Radical addition reaction of bis(naphth-1,8-diyl-8-oxy)hydrophosphorane to olefins

Article abstract of DOI:10.1002/hc.20719

In the presence of 1,1^′-azobis(cyclohexanecarbonitrile) (ACHCN), the reaction of bis(naphth-1,8-diyl-8-oxy)hydrophosphorane with an equimolar amount of terminal and internal olefins gave the corresponding alkylphosphoranes. In the reactions wit

Full text of DOI:10.1002/hc.20719

Heteroatom Chemistry
Volume 22, Number 3/4, 2011
Radical Addition Reaction of
Bis(naphth-1,8-diyl-8-oxy)hydrophosphorane
to Olefins
Kazumasa Kajiyama, Daisuke Itou, Yuki Hazama,
Yusuke Yamamoto, and Takeshi K. Miyamoto
Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato,
Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
Received 30 August 2010; revised 14 January 2011
approaches to organophosphorus compounds, the
ABSTRACT:
In
the
presence
of
1,1ꢀ-
formal addition reaction of a P H bond to an un-
saturated C C bond, catalyzed by transition metal
compounds [1,2] or induced by radical initiators
[3,4], has attracted much attention because most of
the reactions are convenient and regioselective. Al-
though numerous radical addition reactions of tri-
or tetracoordinate phosphorus compounds bearing
P H bond to various olefins have been reported,
only a few examples of the radical addition reactions
of pentacoordinate hydrophosphoranes to terminal
olefins are known [5].
The preparation, structural characterization,
and reactions of phosphoranyl radicals have been
well documented [6]. The substantial issues in-
volving the reaction of phosphoranyl radical have
been the steric demand and α-scission reac-
tion (Scheme 1) of the phosphoranyl radical.
In the case of phosphoranyl radicals containing
alkoxy and sulfenyl groups on the phosphorus
atom, β-scission reaction (Scheme 2) can also
occur. The scission reactions of spiro- or bi-
cyclic phosphoranyl radicals are slower than those
of acyclic ones [5a,6c,6e]. Thus, the reactions
of tetraoxyspirophosphoranyl radicals with ethyl
vinyl ether [5b], 1-hexene [5a], or 3,3-dimethyl-1-
butene [5a] have been reported, whereas the re-
sulting alkylphosphoranes should be unstable to
moisture [7]. However, radical addition reactions
of hydrophosphoranes to haloolefins, aryl or alkyl
acrylates, styrene, and internal olefins have never
azobis(cyclohexanecarbonitrile) (ACHCN), the reac-
tion of bis(naphth-1,8-diyl-8-oxy)hydrophosphorane
with an equimolar amount of terminal and internal
olefins gave the corresponding alkylphosphoranes. In
the reactions with styrene and methyl acrylate, 2:1
olefin–hydrophosphorane adducts were obtained as
a minor product. The reactions with terminal olefins
were entirely regioselective and more efficient than
those with internal olefins. In the absence of ACHCN,
the radical addition reaction of the hydrophosphorane
to terminal and internal olefins could also proceed
ꢁ
C
slowly.
2011 Wiley Periodicals, Inc. Heteroatom
Chem 22:538–544, 2011; View this article online at
wileyonlinelibrary.com. DOI 10.1002/hc.20719
INTRODUCTION
Organophosphorus compounds have played a sig-
nificant role as chemical reagents, transition metal
ligands, and biologically active substances for med-
ical and agricultural use. Among various synthetic
Dedicated to Professor Kin-ya Akiba on the occasion of his 75th
birthday.
Correspondence to: Kazumasa Kajiyama; e-mail: kajiyama@
sci.kitasato-u.ac.jp.
Contract grant sponsor: Kitasato University Research Grant for
Young Researchers.
c
ꢀ
2011 Wiley Periodicals, Inc.
538

Radical Addition Reaction of Bis(naphth-1,8-diyl-8-oxy)hydrophosphorane to Olefins 539
Z4P
Z3P
+
Z
R
O
P
O
1
O
P
O
3
O
P
O
4
R
2 (1 equiv)
H
SCHEME 1
Toluene, reflux
R
R
R_X_PZ3
X=PZ3
+ R
a) R = C8H17, b) R = Ph, c) R = CO2Me, d) R = (CH2)4Br
X = O, S
SCHEME 3
SCHEME 2
TABLE 1 Results of the Radical Addition Reaction of 1 to
Terminal Olefins 2a
been reported. In the presence of a radical initiator,
tri- and tetracoordinate phosphorus compounds
bearing P H bond are known to mediate radical re-
duction of haloolefins [3,8] such as the reaction of
tributyltin hydride [9], whereas acrylates and styrene
are either unreactive with phosphorus hydrides or
susceptible to polymerization [4b,c,g]. Additionally,
to the best of our knowledge, the thermal formal ad-
dition of the P H bond to the unsaturated C C bond
is rare [10,11].
Run ACHCN
R
Time (h) 3 (%)b 4 (%)b (drc)
1
2
3
4
5
6
7
8
0.2 equiv
0.2 equiv
0.2 equiv CO2Me
0.2 equiv (CH2)4Br
None
None
None
None
C8H17
Ph
3
3
3
3
7
7
7
7
92
82
82
97
82
81
78
82
–
5 (52:48)
11 (53:47)
–
C8H17
Ph
CO2Me
CH2)4Br
–
5 (52:48)
8 (53:47)
–
We have reported the synthesis of bis(naphth-
1,8-diyl-8-oxy)hydrophosphorane (1) and the re-
activity of lithium phosphoranide generated from
hydrophosphorane 1 [12]. Subsequently, our atten-
tion was focused on the radical addition reaction
of 1 to unsaturated compounds. The spirophospho-
ranyl radical generated from 1 is compact compared
with reported spirophosphoranyl radicals [5a,b,6f]
and the rigidity of naphthalene moiety should also
suppress the scission reactions of the phospho-
ranyl radical. Additionally, hydrophosphorane 1
and alkylphosphorane derived from 1 are stable to
moisture [12a,b]. The spirophosphorane is poten-
tially useful as a reagent for Horner–Wadsworth–
Emmons-type reaction [12f] and a chiral building
block. Here, we report on the radical addition re-
action of hydrophosphorane 1 to both terminal and
internal olefins induced by a radical initiator or in
the absence of an initiator.
aThe reaction of 1 (0.632 mmol) with olefin (0.632 mmol) was con-
ducted in the absence or presence of ACHCN (0.127 mmol) in toluene
(5.0 mL).
bIsolated yield.
cDetermined by 1H NMR spectroscopic analysis.
amounts were required in contrast to excesses of tri-
or tetracoordinate phosphorus compounds bearing
P H bond usually required in many radical addition
reactions to olefins [4c–f]. The chain mechanism for
the radical addition reaction is depicted in Scheme 4.
The reactions are entirely regioselective, showing
formal anti-Markovnikov selectivity due to the bulk-
iness of the phosphoranyl radical I and the gen-
eration of the more stable carbon-centered radical
intermediate.
In the reaction with styrene (2b) or methyl
acrylate (2c), the formation of
a 2:1 olefin–
hydrophosphorane adduct 4b or 4c as a minor
product was also observed. This implies that the
RESULTS AND DISCUSSION
Radical addition reaction of hydrophosphorane
1 to terminal olefins 2a–d (1 equiv) could be
achieved by refluxing toluene solutions for 3 h
in the presence of a catalytic amount of 1,1ꢀ-
azobis(cyclohexanecarbonitrile) (ACHCN) as the
radical initiator to give alkylphosphoranes 3a–d,
which were 1:1 adducts (Scheme 3, Table 1: run 1–4).
The phosphoranes 3 were formal anti-Markovnikov
O
P
O
1
O
P
ACHCN
H
Δ
2
O
I
4
3
1
1
Polymerization
products, whose H NMR spectra exhibited the di-
O
R
P
O
P
astereotopic resonances for the α-methylene pro-
tons, and no regioisomer was detected. The 31P NMR
analyses of the crude products showed that most,
if not all, of hydrophosphorane 1 has been con-
sumed. It is worth noting that only stoichiometric
R
R
O
II
O
III
2
SCHEME 4
Heteroatom Chemistry DOI 10.1002/hc

540 Kajiyama et al.
abstraction of the hydrogen atom from the P H
bond in 1 by a carbon-centered radical in II and
III (Scheme 4) to give 3 and 4, respectively, is faster
than polymerization probably due to the low bond
dissociation energy of the P H bond in 1 [4h]. The
radical reduction of 6-bromo-1-hexene (2d) to give
methylcyclopentane via radical cyclization of the 5-
hexenyl radical [13] was averted. This may have been
due to the instability of the bromophosphorane that
would have arisen by the abstraction of the bromine
atom from 2d by radical I.
We also examined the reactions with symmetri-
cal internal olefins (Scheme 7). Alkylphosphoranes
6A–C were obtained in good yields (Table 2: run
1–5) by the radical addition of hydrophosphorane 1
to internal olefins 5A–C (cis-stilbene, trans-stilbene,
dimethyl maleate, dimethyl fumarate, and cyclohex-
ene) under conditions similar to those of reactions
to terminal olefins using ACHCN, although the re-
actions were relatively slow (5 h). However, in the
reaction of 1 with 1 equiv of 5 in the absence
of ACHCN, consumption of 1 was not complete
In the absence of ACHCN, completely regioselec-
tive radical addition reaction of 1 to terminal olefins
2a–d could also proceed slower than the ACHCN-
induced reaction under similar conditions (Table 1:
run 5–8). Although the reactions described in
Table 1 were conducted under a nitrogen atmo-
sphere, the radical reaction in the absence of ACHCN
may be initiated by molecular oxygen (Scheme 5)
because oxygen could not be excluded completely.
However, the addition reaction of 1 to 2a–c in the
absence of ACHCN under a nitrogen atmosphere
was not retarded by addition of a radical inhibitor,
hydroquinone, 4-tert-butylcatechol, or 2,6-di-tert-
butyl-4-methylphenol, probably due to high reaction
temperature. A mechanism involving the concerted
addition of the P H bond to the C C double bond,
which could also give 3, may be excluded because
the formation of the 2:1 adducts 4 requires reac-
tion via a stepwise mechanism depicted in Scheme 4
without ACHCN. In the reaction with methyl acry-
late (2c), however, a mechanism involving phospho-
nium zwitterions (Scheme 6) cannot be fully ex-
cluded [11b].
O
O
+ O2
P
O
1
H
P
O
I
+ HOO
SCHEME 5
O
O
OMe
OMe
2c
OH
O
OH
P
P
O
V
3
P
O
1
H
O
IV
2c
OH
P
CO2Me
4
O
O
OMe
VI
SCHEME 6
TABLE 2 Results of Radical Addition Reaction of 1 to Internal Olefins 5a
Run
ACHCN
Olefin
5 (equiv)
Time (h)
6 (%)b (drc)
1
2
3
4
5
6
7
8
0.2 equiv
0.2 equiv
0.2 equiv
0.2 equiv
0.2 equiv
None
None
None
None
None
None
None
None
None
cis-5A
trans-5A
cis-5B
trans-5B
5C
cis-5A
trans-5A
cis-5B
trans-5B
5C
cis-5A
trans-5A
trans-5B
5C
1
1
1
1
1
1
1
1
1
5
5
5
5
5
5
5
5
5
5
7
7
7
7
80 (59:41)
73 (60:40)
91 (60:40)
84 (55:45)
67
16 (60:40)
6 (60:40)
88 (61:39)
63 (53:47)
12
63 (57:43)
69 (57:43)
85 (53:47)
62
9
10
11
12
13
14
1
50
80
4
40
aThe reaction of 1 (0.632 mmol) with 1 equiv or an excess of olefin was conducted in the absence or presence of ACHCN (0.127 mmol) in
toluene (5.0 mL).
bIsolated yield.
cDetermined by 1H NMR spectroscopic analysis.
Heteroatom Chemistry DOI 10.1002/hc

Radical Addition Reaction of Bis(naphth-1,8-diyl-8-oxy)hydrophosphorane to Olefins 541
on a LC-9201 recycling preparative HPLC (Japan An-
alytical Industry Co., Ltd) with tandem GPC columns
(JAIGEL-1H and 2H, chloroform, 3.5 mL/min).
R
R
O
O
P
5
P
H
Toluene, reflux
R
O
O
Melting points were measured with a Yanaco
micro melting point apparatus and are uncorrected.
1H (600 MHz), 13C (151 MHz), and 31P (243 MHz)
NMR spectra were recorded on a Brucker AVANCE-
II (600 MHz) spectrometer. HRMS was measured
on a Hitachi M-2500 mass spectrometer. Elemen-
tal analyses were performed on a Perkin-Elmer 2400
CHN elemental analyzer.
R
6
1
A) R = Ph, B) R = CO2Me, C) R = (CH2)2-
CO2Me
Ph
MeO2C
CO2Me
Ph
Ph
MeO2C
trans-5B
Ph
cis-5A trans-5A
cis-5B
5C
SCHEME 7
2-λ5–2,2ꢀ-Spirobi[2H-naphth[1,8-cd]-1,2-oxapho-
sphole] (1)
(Table 2: run 6,7,9,10) in 5 h except for the case of cis-
5B (Table 2: run 8), whereas it could be achieved by
using a large excess of 5 and elongating the reaction
time (Table 2: run 11–14). The relatively slow reac-
tion with internal olefins must reflect the bulkiness
of phosphoranyl radical I. Thus, the reaction with
tetraphenylethylene did not proceed. The higher re-
activities of cis and trans-5B indicate that the phos-
phoranyl radical I is nucleophilic [14]. The reactions
of cis-5 were more effective than those of trans-5, be-
cause cis-olefins are thermodynamically less stable
than trans-olefins.
To a suspension of 1-naphthol (20 g, 139 mmol)
in 300 mL of hexane was added N,N,Nꢀ,Nꢀ-
tetramethylethylenediamine (41.9 mL, 278 mmol).
n-BuLi (1.60
M n-hexane solution, 175 mL,
280 mmol) was added dropwise to the resulting so-
lution and the mixture was refluxed for 20 h followed
by the slow addition of a solution of PCl3 (6.05 mL,
69.3 mmol) in 100 mL of hexane at −78◦C. After re-
moval of the cooling bath, the reaction mixture was
allowed to warm to ambient temperature and THF
(300 mL) was added. The mixture was quenched
with 6 M HCl (400 mL) and extracted with 2:1
THF/Et2O (300 mL × 5). The collected organic layer
was dried over MgSO4 and the volatile was removed
under reduced pressure. Purification of the residue
was carried out on silica gel column chromatogra-
phy (benzene) to give 1 as pale yellow powder. Yield:
4.70 g, 21%. mp: 273◦C. 1H NMR (CDCl3, 600 MHz):
δ 9.16 (d, 1H, J = 737 Hz), 8.22 (dd, 2H, J = 12.6,
7.2 Hz), 7.98 (dd, 2H, J = 8.4, 3.0 Hz), 7.61 (dt, 2H, J
= 7.8, 6.6 Hz), 7.51 (t, 2H, J = 8.4 Hz), 7.35 (dd, 2H,
J = 8.4, 1.8 Hz), 6.99 (d, 2H, J = 7.8 Hz). 13C NMR
(CDCl3, 151 MHz): δ 156.9, 133.8 (d, J = 9.4 Hz),
132.0 (d, J = 14.5 Hz), 131.2 (d, J = 4.4 Hz), 129.7
(d, J = 26.1 Hz), 129.3, 128.2 (d, J = 16.6 Hz), 122.4
(d, J = 154.1 Hz), 116.1, 104.2. 31P NMR (CDCl3,
243 MHz): δ −49.9. Anal. Calcd for C20H13O2P: C,
75.95; H, 4.14. Found: C, 75.78; H, 4.26.
CONCLUSION
In conclusion, the radical addition reaction of hy-
drophosphorane 1 to both terminal and internal
olefins could be achieved by activation with ACHCN.
The reactions were entirely regioselective, and poly-
merization and reduction of the olefins were sup-
pressed. This reactivity may be intrinsic to hy-
drophosphoranes, i.e., hypervalent [15] phosphorus
hydrides. It was also revealed that the thermal addi-
tion to both terminal and internal olefins of 1 could
also be achieved. The formal addition of the P H
bond to the C C double bond without the use of
extraneous reagents is rare [4a,10,11]. Kinetic ex-
aminations, theoretical studies, and the reactions of
1 with other olefins or alkynes are currently under
investigation.
General Procedure for the Radical Addition
Reaction of Hydrophosphorane 1 Activated with
ACHCN
EXPERIMENTAL
All reactions were carried out under a nitrogen
atmosphere. Hexane, THF, and toluene used in
the reactions were freshly distilled from Na, Na-
benzophenone, and CaH2, respectively, and trans-
ferred under the positive pressure of nitrogen via
a syringe. Column chromatography was performed
using Silica Gel 60N (Kanto Chemical Co., Inc.,
0.063–0.210 mm). Preparative GPC was performed
To a solution of 1 (200 mg, 0.632 mmol) and ACHCN
(31.0 mg, 0.127 mmol) in 5.0 mL of toluene was
added an equimolar amount of an olefin at room
temperature and the solution was refluxed for 3 h
(for terminal olefins) or 5 h (for internal olefins).
The reaction mixture was cooled to room tempera-
ture and the solvents were removed under reduced
Heteroatom Chemistry DOI 10.1002/hc

542 Kajiyama et al.
pressure. Purification of the residue was carried out
by silica gel column chromatography or by silica gel
column chromatography and preparative GPC.
J = 11.9, 7.1 Hz, major isomer), 7.90–7.86 (m, 2H),
7.53; 7.47 (dd, 2H, J = 7.8, 6.5 Hz, major isomer; J =
7.9, 6.5 Hz, minor isomer), 7.46–7.40 (m, 2H), 7.25–
6.80 (m, 14H), 3.17–2.91 (m, 3H), 2.28 (t, J = 8.0 Hz,
2H), 2.25–1.76 (m, 2H). 31P NMR (CDCl3, 243 MHz)
δ −27.1; −27.7 (major isomer; minor isomer). HRMS
Calcd for C36H29O2P: 524.1905. Found: m/z 524.1713.
2-Decyl-2,2ꢀλ5-spirobi[2H-naphth[1,8-cd]-1,2-
oxaphosphole] (3a)
Silica gel column chromatography (benzene/hexane
1:1) afforded 3a as a yellowish white powder.
2-(2-Methoxycarbonylethyl)-2,2ꢀλ5-spirobi[2H-
naphth[1,8-cd]-1,2-oxaphosphole] (3c) and 2-[2,
4-Bis(methoxycarbonyl)butyl]-2,2ꢀλ5-spirobi[2H-
naphth[1,8-cd]-1,2-oxaphosphole] (4c)
1
Yield: 265 mg, 92%. mp: 68–69◦C. H NMR (CDCl3,
600 MHz): δ 8.27 (dd, J = 11.8, 7.2 Hz, 2H), 7.94
(dd, J = 8.0, 2.7 Hz, 2H), 7.58 (ddd, J = 8.0, 7.1,
6.3 Hz, 2H), 7.46 (dd, J = 8.2, 7.6 Hz, 2H), 7.28 (dd,
J = 8.3, 1.9 Hz, 2H), 6.89 (d, J = 7.4 Hz, 2H), 2.67
(dddd, J = 14.4, 12.6, 11.4, 5.3 Hz, 1H), 2.52 (ddt,
J = 12.7, 11.4, 5.2 Hz, 1H), 1.75–1.65 (m, 1H), 1.61–
1.51 (m, 1H), 1.29–1.12 (m, 14H), 0.85 (t, J = 7.3 Hz,
3H). 13C NMR (CDCl3, 151 MHz): δ 156.7, 133.8
(d, J = 8.6 Hz), 132.0 (d, J = 14.0 Hz), 130.8 (d,
J = 4.2 Hz), 129.6 (d, J = 23.8 Hz), 129.2, 128.1 (d,
J = 15.7 Hz), 125.4 (d, J = 154.3 Hz), 115.5, 103.8,
37.5 (d, J = 117.5 Hz), 31.9, 30.7 (d, J = 21.0 Hz),
29.43, 29.37, 29.2, 29.0, 23.9 (d, J = 5.9 Hz), 22.7,
14.1. 31P NMR (CDCl3, 243 MHz): δ −24.0. Anal.
Calcd for C30H33O2P: C, 78.92; H, 7.29. Found: C,
79.08; H, 7.30.
A mixture of 3c and traces of impurities was ob-
tained by silica gel column chromatography (ben-
zene). Preparative GPC afforded 3c as a yellowish
white powder. Yield: 208 mg, 82%. mp: 133–135◦C.
1H NMR (CDCl3, 600 MHz): δ 8.27 (dd, J = 11.9,
7.1 Hz, 2H), 7.96 (dd, J = 8.0, 2.7 Hz, 2H), 7.60 (dt,
J = 6.9, 6.8 Hz, 2H), 7.47 (t, J = 8.0 Hz, 2H), 7.31
(dd, J = 8.3, 2.0 Hz, 2H), 6.89 (d, J = 7.4 Hz, 2H),
3.41 (s, 3H), 3.08–2.95 (m, 2H), 2.74 (ddt, J = 18.1,
17.0, 7.6 Hz, 1H), 2.59 (dddd, J = 20.0, 16.9, 8.1,
6.7 Hz, 1H). 13C NMR (CDCl3, 151 MHz): δ 172.5
(d, J = 15.9 Hz), 156.2, 134.1 (d, J = 8.4 Hz), 132.0
(d, J = 14.3 Hz), 131.0 (d, J = 4.0 Hz), 129.4 (d, J =
25.0 Hz), 129.2, 128.1 (d, J = 16.3 Hz), 125.0 (d, J =
157.3 Hz), 115.8, 104.0, 51.6, 32.5 (d, J = 122.2 Hz),
29.5 (d, J = 4.1 Hz). 31P NMR (CDCl3, 243 MHz): δ
−28.5. Anal. Calcd for C24H19O4P: C, 71.64; H, 4.76.
Found: C, 71.42; H, 4.79.
Silica gel column chromatography (benzene-
ethyl acetate 10:1) afforded 4c as a yellow oil. Yield:
34.1 mg, 11% (diastereomeric mixture). 1H NMR
(CDCl3, 600 MHz): δ 8.26–8.21 (m, 2H), 7.94–7.91
(m, 2H), 7.59–7.54 (m, 2H), 7.47–7.44 (m, 2H), 7.30–
7.27 (m, 2H), 6.88 (d, J = 7.4 Hz, 2H), 3.57; 3.54 (s,
3H, major isomer; minor isomer), 3.37–2.72 (m, 3H),
3.32; 3.04 (s, 3H, minor isomer; major isomer), 2.32–
2.17 (m, 2H), 1.94–1.80 (m, 2H). 31P NMR (CDCl3,
243 MHz): δ −30.1; −30.8 (minor isomer; major iso-
mer). HRMS Calcd for C28H25O6P: 488.1389. Found:
m/z 488.1391.
2-(2-Phenylethyl)-2,2ꢀλ5-spirobi[2H-naphth[1,8-
cd]-1,2-oxaphosphole] (3b) and 2-(2,4-Diphen-
ylbutyl)-2,2ꢀλ5-spirobi[2H-naphth[1,8-cd]-1,2-
oxaphosphole] (4b)
A mixture of 3b and 4b was obtained by silica gel col-
umn chromatography (benzene/hexane 1:1). Prepar-
ative GPC afforded 3b as a yellowish white powder.
Yield: 217 mg, 82%. mp: 137–139◦C. 1H NMR (CDCl3,
600 MHz): δ 8.29 (dd, J = 11.7, 7.1 Hz, 2H), 7.95 (dd,
J = 7.7, 2.7 Hz, 2H), 7.59 (ddd, J = 8.0, 7.1, 6.3 Hz,
2H), 7.47 (dd, J = 8.3, 7.5 Hz, 2H), 7.29 (dd, J = 8.3,
2.0 Hz, 2H), 7.14–7.11 (m, 2H), 7.08–7.04 (m, 3H),
6.91 (d, J = 7.4 Hz, 2H), 3.05–2.96 (m, 2H), 2.93–
2.84 (m, 2H). 13C NMR (CDCl3, 151 MHz): δ 156.5,
141.1 (d, J = 21.0 Hz), 134.0 (d, J = 8.4 Hz), 132.0
(d, J = 14.3 Hz), 130.9 (d, J = 4.3 Hz), 129.6 (d, J
= 24.2 Hz), 129.2, 128.2 (d, J = 18.9 Hz), 128.1 (d,
J = 15.9 Hz), 126.0, 125.1 (d, J = 155.2 Hz), 115.6,
103.9, 38.9 (d, J = 116.6 Hz), 30.1 (d, J = 5.1 Hz).
31P NMR (CDCl3, 243 MHz): δ −26.0. Anal. Calcd
for C28H21O2P: C, 79.99; H, 5.03. Found: C, 80.28; H,
5.11.
2-(6-Bromohexyl)-2,2ꢀλ5-spirobi[2H-naphth[1,8-
cd]-1,2-oxaphosphole] (3d)
Silica gel column chromatography (benzene–hexane
1:1) afforded 3d as a yellowish white powder. Yield:
293 mg, 97%. mp: 106–107◦C. 1H NMR (CDCl3,
600 MHz): δ 8.26 (dd, J = 11.8, 7.1 Hz, 2H), 7.93
(dd, J = 8.0, 2.7 Hz, 2H), 7.58 (ddd, J = 8.0, 7.1,
6.4 Hz, 2H), 7.46 (dd, J = 8.2, 7.6 Hz, 2H), 7.28
(dd, J = 8.3, 2.0 Hz, 2H), 6.90 (d, J = 7.4 Hz, 2H),
The 2:1 adduct 4b was also isolated as a yellow
oil with preparative GPC. Yield: 15.5 mg, 5% (di-
1
astereomeric mixture). H NMR (CDCl3, 600 MHz):
δ 8.17; 8.05 (dd, 2H, J = 11.9, 7.2 Hz, minor isomer;
Heteroatom Chemistry DOI 10.1002/hc

Radical Addition Reaction of Bis(naphth-1,8-diyl-8-oxy)hydrophosphorane to Olefins 543
J = 22.3, 11.6, 3.4 Hz, major isomer; J = 21.4, 11.0,
3.9 Hz, minor isomer), 3.56; 3.55 (s, 3H, minor iso-
mer; major isomer), 3.51; 3.08 (d, J = 0.8 Hz, 3H, mi-
nor isomer; major isomer), 3.13; 2.91–2.79 (1H, ddd,
J = 17.2, 11.7, 9.6 Hz, major isomer; m, minor iso-
mer), 2.91–2.79; 2.44 (1H, m, minor isomer; ddd,
J = 17.1, 12.3, 3.4 Hz, major isomer). 31P NMR
(CDCl3, 243 MHz): δ −29.8; −30.8 (major isomer;
minor isomer). Anal. Calcd for C26H21O6P: C, 67.83;
H, 4.60. Found: C, 67.83; H, 4.53.
3.25 (t, J = 7.8 Hz, 2H), 2.67 (dddd, J = 14.6, 12.7,
11.1, 5.4 Hz, 1H), 2.52 (ddt, J = 12.9, 11.0, 5.3 Hz,
1H), 1.75–1.65 (m, 3H), 1.62–1.55 (m, 1H), 1.30–1.27
(m, 4H). 13C NMR (CDCl3, 151 MHz): δ 156.6, 133.8
(d, J = 8.1 Hz), 132.0 (d, J = 14.2 Hz), 130.9 (d,
J = 3.8 Hz), 129.6 (d, J = 24.1 Hz), 129.2, 128.1
(d, J = 15.7 Hz), 125.3 (d, J = 154.6 Hz), 115.5,
103.8, 37.4 (d, J = 117.9 Hz), 33.7, 32.5, 29.7 (d, J =
20.9 Hz), 27.6, 23.7 (d, J = 6.3 Hz). 31P NMR (CDCl3,
243 MHz): δ −24.5. Anal. Calcd for C26H24BrO2P: C,
65.15; H, 5.05. Found: C, 65.35; H, 5.10.
2-Cyclohexyl-2,2ꢀλ5-spirobi[2H-naphth[1,8-cd]-
1,2-oxaphosphole] (6C)
2-(1,2-Diphenylethyl)-2,2ꢀλ5-spirobi[2H-naphth
[1,8-cd]-1,2-oxaphosphole] (6A)
Silica gel column chromatography (benzene–hexane
1:1) afforded 6C as a yellowish white powder. Yield:
170 mg, 67%. mp: 163–169◦C. 1H NMR (CDCl3,
600 MHz): δ 8.28 (dd, J = 11.4, 7.1 Hz, 2H), 7.93
(dd, J = 8.0, 2.7 Hz, 2H), 7.58 (dt, J = 6.9, 7.3 Hz,
2H), 7.46 (t, J = 7.9 Hz, 2H), 7.27 (dd, J = 8.3,
1.9 Hz, 2H), 6.89 (d, J = 7.4 Hz, 2H), 2.75–2.68 (m,
1H), 1.79–1.62 (m, 6H), 1.50–1.42 (m, 1H), 1.25–1.20
(m, 3H). 13C NMR (CDCl3, 151 MHz) δ 157.0, 134.2
(d, J = 7.8 Hz), 132.0 (d, J = 14.1 Hz), 130.7 (d, J =
3.8 Hz), 129.8 (d, J = 23.2 Hz), 129.1, 128.1 (d, J =
16.1 Hz), 124.9 (d, J = 154.1 Hz), 115.3, 103.5, 48.1
(d, J = 113.4 Hz), 27.9 (d, J = 4.2 Hz), 27.7 (d, J =
3.2 Hz) 26.7 (d, J = 19.0 Hz), 26.3 (d, J = 19.6 Hz),
26.0 (d, J = 2.0 Hz). 31P NMR (CDCl3, 243 MHz): δ
−21.7. Anal. Calcd for C26H23O2P: C, 78.38; H, 5.82.
Found: C, 78.69; H, 5.88.
Silica gel column chromatography (benzene–hexane
1:1) afforded 6A as a yellowish white powder. Yield:
252 mg, 80% (diastereomeric mixture) from cis-
stilbene (cis-5A); Yield: 228 mg, 73% (diastereomeric
mixture) from trans-stilbene (trans-5A). mp: 142–
1
145◦C. H NMR (CDCl3, 600 MHz): δ 8.19; 8.12 (dd,
J = 11.5, 7.1 Hz, 2H, minor isomer; major isomer),
7.84; 7.82 (dd, J = 8.0, 2.7 Hz, 2H, minor isomer;
major isomer), 7.51–7.44 (m, 2H), 7.43; 7.39 (dd,
J = 8.2, 7.5 Hz, 2H, major isomer; minor isomer),
7.30–7.28; 7.15–7.13 (m, 2H, major isomer; minor
isomer), 7.21; 7.19 (dd, J = 8.3, 2.0 Hz, 2H, ma-
jor isomer; minor isomer), 6.94–6.80 (m, 2H), 4.48;
4.42 (ddd, J = 16.6, 10.2, 5.2 Hz, 1H, major isomer;
J = 16.9, 10.0, 5.4 Hz, minor isomer), 3.62; 3.37
(1H, ddd, J = 15.3, 14.9, 10.0 Hz, minor isomer; dt,
J = 14.2, 10.1 Hz, major isomer), 3.53; 3.17 (ddd, 1H,
J = 14.4, 13.9, 5.4 Hz, minor isomer; J = 14.1, 13.5,
5.0 Hz, major isomer). 31P NMR (CDCl3, 243 MHz):
δ −24.1; −24.4 (major isomer; minor isomer). Anal.
Calcd for C34H25O2P: C, 82.24; H, 5.07. Found: C,
82.10; H, 5.09.
General Procedure for the Radical Addition
Reaction of Hydrophosphorane 1 in the Absence
of ACHCN
To a solution of 1 (200 mg, 0.632 mmol), in 5.0 mL of
toluene was added an equimolar (for terminal and
internal olefins) or an excess (for internal olefins)
amount of an olefin at room temperature and the
solution was refluxed for 5 h (for terminal and inter-
nal olefins) or 7 h (for internal olefins). Otherwise,
the procedure is identical to what is described in
the general procedure for the reaction activated with
ACHCN.
2-[1,2-Bis(methoxycarbonyl)ethyl]-2,2ꢀλ5-spirobi
[2H-naphth[1,8-cd]-1,2-oxaphosphole] (6B)
A
mixture of 6B and traces of impurities
was obtained by silica gel column chromatog-
raphy (benzene–ethyl acetate 10:1). Preparative
GPC afforded 6B as a yellowish white pow-
der. Yield: 264 mg, 91% (diastereomeric mixture)
from dimethyl maleate (cis-5B); Yield: 243 mg,
84% (diastereomeric mixture) from dimethyl fu-
marate (trans-5B). mp: 146–150◦C. 1H NMR (CDCl3,
600 MHz): δ 8.30; 8.27 (dd, 2H, J = 12.1, 7.1 Hz,
major isomer; J = 12.0, 7.1 Hz, minor isomer),
8.01–7.98 (m, 2H), 7.65–7.61 (m, 2H), 7.48; 7.46 (dd,
J = 8.3, 7.5 Hz, 2H, minor isomer; major isomer),
7.35–7.32 (m, 2H), 6.91; 6.89 (d, J = 7.4 Hz, 2H,
major isomer; minor isomer), 4.34; 4.14 (ddd, 1H,
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