Ruthenium-catalyzed C-H activation/cyclization for the synthesis of phosphaisocoumarins

Article abstract of DOI:10.1021/jo401608v

An efficient and cost-effective ruthenium-catalyzed oxidative cyclization of phosphonic acid monoesters or phosphinic acids with alkynes has been developed for the synthesis of a wide range of phosphaisocoumarins in good to excellent yields under aerobic conditions. A multitude of arylphosphonic acid monoesters and arylphosphinic acids having electron-donating and -withdrawing groups were oxidatively cyclized. Various diarylacetylenes, dialkylacetylenes, and alkylarylacetylenes effectively underwent the ruthenium-catalyzed oxidative cyclization. A substrate possessing benzoic acid as well as a phenylphosphonic monoester moiety was smoothly cyclized with hex-3-yne to afford a compound having both isocoumarin and phosphaisocoumarin moieties. Alkenylphosphonic monoester afforded phosphorus 2-pyrone through oxidative cyclization with alkyne. Competition experiments between diaryl- and dialkylalkynes and between diarylacetylenes having p-methoxy and p-chloro groups gave results which showed that the present oxidative cyclizations were not affected by the electronic effects of alkynes. Mechanistic studies revealed C-H bond metalation to be the rate-limiting step.

Full text of DOI:10.1021/jo401608v

Article
pubs.acs.org/joc
Ruthenium-Catalyzed C−H Activation/Cyclization for the Synthesis
of Phosphaisocoumarins
Youngchul Park,† Incheol Jeon,† Seohyun Shin, Jiae Min, and Phil Ho Lee*
Department of Chemistry, Kangwon National University, Hyoja-2-dong, 192-1, Chuncheon 200-701, Republic of Korea
S
* Supporting Information
ABSTRACT: An efficient and cost-effective ruthenium-catalyzed oxidative cyclization of phosphonic acid monoesters or
phosphinic acids with alkynes has been developed for the synthesis of a wide range of phosphaisocoumarins in good to excellent
yields under aerobic conditions. A multitude of arylphosphonic acid monoesters and arylphosphinic acids having electron-
donating and -withdrawing groups were oxidatively cyclized. Various diarylacetylenes, dialkylacetylenes, and alkylarylacetylenes
effectively underwent the ruthenium-catalyzed oxidative cyclization. A substrate possessing benzoic acid as well as a
phenylphosphonic monoester moiety was smoothly cyclized with hex-3-yne to afford a compound having both isocoumarin and
phosphaisocoumarin moieties. Alkenylphosphonic monoester afforded phosphorus 2-pyrone through oxidative cyclization with
alkyne. Competition experiments between diaryl- and dialkylalkynes and between diarylacetylenes having p-methoxy and
p-chloro groups gave results which showed that the present oxidative cyclizations were not affected by the electronic effects of
alkynes. Mechanistic studies revealed C−H bond metalation to be the rate-limiting step.
Scheme 1. Ru-Catalyzed Cyclization using Phosphonic and
Phosphinic Acids
INTRODUCTION
■
Because heterocyclic compounds are ubiquitous in nature,
the development of new methods for their preparation is very
important.1 In addition, phosphorus compounds are an
essential component due to their significant biological and
pharmaceutical properties.2 Hence, Kim’s group and ours
have recently been interested in the development of new
phosphoryl-related directing groups in C−H bond activation
and its application to the synthesis of phosphorus heterocyclic
compounds.3 To date, phosphorus heterocycles have been
generally prepared by Pd-catalyzed intramolecuar cyclizations
of alkynes derived from prefunctionalized phosphorus com-
pounds having an o-halo-substituted aryl moiety.4 During
the past decade, transition-metal-catalyzed C−H activation5
without prefunctionalization has been recognized as an
important tool for atom- and step-economical syntheses of
heterocyclic compounds.6 Recently, rhodium- and ruthenium-
catalyzed oxidative cyclizations of alkynes by carboxylic acids
have been reported by Miura,7 Ackermann,8 and Jeganmohan,9
respectively. In addition, synthetic methods of phosphaisocou-
marins were demonstrated through rhodium-catalyzed cycliza-
tion using alkynes and organophosphorus compounds.3c,10
Herein, we report the cost-effective ruthenium-catalyzed
C−H activation/cyclization of phosphonic monoesters and
phosphinic acids for the synthesis of phosphaisocoumarins
(Scheme 1).
RESULTS AND DISCUSSION
■
We commenced our investigations by examining the C−H
activation/cyclization of ethyl phenylphosphonic monoester
(1a) using a variety of oxidants and solvents in the presence
of [RuCl2(p-cymene)]2 (2 mol %) and KPF6 (20 mol %) in
t-BuOH (Table 1). When Cu(OAc)2·H2O, Na2S2O8, and
PhI(OAc)2 were used as oxidants, the cyclization did not
proceed (entries 1−3). However, the use of Ag2CO3 and AgOAc
promoted the cyclization, thus producing the phosphaisocou-
marin 3a in 14% and 32% yields, respectively. Further screening
of oxidant revealed that the addition of Ag2CO3/AgOAc (1 equiv
each) as a co-oxidant improved the yield up to 36% (entry 6).
Solvent screening (t-AmOH, DCE, and PhCl) failed to increase
the yield (entries 7−9). Because phosphaisocoumarin 3a was
Received: July 24, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
a
a
Table 1. Reaction Optimization
Scheme 2. Scope of Alkynes Reacting with Phosphonic Acid
temp
(°C)
time
(h)
b
entry
oxidant (amt (equiv))
solvent
yield (%)
1
2
Cu(OAc)2·H2O (1)
Na2S2O8 (1)
t-BuOH
t-BuOH
t-BuOH
t-BuOH
t-BuOH
120
120
120
120
120
120
120
120
120
90
20
20
20
20
20
20
20
20
20
16
16
16
30
16
0
0
3
PhI(OAc)2 (1)
Ag2CO3 (1)
0
4
14 (76)
32 (65)
36 (56)
20 (60)
17
5
AgOAc (1)
6
Ag2CO3 (1)/AgOAc (1) t-BuOH
Ag2CO3 (1)/AgOAc (1) t-AmOH
Ag2CO3 (1)/AgOAc (1) DCE
Ag2CO3 (1)/AgOAc (1) PhCl
Ag2CO3 (1)/AgOAc (1) t-BuOH
Ag2CO3 (1)/AgOAc (1) t-BuOH
Ag2CO3 (1)/AgOAc (1) t-BuOH
Ag2CO3 (1)/AgOAc (1) t-BuOH
Ag2CO3 (1)/AgOAc (1) t-BuOH
7
8
9
0
10
39 (55)
45 (46)
a
Conditions: 1a (0.2 mmol), 2 (0.3 mmol), [RuCl2(p-cymene)]2
c
11
90
(10 mol %), KPF6 (20 mol %), Ag2CO3 (0.2 mmol), AgOAc (0.2 mmol),
d
f
b
12
90
93 (85, 5)
t-BuOH (1.3 mL). [RuCl2(p-cymene)]2 (15 mol %) was used.
d
f
13
90
97 (91 )
de
,
14
90
63
a
simultaneously at C2 as well as at C6 to afford 3l (55%) and
3m (33%). Formation of 3m in spite of steric hindrance might
be explained by cooperative coordination of both the methoxy
and the phosphonic acid groups.3c Substrates with a halogen
atom furnished the desired compounds in high yields. Indeed,
the p-fluoro-substituted substrate 1e was reacted with
diphenylethyne and hex-3-yne, affording the phosphaisocoumarins
3o,p. Arylphosphonic monoesters possessing chloro (1f), bromo
(1g), and ketone (1h) groups were smoothly cyclized to give
3q−t in high yields. The tolerance of chloro, bromo, and ketone
groups is especially significant, as successive functional group
transformations are hopeful. Substrates 1i,j possessing 2,3-
dimethyl and 2-methyl-4-methoxy groups at the phenyl ring,
respectively, worked equally well. In contrast, in the case of
3,4-(methylenedioxy)phenylphosphonic monoester 1k, C−H
activation took place at C2 instead of C6 to give rise to 3y in
81% yield because coordination of both the 3-oxy and the
phosphonic acid group likely triggers functionalization at the
C2 site. Ethyl naphthalen-1-ylphosphonic monoester 1l gave the
cyclic compound 3z in 82% yield.
Next, reactions of diphenylphosphinic acid 4a with a multitude
of alkynes 2 were screened (Scheme 4). C−H activated cycliza-
tion of 4a proceeded smoothly with diaryl-substituted alkynes
under aerobic conditions. Exposure of 4a to diphenylethyne pro-
duced phosphaisocoumarin 5a in quantitative yield (98%). When
alkynes 2 having a m-methyl, p-methyl, or p-methoxy group at
the phenyl ring were cyclized with 4a, the phosphaisocoumarins
5b−d were obtained in good to excellent yields. Electron-
deficient bis(chlorophenyl)ethyne also produced 5e,f. We were
pleased to obtain phosphaisocoumarins 5g,h, albeit in moderate
yields, from 4a and bis(bromophenyl)ethyne. The tolerance of
chloro and bromo groups at the phenyl ring is especially useful,
providing an opportunity for further functionalization. In addition,
diphenylphosphinic acid 4a was reacted with hex-3-yne or dec-5-yne
smoothly, thus producing the desired phosphaisocoumarins 5i,j
in 82% and 74% yields, respectively.
Conditions: 1a (0.2 mmol), 2a (0.3 mmol), [RuCl2(p-cymene)]2
b
1
(2 mol %), KPF6 (20 mol %). Yields based on H NMR integration
relative to CH2Br2 internal standard. Numbers in parentheses are
c
recovery yields of 1a. [RuCl2(p-cymene)]2 (6 mol %) was used.
d
e
[RuCl2(p-cymene)]2 (10 mol %) was used. KPF6 was not used.
f
Isolated yield.
unstable at 120 °C, the cyclization was conducted at 90 °C,
thus providing 3a in 39% yield for 16 h (entry 10). When 6 and
10 mol % of [RuCl2(p-cymene)]2 were used, the desired product
3a was obtained in 45% and 93% yields, respectively, along
with 1a at 90 °C for 16 h (entries 11 and 12). Optimal results
were obtained with Ag2CO3/AgOAc (1 equiv each) in the pres-
ence of [RuCl2(p-cymene)]2 (10 mol %) and KPF6 (20 mol %)
in t-BuOH (90 °C, 30 h) to afford 3a in 91% isolated yield
under aerobic conditions (entry 13). The reaction gave 3a in
63% yield in the absence of KPF6, indicating that the use of KPF6
is essential for a excellent yield (entry 14).8
First, we examined the scope and limitation of the Ru-
catalyzed C−H activation/cyclization with a variety of internal
alkynes 2 under the optimized reaction conditions (Scheme 2).
Subjecting 1a to diverse electron-rich diaryl-substituted alkynes
produced the desired phosphaisocoumarins 3b−d in good to
excellent yields under aerobic conditions. However, electron-
deficient diaryl-substituted alkynes having a chloro group
were less reactive and the corresponding phosphaisocoumarins
3e,f were isolated in 52% and 64% yields, respectively, in the
presence of 15 mol % of Ru catalyst. Dialkyl-substituted
alkynes such as hex-3-yne and dec-5-yne were cyclized with high
yields, providing the desired phosphaisocoumarins 3g,h. The
unsymmetrical disubstituted alkyne could be used to establish
unique reactivity, thereby demonstrating the effectiveness of
the developed reaction. 1-Phenyl-1-propyne afforded the desired
product 3i (93%) selectively.
Encouraged by these results, we investigated the scope of
arylphosphonic monoesters 1 having useful functional groups
with diphenylethyne and hex-3-yne (Scheme 3). Cyclization of
substrate 1b bearing an electron-donating o-methoxy group
produced the phosphaisocoumarins 3j,k in 76% and 74%
yields, respectively, under aerobic conditions. In the case of 1c,
with an m-methoxy group, C−H bond activation occurred
When substrate 4b, bearing an o-methyl group, was cyclized
with diphenylethyne and hex-3-yne, 5k,l were produced in 76%
and 74% yields, respectively (Scheme 5). The effectiveness
of the present reaction was proved by direct cyclization of
electron-rich and -deficient substrates 4c,d. Phosphinic acid 4e,
B
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
a
Scheme 3. Scope of Phosphonic Acids and Alkynes
a
[RuCl2(p-cymene)]2 (15 mol %) was used.
a
Scheme 4. Scope of Alkynes Reacting with Phosphinic Acid
a
modified reaction conditions (see the Supporting Information
and eq 2).
[RuCl2(p-cymene)]2 (15 mol %) was used.
Competition experiments between alkynes were examined
(Scheme 6). Phenylphosphonic monoester 1a was treated with
diphenylethyne and hex-5-yne (1.5 equiv each) to give the
phosphaisocoumarins 3a (42%) and 3g (42%) (eq 3). A competi-
tion experiment between diarylacetylenes having p-methoxy
and p-chloro groups afforded the phosphaisocoumarins 3d
(27%) and 3f (31%) (eq 4). These results indicate that cyclization
of phosphonic acid monoesters is not affected by the electronic
effects of alkynes.
having a naphthalen-1-yl group, worked as well, resulting in
the formation of 5q in 80% yield. Gratifyingly, we obtained the
single product 5r (70%) from mesityl(phenyl)phosphinic acid
4f and hex-3-yne.
Moreover, compound 4g, possessing benzoic acid as well as a
phenylphosphonic monoester moiety, was smoothly cyclized
with hex-3-yne to afford 3aa in 91% yield under the optimum
reaction conditions (eq 1). We were pleased to obtain the phos-
phorus 2-pyrone 3ab from the reaction of ethyl (1-phenylvinyl)-
phosphonic monoester 4h with diphenylethyne under the
Next, we conducted kinetic isotope effect (KIE) studies to obtain
insight into the reaction mechanism (Scheme 7). A significant
C
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
a
Scheme 5. Scope of Phosphinic Acids with Alkynes
a
[RuCl2(p-cymene)]2 (15 mol %) was used.
Scheme 6. Intermolecular Competition Experiments
KIE was detected (kH/kD = 5.16), suggesting that C−H bond
cleavage at the 2-position of the phosphonic monoester is most
probably associated with the rate-limiting step. We also con-
ducted kinetic isotope effect (KIE) studies of diphenylphos-
phinic acid. An obvious KIE was observed (kH/kD = 5.67),
indicating that the C−H bond cleavage at the 2-position of
phosphinic acid is most likely involved with the rate-limiting
step.
A plausible mechanism for the reaction of phosphonic
and phosphinic acids 1 and 4 with alkynes 2 is described in
Scheme 8. A proposed catalytic cycle began by coordination of
1 and 4 to RuLCl2 to afford the ruthenium(III) phosphonate I.
Successive ortho ruthenation to give the ruthenacycle intermediate
II, alkyne insertion, and reductive elimination occurred to pro-
duce the phosphaisocoumarins 3 and 5.
CONCLUSION
■
In summary, we have developed an efficient and cost-effective
ruthenium-catalyzed oxidative cyclization of phosphonic acid
monoesters or phosphinic acids with alkynes for the synthesis
of a wide range of phosphaisocoumarins in good to excellent
yields under aerobic conditions. A variety of arylphosphonic
acid monoesters and arylphosphinic acids having electron-
donating and -withdrawing groups were oxidatively cyclized. A
number of diarylacetylenes, dialkylacetylenes, and alkylarylace-
tylenes effectively underwent the ruthenium-catalyzed oxidative
D
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
oxidative cyclizations were not affected by the electronic effects
of alkynes. Mechanistic studies revealed the C−H bond
metalation to be the rate-limiting step.
Scheme 7. Studies with Isotopically Labeled Compounds
EXPERIMENTAL SECTION
■
General Procedure for the Ru-Catalyzed Oxidative Cycliza-
tion of Arylphosphonic Monoester 1 with Alkynes 2. In a screw-
top V-vial were added phenyl phosphonic monoester (1a; 37.0 mg,
0.2 mmol), diphenylethyne (2a; 53.0 mg, 0.3 mmol), [RuCl2(p-
cymene)]2 (12.3 mg, 0.02 mmol), KPF6 (7.0 mg, 0.04 mmol), Ag2CO3
(55.0 mg, 0.2 mmol), and AgOAc (33.0 mg, 0.2 mmol) in t-BuOH
(1.3 mL). The resulting mixture was stirred in air at 90 °C (bath
temperature) for 30 h. After Celite filtration and evaporation of the
solvents in vacuo, the crude product was purified by column chromato-
graphy on silica gel (EtOAc/hexane 1/3) to yield 3a (66.0 mg, 91%)
as a white solid.
3,4-Diphenyl-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide (3a):
Rf = 0.3 (EtOAc/hexane 1/3); white solid, mp 123−126 °C; 1H NMR
(400 MHz, CDCl3) δ 7.94−7.92 (m, 1H), 7.50−7.40 (m, 2H), 7.39−
7.33 (m, 3H), 7.25−7.11 (m, 7H), 6.98−6.93 (m, 1H), 4.33−4.19 (m,
2H), 1.32 (t, J = 7.08 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 147.8
(d, J = 10.66 Hz), 140.2 (d, J = 6.95 Hz), 136.0, 134.5 (d, J = 5.85),
132.8 (d, J = 3.50 Hz), 131.5, 129.3 (d, J = 9.11 Hz), 128.89, 128.85,
128.5, 127.8, 127.66, 127.64 (d, J = 15.33 Hz), 127.1 (d, J = 11.91 Hz),
120.9 (d, J = 181.70 Hz), 119.8 (d, J = 12.02 Hz), 63.0 (d, J =
7.21 Hz), 16.4 (d, J = 5.86 Hz); 31P NMR (121 MHz, CDCl3) δ 10.58;
IR (film) 2982, 1591, 1469, 1443, 1275, 1023, 953, 757 cm−1; HRMS
(EI) m/z calcd for C22H19O3P 362.1072, found 362.1072.
Procedure for Rh-Catalyzed Oxidative Cyclization of Ethyl
Phenylvinylphosphonic Monoester 4h with Diphenylethyne.
In a screw-top V-vial were added ethyl phenylvinylphosphonic mono-
ester (4h; 42.4 mg, 0.2 mmol), diphenylethyne (2a; 53.0 mg, 0.3 mmol),
[RuCl2(p-cymene)]2 (12.3 mg, 0.02 mmol), KPF6 (7.0 mg, 0.04 mmol),
Ag2CO3 (55.0 mg, 0.2 mmol), and AgOAc (33.0 mg, 0.2 mmol) in
PhCl (1.3 mL). The resulting mixture was stirred under air at 90 °C
(bath temperature) for 20 h. After Celite filtration and evaporation of
the solvents in vacuo, the crude product was purified by column
chromatography on silica gel (EtOAc/hexane 1/1) to yield 3ab (50.5 mg,
65%) as a colorless oil.
2-Ethoxy-3,5,6-triphenyl-1,2-oxaphosphorin 2-oxide (3ab): Rf =
1
0.3 (EtOAc/hexane 1/1); colorless oil; H NMR (400 MHz, CDCl3)
δ 7.72−7.70 (m, 2H), 7.42−7.34 (m, 3H), 7.31−727 (m, 5H), 7.25−
7.17 (m, 6H), 4.28−4.18 (m, 2H), 1.29 (t, J = 7.08 Hz, 3H); 13C
NMR (100 MHz, CDCl3) δ 150.8 (d, J = 12.76 Hz), 142.1, 142.0,
138.1 (d, J = 1.18 Hz), 134.7 (d, J = 10.11 Hz), 133.2 (d, J = 6.04 Hz),
129.5, 129.3, 129.1, 128.9 (d, J = 4.51 Hz), 128.5, 127.8, 127.6, 127.1
(d, J = 7.30 Hz), 124.2 (d, J = 168.42 Hz), 117.7 (d, J = 16.17 Hz),
63.7 (d, J = 6.99 Hz), 16.3 (d, J = 6.06 Hz); 31P NMR (161 MHz,
CDCl3) δ 9.49; IR (film) 2982, 2240, 1615, 1536, 1444, 1260, 1159,
1036, 968, 756 cm−1; HRMS (EI) m/z calcd for C24H21O3P 388.1228,
found 388.1227.
Scheme 8. Plausible Mechanism
General Procedure for the Ru-Catalyzed Oxidative Cycliza-
tion of Diarylphosphinic Acid 4 with Alkynes 2. In a screw-top
V-vial were added diphenylphosphinic acid (4a; 43.6 mg, 0.2 mmol),
diphenylethyne (2a; 53.0 mg, 0.3 mmol), [RuCl2(p-cymene)]2 (12.3 mg,
0.02 mmol), KPF6 (7.0 mg, 0.04 mmol), Ag2CO3 (55.0 mg, 0.2 mmol),
and AgOAc (33.0 mg, 0.2 mmol) in t-BuOH (1.3 mL). The resulting
mixture was stirred in air at 90 °C (bath temperature) for 30 h. After
Celite filtration and evaporation of the solvents in vacuo, the crude
product was purified by column chromatography on silica gel (EtOAc/
hexane 1/2) to yield 5a (77.3 mg, 98%) as a solid.
cyclization. A substrate possessing benzoic acid as well as a
phenylphosphonic monoester moiety was smoothly cyclized
with hex-3-yne to afford a compound having both isocoumarin
and phosphaisocoumarin moieties. An alkenylphosphonic
monoester provided phosphorus 2-pyrone through oxidative
cyclization with alkyne. Competition experiments between
diaryl- and dialkylalkynes and between diarylacetylenes having
p-methoxy and p-chloro groups gave the results that the present
1,3,4-Triphenyl-1H-2,1-benzoxaphosphorin-1-oxide (5a): Rf = 0.5
1
(EtOAc/hexane 1/1); pale yellow solid, mp 140−142 °C; H NMR
(400 MHz, CDCl3) δ 7.98−7.92 (m, 2H), 7.64−7.57 (m, 2H), 7.55−
7.50 (m, 2H), 7.45 (tt, J = 7.8, 1.3 Hz, 1H), 7.41−7.30 (m, 4H), 7.29−
7.27 (m, 2H), 7.24 (t, J = 1.6 Hz, 1H), 7.23 (t, J = 2.0 Hz, 1H), 7.18−
7.08 (m, 3H), 7.05 (dd, J = 7.9, 4.8, 1H); 13C NMR (100 MHz, CDCl3)
δ 146.9 (d, J = 11.1 Hz) 138.7 (d, J = 5.3 Hz), 136.1, 134.7 (d, J = 5.2
Hz), 133.0 (d, J = 2.8 Hz), 132.5 (d, J = 2.5 Hz), 132.4 (d, J = 11.1 Hz),
E
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
131.6, 130.3 (d, J = 12.4 Hz), 130.1 (d, J = 145.2 Hz), 129.1, 128.9,
128.6, 128.5 (d, J = 3.4 Hz), 127.9, 127.7, 127.5, 126.8 (d, J = 9.5 Hz),
123.2 (d, J = 128.7 Hz), 119.1 (d, J = 11.1 Hz); 31P NMR (161 MHz,
CDCl3) δ 24.43; IR (film) 3056, 1590, 1240, 1122, 950, 736 cm−1;
HRMS (EI) m/z calcd for C26H19O2P 394.1123, found 394.1123.
Experiments with Isotopically Labeled Substrates. A solution
of 2,3,4,5,6-pentadeuteriophenylphosphonic monoester (1a-[D5])
(38.0 mg, 0.2 mmol), hex-3-yne (2g; 35.0 μL, 0.3 mmol), [RuCl2(p-
cymene)]2 (12.3 mg, 0.02 mmol), KPF6 (7.0 mg, 0.04 mmol), Ag2CO3
(55.0 mg, 0.2 mmol), and AgOAc (33 mg, 0.2 mmol) in t-BuOH
(1.3 mL) was stirred in air at 90 °C (bath temperature) for 30 h. After
Celite filtration and evaporation of the solvents in vacuo, the crude
product was purified by column chromatography on silica gel (EtOAc/
hexane 1/3) to yield (3a-[D4]) (38.0 mg, 70%) as a colorless oil.
A mixture of phenylphosphonic monoester (1a; 18 mg, 0.1 mmol),
2,3,4,5,6-pentadeuteriophenyl phosphonic monoester (1a-[D5];
19.0 mg, 0.1 mmol), hex-3-yne (2g; 35.0 μL, 0.3 mmol), [RuCl2(p-
cymene)]2 (12.3 mg, 10 mol %), Ag2CO3 (55.0 mg, 0.2 mmol), and
AgOAc (33.0 mg, 0.2 mmol) in t-BuOH (1.3 mL) was stirred in air at
90 °C (bath temperature) for 1 h. After Celite filtration and evapora-
tion of the solvents in vacuo, the crude product was purified by
column chromatography on silica gel (EtOAc/hexane 1/3) to yield
3a + 3a-[D4] (4.0 mg, 8%) as a colorless oil.
129.91 (d, J = 193.16 Hz), 129.67 (d, J = 18.15 Hz), 123.61 (d, J = 9.65
Hz), 118.79 (d, J = 3.11 Hz), 115.76 (d, J = 11.68 Hz), 62.12 (d, J =
5.81 Hz), 55.38; IR (film) 2983, 1579, 1424, 1241, 1036, 961 cm−1;
HRMS (EI) m/z calcd for C9H13O4P 216.0551, found 216.0550.
(2-Biphenyl)phosphonic acid monoethyl ester (1d): white solid,
mp 107−114 °C; 1H NMR (400 MHz, CDCl3) δ 10.84 (s, 1H), 8.04
(ddd, J = 14.8, 7.7, 0.7 Hz, 1H), 7.56 (t, J = 7.6 Hz, 1H), 7.45−7.40
(m, 3H), 7.38−7.31 (m, 4H), 3.75 (q, J = 7.2 Hz, 2H), 0.98 (t, J = 7.0
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 146.1 (d, J = 10.0 Hz),
141.3 (d, J = 4.3 Hz), 133.4 (d, J = 10.0 Hz), 132.0 (d, J = 2.8 Hz),
131.3 (d, J = 14.3 Hz), 129.4, 127.5, 127.4, 127.0 (d, J = 192.9 Hz),
126.8 (d, J = 15.0 Hz), 61.6 (d, J = 6. Four Hz), 15.7 (d, J = 7.2 Hz);
31P NMR (121 MHz, CDCl3) δ 21.24; IR (film) 2981, 2286, 1468,
1392, 1096, 1039, 957, 778 cm−1; HRMS (EI) m/z calcd for C14H15O3P
262.0759, found 262.0761.
(4-Fluorophenyl)phosphonic acid monoethyl ester (1e): pale
1
yellow oil; H NMR (400 MHz, CDCl3) δ 12.28 (s, 1H), 7.83−7.76
(m, 2H), 7.10 (dt, J = 13.03 Hz, 3.39 Hz, 2H), 4.09−4.02 (m, 2H),
1.29 (t, J = 7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 166.5 (d,
J = 3.80 Hz), 164.0 (d, J = 3.77 Hz), 133.9 (q, J = 6.83 Hz), 115.6 (q,
J = 12.71 Hz), 62.1 (d, J = 5.72 Hz), 16.1 (d, J = 6.68 Hz); 31P NMR
(121 MHz, CDCl3) δ 19.30; IR (film) 2985, 2262, 1594, 1504, 1226,
1132, 994, 834, 776 cm−1; HRMS (EI) m/z calcd for C8H10FO3P
204.0352, found 204.0349.
In a screw-top V-vial were added diphenylphosphinic acid (4a;
43.6 mg, 0.2 mmol), [RuCl2(p-cymene)]2 (12.3 mg, 0.02 mmol),
KPF6 (7.0 mg, 0.04 mmol), Ag2CO3 (55.0 mg, 0.2 mmol), and AgOAc
(33.0 mg, 0.2 mmol) in t-BuOH (1.3 mL) and D2O (0.13 mL). The
resulting mixture was stirred in air at 90 °C (bath temperature) for
30 h. After Celite filtration and evaporation of the solvents in vacuo, the
crude product was purified by column chromatography on silica gel
(EtOAc/hexane 1/2) to yield (39.3 mg, 90%, 4a + 4a-[Dn]) as a solid.
In a screw-top V-vial were added phenyl(2′, 3′, 4′, 5′, 6′-
pentadeuteriophenyl)phosphinic acid (4a-[D5+H5]; 44.6 mg, 0.2 mmol),
hex-3-yne (35.0 μL, 0.3 mmol), [RuCl2(p-cymene)]2 (12.3 mg, 0.02
mmol), KPF6 (7.0 mg, 0.04 mmol), Ag2CO3 (55.0 mg, 0.2 mmol), and
AgOAc (33.0 mg, 0.2 mmol) in t-BuOH (1.3 mL). The resulting mixture
was stirred in air at 90 °C (bath temperature) for 2 h. After Celite
filtration and evaporation of the solvents in vacuo, the crude product was
purified by column chromatography on silica gel (EtOAc/hexane 1/2) to
yield 5i-[D4+H5] + 5i-[D5+H4] (8.0 mg, 13%) as a oil.
(2-Chlorophenyl)phosphonic acid monoethyl ester (1f): yellow
1
oil; H NMR (400 MHz, CDCl3) δ 11.96 (s, 1H), 7.95 (dd, J = 13.7,
7.4 Hz, 1H), 7.48−7.42 (m, 2H), 7.34−7.29 (m, 1H), 4.21−4.13 (m,
2H), 1.36 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 136.9
(d, J = 3.5 Hz), 134.9 (d, J = 7.8 Hz), 133.5 (d, J = 2.3 Hz), 130.7 (d,
J = 10.5 Hz), 127.8 (d, J = 199.1 Hz), 126.3 (d, J = 14.0 Hz), 62.6 (d,
J = 6.0 Hz), 16.2 (d, J = 6.9 Hz); 31P NMR (121 MHz, CDCl3) δ
16.66; IR (film) 2984, 2598, 2261, 1393, 1124, 958, 781, 664 cm−1;
HRMS (EI) m/z calcd for C8H10ClO3P 220.0056, found 220.0054.
(3-Bromophenyl)phosphonic acid monoethyl ester (1g): yellow
oil; 1H NMR (400 MHz, CDCl3) δ 10.50 (br s, 1H), 7.93 (d, J = 14.0
Hz, 1H), 7.72 (dd, J = 13.4 Hz, 7.6 Hz, 1H), 7.67 (d, J = 8.0 Hz, 1H),
7.33 (td, J = 7.8 Hz, 4.9 Hz, 1H). 4.14−4.07 (m, 2H), 1.33 (t, J = 7.1
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 135.4 (d, J = 2.9 Hz), 134.1
(d, J = 11.0 Hz), 131.1 (d, J = 193.7 Hz), 130.1 (d, J = 16.6 Hz), 129.8
(d, J = 9.6 Hz), 122.8 (d, J = 20.5 Hz), 62.5 (d, J = 5.9 Hz), 16.2 (d,
J = 6.8 Hz); 31P NMR (121 MHz, CDCl3) δ 18.48; IR (film) 2983,
1680, 1398, 1140, 1039, 960, 785, 572 cm−1; HRMS (EI) m/z calcd
for C8H10BrO3P 263.9551, found 263.9549.
Preparation of Phosphonic Monoesters 1 and 4.3c The
corresponding diethyl phosphonate (1.0 mmol), NaOH (2.0 mmol),
and H2O (5.0 mL) were stirred at 80 °C for 6−12 h. The reaction
solution was diluted with water (10 mL). The solution was neutralized
with cooled concentrated hydrochloric acid and extracted with EtOAc.
The extracts were evaporated under reduced pressure to give 1a−k
and 4b−h, which were used as such in the next reaction.
(4-Acetylphenyl)phosphonic acid monoethyl ester (1h): pale
1
yellow oil; H NMR (400 MHz, CDCl3) δ 10.26 (s, 1H), 8.00−7.97
(m, 2H), 7.92−7.87 (m, 2H), 4.14−4.06 (m, 2H), 2.62 (s, 3H), 1.31
(d, J = 7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 197.4, 139.8 (d,
J = 3.24 Hz), 133.5 (d, J = 192.73 Hz), 131.6 (d, J = 10.44 Hz), 127.9
(d, J = 15.41 Hz), 62.4 (d, J = 6.09 Hz), 26.7, 16.2 (d, J = 6.70 Hz),
13.9, 13.8; 31P NMR (121 MHz, CDCl3) δ 18.99; IR (film) 2908,
1689, 1396, 1164, 1039, 993, 954, 786 cm−1; HRMS (EI) m/z calcd
for C10H13O4P 228.0551, found 228.0549.
1
Phenylphosphonic acid monoethyl ester (1a): colorless oil; H
NMR (400 MHz, CDCl3) δ 11.12 (s, 1H), 7.83−7.77 (m, 2H), 7.54−
7.50 (m, 1H), 7.44−7.37 (m, 2H), 4.09−4.02 (m, 2H), 1.28 (t, J =
7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 132.1 (d, J = 2.95 Hz),
131.3 (d, J = 10.15 Hz), 128.9 (d, J = 194.07 Hz), 128.3 (q, J = 15.34
Hz), 61.9 (d, J = 5.81 Hz), 16.1 (d, J = 6.81 Hz); 31P NMR (121 MHz,
CDCl3) δ 20.36; IR (film) 2983, 2601, 1669, 1439, 1208, 1134, 1041,
990, 749 cm−1; HRMS (EI) m/z calcd for C8H11O3P 186.0446, found
186.0448.
(2,3-Dimethylphenyl)phosphonic acid monoethyl ester (1i):
brown solid, mp 110−119 °C; 1H NMR (400 MHz, CDCl3) δ
10.14 (s, 1H), 7.78 (dd, J = 14.5, 7.3 Hz, 1H), 7.30 (d, J = 7.5 Hz, 1H),
7.13 (td, J = 11.4, 4.3 Hz, 1H), 4.11−4.04 (m, 2H), 2.50 (d, J = 1.5 Hz,
3H), 2.30 (s, 3H), 1.31 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 140.1 (d, J = 10.9 Hz), 137.9 (d, J = 15.0 Hz), 134.1 (d, J =
3.0 Hz), 131.2 (d, J = 10.3 Hz), 127.4 (d, J = 189.5 Hz), 125.2 (d, J =
16.3 Hz), 61.6 (d, J = 6.0 Hz), 20.3 (d, J = 1.9 Hz), 17.7 (d, J = 4.6
Hz), 16.2 (d, J = 6.7 Hz); 31P NMR (121 MHz, CDCl3) δ 22.82; IR
(film) 2980, 2309, 1681, 1451, 1391, 1038, 983, 778 cm−1; HRMS
(EI) m/z calcd for C10H15O3P 214.0759, found 214.0757.
(2-Methoxyphenyl)phosphonic acid monoethyl ester (1b): color-
1
less solid, mp 95−100 °C; H NMR (400 MHz, CDCl3) δ 10.49 (s,
1H), 7.82 (ddd, J = 15.2, 7.5, 1.7 Hz, 1H), 7.49 (t, J = 7.5 Hz, 1H),
6.98 (td, J = 11.3, 3.0, 1H), 6.93 (dd, J = 7.7, 7.5 Hz, 1H) 4.18−4.11
(m, 2H), 3.87 (s, 3H), 1.33 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 161.4 (d, J = 2.6 Hz), 134.4 (d, J = 7.1 Hz), 134.2, 120.3 (d,
J = 14.9 Hz), 117.1 (d, J = 194.0 Hz), 111.2 (d, J = 9.5 Hz), 62.1 (d,
J = 5.9 Hz), 55.9, 16.3 (d, J = 6.7 Hz); 31P NMR (121 MHz, CDCl3) δ
20.02; IR (film) 2981, 2265, 1576, 1462, 1432, 1045, 987, 732 cm−1;
HRMS (EI) m/z calcd for C9H13O4P 216.0551, found 216.0551.
(3-Methoxyphenyl)phosphonic acid monoethyl ester (1c): color-
less oil; 1H NMR (400 MHz, CDCl3) δ 10.18 (s, 1H), 7.42−7.29 (m,
3H), 7.08−7.05 (m, 1H), 4.12−4.05 (m, 2H), 3.82 (s, 3H), 1.31 (t, J =
7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 159.4 (d, J = 19.19 Hz),
(4-Methoxy-2-methylphenyl)phosphonic acid monoethyl ester
1
(1j): colorless solid, mp 95−100 °C; H NMR (400 MHz, CDCl3) δ
11.12 (s, 1H), 7.82 (dd, J = 14.1, 8.5 Hz, 1H), 6.76−6.71 (m, 2H),
4.05 (q, J = 7.3 Hz, 2H), 3.82 (s, 3H), 2.55 (s, 3H), 1.30 (t, J = 7.1 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 162.7 (d, J = 3.4 Hz), 143.9 (d,
J = 12.1 Hz), 135.3 (d, J = 11.8 Hz), 118.8 (d, J = 198.0 Hz), 116.9
(d, J = 16.1 Hz), 110.2 (d, J = 16.3 Hz), 61.5 (d, J = 5.9 Hz), 55.2,
F
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
21.4 (d, J = 3.6 Hz), 16.2 (d, J = 6.8 Hz); 31P NMR (121 MHz,
CDCl3) δ 22.63; IR (film): 2980, 2590, 2291, 1565, 1463, 1393, 1089,
982, 727 cm−1; HRMS (EI) m/z calcd for C10H15O4P 230.0708, found
230.0710.
4-(Ethoxy(hydroxy)phosphoryl)benzoic acid (4g): white solid, mp
167−170 °C; 1H NMR (400 MHz, DMSO-d6) δ 8.05−8.03 (m, 2H),
7.83−7.78 (m, 2H), 3.94−3.86 (m, 2H), 1.18 (t, J = 7.04 Hz, 3H); 13C
NMR (100 MHz, DMSO-d6) δ 166.7, 135.8 (d, J = 180.78 Hz), 133.4
(d, J = 3.02 Hz), 131.1 (d, J = 10.09 Hz), 129.0 (q, J = 14.29 Hz), 60.8
(d, J = 5.18 Hz), 16.1 (d, J = 6.20 Hz); 31P NMR (121 MHz, DMSO-
d6) δ 13.46; IR (film) 2850, 1681, 1393, 1205, 1161, 1041, 956, 762
cm−1; HRMS (EI) m/z calcd for C9H11O5P 230.0344, found 230.0346
(1-Phenylethenyl)phosphonic acid monoethyl ester (4h): pale
(1,3-Benzodioxol-5-yl)phosphonic acid monoethyl ester (1k):
1
pale yellow oil; H NMR (400 MHz, CDCl3) δ 10.04 (s, 1H), 7.34
(q, J = 7.42 Hz, 1H), 7.17 (d, J = 13.24 Hz, 1H), 6.84 (q, J = 3.81 Hz,
1H), 6.00 (s, 2H), 4.09−4.02 (m, 2H), 1.30 (t, J = 7.04 Hz, 3H); 13C
NMR (100 MHz, CDCl3) δ 151.0 (d, J = 2.97 Hz), 147.7 (d, J = 23.32
Hz), 126.8 (d, J = 11.23 Hz), 121.7 (d, J = 199.76 Hz), 110.9 (d, J =
12.77 Hz), 108.4 (d, J = 19.00 Hz), 101.5, 62.0 (d, J = 5.73 Hz), 16.1
(d, J = 6.68 Hz); 31P NMR (121 MHz, CDCl3) δ 20.85; IR (film)
2984, 2588, 1667, 1486, 1247, 1038, 962, 778 cm−1; HRMS (EI) m/z
calcd for C9H11O5P 230.0344, found 230.0344.
(1-Naphthalenyl)phosphonic acid monoethyl ester (1l): brown
oil; 1H NMR (400 MHz, CDCl3) δ 10.79 (s, 1H), 8.50 (d, J = 8.36 Hz,
1H), 8.21−8.15 (m, 1H), 8.00 (d, J = 8.24 Hz, 1H), 7.89−7.86 (m,
1H), 7.59−7.51 (m, 2H), 7.48−7.43 (m, 1H), 4.12−4.05 (m, 2H),
1.27 (t, J = 7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 133.6 (d,
J = 6.05 Hz), 133.5 (d, J = 4.45 Hz), 133.4, 132.5 (d, J = 11.51 Hz),
128.6 (d, J = 1.53 Hz), 127.4, 126.7 (d, J = 4.69 Hz), 126.3, 125.0 (d,
J = 190.11 Hz), 124.4 (d, J = 16.92 Hz), 62.1 (d, J = 5.77 Hz), 16.2 (d,
J = 7.33 Hz); 31P NMR (121 MHz, CDCl3) δ 21.32; IR (film) 2982,
2600, 2289, 1671, 1508, 1196, 981, 775 cm−1; HRMS (EI) m/z calcd
for C12H13O3P 236.0602, found 236.0603.
Bis(2-methylphenyl)phosphinic acid (4b): white solid, mp 166−
169 °C; 1H NMR (400 MHz, CDCl3) δ 7.91 (dd, J = 7.6, 1.2 Hz, 1H),
7.87 (dd, J = 7.6, 1.2 Hz, 1H), 7.37 (t, J = 2.2 Hz, 2H), 7.21 (t, J = 3.4
Hz, 2H), 7.13 (t, J = 6.3 Hz, 2H), 2.30 (s, 6H); 13C NMR (100 MHz,
CDCl3) δ 141.4 (d, J = 11.2 Hz), 133.1 (d, J = 10.5 Hz), 132.0 (d, J =
2.5 Hz), 131.1 (d, J = 12.7 Hz), 131.0 (d, J = 135.1 Hz), 125.3 (d, J =
13.1 Hz), 21.1 (d, J = 4.4 Hz); 31P NMR (161 MHz, CDCl3) δ 77.01;
IR (film) 3059, 2960, 2870, 1668, 1566, 1275, 944, 699 cm−1; HRMS
(EI) m/z calcd for C14H15O2P 246.0810, found 246.0807.
1
yellow oil; H NMR (400 MHz, CDCl3) δ 9.56 (s, 1H), 7.55−7.53
(m, 2H), 7.37−7.31 (m, 3H), 6.31 (dd, J = 22.48 Hz, 1.36 Hz, 1H),
6.12 (dd, J = 46.53 Hz, 1.36 Hz, 1H), 4.09−4.02 (m, 2H), 1.26 (d, J =
7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 139.7 (d, J = 180.91
Hz), 136.3 (d, J = 12.33 Hz), 131.0 (d, J = 7.94 Hz), 128.4, 128.3,
127.5 (d, J = 5.88 Hz), 62.2 (d, J = 6.10 Hz), 16.1 (d, J = 6.47 Hz);
31P NMR (161 MHz, CDCl3) δ 19.55; IR (film) 2983, 2599, 2275,
1676, 1493, 1202, 1040, 959, 778 cm−1; HRMS (EI) m/z calcd for
C10H13O3P 212.0602, found 212.0601
Representative Procedure for the Preparation of Alkynes
2.11 1,2-Di-m-tolylethyne (2b): Rf = 0.4 (hexane); white solid, mp
1
115−118 °C; H NMR (400 MHz, CDCl3) δ 7.36−7.32 (m, 4H),
7.23 (t, J = 7.60 Hz, 2H), 7.13 (d, J = 7.65 Hz, 2H), 2.34 (s, 6H); 13C
NMR (100 MHz, CDCl3) δ 138.0, 132.2, 129.1, 128.7, 128.3, 123.2,
89.2, 21.3; IR (film) 3038, 2976, 2251, 2208, 1602, 1579 cm−1; HRMS
(EI) m/z calcd for C16H14: 206.2824, found 206.2827.
1,2-Di-p-tolylethyne (2c): Rf = 0.4 (hexane); white solid, mp 138−
1
140 °C; H NMR (400 MHz, CDCl3) δ 7.41 (d, J = 8.12 Hz, 4H),
7.15 (d, J = 7.92 Hz, 4H), 2.36 (s, 6H); 13C NMR (100 MHz, CDCl3)
δ 138.1, 131.4, 129.1, 120.4, 88.9, 21.5; IR (film) 3026, 2915, 2299,
2136, 1654, 1638 cm−1; HRMS (EI) m/z calcd for C16H14 206.2824,
found 206.2826.
1,2-Bis(4-methoxyphenyl)ethyne (2d): Rf = 0.3 (EtOAc/hexane
1/15); pale yellow solid, mp 147−148 °C; 1H NMR (400 MHz,
CDCl3) δ 7.45 (d, J = 8.92 Hz, 4H), 6.86 (d, J = 8.92 Hz, 4H), 3.82 (s,
6H); 13C NMR (100 MHz, CDCl3) δ 159.4, 132.8, 115.7, 113.9, 87.9,
55.3; IR (film) 2840, 2254, 1244, 1026 cm−1; HRMS (EI) m/z calcd
for C16H14O2: 238.0994, found 238.0992.
Bis(4-methoxyphenyl)phosphinic acid (4c): white solid, mp 156−
1
159 °C; H NMR (400 MHz, CDCl3) δ 7.62 (dd, J = 8.8, 12.1 Hz,
4H), 7.13 (s, 1H), 6.84 (dd, J = 8.8, 2.7 Hz, 4H), 3,80 (s, 6H); 13C
NMR (100 MHz, CDCl3) δ 162.3 (d, J = 2.5 Hz), 133.1 (d, J = 11.9
Hz), 124.4 (d, J = 147.8 Hz), 113.8 (d, J = 14.5 Hz), 55.2; 31P NMR
(161 MHz, CDCl3) δ 33.92; IR (film) 3419, 2932, 1599, 1504, 1296,
1254, 1177, 1130, 1027, 957 cm−1; HRMS (EI) m/z calcd for
C14H15O4P 278.0708, found 278.0706.
1,2-Bis(3-chlorophenyl)ethyne (2e): Rf = 0.6 (hexane); white solid,
1
mp 81−82 °C; H NMR (400 MHz, CDCl3) δ 7.52−7.51 (m, 2H),
7.42−7.39 (m, 2H), 7.36−7.32 (m, 2H), 7.30−7.27 (m, 2H); 13C
NMR (100 MHz, CDCl3) δ 134.3, 131.5, 129.8, 129.6, 128.8, 124.5,
89.0; IR (film) 2328, 2303, 1591, 1556, 909, 788 cm−1; HRMS (EI)
m/z calcd for C14H8Cl2 246.0003, found 246.0005.
Bis(4-chlorophenyl)phosphinic acid (4d): pale yellow solid, mp
1,2-Bis(4-chlorophenyl)ethyne (2f): Rf = 0.6 (hexane); white solid,
mp 174−176 °C; 1H NMR (400 MHz, CDCl3) δ 7.46−7.43 (m, 4H),
7.34−7.31 (m, 4H); 13C NMR (100 MHz, CDCl3) δ 134.5, 132.8,
128.8, 121.4, 89.1; IR (film) 2348, 2309, 683 cm−1; HRMS (EI) m/z
calcd for C14H8Cl2 246.0003, found 246.0000.
1
126−129 °C; H NMR (400 MHz, CDCl3) δ 7.61−7.56 (m, 4H),
7.33−7.31 (m, 4H); 13C NMR (100 MHz, CDCl3) δ 138.7 (d, J = 3.6
Hz), 132.6 (d, J = 11.4 Hz), 130.6 (d, J = 143.8 Hz), 128.8 (d, J = 14.2
Hz); 31P NMR (161 MHz, CDCl3) δ 29.12; IR (film) 3418, 3086,
1650, 1173, 1087, 762, 549 cm−1; HRMS (EI) m/z calcd for
C12H9Cl2O2P 285.9717, found 285.9718.
3,4-Bis(3-methylphenyl)-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide
1
(3b): Rf = 0.3 (EtOAc/hexane 1/3); pale yellow oil; H NMR (400
Dinaphthalen-1-ylphosphinic acid (4e): white solid, mp 124−
127 °C; 1H NMR (400 MHz, CDCl3) δ 8.51 (d, J = 8.5 Hz, 3H, −OH
overlapped), 8.19 (dd, J = 7.1, 0.9 Hz, 1H), 8.15 (dd, J = 7.0, 0.9, Hz,
1H), 7.94 (d, J = 7.9 Hz, 2H), 7.81 (d, J = 8.0 Hz, 2H), 7.45−7.68 (m,
4H), 7.35−7.31 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 133.6,
133.5 (d, J = 3.6 Hz), 133.35 (d, J = 3.2 Hz), 133.32 (d, J = 2.6 Hz),
132.7 (d, J = 11.2 Hz), 128.7, 126.7 (d, J = 103.4 Hz), 126.6 (d, J = 5.1
Hz), 124.6, 124.4; 31P NMR (161 MHz, CDCl3) δ 77.01 IR (film)
3434, 1651, 1334, 1152, 1026, 997, 944, 773 cm−1; HRMS (EI) m/z
calcd for C20H15O2P 318.0810, found 318.0810.
Mesityl(phenyl)phosphinic acid (4f): white solid, mp 155−157 °C;
1H NMR (400 MHz, CDCl3) δ 8.94 (s, 1H), 7.64−7.58 (m, 2H),
7.45−7.41 (m, 1H), 7.35−7.31 (m, 2H), 6.85 (s, 1H), 2.48 (s, 6H),
2.28 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 143.4 (d, J = 11.7 Hz),
141.8 (d, J = 2.6 Hz), 135.2 (d, J = 135.9 Hz), 131.4 (d, J = 2.7 Hz),
130.6 (d, J = 13.2 Hz), 130.1 (d, J = 11.6 Hz), 128.3 (d, J = 13.5 Hz),
124.9 (d, J = 135.2 Hz), 23.5 (d, J = 3.5 Hz), 21.1; 31P NMR
(161 MHz, CDCl3) δ 39.55; IR (film) 3421, 2971, 1606, 1437, 1167,
949 cm−1; HRMS (EI) m/z calcd for C15H17O2P 260.0966, found
260.0963.
MHz, CDCl3) δ 7.97−7.91 (m, 1H), 7.49−7.39 (m, 2H), 7.26−7.15
(m, 4H), 7.02−6.94 (m, 5H), 4.30−4.17 (m, 2H), 2.31 (s, 3H), 2.20 (s,
3H), 1.31 (t, J = 7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 147.7
(d, J = 10.55 Hz), 140.4 (d, J = 6.91 Hz), 138.5, 137.2, 136.0, 134.3 (d,
J = 5.40 Hz), 132.7 (d, J = 2.87 Hz), 131.9, 129.34, 129.30, 129.26,
129.21, 128.7, 128.5, 127.4 (d, J = 15.74 Hz), 127.3, 127.2 (d,
J = 11.92 Hz), 126.0, 120.8 (d, J = 181.33 Hz), 119.7 (d, J = 11.74 Hz),
62.9 (d, J = 6.60 Hz), 21.3 (d, J = 6.79 Hz), 16.4 (d, J = 5.94 Hz);
31P NMR (121 MHz, CDCl3) δ 10.65; IR (film) 2980, 1591, 1469,
1275, 1031, 963, 772, 701 cm−1; HRMS (EI) m/z calcd for C24H23O3P
390.1385, found 390.1383.
3,4-Bis(4-methylphenyl)-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide
(3c): Rf = 0.3 (EtOAc/hexane 1/3); yellow solid, mp 44−
1
47 °C; H NMR (400 MHz, CDCl3) δ 7.96−7.90 (m, 1H), 7.46−
7.37 (m, 2H), 7.25−7.07 (m, 6H), 6.97−6.94 (m, 3H), 4.30−4.16 (m,
2H), 2.38 (s, 3H), 2.26 (s, 3H), 1.30 (t, J = 7.06 Hz, 3H); 13C NMR
(100 MHz, CDCl3) δ 147.8 (d, J = 10.47 Hz), 140.6 (d, J = 6.75 Hz),
138.4, 137.5, 133.1 (d, J = 0.94 Hz), 132.7 (d, J = 2.35 Hz), 131.7 (d,
J = 5.58 Hz), 131.3, 129.6, 129.2 (d, J = 9.05 Hz), 128.7, 128.4, 127.3
(d, J = 15.70 Hz), 127.0 (d, J = 12.20 Hz), 120.8 (d, J = 181.35 Hz),
G
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
119.2 (d, J = 11.75 Hz), 62.8 (d, J = 6.67 Hz), 21.2 (d, J = 6.82 Hz),
16.4 (d, J = 5.97 Hz); 31P NMR (121 MHz, CDCl3) δ 10.66; IR (film)
2981, 2239, 1606, 1469, 1274, 1030, 955, 773 cm−1; HRMS (EI) m/z
calcd for C24H23O3P 390.1385, found 390.1382.
3-Phenyl-4-methyl-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide
(3i): Rf = 0.2 (EtOAc/hexane 1/3); pale yellow solid, mp 106−108
1
°C; H NMR (400 MHz, CDCl3) δ 7.94−7.88 (m, 1H), 7.69−7.65
(m, 1H), 7.56−7.52 (m, 3H), 7.49−7.39 (m, 4H), 4.28−4.19 (m, 2H),
2.21 (d, J = 0.92, 3H), 1.33 (t, J = 7.08 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 147.5 (d, J = 10.26 Hz), 140.0 (d, J = 7.21 Hz), 134.7 (d, J =
5.80 Hz), 133.0 (d, J = 2.35), 129.4, 129.3 (d, J = 8.85 Hz), 129.1,
128.1, 127.4 (d, J = 15.54 Hz), 124.7 (d, J = 12.38 Hz), 121.4 (d, J =
180.04 Hz), 111.3 (d, J = 11.69 Hz), 62.9 (d, J = 6.52 Hz), 16.4 (d, J =
6.02 Hz), 15.6; 31P NMR (121 MHz, CDCl3) δ 10.71; IR (film) 2983,
1629, 1473, 1269, 1030, 1007, 962, 760 cm−1; HRMS (EI) m/z calcd
for C17H17O3P 300.0915, found 300.0914.
3,4-Bis(4-methoxyphenyl)-1-ethoxybenz[c-1,2]oxaphosphinine
1-oxide (3d): Rf = 0.3 (EtOAc/hexane 1/1); pale yellow solid, mp
1
114−116 °C; H NMR (400 MHz, CDCl3) δ 7.95−7.89 (m, 1H),
7.48−7.43 (m, 1H), 7.41−7.37 (m, 1H), 7.19 (dt, J = 9.17 Hz, 2.56
Hz, 2H), 7.14−7.10 (m, 2H), 7.00−6.96 (m, 1H), 6.93−6.89 (m, 2H),
7.19 (dt, J = 9.20 Hz, 2.52 Hz, 2H), 4.30−4.15 (m, 2H), 3.84 (s, 3H),
3.75 (s, 3H), 1.31 (t, J = 4.82 Hz, 3H); 13C NMR (100 MHz, CDCl3)
δ 159.5, 159.1, 147.7 (d, J = 10.65 Hz), 140.8 (d, J = 6.99 Hz), 132.7
(d, J = 2.35 Hz), 132.6, 130.2, 129.2 (d, J = 9.13), 128.4, 127.2 (d, J =
15.55 Hz), 127.0, 126.9 (d, J = 12.19 Hz), 120.7 (d, J = 181.49 Hz)
118.2 (d, J = 11.67 Hz), 114.4, 113.1, 62.8 (d, J = 6.60 Hz), 55.2 (d,
J = 9.28 Hz), 16.4 (d, J = 5.86 Hz), 14.1, 11.7; 31P NMR (121 MHz,
CDCl3) δ 10.73; IR (film) 2907, 1605, 1508, 1252, 1029, 954, 827,
774 cm−1; HRMS (EI) m/z calcd for C24H23O5P 422.1283, found
422.1282.
3,4-Diphenyl-1-ethoxy-8-methoxybenz[c-1,2]oxaphosphinine 1-oxide
(3j): Rf = 0.3 (EtOAc/hexane 1/1); white solid, mp 164−166 °C;
1H NMR (400 MHz, CDCl3) δ 7.39 (t, J = 8.22 Hz, 1H), 7.35−7.33
(m, 3H), 7.24−7.10 (m, 7H), 6.91−6.88 (m, 1H), 6.57−6.54 (m, 1H),
4.41−4.33 (m, 2H), 4.00 (s, 3H), 1.41 (t, J = 7.08 Hz, 3H); 13C NMR
(100 MHz, CDCl3) δ 160.7, 147.9 (d, J = 9.91 Hz), 141.9 (d,
J = 5.18 Hz), 136.3, 134.6 (d, J = 6.00 Hz), 133.9, 131.7, 129.1, 128.8,
128.5, 127.7, 127.5, 120.0 (d, J = 12.06 Hz), 118.3 (d, J = 12.01 Hz),
109.5 (d, J = 9.22 Hz), 109.4 (d, J = 178.10), 63.9 (d, J = 6.18 Hz),
56.2, 16.5 (d, J = 6.66 Hz); 31P NMR (121 MHz, CDCl3) δ 8.67; IR
(film) 2982, 1561, 1465, 1271, 1035, 974 cm−1; HRMS (EI) m/z calcd
for C23H21O4P 392.1177, found 392.1178.
3,4-Diethyl-1-ethoxy-8-methoxybenz[c-1,2]oxaphosphinine 1-oxide
(3k): Rf = 0.3 (EtOAc/hexane 1/1); colorless oil; 1H NMR (400 MHz,
CDCl3) δ 7.53 (t, J = 8.22 Hz, 1H), 7.06−7.02 (m, 1H), 6.87−6.83
(m, 1H), 4.27−4.20 (m, 2H), 3.95 (s, 3H), 2.53−2.45 (m, 4H), 1.36
(t, J = 7.08 Hz, 3H), 7.23 (t, J = 7.50 Hz, 3H), 1.13 (t, J = 7.50 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 160.9, 151.8 (d, J = 10.54 Hz),
140.8 (d, J = 5.16 Hz), 134.0, 116.6 (d, J = 12.70 Hz), 113.4 (d, J =
11.94 Hz), 109.9 (d, J = 176.70 Hz), 108.6 (d, J = 9.36 Hz), 63.4 (d,
J = 6.25 Hz), 56.0, 25.4 (d, J = 5.67 Hz), 21.0, 16.4 (d, J = 6.74 Hz),
14.2, 11.7; 31P NMR (121 MHz, CDCl3) δ 8.84; IR (film) 2972, 1631,
1265, 1028, 948 cm−1; HRMS (EI) m/z calcd for C15H21O4P
296.1177, found 296.1177.
3,4-Bis(3-chlorophenyl)-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide
(3e): Rf = 0.3 (EtOAc/hexane =1/1); pale yellow solid, mp 134−
1
137 °C; H NMR (400 MHz, CDCl3) δ 7.99−7.93 (m, 1H), 7.54−
7.45 (m, 2H), 7.39−7.30 (m, 3H), 7.26−7.18 (m, 2H), 7.11−7.02 (m,
3H), 6.95−6.91 (m, 1H), 4.35−4.21 (m, 2H), 1.34 (t, J = 7.06 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 146.6 (d, J = 10.34 Hz), 139.2
(d, J = 6.75 Hz), 137.4, 135.8 (d, J = 5.70 Hz), 134.9, 133.9, 133.0 (d,
J = 3.33 Hz), 131.3, 130.3, 129.7, 129.5 (d, J = 9.01 Hz), 129.0 (d, J =
6.60 Hz), 128.7, 128.5, 128.2 (d, J = 15.75 Hz), 127.09, 127.00, 126.9,
121.0 (d, J = 182.26 Hz), 119.5 (d, J = 13.04 Hz), 63.2 (d, J = 6.69
Hz), 16.4 (d, J = 5.86 Hz); 31P NMR (121 MHz, CDCl3) δ 10.28; IR
(film) 2981, 2242, 1592, 1470, 1276, 1194, 1028, 974, 776 cm−1;
HRMS (EI) m/z calcd for C22H17Cl2O3P 430.0292, found 430.0290.
3,4-Bis(4-chlorophenyl)-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide
1
(3f): Rf = 0.3 (EtOAc/hexane 1/3); pale yellow oil; H NMR (400
MHz, CDCl3) δ 7.98−7.92 (m, 1H), 7.52−7.44 (m, 1H), 7.37 (d, J =
7.72 Hz, 2H), 7.21−7.12 (m, 6H), 6.92 (t, J = 7.40 Hz, 1H), 4.34−
4.20 (m, 2H), 1.32 (t, J = 7.08, 3H); 13C NMR (100 MHz, CDCl3) δ
146.9 (d, J = 10.35 Hz), 139.5 (d, J = 6.81 Hz), 134.8, 134.2 (d, J =
1.98 Hz), 133.0 (d, J = 2.63 Hz), 132.8, 132.7 (d, J = 5.62 Hz), 130.1,
129.5, 129.4, 128.2, 128.0 (d, J = 15.54 Hz), 126.9 (d, J = 11.93 Hz),
121.9, 120.1, 119.2 (d, J = 12.11 Hz), 63.2 (d, J = 6.63 Hz), 16.5 (d,
J = 5.83 Hz); 31P NMR (121 MHz, CDCl3) δ 10.38; IR (film) 3062,
2982, 1487, 1273, 1092, 1028, 954 cm−1; HRMS (EI) m/z calcd for
C22H17Cl2O3P 430.0292, found 430.0290.
Rf = 0.2 (EtOAc/hexane 1/3); pale yellow oil; 1H NMR (400 MHz,
CDCl3) data for major isomer δ 7.49−7.34 (m, 2H), 7.18−7.13 (m,
1H), 4.26−4.11 (m, 2H), 3.88 (s, 3H), 2.65−2.38 (m, 4H), 1.34 (t, J =
7.08 Hz, 3H), 1.24 (t, J = 7.44 Hz, 3H), 1.17 (t, J = 7.50 Hz, 3H), data
for minor isomer δ 7.49−7.34 (m, 2H), 7.18−7.13 (m, 1H), 4.26−4.11
(m, 2H), 3.88 (s, 3H), 2.65−2.38 (m, 4H), 1.33 (t, J = 7.08 Hz, 3H),
1.24 (t, J = 7.44 Hz, 3H), 1.10 (t, J = 7.50 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 158.0 (d, J = 19.07 Hz), 155.8 (d, J = 17.38 Hz),
150.2 (d, J = 10.30 Hz), 149.7 (d, J = 11.09 Hz), 131.7 (d, J = 6.16
Hz), 128.3 (d, J = 18.99 Hz), 127.9 (d, J = 7.39 Hz), 125.6 (d, J = 7.45
Hz), 123.9, 123.3, 121.5 (d, J = 8.81 Hz), 120.3 (d, J = 2.88 Hz), 116.7
(d, J = 13.07 Hz), 116.0 (d, J = 2.96 Hz), 114.6 (d, J = 11.74 Hz),
112.7 (d, J = 10.19 Hz), 62.6 (d, J = 6.31 Hz), 62.5 (d, J = 6.51 Hz),
55.6, 55.5, 25.0 (d, J = 5.08 Hz), 24.9 (d, J = 4.50 Hz), 22.6, 20.9, 16.4
(d, J = 5.87 Hz), 16.3 (d, J = 6.65 Hz), 14.8, 14.2, 11.9, 11.5; 31P NMR
(121 MHz, CDCl3) δ 11.82, 10.90; IR (film) 2971, 1464, 1268, 1030,
980 cm−1; HRMS (EI) m/z calcd for C15H21O4P 296.1177, found
296.1179.
3,4-Diethyl-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide (3g):
1
Rf = 0.2 (EtOAc/hexane 1/3); pale yellow oil; H NMR (400 MHz,
CDCl3) δ 7.89−7.82 (m, 1H), 7.63−7.58 (m, 1H), 7.45 (t, J = 7.26
Hz, 1H), 7.40−7.35 (m, 1H), 4.23−4.09 (m, 2H), 2.60−2.42 (m, 4H),
1.31 (t, J = 7.25 Hz, 3H), 1.23 (t, J = 7.50 Hz, 3H), 1.16 (t, J = 7.25
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 151.7 (d, J = 10.98 Hz),
138.8 (d, J = 6.71 Hz), 132.9 (d, J = 2.60 Hz), 129.6 (d, J = 8.88 Hz),
126.6 (d, J = 15.60 Hz), 123.7 (d, J = 12.46 Hz), 121.3 (d, J = 179.67
Hz) 114.8 (d, J = 12.47 Hz), 62.5 (d, J = 6.46 Hz), 25.3 (d, J = 5.41
Hz), 20.8, 16.4 (d, J = 6.06 Hz), 14.1, 11.7; 31P NMR (121 MHz,
CDCl3) δ 6.23; IR (film) 2971, 1631, 1470, 1270, 1030, 982, 856,
774 cm−1; HRMS (EI) m/z calcd for C14H19O3P 266.1072, found
266.1073.
3,4-Diethyl-1-ethoxy-8-phenylbenz[c-1,2]oxaphosphinine 1-oxide
1
(3n): Rf = 0.3 (EtOAc/hexane 1/4); pale yellow oil; H NMR (400
MHz, CDCl3) δ 7.60−7.55 (m, 3H), 7.48−7.37 (m, 4H), 7.25−7.22
(m, 1H), 3.81−3.71 (m, 1H), 3.51−3.41 (m, 1H), 2.66−2.39 (m, 4H),
1.24−1.19 (m, 6H), 0.94 (t, J = 7.06 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 150.6 (d, J = 9.69 Hz), 144.9 (d, J = 8.69 Hz), 141.2 (d, J =
5.14 Hz), 140.0 (d, J = 7.18 Hz), 131.9 (d, J = 2.22 Hz), 129.2, 129.0
(d, J = 14.18 Hz), 128.0, 127.8, 123.0 (d, J = 12.29 Hz), 121.2 (d, J =
174.32 Hz), 115.1 (d, J = 12.10 Hz), 62.9 (d, J = 6.69 Hz), 25.2 (d, J =
4.75 Hz), 21.4, 15.8 (d, J = 7.10 Hz), 14.4, 11.5; 31P NMR (121 MHz,
CDCl3) δ 9.41; IR (film) 2971, 1641, 1455, 1258, 1035, 981 cm−1;
HRMS (EI) m/z calcd for C20H23O3P 342.1385, found 342.1388.
3,4-Diphenyl-1-ethoxy-6-fluorobenz[c-1,2]oxaphosphinine 1-oxide
(3o): Rf = 0.2 (EtOAc/hexane 1/3); pale yellow solid, mp 126−129 °C;
1H NMR (400 MHz, CDCl3) δ 7.98−7.91 (m, 1H), 7.39−7.35 (m,
3,4-Dibutyl-1-ethoxybenz[c-1,2]oxaphosphinine 1-oxide (3h):
1
Rf = 0.3 (EtOAc/hexane 1/3); pale yellow oil; H NMR (400 MHz,
CDCl3) δ 7.87−7.82 (m, 1H), 7.62−7.57 (m, 1H), 7.44−7.35 (m,
2H), 4.22−4.08 (m, 2H), 2.58−2.41 (m, 2H), 1.69−1.61 (m, 2H),
1.53−1.36 (m, 6H), 1.30 (t, J = 7.06 Hz, 3H), 0.95 (dt, J = 7.25 Hz,
1.62 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ 150.8 (d, J = 10.97
Hz), 139.0 (d, J = 6.77 Hz), 132.8 (d, J = 2.32 Hz), 129.5 (d, J = 9.16
Hz), 126.6 (d, J = 15.63 Hz), 123.9 (d, J = 12.44 Hz), 121.3 (d, J =
179.63 Hz), 114.1 (d, J = 12.03 Hz), 62.4 (d, J = 6.47 Hz), 31.7 (d, J =
5.29 Hz), 31.5, 29.2, 27.4, 22.7, 22.3, 16.4, 16.3, 13.9 (d, J = 1.33 Hz);
31P NMR (121 MHz, CDCl3) δ 10.84; IR (film) 2930, 1630, 1468,
1270, 1031, 960, 774 cm−1; HRMS (EI) m/z calcd for C18H27O3P
322.1698, found 322.1700.
3H), 7.26−7.10 (m, 8H), 6.67−6.62 (m, 1H), 4.33−4.19 (m, 2H),
H
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
1.32 (t, J = 7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 166.8 (d, J =
3.69 Hz), 164.3 (d, J = 2.55 Hz), 148.9 (d, J = 10.41), 143.4 (t, J = 8.96
Hz), 135.4, 134.1 (d, J = 3.68 Hz), 132.0 (t J = 9.85 Hz), 131.4, 129.1,
128.8 (d, J = 1.72 Hz), 128.2, 127.7, 119.2 (dd, J = 11.14 Hz, 2.19 Hz),
116.9 (dd, J = 186.17 Hz, 12.02 Hz), 115.1 (q, J = 13.08 Hz), 114.0 (q,
J = 12.42 Hz), 63.1 (d, J = 6.61 Hz), 16.4 (d, J = 5.94 Hz); 31P NMR
(121 MHz, CDCl3) δ 7.53; IR (film) 2983, 1593, 1470, 1269, 1213,
1025, 974, 753 cm−1; HRMS (EI) m/z calcd for C22H18FO3P 380.0978,
found 380.0979.
3,4-Diphenyl-1-ethoxy-7,8-dimethylbenz[c-1,2]oxaphosphinine
1-oxide (3u): Rf = 0.3 (EtOAc/hexane 1/3); white solid, mp 110−
1
113 °C; H NMR (400 MHz, CDCl3) δ 7.35−7.33 (m, 3H), 7.22−
7.11 (m, 8H), 6.69 (t, J = 7.34, 1H), 4.33−4.15 (m, 2H), 2.70 (s, 3H),
2.32 (s, 3H), 1.35 (t, J = 7.06 Hz, 3H); 13C NMR (100 MHz, CDCl3)
δ 146.2 (d, J = 10.65 Hz), 139.5 (d, J = 9.52 Hz), 138.9 (d, J = 7.42
Hz), 137.2 (d, J = 14.80 Hz), 136.7, 134.5 (d, J = 5.61 Hz), 134.1 (d,
J = 2.63 Hz), 131.7, 128.8, 128.7, 128.3, 127.7, 127.6, 125.3 (d, J =
13.15 Hz), 120.9, 119.4 (d, J = 55.97 Hz), 62.69 (d, J = 7.20 Hz),
20.22, 18.42 (d, J = 5.61 Hz), 16.39 (d, J = 6.31 Hz); 31P NMR (121
MHz, CDCl3) δ 10.93; IR (film) 3054, 2980, 1464, 1260, 1029,
752 cm−1; HRMS (EI) m/z calcd for C24H23O3P 390.1385, found
390.1387.
3,4-Diethyl-1-ethoxy-6-fluorobenz[c-1,2]oxaphosphinine 1-oxide
1
(3p): Rf = 0.3 (EtOAc/hexane 1/5); Pale yellow oil; H NMR (400
MHz, CDCl3) δ 7.88−7.81 (m, 1H), 7.14−7.05 (m, 2H), 4.24−4.12
(m, 2H), 1.32 (t, J = 4.92 Hz, 3H), 1.23 (t, J = 7.50 Hz, 3H), 1.16 (t,
J = 7.54 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 167.1 (d, J = 4.28
Hz), 164.6 (d, J = 3.65 Hz), 153.0 (d, J = 10.84 Hz), 142.0 (t, J = 8.43
Hz), 132.2 (t, J = 10.22 Hz), 117.4 (dd J = 183.78 Hz, 9.85 Hz), 114.1
(q, J = 12.92 Hz), 110.8 (q, J = 12.38 Hz), 62.7 (d, J = 6.51 Hz), 25.4
(d, J = 5.86 Hz), 20.9, 16.4 (d, J = 6.50 Hz), 14.0, 11.6; 31P NMR (121
MHz, CDCl3) δ 10.37; IR (film) 2973, 1600, 1474, 1273, 1162, 1031,
959, 828, 758 cm−1; HRMS (EI) m/z calcd for C14H18FO3P 284.0978,
found 284.0980.
3,4-Diethyl-1-ethoxy-7,8-dimethylbenz[c-1,2]oxaphosphinine 1-oxide
(3v): Rf = 0.3 (EtOAc/hexane 1/3); colorless oil; 1H NMR (400 MHz,
CDCl3) δ 7.36 (d, J = 8.20 Hz, 1H), 7.20 (t, J = 7.42 Hz, 1H), 4.22−
4.03 (m, 2H), 2.62 (d, J = 1.68 Hz, 3H), 2.53−2.45 (m, 4H), 2.31 (s,
3H), 1.33 (t, J = 7.06 Hz, 3H), 1.22 (t, J = 7.50 Hz, 3H), 1.13 (t, J =
7.50 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 150.1 (d, J = 11.12
Hz), 139.8 (d, J = 9.56 Hz), 137.4 (d, J = 7.34 Hz), 136.0 (d, J = 15.05
Hz), 134.3 (d, J = 2.35 Hz), 121.7 (d, J = 13.74 Hz), 120.4 (d, J =
174.67 Hz), 114.3 (d, J = 11.74 Hz), 62.3 (d, J = 6.83 Hz), 25.1 (d, J =
5.28 Hz), 21.1, 20.1 (d, J = 1.28 Hz), 18.3 (d, J = 5.70 Hz), 16.3 (d,
J = 6.53 Hz), 14.3, 11.9; 31P NMR (121 MHz, CDCl3) δ 11.11; IR
(film) 2971, 1466, 1263, 1033, 964 cm−1; HRMS (EI) m/z calcd for
C16H23O3P 294.1385, found 294.1386.
3,4-Diphenyl-1-ethoxy-6-methoxy-8-methylbenz[c-1,2]-
oxaphosphinine 1-oxide (3w): Rf = 0.2 (EtOAc/hexane 1/3); white
solid, mp 96−99 °C; 1H NMR (400 MHz, CDCl3) δ 7.32 (d, J = 1.76
Hz, 3H), 7.23−7.10 (m, 7H), 6.75 (t, J = 2.82, 1H), 6.30−6.28 (m,
1H), 4.31−4.14 (m, 2H), 3.64 (s, 3H), 2.75 (s, 3H), 1.34 (t, J = 7.08,
3H); 13C NMR (100 MHz, CDCl3) δ 126.5 (d, J = 2.98 Hz), 147.6 (d,
J = 10.32 Hz), 143.7 (d, J = 10.80 Hz), 143.2 (d, J = 8.73 Hz), 136.5,
134.6 (d, J = 5.82 Hz), 131.6, 128.9, 128.4, 127.8, 127.6, 119.3 (d, J =
11.24 Hz), 115.5 (d, J = 5.72 Hz), 112.5, 110.9 (d, J = 12.91 Hz),
110.7, 62.6 (d, J = 6.92 Hz), 55.1, 21.9 (d, J = 4.77 Hz), 16.4 (d, J =
6.29 Hz); 31P NMR (121 MHz, CDCl3) δ 11.14; IR (film) 2980, 1589,
1262, 1029, 862 cm−1; HRMS (EI) m/z calcd for C24H23O4P
406.1334, found 406.1333.
3,4-Diphenyl-1-ethoxy-8-chlorobenz[c-1,2]oxaphosphinine 1-oxide
(3q): Rf = 0.3 (EtOAc/hexane 1/3); pale yellow solid, mp 168−171
1
°C; H NMR (400 MHz, CDCl3) δ 7.40−7.33 (m, 5H), 7.25−7.11
(m, 7H), 6.90−6.87 (m, 1H), 4.44−4.37 (m, 2H), 1.43 (t, J = 7.08,
3H); 13C NMR (100 MHz, CDCl3) δ 148.2 (d, J = 10.55 Hz), 142.6
(d, J = 5.69 Hz), 136.2 (d, J = 1.40 Hz), 135.9, 134.1 (d, J = 6.02 Hz),
133.2 (d, J = 1.64 Hz), 131.6, 129.0, 128.95, 128.9, 128.8, 128.1, 127.7,
125.9 (d, J = 11.26 Hz), 120.3 (d, J = 183.80 Hz), 118.4 (d, J = 11.27
Hz), 64.3 (d, J = 6.71 Hz), 16.4 (d, J = 6.61 Hz); 31P NMR (121 MHz,
CDCl3) δ 5.33; IR (film) 3057, 2981, 1443, 1266, 1026, 969 cm−1;
HRMS (EI) m/z calcd for C22H18ClO3P 396.0682, found 396.0683.
3,4-Diethyl-1-ethoxy-8-chlorobenz[c-1,2]oxaphosphinine 1-oxide
1
(3r): Rf = 0.3 (EtOAc/hexane 1/3); pale yellow oil; H NMR (400
MHz, CDCl3) δ 7.51 (t, J = 8.06 Hz, 1H), 7.37−7.34 (m, 2H), 4.33−
4.24 (m, 2H), 2.55−2.48 (m, 4H), 1.40 (t, J = 7.08 Hz, 3H), 1.24 (t,
J = 7.50 Hz, 3H), 1.14 (t, J = 7.50 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 152.1 (d, J = 11.27 Hz), 141.4 (d, J = 5.66 Hz), 136.3 (d, J =
1.82 Hz), 133.3 (d, J = 1.80 Hz), 128.1 (d, J = 10.35 Hz), 122.5 (d, J =
11.18 Hz), 120.8 (d, J = 182.47 Hz), 113.7 (d, J = 11.66 Hz), 63.8 (d,
J = 6.78 Hz), 25.4 (d, J = 5.41 Hz), 21.1 16.3 (d, J = 6.65 Hz), 14.1,
11.6; 31P NMR (121 MHz, CDCl3) δ 5.49; IR (film) 2972, 1638,
1445, 1267, 1031, 797 cm−1; HRMS (EI) m/z calcd for C14H18ClO3P
300.0682, found 300.0682.
3,4-Diethyl-1-ethoxy-6-methoxy-8-methylbenz[c-1,2]-
oxaphosphinine 1-oxide (3x): Rf = 0.2 (EtOAc/hexane 1/3);
1
colorless oil; H NMR (400 MHz, CDCl3) δ 6.80−6.78 (m, 1H),
6.71−6.70 (m, 1H), 4.20−4.02 (m, 2H), 3.86 (s, 3H), 2.67 (d, J = 1.60
Hz, 3H), 2.56−2.41 (m, 4H), 1.32 (t, J = 7.08 Hz, 3H), 1.23 (t, J =
7.50 Hz, 3H), 1.14 (t, J = 7.50 Hz, 3H); 13C NMR (100 MHz, CDCl3)
δ 162.8 (d, J = 3.00 Hz), 151.6 (d, J = 10.99 Hz), 143.9 (d, J = 10.50
Hz), 141.7 (d, J = 8.65 Hz), 114.3 (d, J = 15.74 Hz), 114.1 (d, J =
11.64 Hz), 112.0 (d, J = 182.57 Hz), 107.7 (d, J = 13.38 Hz), 62.2 (d,
J = 6.76 Hz), 55.2, 25.4 (d, J = 5.34 Hz), 22.0 (d, J = 4.59 Hz), 21.3,
16.4 (d, J = 6.53 Hz), 14.2, 11.9; 31P NMR (121 MHz, CDCl3) δ
11.24; IR (film) 2969, 1591, 1261, 1033, 959 cm−1; HRMS (EI) m/z
calcd for C16H23O4P 310.1334, found 310.1331.
3,4-Diethyl-1-ethoxy-7-bromobenz[c-1,2]oxaphosphinine 1-oxide
1
(3s): Rf = 0.3 (EtOAc hexane 1/4); pale yellow oil; H NMR (400
MHz, CDCl3) δ 7.95 (dd, J = 2.20 Hz, J = 15.16 Hz, 1H), 7.71−7.69
(m, 1H), 7.33−7.28 (m, 1H), 4.23−4.16 (m, 2H), 2.60−2.41 (m, 4H),
1.34 (t, J = 7.08 Hz, 3H), 1.23 (t, J = 7.50 Hz, 3H), 1.14 (t, J = 7.52
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 152.2 (d, J = 11.03 Hz),
137.6 (d, J = 6.48 Hz), 135.9 (d, J = 2.68 Hz), 132.2 (d, J = 9.93 Hz),
125.7 (d, J = 13.42 Hz), 123.5 (d, J = 179.0 Hz), 120.3 (d, J = 20.51
Hz), 114.5 (d, J = 11.76 Hz), 63.0 (d, J = 6.53 Hz), 25.3 (d, J = 5.24
Hz), 20.9, 16.4 (d, J = 6.07), 14.1, 11.7; 31P NMR (121 MHz, CDCl3)
δ 8.45; IR (film) 2970, 1468, 1265, 1028, 965 cm−1; HRMS (EI) m/z
calcd for C14H18BrO3P 344.0177, found 344.0180.
3,4-Diethyl-7,8-(methylenedioxy)-1-ethoxybenz[c-1,2]-
oxaphosphinine 1-oxide (3y): Rf = 0.3 (EtOAc/hexane =1/7); pale
yellow oil; 1H NMR (400 MHz, CDCl3) δ 7.42 (q, J = 7.72 Hz, 1H),
6.87 (q, J = 3.69 Hz, 1H), 6.02 (dd, J = 6.30 Hz, 1.38 Hz, 2H), 4.18−
4.07 (m, 2H), 2.72−2.37 (m, 4H), 1.29 (t, J = 7.06 Hz, 3H), 1.21 (t,
J = 7.48 Hz, 3H), 1.10 (t, J = 7.36 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 151.6 (d, J = 3.89 Hz), 151.5 (d, J = 10.38 Hz), 142.3 (d, J =
20.12 Hz), 125.1 (d, J = 10.05), 122.2 (d, J = 9.08 Hz), 115.6 (d, J =
186.93 Hz), 113.9 (d, J = 11.93 Hz), 107.8 (d, J = 19.15 Hz), 100.9,
62.3 (d, J = 6.43 Hz), 24.8 (d, J = 4.85 Hz), 21.5, 16.3 (d, J = 6.16 Hz),
14.8, 11.7; 31P NMR (121 MHz, CDCl3) δ 11.44; IR (film) 2976,
1632, 1440, 1271, 1192, 1035, 905, 774 cm−1; HRMS (EI) m/z calcd
for C15H19O5P 310.0970, found 310.0970.
3,4-Diphenyl-1-ethoxy-6-acetylbenz[c-1,2]oxaphosphinine 1-oxide
1
(3t): Rf = 0.3 (EtOAc/hexane 1/5); yellow solid, mp 97−102 °C; H
NMR (400 MHz, CDCl3) δ 8.08−8.02 (m, 1H), 7.98−7.95 (m, 1H),
7.53−7.51 (m, 1H), 7.39−7.37 (m, 3H), 7.26−7.13 (m, 7H), 4.36−
4.22 (m, 2H), 2.44 (s, 3H), 1.33 (t, J = 7.08 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 197.2, 148.6 (d, J = 10.40 Hz), 140.8 (d, J = 7.06 Hz),
140.4 (d, J = 2.81), 135.3, 134.1 (d, J = 5.73 Hz), 131.3, 129.8 (d, J =
9.35 Hz), 129.1, 128.8, 128.3, 127.7, 126.7 (d, J = 2.87 Hz), 126.6,
124.9 (d, J = 180.38 Hz), 119.6 (d, J = 11.36 Hz), 63.4 (d, J = 6.64
Hz), 26.6, 16.4 (d, J = 5.85 Hz); 31P NMR (121 MHz, CDCl3) δ 9.07;
IR (film) 3059, 2984, 2243, 1692, 1398, 1277, 1185, 1024, 955,
751 cm−1; HRMS (EI) m/z calcd for C24H21O4P 404.1177, found
404.1178.
3,4-Diphenyl-1-ethoxynaphth[c-1,2]oxaphosphinine 1-oxide
(3z): Rf = 0.3 (EtOAc/hexane 1/4); pale yellow solid, mp 144−
148 °C; 1H NMR (400 MHz, CDCl3) δ 8.84 (d, J = 8.48 Hz,
1H), 7.88−7.82 (m, 2H), 7.69−7.65 (m, 1H), 7.58−7.54 (m, 1H),
7.40−7.39 (m, 3H), 7.29−7.15 (m, 7H), 7.08−7.04 (m, 1H),
I
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
4.37−4.21 (m, 2H), 1.33 (t, J = 7.08, 3H); 13C NMR (100 MHz,
CDCl3) δ 148.4 (d, J = 11.31 Hz), 140.6 (d, J = 5.97 Hz), 136.4, 134.3,
133.1 (d, J = 2.89 Hz), 132.2 (d, J = 1.68 Hz), 132.1 (d, J = 4.47 Hz),
131.7, 129.1, 128.9, 128.7, 128.4 (d, J = 11.00 Hz), 128.4, 128.0, 127.7,
127.0, 126.7 (d, J = 5.76 Hz), 124.6 (d, J = 13.40 Hz), 119.8 (d, J =
13.03 Hz), 116.2 (d, J = 177.19 Hz), 63.2 (d, J = 6.93 Hz), 16.4 (d, J =
6.39 Hz); 31P NMR (121 MHz, CDCl3) δ 9.92; IR (film) 3056, 2982,
1243, 1022, 963, 748 cm−1; HRMS (EI) m/z calcd for C26H21O3P
412.1228, found 412.1230.
128.4, 128.2, 128.1, 127.3, 126.7 (d, J = 9.4 Hz), 123.3 (d, J = 128.9
Hz). 118.9 (d, J = 11.2 Hz); 31P NMR (161 MHz, CDCl3) δ 24.54; IR
(film) 3059, 1592, 1470, 1237, 1064, 733 cm−1; HRMS (EI) m/z calcd
for C26H17Cl2O2P 462.0343, found 462.0345.
3,4-Bis(4-chlorophenyl)-1-phenyl-1H-2,1-benzoxaphosphorin 1-oxide
(5f): Rf = 0.4 (EtOAc/hexane 1/1); yellow solid, mp 58−60 °C;
1H NMR (400 MHz, CDCl3) δ 7.95−7.89 (m, 2H), 7.66−7.45 (m,
5H), 7.40−7.34 (m, 3H), 7.21 (d, J = 8.2 Hz, 2H), 7.17−7.11 (m,
4H), 7.01 (dd, J = 7.9, 4.8 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ
146.0 (d, J = 11.0 Hz), 138.0 (d, J = 5.2 Hz), 134.7, 134.2 (d, J = 8.5
Hz), 133.2 (d, J = 2.8 Hz), 133.0, 132.9, 132.7 (d, J = 2.4 Hz), 132.4
(d, J = 11.2 Hz), 130.5, 130.4, 130.2, 129.4, 128.7 (d, J = 14.2 Hz),
128.1 (overlapped), 128.0 (d, J = 11.4 Hz), 126.6 (d, J = 9.5 Hz),
123.3 (d, J = 129.7 Hz), 118.5 (d, J = 11.3 Hz); 31P NMR (161 MHz,
CDCl3) δ 24.52; IR (film) 3057, 1590, 1236, 1091, 728 cm−1; HRMS
(EI) m/z calcd for C26H17Cl2O2P 462.0343, found 462.0345.
3,4-Bis(3-bromophenyl)-1-phenyl-1H-2,1-benzoxaphosphorin 1-oxide
(5g): Rf = 0.45 (EtOAc/hexane 1/1); pale yellow solid, mp 115−
1
3aa: Rf = 0.3 (EtOAc/hexane 1/5); pale green oil; H NMR (400
MHz, CDCl3) δ 8.36 (d, J = 6.36, 1H), 8.02 (d, J = 16.08, 1H), 4.28−
4.15 (m, 2H), 2.74−2.45 (m, 8H), 1.34−1.17 (m, 15H); 13C NMR
(100 MHz, CDCl3) δ 162.3, 155.7, 152.4 (d, J = 10.91 Hz), 136.9 (d,
J = 6.53 Hz), 135.6 (d, J = 16.16 Hz), 128.2 (d, J = 176.81 Hz), 125.0
(d, J = 12.05 Hz), 124.5 (d, J = 10.00 Hz), 124.2, 115.2 (d, J = 11.23
Hz), 112.9, 63.0 (d, J = 6.52 Hz), 25.4 (d, J = 5.23 Hz), 24.1, 21.0,
19.3, 16.5 (d, J = 6.00 Hz), 14.5, 14.2, 12.5, 11.7; 31P NMR (121 MHz,
CDCl3) δ 8.62; IR (film) 2971, 2876, 1732, 1632, 1470, 1278, 1029,
947, 789 cm−1; HRMS (EI) m/z calcd for C21H27O5P 390.1596, found
390.1596.
1
117 °C; H NMR (400 MHz, CDCl3) δ 7.95−7.89 (m, 2H), 7.67−
7.52 (m, 5H), 7.50−7.46 (m, 3H), 7.40−7.36 (m, 1H), 7.33−7.26 (m,
2H), 7.21 (d, J = 7.6 Hz, 1H), 7.08−6.97 (m, 3H); 13C NMR (100
MHz, CDCl3) δ 145.7 (d, J = 10.9 Hz), 137.8, 137.7 (d, J = 5.1 Hz),
136.3 (d, J = 5.1 Hz), 134.3, 133.3 (d, J = 2.8 Hz), 132.7 (d, J = 2.6
Hz), 132.4 (d, J = 11.2 Hz), 131.9 (d, J = 4.5 Hz), 131.4, 130.6 130.4
(d, J = 12.6 Hz), 130.3, 130.1, 129.2, 128.7 (d, J = 14.0 Hz), 128.2 (d,
J = 14.3 Hz), 127.8, 126.7 (d, J = 9.5 Hz), 123.3 (d, J = 129.1 Hz),
161.9, 118.8 (d, J = 11.1 Hz); 31P NMR (161 MHz, CDCl3) δ 24.60;
IR (film) 3058, 2925, 1590, 1242, 1062, 747 cm−1; HRMS (EI) m/z
calcd for C26H17Br2O2P 549.9333, found 549.9333.
3,4-Bis(3-methylphenyl)-1-phenyl-1H-2,1-benzoxaphosphorin 1-oxide
1
(5b): Rf = 0.4 (EtOAc/hexane 1/1); yellow oil; H NMR (400 MHz,
CDCl3) δ 7.96−7.91 (m, 2H), 7.63−7.49 (m, 4H), 7.44 (tt, J = 7.4, 1.3
Hz, 1H), 7.35−7.25 (m, 2H), 7.18−7.15 (m, 2H), 7.10 (s, 1H), 7.08−
7.05 (m, 2H), 6.98−6.95 (m, 3H), 2.33 (s, 3H), 2.17 (s, 3H); 13C
NMR (100 MHz, CDCl3) δ 146.9 (d, J = 11.0 Hz), 138.9 (d, J = 5.2
Hz), 137.1, 136.0, 134.6 (d, J = 5.1 Hz), 132.9 (d, J = 2.9 Hz), 132.45
(d, J = 2.5 Hz), 132.41, 132.3, 132.1, 131.0, 130.2 (d, J = 12.3 Hz),
129.6, 129.5, 129.2, 129.0, 128.5 (d, J = 1.4 Hz), 127.5 (d, J = 14.5
Hz), 127.3, 126.9 (d, J = 9.6 Hz), 126.3, 123.1 (d, J = 129.6 Hz), 119.0
(d, J = 11.0 Hz), 21.4, 21.3; 31P NMR (161 MHz, CDCl3) δ 24.38; IR
(film) 3054, 2920, 1590, 1240, 1065 cm−1; HRMS (EI) m/z calcd for
C28H23O2P 422.1436, found 422.1437.
3,4-Bis(4-methylphenyl)-1-phenyl-1H-2,1-benzoxaphosphorin 1-oxide
(5c): Rf = 0.3 (EtOAc/hexane 1/1); yellow solid, mp 219−221 °C;
1H NMR (400 MHz, CDCl3) δ 7.95−7.90 (m, 2H), 7.62−7.48 (m,
4H), 7.43 (t, J = 7.7 Hz, 1H), 7.33−7.29 (m, 1H), 7.21−7.13 (m, 6H),
7.05 (dd, J = 8.4, 4.8 Hz, 1H), 6.92 (d, J = 8.1, 2H), 2.40 (s, 3H), 2.24
(s, 3H); 13C NMR (100 MHz, CDCl3) δ 146.9 (d, J = 10.9 Hz), 139.1
(d, J = 5.5 Hz), 138.4, 137.3, 133.1, 132.9 (d, J = 2.7 Hz), 132.4 (d, J =
2.6 Hz), 132.3 (d, J = 11.0 Hz), 131.9 (d, J = 5.0 Hz), 131.4, 131.0,
130.2 (d, J = 12.3 Hz), 129.7, 129.6 (d, J = 11.5 Hz), 128.6 (d, J = 71.0
Hz), 128.5 (d, J = 13.9 Hz), 127.4 (d, J = 14.3 Hz), 126.7 (d, J = 9.6
Hz), 123.1 (d, J = 129.7 Hz), 118.4 (d, J = 11.0 Hz), 21.3, 21.2; 31P
NMR (161 MHz, CDCl3) δ 24.39; IR (film) 3054, 2920, 1590, 1240,
1060, 738 cm−1; HRMS (EI) m/z calcd for C28H23O2P 422.1436,
found 422.1436.
3,4-Bis(4-methoxyphenyl)-1-phenyl-1H-2,1-benzoxaphosphorin
1-oxide (5d): Rf = 0.3 (EtOAc/hexane 1/1); yellow solid, mp 58−
60 °C; 1H NMR (400 MHz, CDCl3) δ 7.95−7.90 (m, 2H), 7.63−7.49
(m, 4H), 7.43 (t, J = 7.7 Hz, 1H), 7.33−7.28 (m, 1H), 7.19 (app d, J =
8.9 Hz, 4H), 7.07 (dd, J = 8.04, 4.82 Hz, 1H), 6.94 (d, J = 8.7 Hz, 2H),
6.65 (app d, J = 9.0, 2H), 3.85 (s, 3H), 3.73 (s, 3H); 13C NMR (100
MHz, CDCl3) δ 159.4, 159.1, 146.8 (d, J = 11.0 Hz), 139.3 (d, J = 5.4
Hz), 132.9 (d, J = 2.7 Hz), 132.7, 132.4 (d, J = 4.5 Hz), 132.3 (d, J =
11.1 Hz), 130.5, 130.22 (d, J = 144.9 Hz), 130.21 (d, J = 12.4 Hz),
128.5 (d, J = 13.9 Hz), 128.4 (d, J = 6.0 Hz), 127.3 (d, J = 5.3 Hz),
127.2 (d, J = 15.0 Hz), 126.6 (d, J = 9.8 Hz), 123.0 (d, J = 129.9 Hz),
117.5 (d, J = 11.0 Hz), 114.5, 113.0, 55.3, 55.2; 31P NMR (161 MHz,
CDCl3) δ 24.45; IR (film) 3055, 2959, 1605, 1245, 1175, 1028,
741 cm−1; HRMS (EI) m/z calcd for C28H23O4P 454.1334, found
454.1333.
3,4-Bis(4-bromophenyl)-1-phenyl-1H-2,1-benzoxaphosphorin 1-oxide
(5h): Rf = 0.5 (EtOAc/hexane 1/1); pale yellow solid, mp 169−171 °C;
1H NMR (400 MHz, CDCl3) δ 7.94−7.89 (m, 2H), 7.66−7.51 (m,
6H), 7.47 (tt, J = 7.7, 1.2 Hz, 1H), 7.39−7.34 (m, 1H), 7.28 (app d, J =
8.7 Hz, 2H), 7.15 (d, J = 8.2 Hz, 2H), 7.09 (app d, J = 8.7 Hz, 2H),
7.01 (dd, J = 8.0, 4.7 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 146.0
(d, J = 11.1 Hz), 137.9 (d, J = 5.2 Hz), 134.8, 133.4 (d, J = 5.1 Hz),
133.24, 133.20, 132.7 (d, J = 2.3 Hz), 132.5, 132.4, 131.0, 130.6, 130.4
(d, J = 12.5 Hz), 130.2, 128.6 (d, J = 14.1 Hz), 128.0 (d, J = 14.3 Hz),
126.6 (d, J = 9.4 Hz), 123.3 (d, J = 129.7 Hz), 123.1, 122.4, 118.6 (d,
J = 11.5 Hz); 31P NMR (161 MHz, CDCl3) δ 24.49; IR (film) 3057,
1586, 1484, 1236, 1072, 950, 740 cm−1; HRMS (EI) m/z calcd for
C26H17Br2O2P 549.9333, found 549.9333.
1-Phenyl-3,4-diethyl-1H-2,1-benzoxaphosphorin 1-oxide (5i):
1
Rf = 0.3 (EtOAc/hexane 1/1); colorless oil; H NMR (400 MHz,
CDCl3) δ 7.82−7.77 (m, 2H), 7.59−7.51 (m, 2H), 7.50−7.44 (m,
3H), 7.30−7.26 (m, 1H), 2.60−2.34 (m, 4H), 1.23−1.16 (m, 6H);
13C NMR (100 MHz, CDCl3) δ 150.8 (d, J = 11.5 Hz), 137.4 (d, J =
5.3 Hz), 132.7 (d, J = 2.8 Hz), 132.6 (d, J = 2.3 Hz), 132.2 (d, J = 10.9
Hz), 130.6 (d, J = 12.4 Hz), 130.3 (d, J = 144.2 Hz), 128.4 (d, J =
13.8 Hz), 126.7 (d, J = 14.5 Hz), 123.6 (d, J = 129.8 Hz), 123.5 (d, J =
10.0 Hz), 114.4 (d, J = 11.2 Hz), 25.5 (d, J = 4.8 Hz), 20.9, 14.2, 11.6;
31P NMR (161 MHz, CDCl3) δ 10.34; IR (film) 3059, 1633, 1469,
1240, 1130, 1046 cm−1; HRMS (EI) m/z calcd for C18H19O2P
298.1123, found 298.1123.
1-Phenyl-3.4-dibutyl-1H-2,1-benzoxaphosphorin 1-oxide (5j):
Rf = 0.4 (EtOAc/hexane 1/1); yellow oil; 1H NMR (400 MHz,
CDCl3) δ 7.81−7.75 (m, 2H), 7.59−7.55 (m, 2H), 7.51−7.44 (m,
4H), 7.31−7.26 (m, 1H), 2.60−2.40 (m, 4H), 1.64−1.50 (m, 4H),
1.49−1.28 (m, 4H), 0.98 (t, J = 7.2, 3H), 0.89 (t, J = 7.34, 3H); 13C
NMR (100 MHz, CDCl3) δ 149.9 (d, J = 11.1 Hz), 137.7 (d, J = 5.2
Hz), 132.7 (d, J = 2.9 Hz), 132.6 (d, J = 2.2 Hz), 132.1 (d, J = 10.9
Hz), 130.6 (d, J = 12.4 Hz), 130.4 (d, J = 143.8 Hz), 128.4 (d, J = 13.7
Hz), 126.6 (d, J = 14.6 Hz), 123.58 (d, J = 9.9 Hz), 123.57 (d, J =
129.8 Hz), 113.7 (d, J = 11.4 Hz), 32.0 (d, J = 4.7 Hz), 31.7, 29.0, 27.5,
22.9, 22.4, 14.0, 13.9; 31P NMR (161 MHz, CDCl3) δ 23.94; IR (film)
2957, 2930, 1630, 1467, 1242, 1130, 745 cm−1; HRMS (EI) m/z calcd
for C22H27O2P 354.1749, found 354.1750.
3,4-Bis(3-chlorophenyl)-1-phenyl-1H-2,1-benzoxaphosphorin 1-oxide
1
(5e): Rf = 0.4 (EtOAc/hexane 1/1); yellow oil; H NMR (400 MHz,
CDCl3) δ 7.95−7.90 (m, 2H), 7.67−7.47 (m, 5H), 7.41−7.33 (m,
3H), 7.31 (d, J = 1.5 Hz, 2H), 7.18−7.15 (m, 2H), 7.07−7.01 (m,
3H); 13C NMR (100 MHz, CDCl3) δ 145.8 (d, J = 10.9 Hz), 137.7 (d,
J = 5.1 Hz), 137.5, 136.1 (d, J = 5.1 Hz), 133.9, 133.3 (d, J = 2.8 Hz),
132.7 (d, J = 2.5 Hz), 132.4 (d, J = 11.1 Hz), 131.4, 130.5 (d, J = 12.5
Hz), 130.1, 129.8, 129.0 (d, J = 7.2 Hz), 128.9, 128.8, 128.7, 128.6,
8-Methyl-1-(2-methylphenyl)-3,4-diphenyl-1H-2,1-benzoxaphos-
phorin 1-oxide (5k): Rf = 0.4 (EtOAc/hexane 1/1); white solid, mp
53−55 °C; 1H NMR (400 MHz, CDCl3) δ 8.28−8.22 (m, 1H),
J
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
7.49 (tt, J = 7.5, 1.4 Hz, 1H), 7.42−7.30 (m, 5H), 7.25−7.21 (m, 3H),
7.20−7.18 (m, 2H), 7.13−7.06 (m, 4H), 6.88 (dd, J = 8.1, 4.5 Hz,
1H), 2.29 (s, 3H), 2.19 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 146.3
(d, J = 11.8 Hz), 141.8 (d, J = 10.3 Hz), 140.6 (d, J = 11.7 Hz), 139.5
(d, J = 5.5 Hz), 136.7, 134.8 (d, J = 5.1 Hz), 134.5 (d, J = 11.5 Hz),
133.0 (d, J = 2.5 Hz), 132.2 (d, J = 2.0 Hz), 131.8, 131.5 (d, J = 12.7
Hz), 130.2 (d, J = 12.7 Hz), 130.0 (d, J = 142.1 Hz), 129.0, 128.8,
128.3, 127.7, 127.5, 125.8 (d, J = 14.0 Hz), 125.2 (d, J = 9.5 Hz), 161.8
(d, J = 126.2 Hz), 118.8 (d, J = 11.4 Hz), 21.3 (d, J = 6.0 Hz), 20.6 (d,
J = 4.5 Hz); 31P NMR (161 MHz, CDCl3) δ 21.68; IR (film) 3054,
2979, 1619, 1455, 1234, 1093 cm−1; HRMS (EI) m/z calcd for
C28H23O2P 422.1436, found 422.1436.
8-Methyl-1-(2-methylphenyl)-3,4-diethyl-1H-2,1-benzoxaphos-
phorin 1-oxide (5l): Rf = 0.4 (EtOAc/hexane 1/1); pale yellow solid,
mp 117−119 °C; 1H NMR (400 MHz, CDCl3) δ 8.18−8.12 (m, 1H),
7.49−7.43 (m, 2H), 7.38−7.33 (m, 2H), 7.18 (t, J = 6.5 Hz, 1H), 7.06
(dd, J = 7.6, 4.3 Hz, 1H), 2.66−2.45 (m, 4H), 2.18 (s, 3H), 2.01 (s,
3H), 1.18 (td, J = 7.5, 3.2 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ
150.1 (d, J = 11.8 Hz), 141.7 (d, J = 10.2 Hz), 140.7 (d, J = 11.8 Hz),
138.0 (d, J = 5.4 Hz), 134.3 (d, J = 11.5 Hz), 132.7 (d, J = 2.7 Hz),
132.3 (d, J = 2.1 Hz), 131.3 (d, J = 12.6 Hz), 130.2 (d, J = 141.49 Hz),
129.2 (d, J = 12.9 Hz), 125.7 (d, J = 13.9 Hz), 122.4 (d, J = 126.6 Hz),
161.6 (d, J = 9.7 Hz), 113.9 (d, J = 11.7 Hz), 25.5 (d, J = 4.8 Hz),
21.4 (d, J = 6.0 Hz), 21.2, 20.5 (d, J = 4.5 Hz), 14.4, 11.7; 31P NMR
(161 MHz, CDCl3) δ 20.94; IR (film) 2969, 1640, 1456, 1232, 1054,
734 cm−1; HRMS (EI) m/z calcd for C20H23O2P 326.1436, found
326.1438.
6-Chloro-1-(4-chlorophenyl)-3,4-diethyl-1H-2,1-benzoxaphos-
1
phorin 1-oxide (5p): Rf = 0.55 (EtOAc/hexane 1/1); yellow oil; H
NMR (400 MHz, CDCl3) δ 7.73−7.68 (m, 2H), 7.48−7.45 (m, 3H),
7.39 (dd, J = 13.9, 8.1 Hz, 1H), 7.29−7.26 (m, 1H), 2.63−2.44 (m,
4H), 1.21 (t, J = 7.3 Hz, 3H), 1.18 (t, J = 7.4 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 152.1 (d, J = 11.1 Hz), 139.7 (d, J = 3.6 Hz), 139.5
(d, J = 3.4 Hz), 139.3 (d, J = 6.2 Hz), 133.5 (d, J = 11.8 Hz), 131.9 (d,
J = 13.2 Hz), 128.9 (d, J = 14.6 Hz), 127.6, 127.0 (d, J = 15.2 Hz),
123.8 (d, J = 10.6 Hz), 161.5 (d, J = 132.6 Hz), 113.9 (d, J = 11.1 Hz),
25.6 (d, J = 4.8 Hz), 20.8, 14.1, 11.5; 31P NMR (161 MHz, CDCl3) δ
22.30; IR (film) 3054, 2970, 1583, 1242, 1087, 798 cm−1 HRMS (EI)
m/z calcd for C18H17Cl2O2P 366.0343, found 366.0345.
1-(Naphthalen-1-yl)-3,4-bis(p-methoxyphenyl)-1H-naphtho[1,2-
c][1,2]oxaphosphinine 1-oxide (5q): Rf = 0.45 (EtOAc/hexane 1/1);
1
yellow solid, mp 148−150 °C; H NMR (400 MHz, CDCl3) δ 8.43−
8.38 (m, 2H), 8.24 (d, J = 8.0 Hz, 1H), 8.05 (d, J = 8.2 Hz, 1H), 7.87−
7.85 (m, 2H), 7.73 (d, J = 8.1 Hz, 1H), 7.58 (td, J = 7.6, 2.9 Hz, 1H),
7.44−7.40 (m, 2H), 7.35 (d, J = 7.8 Hz, 1H), 7.32−7.23 (m, 4H), 7.11
(d, J = 8.7 Hz, 2H), 6.98 (d, J = 8.4 Hz, 2H), 6.56 (d, J = 8.8 Hz, 2H),
3.86 (s, 3H), 3.66 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 159.5,
159.2, 147.7 (d, J = 12.1 Hz), 139.7 (d, J = 5.0 Hz), 134.7 (d, J = 12.0
Hz), 134.1 (d, J = 3.1 Hz), 133.8 (d, J = 10.9 Hz), 133.1, 133.0, 132.8,
132.4 (d, J = 11.3 Hz), 132.1 (d, J = 11.2 Hz), 130.6, 129.2, 129.0,
128.8, 128.4, 127.9, 127.8, 127.5, 127.0 (d, J = 5.6 Hz), 126.4 (d, J =
18.1 Hz), 126.1 (d, J = 7.3 Hz), 125.6 (d, J = 5.6 Hz), 124.7, 124.6 (d,
J = 2.6 Hz), 117.8 (d, J = 127.4 Hz), 117.5 (d, J = 12.2 Hz), 114.6,
112.9, 55.3, 55.1; 31P NMR (161 MHz, CDCl3) δ 23.77; IR (film)
3055, 2957, 1606, 1508, 1250, 1026, 806 cm−1; HRMS (EI) m/z calcd
for C36H27O4P 554.1647, found 554.1650.
6-Methoxy-1-(4-methoxyphenyl)-3,4-diphenyl-1H-2,1-benzoxa-
phosphorin 1-oxide (5m): Rf = 0.40 (EtOAc/hexane 1/1); pale yellow
1-(2,4,6-Trimethylphenyl)-3,4-diethyl-1H-2,1-benzoxaphosphorin
1-oxide (5r): Rf = 0.5 (EtOAc/hexane 1/1); pale yellow oil; 1H NMR
(400 MHz, CDCl3) δ 7.54−7.47 (m, 2H), 7.35−7.30 (m, 1H), 7.24−
7.19 (m, 1H), 6.92 (s, 1H), 6.91 (s, 1H), 2.70−2.49 (m, 4H), 2.36 (s,
6H), 2.31 (s, 3H), 1.23 (t, J = 7.9 Hz, 3H), 1.21 (t, J = 7.9 Hz, 3H);
13C NMR (100 MHz, CDCl3) δ 150.1 (d, J = 11.2 Hz), 145.1 (d, J =
11.9 Hz), 142.9 (d, J = 2.8 Hz), 136.2 (d, J = 5.0 Hz), 131.9 (d, J = 2.3
Hz), 130.9 (d, J = 13.6 Hz), 129.1 (d, J = 13.8 Hz), 126.5 (d, J = 15.0
Hz), 126.3 (d, J = 127.1 Hz), 123.4 (d, J = 9.5 Hz), 122.0 (d, J = 142.3
Hz), 114.1 (d, J = 11.7 Hz), 25.7 (d, J = 4.6 Hz), 22.9 (d, J = 3.6 Hz),
21.1, 20.9, 14.4, 11.7; 31P NMR (161 MHz, CDCl3) δ 23.97; IR (film)
2969, 1629, 1469, 1230, 1046, 746 cm−1; HRMS (EI) m/z calcd for
C21H25O2P 340.1592, found 340.1594.
1
solid; H NMR (400 MHz, CDCl3) δ 7.84 (dd, J 12.7, 8.7 Hz, 2H),
7.54 (dd, J = 13.7, 8.4 Hz, 1H), 7.39−7.32 (m, 3H), 7.28−7.26 (m,
2H), 7.23−7.20 (m, 2H), 7.15−7.07 (m, 3H), 7.00 (dd, J = 8.7, 2.8
Hz, 2H), 6.87 (dt, J = 8.4, 2.3 Hz, 1H), 6.54−6.52 (m, 1H), 3.86 (s,
3H), 3.67 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 163.3 (d, J = 3.1
Hz), 162.7 (d, J = 2.9 Hz), 147.5 (d, J = 10.9 Hz), 140.9 (d, J = 6.5
Hz), 136.2, 134.9 (d, J = 5.1 Hz), 134.3 (d, J = 12.6 Hz), 132.3 (d, J =
13.7 Hz), 131.6, 129.1, 128.9, 128.4, 127.8, 127.5, 121.8 (d, J = 152.8
Hz), 118.9 (d, J = 10.8 Hz), 115.6 (d, J = 136.0 Hz), 114.1 (d, J = 15.2
Hz), 113.4 (d, J = 15.2 Hz), 112.3 (d, J = 10.5 Hz), 55.4, 55.2; 31P
NMR (161 MHz, CDCl3) δ 26.00; IR (film) 3656, 3452, 3056, 3021,
2966, 2937, 1572, 1555, 1304, 1227, 1165, 1125 cm−1; HRMS (EI) m/z
calcd for C28H23O4P 454.1334, found 454.1337.
6-Methoxy-1-(4-methoxyphenyl)-3,4-diethyl-1H-2,1-benzoxa-
ASSOCIATED CONTENT
■
phosphorin 1-oxide (5n): Rf = 0.45 (EtOAc/hexane 1/1); colorless
S
* Supporting Information
1
oil, H NMR (400 MHz, CDCl3) δ 7.70 (dd, J = 12.6, 8.8 Hz, 2H),
Text, tables, and figures giving general comments, additional
7.42 (dd, J = 13.8, 8.4 Hz, 1H), 6.98−6.93 (m, 3H), 6.82 (dt, J = 8.4,
2.3 Hz, 1H), 3.86 (s, 3H), 2.60−2.41 (m, 4H), 1.21 (t, J = 7.5 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 1630 (d, J = 3.0 Hz), 162.9 (d,
J = 2.8 Hz), 151.4 (d, J = 11.3 Hz), 139.6 (d, J = 6.5 Hz), 134.0 (d, J =
12.4 Hz), 132.5 (d, J = 13.4 Hz), 122.1 (d, J = 151.7 Hz), 116.1 (d, J =
136.4 Hz), 114.0 (d, J = 11.0 Hz), 113.9 (d, J = 14.9 Hz), 111.9 (d, J =
15.3 Hz), 109.4 (d, J = 10.8 Hz), 55.3 (d, J = 2.5 Hz), 21.6 (d, J = 4.9),
21.0; 31P NMR (161 MHz, CDCl3) δ 25.12; 26.00; IR (film) 2967,
2936, 2875, 2839, 1597, 1305, 1257, 1226, 1129 cm−1; HRMS (EI)
m/z calcd for C20H23O4P 358.1334, found 358.1331.
data for optimization of reaction conditions, and H and 13C
1
NMR spectra. This material is available free of charge via the
Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail for P.H.L.: phlee@kangwon.ac.kr.
■
Author Contributions
†These authors contributed equally to this work.
6-Chloro-1-(4-chlorophenyl)-3,4-bis(4-methoxyphenyl)-1H-2,1-
benzoxaphosphorin 1-oxide (5o): Rf = 0.55 (EtOAc/hexane 1/1);
Notes
1
pale yellow solid, mp 197−199 °C; H NMR (400 MHz, CDCl3) δ
The authors declare no competing financial interest.
7.87−7.81 (m, 2H), 7.52−7.44 (m, 3H), 7.29 (td, J = 8.1, 2.1 Hz, 1H),
7.17−7.14 (m, 4H), 7.05 (dd, J = 4.1, 4.8 Hz, 1H), 6.95 (app d, J = 8.7,
2H), 6.67−6.63 (m, 2H), 3.87 (s, 3H), 3.73 (s, 3H); 13C NMR (100
MHz, CDCl3) δ 159.8, 159.4, 147.9 (d, J = 11.2 Hz), 141.2 (d, J = 6.0
Hz), 139.9 (d, J = 3.6 Hz), 139.4 (d, J = 3.3 Hz), 133.7 (d, J = 11.8
Hz), 132.6, 131.5 (d, J = 13.2 Hz), 130.6, 129.1 (d, J = 14.8 Hz), 129.0
(d, J = 3.7 Hz), 127.54 (d, J = 15.7 Hz), 127.50 (d, J = 4.1 Hz), 126.6
(d, J = 3.6 Hz), 126.6 (d, J = 10.2 Hz), 120.8 (d, J = 132.5 Hz), 116.8
(d, J = 10.6 Hz), 114.7, 113.1, 55.3, 55.2; 31P NMR (161 MHz,
CDCl3) δ 22.77; IR (film) 3052, 2958, 1606, 1252, 1060, 765 cm−1;
HRMS (EI) m/z calcd for C28H21Cl2O4P 522.0555, found 522.0557.
ACKNOWLEDGMENTS
■
This work was supported by a National Research Foundation of
Korea (NRF) grant funded by the Korea government (MSIP)
(No. 2011-0018355).
DEDICATION
■
Dedicated to Professor Hong-SeoK Kim, Kyungpook National
University, on the occasion of his 60th birthday.
K
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
REFERENCES
■
(1) (1) Name Reactions in Heterocyclic Chemistry; Li, J.-J., Corey, E. J.,
Eds.; Wiley-Interscience: Hoboken, NJ, 2005.
(2) (a) Dillon, K. B.; Mathey, F.; Nixon, J. F. in Phosphorus: The
Carbon Copy, John Wiley & Sons, Chichester, 1998. (b) Seto, H.;
Kuzuyama, T. Nat. Prod. Rep. 1999, 16, 589. (c) Li, X. S.; Zhang, D.
W.; Pang, H.; Shen, F.; Fu, H.; Jiang, Y. Y.; Zhao, Y. F. Org. Lett. 2005,
7, 4919. (d) Peng, A.-Y.; Ding, Y.-X. Org. Lett. 2005, 7, 3299. (e) Wei,
T.; Ding, Y.-X. J. Org. Chem. 2006, 71, 8489. (f) Li, B.; Zhou, B.; Lu,
H.; Ma, L.; Peng, A.-Y. Eur. J. Med. Chem. 2010, 45, 1955. (g) Ruda, G.
F.; Wong, P. E.; Alibu, V. P.; Norval, S.; Read, K. D.; Barrett, M. P.;
Gilbert, I. H. J. Med. Chem. 2010, 53, 6071.
(3) (a) Chan, L. Y.; Kim, S.; Ryu, T.; Lee, P. H. Chem. Commun.
2013, 49, 4682. (b) Chary, B. C.; Kim, S.; Park, Y.; Kim, J.; Lee, P. H.
Org. Lett. 2013, 15, 2692. (c) Seo, J.; Park, Y.; Jeon, I.; Ryu, T.; Park,
S.; Lee, P. H. Org. Lett. 2013, 15, 3358. (d) Ryu, T.; Kim, J.; Park, Y.;
Kim, S.; Lee, P. H. Org. Lett. 2013, 15, 3986. (e) Park, S.; Seo, B.; Shin,
S.; Son, J.-Y.; Lee, P. H. Chem. Commun. 2013, 49, 8671. (f) Mo, J.;
Lim, S.; Ryu, T.; Kim, S.; Lee, P. H. RSC Adv. 2013, DOI: 10.1039/
C3RA43764G. (g) Park, Y.; Seo, J.; Park, S.; Yoo, E. J.; Lee, P. H. Chem.
Eur. J. 2013, DOI: 10.1002/chem.201302652. (h) Meng, X.; Kim, S. Org.
Lett. 2013, 15, 1910. (i) Chan, L. Y.; Cheong, L.; Kim, S. Org. Lett. 2013,
15, 2186. (j) Chan, L. Y.; Meng, X.; Kim, S. J. Org. Chem. 2013, 78,
8826. (k) Chary, B. C.; Kim, S. Org. Biomol. Chem. 2013, DOI: 10.1039/
C3OB41548A. (l) Chary, B. C.; Low, W. S.; Kim, S.; Kim, H.; Lee, P. H.
Chem. Asian J. 2011, 6, 1970. (m) Mo, J. T.; Kang, D.; Eom, D.; Kim, S.
H.; Lee, P. H. Org. Lett. 2013, 15, 26. (n) Kang, D.; Cho, J.; Lee, P. H.
Chem. Commun. 2013, DOI: 10.1039/C3CC45874A.
(4) (a) Peng, A.-Y.; Ding, Y.-X. J. Am. Chem. Soc. 2003, 125, 15006.
(b) Peng, A.-Y.; Ding, Y.-X. Org. Lett. 2004, 6, 1119. (c) Peng, A.-Y.;
Hao, F.; Li, B.; Wang, Z.; Du, Y. J. Org. Chem. 2008, 73, 9012.
(5) (a) Kakiuchi, F.; Kochi, T. Synthesis 2008, 3013. (b) Giri, R.; Shi,
B.-F.; Engle, K. M.; Maugel, N.; Yu, J.-Q. Chem. Soc. Rev 2009, 38,
3242. (c) Ackermann, L.; Vicente, R.; Kapdi, A. Angew. Chem., Int. Ed.
2009, 48, 9792. (d) Thansandote, P.; Lautens, M. Chem. Eur. J. 2009,
15, 5874. (e) Yoo, W.-J.; Li, C.-J. Top. Curr. Chem. 2010, 292, 281.
(f) Ackermann, L.; Potukuchi, H. K. Org. Biomol. Chem. 2010, 8, 4503.
(g) Daugulis, O. Top. Curr. Chem. 2010, 292, 57. (h) Ackermann, L.
Chem. Commun. 2010, 46, 4866. (i) Fagnou, K. Top. Curr. Chem. 2010,
292, 35. (j) Cho, S. H.; Kim, J. Y.; Kwak, J.; Chang, S. Chem. Soc. Rev.
2011, 40, 5068. (k) Yeung, C. S.; Dong, V. M. Chem. Rev. 2011, 111,
1215. (l) Wencel-Delord, J.; Droege, T.; Liu, F.; Glorius, F. Chem. Soc.
Rev. 2011, 40, 4740.
(6) (a) Dangel, B. D.; Johnson, J. A.; Sames, D. J. Am. Chem. Soc.
2001, 123, 8149. (b) Tsang, W. C. P.; Zheng, N.; Buchwald, S. L. J.
Am. Chem. Soc. 2005, 127, 14560. (c) Inamoto, K.; Saito, T.; Katsuno,
M.; Sakamoto, T.; Hiroya, K. Org. Lett. 2007, 9, 2931. (d) Brasche, G.;
Buchwald, S. L. Angew. Chem., Int. Ed. 2008, 47, 1932. (e) Jordan-
Hore, J. A.; Johansson, C. C. C.; Gulias, M.; Beck, E. M.; Gaunt, M. J.
J. Am. Chem. Soc. 2008, 130, 16184. (f) Wasa, M.; Yu, J. Q. J. Am.
Chem. Soc. 2008, 130, 14058. (g) Ueda, S.; Nagasawa, H. Angew.
Chem., Int. Ed. 2008, 47, 6411. (h) Mei, T. S.; Wang, X.; Yu, J. Q. J.
Am. Chem. Soc. 2009, 131, 10806. (i) Thansandote, P.; Lautens, M.
Chem. Eur. J. 2009, 15, 5874. (j) Neumann, J. J.; Rakshit, S.; Droge, T.;
̈
Glorius, F. Angew. Chem., Int. Ed. 2009, 48, 6892. (k) Wang, H.; Wang,
Y.; Peng, C.; Zhang, J.; Zhu, Q. J. Am. Chem. Soc. 2010, 132, 13217.
(l) Wang, X.; Lu, Y.; Dai, H.-X.; Yu, J.-Q. J. Am. Chem. Soc. 2010, 132,
12203. (m) Tan, Y.; Hartwig, J. F. J. Am. Chem. Soc. 2010, 132, 3676.
(7) Ueura, K.; Satoh, T.; Miura, M. J. Org. Chem. 2007, 72, 5362.
(8) Ackermann, L.; Pospech, J.; Graczyk, K.; Rauch, K. Org. Lett.
2012, 14, 930.
(9) Chinnagolla, R. K.; Jeganmohan, M. Chem. Commun. 2012, 48,
2030.
(10) Unoh, Y.; Hashimoto, Y.; Takeda, D.; Hirano, K.; Satoh, T.;
Miura, M. Org. Lett. 2013, 15, 3258.
(11) (a) Mio, M. J.; Kopel, L. C.; Braun, J. B.; Gadzikwa, T. L.; Hull,
K. L.; Brisbois, R. G.; Markworth, C. J.; Grieco, P. A. Org. Lett. 2002, 4,
3199. (b) Severin, R.; Reimer, J.; Doye, S. J. Org. Chem. 2010, 75, 3518.
L
dx.doi.org/10.1021/jo401608v | J. Org. Chem. XXXX, XXX, XXX−XXX