mg, 76%).
Phenanthridinꢀ6ꢀyldiphenylphosphine oxide (3a)9e. White solid; mp 194−196 °C; Rf = 0.42
1
(PE/EA = 2:1 v/v); 115 mg, 76% yield. H NMR (CDCl3, 500 MHz):
δ 7.43−7.47 (m, 4H),
7.50−7.54 (m, 2H), 7.68−7.76 (m, 3H), 7.86 (t, J = 7.6 Hz, 1H), 7.92−7.96 (m, 4H), 8.06 (t, J =
4.6 Hz, 1H), 8.61 (t, J = 4.6 Hz, 1H), 8.67 (d, J = 8.2 Hz, 1H), 9.51 (d, J = 7.9 Hz, 1H). 13C NMR
(CDCl3, 125 MHz):
δ
122.2, 124.4, 128.0, 128.2 (d, J = 10.9 Hz), 128.6, 128.7, 128.8, 131.2 (d, J
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= 14.2 Hz), 131.7, 132.4 (d, J = 6.5 Hz), 133.4, 142.8 (d, J = 21.9 Hz), 156.9 (d, J = 128.3 Hz).
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(8ꢀMethylphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3b)9e. White solid; mp 205−207 °C;
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9
1
Rf = 0.58 (PE/EA = 2:1 v/v); 118 mg, 75% yield. H NMR (CDCl3, 500 MHz):
δ 2.56 (s, 3H),
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7.42−7.45 (m, 4H), 7.51 (t, J = 7.3 Hz, 2H), 7.65−7.72 (m, 3H), 7.94 (q, J = 6.3 Hz, 4H), 8.03 (d,
J = 7.9 Hz, 1H), 8.54 (d, J = 3.7 Hz, 2H), 9.33 (s, 1H). 13C NMR (CDCl3, 125 MHz):
21.9,
δ
121.9, 124.4, 127.7, 128.1 (d, J = 12.0 Hz), 128.7, 130.5, 131.0, 131.6, 132.3 (d, J = 8.0 Hz),
132.8 (d, J = 16.4 Hz), 133.6, 138.1, 142.4 (d, J = 23.9 Hz), 156.3 (d, J = 128.7 Hz).
8ꢀMethoxyphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3c)9e. White solid; mp 182−184 °C;
1
Rf = 0.36 (PE/EA = 2:1 v/v); 134 mg, 82% yield. H NMR (CDCl3, 500 MHz):
δ 3.94 (s, 3H),
7.43−7.48 (m, 5H), 7.64 (t, J = 7.4 Hz, 2H), 7.69 (t, J = 7.6 Hz, 2H), 7.97 (q, J = 6.3 Hz, 4H), 8.04
(d, J = 8.1 Hz, 1H), 8.50 (d, J = 7.9 Hz, 1H), 8.54 (d, J = 9.1 Hz, 1H), 9.03 (d, J = 2.2 Hz, 1H).
13C NMR (CDCl3, 125 MHz):
δ 55.6, 107.5, 121.6, 122.6, 123.6, 124.5, 127.1, 127.6, 128.1 (d, J
= 11.4 Hz), 128.8, 129.4 (d, J = 22.9 Hz), 131.1, 131.6, 132.3 (d, J = 7.9 Hz), 132.6, 133.5, 142.1
(d, J = 22.8 Hz), 155.5 (d, J = 129.6 Hz), 158.8.
Diphenyl(8ꢀphenylphenanthridinꢀ6ꢀyl)phosphine oxide (3d)9f. White solid; mp 221−223 °C;
1
Rf = 0.46 (PE/EA = 2:1 v/v); 146 mg, 80% yield. H NMR (CDCl3, 500 MHz):
δ 7.38 (t, J = 7.3
Hz, 1H), 7.44−7.48 (m, 6H), 7.52 (t, J = 7.2 Hz, 2H), 7.71 (t, J = 9.5 Hz, 4H), 7.98−8.02 (m, 4H),
8.07−8.11 (m, 2H), 8.58 (d, J = 6.4 Hz, 1H), 8.68 (d, J = 8.7 Hz, 1H), 9.84 (s, 1H). 13C NMR
(CDCl3, 125 MHz):
δ 122.1, 122.7, 124.2, 126.4, 127.5, 127.8, 128.2 (d, J = 12.1 Hz), 128.4,
128.6, 128.9, 129.0, 130.0, 131.1, 131.6, 132.2 (d, J = 9.0 Hz), 133.5, 140.1 (d, J = 55.2 Hz),
142.7 (d, J = 22.9 Hz), 157.0 (d, J = 128.7 Hz).
(8,9ꢀDimethoxyphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3e)9b. White solid; mp
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215−217 °C; Rf = 0.16 (PE/EA = 2:1 v/v); 160 mg, 91% yield. H NMR (CDCl3, 500 MHz):
δ
5
6
7
8
9
4.03 (s, 3H), 4.13 (s, 3H), 7.43−7.46 (m, 4H), 7.51 (t, J = 7.2 Hz, 2H), 7.64−7.70 (m, 2H), 7.92 (s,
1H), 7.98 (q, J = 6.3 Hz, 4H), 8.05 (d, J = 8.2 Hz, 1H), 8.46 (d, J = 7.9 Hz, 1H), 9.11(s, 1H). 13
NMR (CDCl3, 125 MHz): 56.0, 56.2, 101.7, 107.8, 121.6, 124.0 (d, J = 22.9 Hz), 127.7, 128.1
C
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δ
(d, J = 12.1 Hz), 128.8 (d, J = 6.5 Hz), 131.1, 131.6, 132.3 (d, J = 9.0 Hz), 132.8, 133.6, 142.5 (d,
J = 22.9 Hz), 149.7, 152.6, 154.3 (d, J = 129.6 Hz).
[1,3]Dioxolo[4,5ꢀj]phenanthridinꢀ6ꢀyldiphenylphosphine oxide (3f)9e. White solid; mp
1
231−233 °C; Rf = 0.23 (PE/EA = 2:1 v/v); 149 mg, 88% yield. H NMR (CDCl3, 500 MHz):
δ
6.13 (s, 2H), 7.42−7.46 (m, 4H), 7.51 (q, J = 4.9 Hz, 2H), 7.63−7.68 (m, 2H), 7.92−7.96 (m, 5H),
8.00 (t, J = 4.6 Hz, 1H), 8.39 (t, J = 4.6 Hz, 1H), 9.04 (s, 1H). 13C NMR (CDCl3, 125 MHz):
δ
99.8, 102.0, 105.7, 121.9, 124.5, 125.0 (d, J = 23.4 Hz), 128.1 (d, J = 11.8 Hz), 128.3, 131.0,
131.6, 132.3 (d, J = 8.0 Hz), 132.6, 133.5, 142.5 (d, J = 22.9 Hz), 148.3, 151.3, 154.6 (d, J = 130.6
Hz).
(8ꢀFluorophenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3g)9e. White solid; mp 218−220 °C;
Rf = 0.37 (PE/EA = 2:1 v/v); 99 mg, 62% yield. 1H NMR (CDCl3, 500 MHz):
δ 7.46−7.54 (m, 6H),
7.60 (t, J = 7.0 Hz, 1H), 7.73 (q, J = 6.8 Hz, 2H), 7.96 (q, J = 6.3 Hz, 4H), 8.08 (d, J = 7.6 Hz, 1H),
8.54 (d, J = 7.3 Hz, 1H), 8.64 (d, J = 5.1 Hz, 1H), 9.33 (dd, J = 1.9, 9.8 Hz, 1H). 13C NMR (CDCl3,
125 MHz):
δ 113.2 (d, J = 23.3 Hz), 120.5 (d, J = 23.9 Hz), 121.9, 124.0, 124.5 (d, J = 8.0 Hz),
128.2 (d, J = 12.2 Hz), 128.6, 129.0 (d, J = 9.2 Hz), 129.2, 129.3 (d, J = 6.4 Hz), 131.2, 131.8,
132.3 (d, J = 9.0 Hz), 133.2, 142.4 (d, J = 21.9 Hz), 156.0 (dd, J = 3.8, 128.3 Hz), 161.3 (d, J =
249.3 Hz).
(8ꢀChlorophenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3h)9e. White solid; mp 226−228 °C;
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Rf = 0.46 (PE/EA = 2:1 v/v); 94 mg, 57% yield. 1H NMR (CDCl3, 500 MHz):
δ 7.45−7.54 (m, 6H),
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6
7
8
9
7.73 (s, 2H), 7.79 (t, J = 8.0 Hz, 1H), 7.95 (q, J = 6.3 Hz, 4H), 8.06 (s, 1H), 8.56 (q, J = 8.9 Hz,
2H), 9.67 (d, J = 1.5 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
122.0, 123.7, 127.7, 128.2 (d, J =
δ
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11.8 Hz), 128.7, 129.1 (d, J = 25.5 Hz), 131.1 (d, J = 19.0 Hz), 131.8, 132.3 (d, J = 7.8 Hz), 133.2,
134.0, 142.6 (d, J = 22.9 Hz), 155.9 (d, J = 128.7 Hz).
Diphenyl(8ꢀ(trifluoromethyl)phenanthridinꢀ6ꢀyl)phosphine oxide (3i)9e. White solid; mp
176−178 °C; Rf = 0.58 (PE/EA = 2:1 v/v); 95 mg, 53% yield. 1H NMR (CDCl3, 500 MHz):
δ 7.46
(q, J = 3.8 Hz, 4H), 7.53 (t, J = 7.2 Hz, 2H), 7.79 (t, J = 3.7 Hz, 2H), 7.96−8.04 (m, 5H), 8.13 (d, J
= 6.6 Hz, 1H), 8.61 (d, J = 7.9 Hz, 1H), 8.76 (d, J = 8.1 Hz, 1H), 10.04 (s, 1H). 13C NMR (CDCl3,
125 MHz):
δ 122.4, 122.7, 123.2, 123.3, 123.8 (d, J = 272.1 Hz), 126.2, 126.9, 127.2 (d, J = 23.5
Hz), 128.2 (d, J = 11.5 Hz), 129.3, 129.7, 129.9, 131.2, 131.8, 132.3 (d, J = 8.0 Hz), 133.0, 134.7,
143.3 (d, J = 22.9 Hz), 157.1 (d, J = 127.6 Hz).
Methyl 6ꢀ(diphenylphosphoryl)phenanthridineꢀ8ꢀcarboxylate (3j). White solid; mp
1
207−209 °C; Rf = 0.35 (PE/EA = 2:1 v/v); 103 mg, 59% yield. H NMR (CDCl3, 500 MHz):
δ
3.98 (s, 3H), 7.44−7.46 (m, 4H), 7.52 (t, J = 7.0 Hz, 2H), 7.78 (t, J = 3.8 Hz, 2H), 7.98 (q, J = 6.3
Hz, 4H), 8.10 (t, J = 4.6 Hz, 1H), 8.47 (d, J = 8.5 Hz, 1H), 8.62 (d, J = 7.6 Hz, 1H), 8.70 (d, J =
8.6 Hz, 1H), 10.31 (s, 1H). 13C NMR (CDCl3, 125 MHz):
δ 52.5, 122.5 (d, J = 23.1 Hz), 123.6,
127.4 (d, J = 21.9 Hz), 128.2 (d, J = 11.4 Hz), 129.1, 120.3, 129.8, 130.7, 131.0 (d, J = 24.3 Hz),
131.8, 132.4, 133.2, 135.5, 143.4 (d, J = 21.9 Hz), 157.5 (d, J = 127.6 Hz), 166.5. HRMS
(ESIꢀTOF, [M + H]+): calcd for C27H21NO3P, 438.1253, found 438.1255.
(9ꢀMethylphenanthridinꢀ6ꢀyl)diphenylphosphine oxide and (7ꢀMethylphenanthridinꢀ6ꢀyl)
diphenylphosphine oxide (3k/3k’)9b. White solid; Rf = 0.49 (PE/EA = 2:1 v/v); 123 mg, 78%
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yield. 1H NMR (CDCl3, 500 MHz):
δ 2.62 (s, 3H), 2.99 (s, 0.38H), 7.42−7.45 (m, 4.5H), 7.50 (t, J
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6
7
8
9
= 7.3 Hz, 3.25H), 7.62 (t, J = 7.5 Hz, 0.21H), 7.68−7.74 (m, 2.32H), 7.76−7.82 (m, 0.58H),
7.91−7.95 (m, 4H), 8.03 (t, J = 4.6 Hz, 1H), 8.43 (s, 1H), 8.56 (t, J = 9.5 Hz, 1.28H), 9.40 (d, J =
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8.5 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
δ 22.4, 25.0, 120.2, 121.7, 122.1, 122.2, 124.2, 126.1
(d, J = 23.3 Hz), 128.1 (d, J = 12.1 Hz), 128.4, 128.5, 128.9, 129.6, 130.5 (d, J = 8.2 Hz), 131.1,
131.2, 132.0 (d, J = 8.7 Hz), 132.6, 132.8 (d, J = 6.2 Hz), 133.5, 134.1,134.4, 137.9, 141.6, 142.9
(d, J = 22.9 Hz), 156.5 (d, J = 128.7 Hz).
(10ꢀMethylphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3l)9e. White solid; mp 211−213 °C;
Rf = 0.44 (PE/EA = 2:1 v/v); 110 mg, 70% yield. 1H NMR (CDCl3, 500 MHz):
(q, J = 4.0 Hz, 4H), 7.51 (t, J = 6.8 Hz, 2H), 7.60 (t, J = 7.7 Hz, 1H), 7.70 (q, J = 5.4 Hz, 3H),
7.89−7.92 (m, 4H), 8.06 (t, J = 4.7 Hz, 1H), 8.86 (d, J = 9.2 Hz, 1H), 9.45 (d, J = 7.9 Hz, 1H). 13
NMR (CDCl3, 125 MHz): 26.9, 122.0, 125.7, 126.6, 127.2 (d, J = 22.4 Hz), 127.9, 128.1 (d, J =
δ 3.14 (s, 3H), 7.44
C
δ
11.3 Hz), 128.6, 129.2 (d, J = 22.9 Hz), 131.5, 132.3 (d, J = 8.0 Hz), 132.7, 133.5, 135.2, 143.9 (d,
J = 22.9 Hz), 157.3 (d, J = 128.7 Hz).
(3ꢀMethylphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3m). White solid; mp 193−195 °C;
1
Rf = 0.46 (PE/EA = 2:1 v/v); 118 mg, 75% yield. H NMR (CDCl3, 500 MHz):
δ 2.55 (s, 3H),
7.43−9.46 (m, 4H), 7.49−7.55 (m, 3H), 7.64 (t, J = 7.6 Hz, 1H), 7.82 (t, J = 10.2 Hz, 2H), 7.94 (q,
J = 6.4 Hz, 4H), 8.47 (d, J = 7.9 Hz, 1H), 8.60 (d, J = 7.1 Hz, 1H), 9.49 (d, J = 7.9 Hz, 1H). 13
NMR (CDCl3, 125 MHz): 21.3, 121.8, 122.0, 127.3, 127.3, 127.6, 127.8, 128.1 (d, J = 11.1 Hz),
C
δ
128.5, 130.5 (d, J = 8.0 Hz), 130.8, 131.5, 132.3 (d, J = 7.0 Hz), 132.7 (d, J = 9.8 Hz), 133.6,
138.9, 142.8 (d, J = 22.9 Hz), 156.8 (d, J = 128.6 Hz). HRMS (ESIꢀTOF, [M + H]+): calcd for
C26H21NOP, 394.1355, found 394.1356.
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(2ꢀMethylphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3n)9e. White solid; mp 210−212 °C;
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6
7
1
Rf = 0.54 (PE/EA = 2:1 v/v); 104 mg, 66% yield. H NMR (CDCl3, 500 MHz):
δ 2.63 (s, 3H),
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7.72−7.45 (m, 4H), 7.49−7.54 (m, 3H), 7.67 (t, J = 7.6 Hz, 1H), 7.82 (t, J = 7.6 Hz, 1H), 7.93 (q, J
= 6.6 Hz, 5H), 8.37 (s, 1H), 8.63 (d, J = 7.93 Hz, 1H), 9.48 (d, J = 8.3 Hz, 1H). 13C NMR (CDCl3,
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125 MHz):
δ 22.1, 121.6, 122.0, 124.2, 127.7, 128.1 (d, J = 11.0 Hz), 128.5, 130.4, 130.8 (d, J =
18.9 Hz), 131.6, 132.3 (d, J = 7.1 Hz), 132.8, 133.6, 139.0, 141.2 (d, J = 23.4 Hz), 155.6 (d, J =
129.4 Hz).
Diphenyl(9ꢀ(trifluoromethyl)phenanthridinꢀ6ꢀyl)phosphine
Diphenyl(7ꢀ(trifluoromethyl)phenanthridinꢀ6ꢀyl)phosphine oxide (3o/3o’). Colorless oil; Rf =
0.62 (PE/EA = 2:1 v/v); 56 mg, 31% yield. 1H NMR (CDCl3, 500 MHz):
7.10−7.22 (m, 5.78H),
oxide
and
δ
7.32−7.40 (m, 6.19H), 7.44−7.60 (m, 7.66H), 7.69−7.74 (m, 2.44H), 7.79−7.86 (m, 5.18H), 8.02 (t,
J = 4.5 Hz, 0.94H), 8.20 (d, J = 8.2 Hz, 1.42H), 8.54 (d, J = 9.6 Hz, 1.99H), 8.84 (s, 1.20H), 9.62
(d, J = 8.7 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
δ 118.3, 118.7 (d, J = 4.2 Hz), 120.1 (d, J = 3.3
Hz), 121.0, 121.5, 121.9 (d, J = 3.0 Hz), 122.7 (d, J = 2.6 Hz), 123.7 (d, J = 2.0 Hz), 123.8, 123.9
(d, J = 3.4 Hz), 124.0 (d, J = 3.7 Hz), 124.2, 124.7, 125.0, 125.1 (d, J = 2.4 Hz), 125.2 (d, J = 3.7
Hz), 125.5, 127.3 (d, J = 12.3 Hz), 127.9, 128.1, 128.2, 128.4, 128.5, 128.7 (d, J = 12.4 Hz), 129.2,
130.1 (d, J = 6.6 Hz), 130.2, 130.3, 130.5 (d, J = 14.4 Hz), 130.7 (d, J = 14.0 Hz), 130.8, 130.9 (d,
J = 2.7 Hz), 131.2 (d, J = 9.4 Hz), 131.4 (t, J = 3.4 Hz), 131.5, 131.6, 131.7 (d, J = 3.6 Hz), 132.7
(d, J = 19.0 Hz), 137.5 (d, J = 70.4 Hz), 142.0 (d, J = 22.0 Hz), 155.7 (d, J = 127.6 Hz), 158.1,
161.1. HRMS (ESIꢀTOF, [M + H]+): calcd for C26H18F3NOP, 448.1078, found 448.1079.
(2ꢀFluorophenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3p)9e. White solid; mp 233−235 °C;
1
Rf = 0.33 (PE/EA = 2:1 v/v); 92 mg, 58% yield. H NMR (CDCl3, 500 MHz):
δ 7.45 (q, J = 5.1
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Hz, 5H), 7.53 (t, J = 7.1 Hz, 2H), 7.73 (t, J = 7.6 Hz, 1H), 7.86 (t, J = 7.6 Hz, 1H), 7.91 (q, J = 6.3
Hz, 4H), 8.05 (q, J = 4.9 Hz, 1H), 8.19 (dd, J = 9.7, 2.0 Hz, 1H), 8.53 (d, J = 7.9 Hz, 1H), 9.50 (d,
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8
9
J = 7.9 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
δ 107.1 (d, J = 23.1 Hz), 117.8 (d, J = 24.9 Hz),
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122.3, 126.0, 127.8 (d, J = 22.9 Hz), 128.2 (d, J = 11.6 Hz), 128.6 (d, J = 18.9 Hz), 131.1, 131.7,
132.2 (d, J = 8.0 Hz), 133.2, 133.6, 139.6 (d, J = 24.0 Hz), 156.1 (d, J = 128.6 Hz), 162.4 (d, J =
250.2 Hz).
(2ꢀChlorophenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3q)9b. White solid; mp 237−239 °C;
1
Rf = 0.48 (PE/EA = 2:1 v/v); 111 mg, 67% yield. H NMR (CDCl3, 500 MHz):
δ 7.43−7.46 (m,
4H), 7.52 (t, J = 7.2 Hz, 2H), 7.64 (dd, J = 8.9, 2.2 Hz, 1H), 7.72 (t, J = 7.6 Hz, 1H), 7.85−7.93 (m,
5H), 7.98 (d, J = 8.7 Hz, 1H), 8.55 (d, J = 2.1 Hz, 1H), 8.6 (s, 1H), 9.50 (d, J = 9.5 Hz, 1H). 13
NMR (CDCl3, 125 MHz): 121.8, 122.1, 125.5, 128.2 (d, J = 11.0 Hz), 128.7 (d, J = 26.3 Hz),
C
δ
129.3, 131.3, 131.8, 132.3 (d, J = 7.4 Hz), 132.6, 133.2, 134.9, 141.1 (d, J = 22.9 Hz), 157.4 (d, J
= 127.7 Hz).
(2,4ꢀDichlorophenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3r). White solid; mp
1
252−254 °C; Rf = 0.42 (PE/EA = 2:1 v/v); 111 mg, 62% yield. H NMR (CDCl3, 500 MHz):
δ
7.47 (t, J = 3.8 Hz, 4H), 7.52 (t, J = 7.0 Hz, 2H), 7.77−7.82 (m, 2H), 7.90 (t, J = 7.6 Hz, 1H), 8.08
(q, J = 6.3 Hz, 4H), 8.47 (d, J = 1.8 Hz, 1H), 8.55 (d, J = 8.2 Hz, 1H), 9.69 (d, J = 8.5 Hz, 1H).
13C NMR (CDCl3, 125 MHz):
δ 120.6, 122.4, 126.6, 128.2 (d, J = 12.2 Hz), 128.9, 129.3 (d, J =
34.8 Hz), 131.4, 131.8, 132.0, 132.4 (d, J = 8.0 Hz), 132.9, 134.3, 136.9, 137.7 (d, J = 22.9 Hz),
158.1 (d, J = 126.6 Hz). HRMS (ESIꢀTOF, [M + H]+): calcd for C25H17Cl2NOP, 448.0419, found
448.0419.
(2ꢀChloroꢀ8ꢀfluorophenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3s). White solid; mp
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241−243 °C; Rf = 0.52 (PE/EA = 2:1 v/v); 98 mg, 57% yield. H NMR (CDCl3, 500 MHz):
δ
5
6
7
8
9
7.44−7.48 (m, 4H), 7.53 (q, J = 4.9 Hz, 2H), 7.59−7.65 (m, 2H), 7.91−7.95 (m, 4H), 7.99 (d, J =
8.5 Hz, 1H), 8.48 (s, 1H), 8.55 (q, J = 4.6 Hz, 1H), 9.33 (dd, J = 2.4, 10.0 Hz, 1H). 13C NMR
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(CDCl3, 125 MHz):
δ 113.4 (d, J = 23.3 Hz), 120.8 (d, J = 24.9 Hz), 121.6, 124.7 (d, J = 8.0 Hz),
125.0, 128.3 (d, J = 11.9 Hz), 129.2, 131.9, 132.2 (d, J = 9.2 Hz), 132.6, 132.8, 135.4, 140.8 (d, J
= 21.9 Hz), 156.4 (d, J = 127.7 Hz), 161.6 (d, J = 250.3 Hz). HRMS (ESIꢀTOF, [M + H]+): calcd
for C25H17ClFNOP, 432.0714, found 432.0711.
(10ꢀMethoxyꢀ2ꢀmethylphenanthridinꢀ6ꢀyl)diphenylphosphine oxide (3t)9c. White solid; mp
1
223−225 °C; Rf = 0.32 (PE/EA = 2:1 v/v); 122 mg, 72% yield. H NMR (CDCl3, 500 MHz):
δ
2.62 (s, 3H), 4.12 (s, 3H), 7.29 (d, J = 8.0 Hz, 1H), 7.41−7.44 (m, 4H), 7.50 (t, J = 9.4 Hz, 3H),
7.61 (t, J = 8.2 Hz, 1H), 7.89 (d, J = 6.5 Hz, 5H), 9.11 (d, J = 7.9 Hz, 1H), 9.31 (s, 1H). 13C NMR
(CDCl3, 125 MHz):
δ 22.6, 55.8, 111.8, 120.7, 124.0, 127.5, 128.1 (d, J = 13.3Hz), 129.6, 130.6,
131.5, 132.3 (d, J = 7.6 Hz), 132.8, 133.6, 138.8, 141.7, 155.6, 158.1.
Diphenyl(thieno[3,2ꢀc]quinolinꢀ4ꢀyl)phosphine oxide (3u)9f. Light yellow solid; mp
1
240−242 °C; Rf = 0.36 (PE/EA = 2:1 v/v); 83 mg, 54% yield. H NMR (CDCl3, 500 MHz):
δ
7.43−7.47 (m, 4H), 7.50−7.53 (m, 2H), 7.60 (d, J = 5.4 Hz,1H), 7.65−7.72 (m, 2H), 7.78−8.02 (m,
4H), 8.14−8.18 (m, 2H), 8.67 (d, J = 5.5 Hz,1H). 13C NMR (CDCl3, 125 MHz):
123.4, 124.4,
δ
125.3, 126.6, 128.2 (d, J = 11.8 Hz), 128.6, 131.1, 131.8, 132.3 (d, J = 8.9 Hz), 133.1, 135.4 (d, J
= 23.9 Hz), 142.8 (d, J = 21.9 Hz), 146.4 (d, J = 8.9 Hz), 152.3 (d, J = 130.6 Hz).
Benzofuro[3,2ꢀk]phenanthridinꢀ6ꢀyldiphenylphosphine oxide (3v). White solid; mp
1
271−273 °C; Rf = 0.21 (PE/EA = 2:1 v/v); 128 mg, 68% yield. H NMR (CDCl3, 500 MHz):
δ
7.46 (s, 5H), 7.53 (t, J = 7.1 Hz, 2H), 7.59 (t, J = 7.6 Hz, 1H), 7.81 (q, J = 8.9 Hz, 2H), 7.90 (t, J =
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7.5 Hz, 1H), 7.97 (q, J = 6.4 Hz, 4H), 8.11 (t, J = 9.2 Hz, 2H), 8.26 (d, J = 8.5 Hz, 1H), 9.60 (d, J
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= 8.5 Hz, 1H), 9.67 (d, J = 8.2 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
δ 112.1, 120.8 (d, J = 114.7
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Hz), 122.4, 123.5 (d, J = 13.9 Hz), 125.6, 127.2, 127.5 (d, J = 24.3 Hz), 128.1 (d, J = 11.2 Hz),
129.0 (d, J = 39.0 Hz), 130.8, 131.7, 132.4 (d, J = 8.0 Hz), 133.4, 143.2 (d, J = 22.9 Hz), 151.8,
156.5 (d, J = 129.1 Hz), 156.7. HRMS (ESIꢀTOF, [M + H]+): calcd for C31H21NO2P, 470.1304,
found 470.1303.
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Phenanthridinꢀ6ꢀyldiꢀpꢀtolylphosphine oxide (3w)9e. White solid; mp 204−206 °C; Rf = 0.28
(PE/EA = 2:1 v/v); 106 mg, 65% yield. 1H NMR (CDCl3, 500 MHz):
7.66−7.71 (m, 3H), 7.81 (t, J = 9.6 Hz, 5H), 8.06 (t, J = 4.6 Hz, 1H), 8.59 (d, J = 7.7 Hz, 1H), 8.64
(d, J = 7.7 Hz, 1H), 9.52 (d, J = 7.9 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
21.6, 122.0, 124.3,
δ 2.38 (s, 6H), 7.24 (s, 4H),
δ
127.8, 128.6, 128.7 (d, J = 5.4 Hz), 128.9 (d, J = 11.8 Hz), 129.4, 130.3, 130.9, 131.2, 132.3 (d, J
= 8.0 Hz), 132.5, 142.0, 142.8 (d, J = 22.9 Hz), 157.4 (d, J = 125.7 Hz).
Bis(4ꢀmethoxyphenyl)(phenanthridinꢀ6ꢀyl)phosphine oxide (3x). White solid; mp 89−91 °C;
Rf = 0.17 (PE/EA = 2:1 v/v); 93 mg, 53% yield. 1H NMR (CDCl3, 500 MHz):
δ 3.82 (s, 6H), 6.95
(q, J = 3.5 Hz, 4H), 7.67−7.73 (m, 3H), 7.84 (q, J = 6.64 Hz, 5H), 8.07 (t, J = 4.6 Hz, 1H), 8.59 (t,
J = 4.58 Hz, 1H), 8.65 (d, J = 8.06 Hz, 1H), 9.53 (d, J = 8.54 Hz, 1H). 13C NMR (CDCl3, 125
MHz):
δ 55.2, 113.7 (d, J = 12.0 Hz), 122.0, 124.1 (d, J = 34.9 Hz), 124.9, 127.8, 128.6 (d, J =
13.9 Hz), 131.0 (d, J = 28.2 Hz), 132.5, 134.1 (d, J = 8.0 Hz), 142.7 (d, J = 22.9 Hz), 157.6 (d, J =
127.7 Hz), 162.2. HRMS (ESIꢀTOF, [M + H]+): calcd for C27H23NO3P, 440.1410, found 440.1410.
Bis(4ꢀfluorophenyl)(phenanthridinꢀ6ꢀyl)phosphine oxide (3y). Light yellow solid; mp
1
135−137 °C; Rf = 0.36 (PE/EA = 2:1 v/v); 111 mg, 67% yield. H NMR (CDCl3, 500 MHz):
δ
7.13−7.17 (m, 4H), 7.70−7.77 (m, 3H), 7.88 (t, J = 7.6 Hz, 1H), 7.90−7.96 (m, 4H), 8.06 (t, J =
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4.8 Hz, 1H), 8.62 (t, J = 4.6 Hz, 1H), 8.68 (d, J = 8.2 Hz, 1H), 9.48 (d, J = 8.5 Hz, 1H). 13C NMR
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(CDCl3, 125 MHz): δ 115.6 (dd, J = 13.6, 20.7 Hz), 122.2, 124.4, 127.7 (d, J = 23.9 Hz), 128.2 (d,
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J = 43.9 Hz), 128.2, 128.9 (d, J = 21.6 Hz), 131.1 (d, J = 25.9 Hz), 132.6 (d, J = 5.6 Hz), 134.7 (t,
J = 8.8 Hz), 142.6 (d, J = 23.9 Hz), 156.3 (d, J = 130.6 Hz), 165.1 (d, J = 252.3 Hz). HRMS
(ESIꢀTOF, [M + H]+): calcd for C25H17F2NOP, 416.1010, found 416.1010.
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Bis(4ꢀchlorophenyl)(phenanthridinꢀ6ꢀyl)phosphine oxide (3z). White solid; mp 211−213 °C;
1
Rf = 0.48 (PE/EA = 2:1 v/v); 125 mg, 70% yield. H NMR (CDCl3, 500 MHz):
δ 7.44 (t, J = 4.0
Hz, 4H), 7.70−7.78 (m, 3H), 7.84−7.90 (m, 5H), 8.07 (t, J = 4.3 Hz, 1H), 8.62 (d, J = 7.3 Hz, 1H),
8.68 (d, J = 8.3 Hz, 1H), 9.45 (d, J = 8.5 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
122.2, 124.4,
δ
127.7 (d, J = 23.8 Hz), 128.1 (d, J = 33.0), 128.6 (d, J = 11.6 Hz), 128.9 (d, J = 25.1 Hz), 130.8,
131.1 (d, J = 31.1 Hz), 131.6, 132.6, 133.6 (d, J = 7.0 Hz), 138.5, 142.6 (d, J = 23.9 Hz), 155.9 (d,
J = 130.6 Hz). HRMS (ESIꢀTOF, [M + H]+): calcd for C25H17Cl2NOP, 448.0419, found 448.0420.
Cyclohexyl(phenanthridinꢀ6ꢀyl)(phenyl)phosphine oxide (3aa). White solid; mp 189−191 °C;
Rf = 0.32 (PE/EA = 2:1 v/v); 71 mg, 46% yield. 1H NMR (CDCl3, 500 MHz):
δ 1.26−1.42 (m, 3H),
1.61 (s, 2H), 1.72−1.81 (m, 4H), 2.04 (d, J = 8.2 Hz, 1H), 3.12 (t, J = 8.0 Hz, 1H), 7.41 (t, J = 8.1
Hz, 3H), 7.66 (t, J = 7.6 Hz, 1H), 7.74 (t, J = 7.4 Hz, 1H), 7.78−7.82 (m, 2H), 7.99 (t, J = 8.8 Hz,
2H), 8.29 (d, J = 7.9 Hz, 1H), 8.60 (t, J = 9.2 Hz, 2H), 9.50 (d, J = 7.9 Hz, 1H). 13C NMR (CDCl3,
125 MHz):
δ 24.2, 24.9, 26.0, 26.4 (q, J = 6.6 Hz), 37.2 (d, J = 75.8 Hz), 122.0 (d, J = 32.9 Hz),
124.4, 127.8, 128.1, 128.3 (d, J = 11.2 Hz), 128.5 (d, J = 2.3 Hz), 128.7, 130.9 (d, J = 6.0 Hz),
131.3, 131.5 (d, J = 8.0 Hz), 131.8, 132.4 (d, J = 7.0 Hz), 132.5, 142.9 (d, J = 21.9 Hz), 157.5 (d, J
= 115.7 Hz). HRMS (ESIꢀTOF, [M + H]+): calcd for C25H25NOP, 386.1668, found 386.1667.
Ethyl(phenanthridinꢀ6ꢀyl)(phenyl)phosphine oxide (3ab). White solid; mp 170−172 °C; Rf =
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0.30 (PE/EA = 2:1 v/v); 56 mg, 42% yield. H NMR (CDCl3, 500 MHz):
δ 1.29ꢀ1.36 (m, 3H),
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2.55ꢀ2.65 (m, 1H), 2.90ꢀ2.99 (m, 1H), 7.38ꢀ7.46 (m, 3H), 7.65 (t, J = 7.6 Hz, 1H), 7.76 (t, J = 7.1
Hz, 1H), 7.81 (q, J = 7.0 Hz, 2H), 7.91 (q, J = 6.1 Hz, 2H), 8.28 (d, J = 7.9 Hz, 1H), 8.61 (q, J =
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7.1 Hz, 2H), 7.32 (d, J = 8.5 Hz, 1H). 13C NMR (CDCl3, 125 MHz):
δ 5.5, 23.1 (d, J = 78.6 Hz),
122.1 (d, J = 15.0 Hz), 124.5, 127.3 (d, J = 20.9 Hz), 127.8, 128.4 (t, J = 9.9 Hz), 128.7 (d, J =
14.4 Hz), 130.9, 131.6, 132.5 (d, J = 26.9 Hz), 133.4, 142.9 (d, J = 22.9 Hz), 157.6 (d, J = 120.7
Hz). HRMS (ESIꢀTOF, [M + H]+): calcd for C21H19NOP, 332.1199, found 332.1197.
Procedure for the synthesis of compound 4. To a 15 mL sealed tube was charged
with a mixture of 1a (84.5 mg, 0.4 mmol), 2a (97 mg, 0.48 mmol), and DMF (2.0
o
mL). The reaction mixture was allowed to stir at 40 C for 6 h monitored by TLC.
After that, the mixture was cooled to room temperature, diluted with EtOAc (20 mL),
and washed by saturated NaCl (5 x 5.0 mL). The organic layer was dried over
anhydrous MgSO4, filtered, and concentrated in vacuo. The crude residue was
purified by flash column chromatography on silica gel to afford the product 4 as a
yellow solid (142 mg, 86%).
Nꢀ([1,1'ꢀbiphenyl]ꢀ2ꢀyl)ꢀ1ꢀ(diphenylphosphoryl)methanethioamide (4). Yellow solid; mp
1
136−138 °C; Rf = 0.45 (PE/EA = 2:1 v/v). H NMR (CDCl3, 500 MHz):
δ 7.32−7.38 (m, 5H),
7.39−7.48 (m, 7H), 7.57 (t, J = 7.2 Hz, 2H), 7.89 (q, J = 6.5 Hz, 4H), 8.28 (d, J = 7.3 Hz, 1H),
10.99 (br s, 1H). 13C NMR (CDCl3, 125 MHz):
124.7, 128.0 (d, J = 15.7 Hz), 128.3 (d, J = 12.5
δ
Hz), 128.6, 128.9 (d, J = 41.2 Hz), 129.5, 130.8, 132.5, 132.8 (d, J = 8.0 Hz), 134.9 (d, J = 10.0
Hz), 137.1 (d, J = 14.0 Hz), 196.0 (d, J = 88.9 Hz). HRMS (ESIꢀTOF, [M + H]+): calcd for
C25H21NOPS, 414.1076, found 414.1076.
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Supporting Information Available: Xꢀray data for 3a and 4 CIF format; 1H and 13C
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NMR spectra of all new compounds. This material is available free of charge via the
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Internet at http://pubs.acs.org.
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ACKNOWLEDGEMENTS
This work was financially supported by the National Natural Science Foundation of
China (21372137 and 21572110), the Natural Science Foundation of Shandong
Province (ZR2014BM006), the Science and Technology Development Project in
University of Shandong Province (J16LC12), the Applied Basic Research Project
(Youth Special) of Qingdao (16ꢀ5ꢀ1ꢀ98ꢀjch), and the Research Fund of State Key
Laboratory for Marine Corrosion and Protection of Luoyang Ship Material Research
Institute (No. KF160404).
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ACS Paragon Plus Environment