Organophosphorus compounds. Part 151:1 Synthesis and reactivity of a novel isophosphinoline derivative

Article abstract of DOI:10.1016/S0040-4020(00)00555-X

Regiospecific 1,3-dipolar cycloadditions of the carbonyl ylide 2, generated thermally from the oxirane 1, to the phosphaalkynes 3 furnish the polycyclic phosphaalkenes 4. The reaction of 4a with sulfur or gray selenium leads to the thia- or selenaphosphirane derivatives 5. An oxidation of the phosphorus atom in 5a can be achieved by the addition of a stoichiometric amount of sulfur and affords the thioxothiaphosphirane derivative 6. Thermolysis of the phosphaalkenes 4a-c gives an unexpected result: rearrangement of the ring skeleton with cleavage of the alkyl substituent at the P/C double bond to afford the isophospholine system 7 occurs. The constitution of compound 7 was deduced from its spectral data and confirmed by reactivity studies. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00555-X

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 6259±6267
Organophosphorus Compounds. Part 151:1 Synthesis and
Reactivity of a Novel Isophosphinoline Derivative
*
Sven G. Ruf, Jochen Dietz and Manfred Regitz
È È
Fachbereich Chemie der Universitat Kaiserslautern, Erwin-Schrodinger-Straûe, D-67663 Kaiserslautern, Germany
Dedicated to Professor Rolf Huisgen on the occasion of his 80th birthday
Received 18 November 1999; revised 31 May 2000; accepted 20 June 2000
AbstractÐRegiospeci®c 1,3-dipolar cycloadditions of the carbonyl ylide 2, generated thermally from the oxirane 1, to the phosphaalkynes 3
furnish the polycyclic phosphaalkenes 4. The reaction of 4a with sulfur or gray selenium leads to the thia- or selenaphosphirane derivatives 5.
An oxidation of the phosphorus atom in 5a can be achieved by the addition of a stoichiometric amount of sulfur and affords the thioxo-
thiaphosphirane derivative 6. Thermolysis of the phosphaalkenes 4a±c gives an unexpected result: rearrangement of the ring skeleton with
cleavage of the alkyl substituent at the P/C double bond to afford the isophospholine system 7 occurs. The constitution of compound 7 was
deduced from its spectral data and con®rmed by reactivity studies. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
is warmed and leads to the dark-red carbonyl ylide dipole
2.10
Just recently, the synthetic potential of carbonyl ylide
dipoles for the preparation of oxygen-containing heterocyc-
lic systems, which has been widely used in the synthesis of
natural products for a long time,2±4 has also been exploited
in the chemistry of phosphaalkynes.5 In this way, the reac-
tions of isomuÈnchnones with phosphaalkynes have led to
novel 1,3-oxaphosphole derivatives.6 The carbonyl ylide
dipole 2, generated under thermal conditions from 2,3-
diphenylindenone oxide (1), has proved in this context to
be a suitable reaction partner for the phosphaalkyne 3a.7
Since the thus formed polycyclic phosphaalkene derivative
4a exhibited a remarkable reactivity in initial studies,
further investigations of this system were undertaken and
the results are presented in the actual paper.
On thermolysis of 1 in the presence of the phosphaalkynes
3a±d in dichloromethane as solvent the polycyclic, oxygen-
bridged phosphaalkene derivatives 4a±d are obtained
through the intermediate 2 (Scheme 1). Work-up and puri-
®cation by ¯ash chromatography affords the products as
light yellow solids, some of which are even analytically
pure. The phosphaalkene derivatives 4a±d can be stored
for several days without the necessity for inert gas protec-
tion. This remarkable stability towards atmospheric oxygen
and moisture is, on the whole, rather unusual for phos-
phaalkenes.11 However, it can be easily explained in terms
of the high steric shielding of the reactive phosphaalkene
increment by the voluminous alkyl group and the two
phenyl rings.5
The yields of 4a, 4b and 4d obtained (52±75%) are satis-
factory while that of 4c is disappointingly low (28%).
Results and Discussion
Synthesis of the phosphaalkenes 4a±d
A regiospeci®c reaction was observed in each case, the
employed phosphaalkynes 3a±d always attacked the car-
bonyl ylide dipole 2 in a non-charged controlled cycloaddi-
tion. This behavior has already been recognized as a
characteristic property of this class of dipoles.5
Cleavage of the C±C single bond in acceptor-substituted
oxiranes under thermal stress can be considered as a char-
acteristic reaction for this class of compounds.8 This leads to
the formation of carbonyl ylide structures, as has been
unambiguously demonstrated by numerous trapping reac-
tions with suitable dipolarophiles.9 A ring opening of this
type is also observed when 2,3-diphenylindenone oxide (1)
The constitutions of compounds 4a±d were unambiguously
deduced from their NMR and mass spectral data. Thus, the
31P NMR signals between dˆ261 and dˆ268 indicate the
presence of a P/C double bond in the isolated products 4a±
d.11 Further diagnostically relevant signals are found in the
13C NMR spectra. Here, the two bridgehead carbon atoms
C-1 and C-9 as well as the carbon atom C-10 of the P/C
Keywords: phosphaalkynes; ylides; phosphaalkenes; phosphorus hetero-
cycles.
* Corresponding author. Tel.: 149-631-205-2431; fax: 149-631-205-
3921; e-mail: regitz@rhrk.uni-kl.de
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00555-X

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S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
Scheme 1.
double bond give rise to three characteristic signals that
differ only slightly among the newly prepared compounds
4a±d and thus demonstrate the identical regiochemistries.
dˆ94.8 and dˆ97.6 and dˆ98.2, respectively. As a result
of the neighboring carbonyl group the carbon atoms C-9 are
assigned to the more strongly down®eld shifted signals.
However, in all the products these signals show a doublet
2
The signals of the carbon atom C-10 with chemical shifts
between dˆ210 and dˆ214 are in the typical region for
splitting of on average 9 Hz which corresponds to a JC,P
coupling. When the signals of the bridgehead carbon atoms
C-1 are considered an appreciably larger doublet splitting of
on average 38 Hz is seen which is obviously caused by a
1JC,P coupling. Thus, it is possible to determine the consti-
tutions of the phosphaalkenes 4a±d on the basis of these
data.
1
phosphaalkenes. The measured JC,P coupling constants
are on average 45 Hz. The signals of the bridgehead carbon
atoms C-1 and C-9 are also of major importance for the
exact structural elucidation of the cycloaddition products
4a±d with their chemical shifts between dˆ94.4 and
Scheme 2.

S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
6261
approach of the sulfur atom to the P/C double bond in 4a
must have occurred from the side of the molecule opposite
the oxygen bridge and this de®nes the structure of 5a. Since
compound 5a occurs as an intermediate in the formation of
6, the stereochemistry of 6 can also be deduced on the basis
of this discussion.
The 31P NMR spectrum of 6 shows a typical resonance at
dˆ21.5 for a compound with a l5s4-phosphorus atom.17
Thus, compound 6 well complements the series of known
thioxothiaphosphiranes exhibiting signals with similar
chemical shifts in their 31P NMR spectra.18±21
Scheme 3.
Reactivity of the phosphaalkene 4a towards chalcogens
In the 31P NMR spectrum of the newly synthesized selena-
phosphirane 5b an additional JP,Se coupling constant of
1
On reaction of the phosphaalkene 4a with an equimolar
amount of sulfur or gray selenium at room temperature
the polycyclic compounds 5a,b are obtained in high selec-
tivities (Scheme 2). Although the reactions do proceed at
room temperature, the addition of triethylamine to the reac-
tion mixture is essential in order to avoid excessively long
reaction times.
125 Hz is also observed and can be considered to be of a
magnitude typical for this class of compounds.13 As
expected the 13C NMR spectrum of 5b is closely analogous
to that of 5a. Similar to the case for compound 5a, an
2
analysis of the JC,P coupling constants allows the unequi-
vocal determination of the con®gurations at C-10 and P-12.
As expected, the directions of attack of selenium and sulfur
at the P/C double bond are the same.
When the thiaphosphirane 5a is treated with a further
equivalent of sulfur, selective formation of the thioxothia-
phosphirane 6 occurs. Compound 6 is also obtained when
the phosphaalkene 4a is allowed to react with 2 equiv. of
sulfur; 5a can be detected as an intermediate by 31P NMR
spectroscopy in the latter reaction.
Thermolysis of the phosphaalkenes 4a±c
When the polycyclic phosphaalkenes 4a±c are heated for
72 h at 1508C, the highly selective formation of a single new
compound giving a signal at dˆ197.4 is observed by 31P
NMR spectroscopy. The formation of this new compound is
strongly dependent on the solvent used. The synthesis
proceeds best in toluene, less ef®ciently in THF, while in
dichloromethane only a very low conversion is observed.
The new compound was puri®ed by ¯ash chromatography
and then obtained in the form of an analytically pure, bright
yellow solid in a yield of up to 82%. Evaluation of the
analytical data leads to the sole conclusion that the product
must be the isophosphinoline derivative 7 shown (Scheme
3).
The 31P NMR spectra of products 5a,b exhibit signals at
dˆ265.0 and dˆ241.1, i.e. in the typical region for the
currently known thia- and selenaphosphiranes and thus
support the proposed structures.12,13 Further evidence for
these structures is provided by the 13C NMR spectra
which no longer contain the characteristic signal for the
phosphaalkene carbon atom of the starting material 4a at
dˆ212.5. In its place the spectrum of compound 5a contains
1
a new signal at dˆ73.2 which, on account of its JC,P
coupling constant of 43.8 Hz, can be assigned to the carbon
atom C-10.
A remarkable feature of this conversion of the phosphaalk-
enes 4a±c into the isophosphinoline 7 is the complete loss
of the alkyl substituents present on the original P/C double
bond of 4a±c; the mechanism for this reaction cannot as yet
be satisfactorily rationalized.
From the stereochemical point of view, the described synth-
eses of 5a,b could furnish two diastereomers that differ in
the position of the sulfur or selenium atom, respectively,
relative to the oxygen bridge. However, as can be seen
already from the respective 31P NMR spectra, only one dia-
stereomer is formed in each case. Analysis of the con®gura-
Compound 7 also exhibits a remarkable stability to atmo-
spheric oxygen. Apparently, the complete substitution of the
phosphorus-containing ring of the structure has a stabilizing
effect on compound 7. The unsubstituted isophosphinoline
skeleton was described by Bickelhaupt as being extremely
reactive and very sensitive to hydrolysis.22
2
tions requires a detailed discussion of the JC,P coupling
constants: in general, JC,P coupling constants show a
2
pronounced dependence on the relative positions of the
respective carbon atom to the free electron pair at the phos-
2
phorus atom.14±16 If they are in a syn-orientation the JC,P
coupling constants reach relatively large values whereas
with an anti-orientation only small values are achieved. In
the case of compound 5a, therefore, the doublet splittings of
the signals for the quaternary carbon of the tert-butyl substi-
tuents and for the ipso-carbon atom C-100 of the phenyl
substituents at C-1 would be decisive. In the present case,
2JC,P coupling constants of 7.2 and 17.7 Hz were measured
for these signals. From this it can be deduced that not only
the tert-butyl substituent at C-10 but also the phenyl group
at C-1 must be in approximately syn-relationships to the free
electron pair at the phosphorus atom. This means that the
The isophosphinoline derivative 7 described here is the ®rst
member of this class of compounds to be isolated in pure
form. Although the synthesis of two further 4-hydroxyiso-
È
phosphinolines was reported by Dotz in 1993, these
compounds, however, could not be separated from accom-
panying products present in the reaction mixture.23
The 31P NMR spectrum provides the ®rst useful information
for the structural elucidation of compound 7. Thus, the
phosphorus chemical shift of dˆ197.4 is in the typical

6262
S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
Scheme 4.
range for a phosphorus-containing aromatic system.24 The
1H NMR spectrum contains a signal for the hydroxy proton
at dˆ15.6. This dramatic low ®eld shift is a convincing
indication for its incorporation in an intramolecular, chelat-
ing hydrogen bond.25 A similar situation is found in the enol
form of acetylacetone with a signal at dˆ15.4.26 The IR
spectrum of 7 also provides evidence for the presence of a
hydrogen bond. Thus, a very broad band of weak intensity is
observed in the region between 2300 and 3200 cm21 which
is typical for systems of this type.26 In addition, the IR
spectrum no longer contains any characteristic absorptions
for a carbonyl group but instead only a broad band at
preferentially in toluene as solvent. Non-polar solvents
such as toluene are known to favor homolytic bond cleaving
processes leading to radicals.27 In addition, it is not possible
to achieve an ionic ring opening of the polycyclic system 4a
by addition of electrophiles to the oxygen bridge.
As a ®rst working hypothesis, we can formulate a cleavage
of the alkyl substituents by way of the corresponding
tertiary alkyl radical which is stabilized by formation of
the corresponding alkene. The formal transfer of hydrogen
from the detached alkyl residue also offers an elegant expla-
nation for the formation of the hydroxy group. However,
this mode of reaction is not possible for the adamantyl-
substituted derivative 4d since Bredt's rule forbids the crea-
tion of a C/C double bond in the adamantane skeleton.
When the thermolysis of the derivative 4d is carried out
under the respective reaction conditions the formation of
the isophosphinoline 7 is indeed not observed, instead the
phosphaalkene 4d decomposes in an unspeci®c manner.
1601 cm21
.
The 13C NMR spectrum of the isophosphinoline 7 contains a
signal for the carbon atom C-1 at dˆ203.8, the correspond-
1
ing JC,P coupling constant of 32.9 Hz is relatively small.
The carbon atoms C-3 and C-4 give rise to further charac-
teristic signals at dˆ140.9 and dˆ164.9.
A mechanistic rationalization for the formation of the
isophosphinoline 7 upon thermolysis of the phosphaalkenes
4a±c is dif®cult, especially since no intermediates can be
detected or identi®ed by 31P NMR spectroscopy. Various
experimental ®ndings, however, are suggestive of a radical
course for these reactions.
Reactivity of the isophosphinoline 7
Esteri®cation. The chemical con®rmation of the presence
of the hydroxy group in 7 is provided by deprotonation with
n-butyllithium and subsequent reaction with the acid chlo-
ride 8. The ester 9 (Scheme 4) is formed in this manner.
The esteri®cation of 7 is evident from the 1H NMR spectra
Thus, the formation of the isophosphinoline 7 proceeds
Scheme 5.

S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
6263
Scheme 6.
of the product 9 in which the signal for the hydroxy proton is
no longer present. Instead the spectrum of 9 contains a
signal for the newly introduced alkyl group. The 31P NMR
signal of the newly prepared compound 9 is, as expected,
relatively similar and, in comparison to the starting material
7, shows a slight shift to higher ®eld. As a result of the
absence of the intramolecular hydrogen bond in 9 a typical
carbonyl band at around 1700 cm21 is now visible in the IR
spectra. Also, the characteristic 13C NMR chemical shifts of
the carbon atoms C-1, C-3, C-4 in compound 9 show only
minor differences to those of the starting material 7.
partner for the isophosphinoline 7, complete conversion to
the polycyclic compound 13 occurs under appreciably
milder conditions. After recrystallization of the crude
product from dichloromethane/n-pentane the addition
product 13 is obtained as an analytically pure, light yellow
solid (Scheme 5).
The mass spectrum of the obtained product provides deci-
sive evidence for its constitution: the observed isotope
distribution of the molecular ion peak resulting from the
halogen substitution is exactly simulated by the usual meth-
ods.5 The 31P NMR spectrum of compound 13 also shows an
appropriate signal at dˆ76.9. In the 13C NMR spectrum the
structurally relevant signals for C-5, C-6, and C-12a are
closely analogous to those in the spectrum of 11.
[412] Cycloaddition. According to our current knowledge,
phosphinine derivatives can only act as dienophiles in
[412] cycloaddition reactions with 2,3-dimethylbutadiene
10 to give satisfactory yields of products when the phos-
phorus atom has been complexed with a transition metal
fragment prior to the reaction.28 The isophosphinoline deri-
vative 7, on the other hand, reacts completely with the diene
10 on heating at 1508C. Chromatographic work-up furnishes
the cycloaddition product 11 as a light yellow solid in 60%
yield (Scheme 5).
[312] Cycloaddition. The isophospholine 7 reacts with
mesityl nitrile oxide 14, also under very mild conditions,
in a 1,3-dipolar cycloaddition to furnish the oxazaphospho-
line 15. The product 15 is isolated after column chromato-
graphic work-up in 81% yield as a yellow solid that is not
sensitive to atmospheric oxygen or moisture (Scheme 6).
The 31P NMR signal of the cycloaddition product 11 at
dˆ249.5 by itself is rather characteristic for a cycloaddi-
tion product from dimethylbutadiene and an alkyl- or aryl-
substituted phosphaalkene.29 Further con®rmation for the
The directions of addition and thus the constitution of 15 is
unambiguously derived from an analysis of the 13C NMR
spectrum. The decisive ®nding here is the signal for the
carbon atom C-3 at dˆ160.2. It appears as a doublet with
a coupling constant of 49.4 Hz which is indisputable
evidence for the occurrence of a 1JC,P coupling. The chemi-
cal shifts of the signals for the carbon atoms C-5 and C-6
are, as expected, very similar to those of the corresponding
1
proposed structure is provided by the H NMR spectrum.
The signal for the bridging hydrogen atom is seen at
dˆ17.8, and the diastereotopic protons at C-5 and C-8
give rise to three complex multiplets between dˆ1.90 and
dˆ2.87. As in the starting material 7 typical carbonyl
absorptions cannot be seen in the IR spectrum of 11 on
account of the hydrogen bond to the benzoyl substituent at
C-9, instead only a broad absorption at 1600 cm21 is
present. In the 13C NMR spectrum, the signal at dˆ42.2
can be attributed to the carbon atom C-4b; the differentia-
tion from the methylene carbon atoms C-5 and C-8 is unam-
biguously achieved by means of a 13C-DEPT experiment. In
this respect, however, the very small 1JC,P coupling constant
of merely 3.9 Hz to the quaternary carbon atom is worthy of
note.
1
atoms in compounds 11 and 13. The H NMR spectrum of
compound 15 is of particular interest. Besides the character-
istic signal for the proton of the chelating hydrogen bond at
dˆ18.3, three different signals, two of which are markedly
broadened, are observed for the methyl groups of the mesi-
tyl substituent. The fact that the ortho-methyl groups are no
longer chemically equivalent is indicative of a hindered
1
rotation. This assumption is impressively con®rmed by H
NMR spectra recorded at various temperatures. From these
measurements a coalescence temperature of 333 K was
determined which corresponds to an energy of 69.9 kJ/mol
for the barrier to rotation.30
The constitution of the polycyclic compound 11 was also
con®rmed by X-ray crystallography. However, the quality
of the data set obtained does not allow a detailed discussion
of bond lengths and angles.
Conclusion
Not only the novel phosphaalkenes 4 but also the isophos-
phinoline 7 obtained by thermolysis from 4a±c exhibit a
When the heterodiene 12 is used as the [412] cycloaddition

6264
S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
surprising and diverse reactivity. The formation of 7, in
particular, poses a number of as yet unresolved mechanistic
questions. Further investigations with this objective are at
present in progress.
From 1000 mg oxirane (1, 3.35 mmol) and 3.35 mmol phos-
phaalkyne 3b, yield: 983 mg (70%), mp 938C; 31P NMR
(C6D6): dˆ267.2 (s); H NMR (C6D6): dˆ0.55 (pt, 3H,
1
4
3JH,Hˆ7.4 Hz, ±C(CH3)(CH3)CHHCH3), 0.89 (d, 3H, JH,P
ˆ
1.0 Hz, ±C(CH3)(CH3)CHHCH3), 1.11 (s, 3H, ±C(CH3)(CH3)
CHHCH3), 1.10±1.19 (m, 1H, ±C(CH3)(CH3)CHHCH3),
1.37±1.46 (m, 1H, ±C(CH3)(CH3)CHHCH3), 6.69±8.83 (m,
Experimental
14H, aryl-H); 13C NMR (C6D6): dˆ8.7 (d, JC,Pˆ1.2 Hz,
4
3
±C(CH3)(CH3)CHHCH3), 30.3 (d, JC,Pˆ13.7 Hz, ±C(CH3)
General
3
(CH3)CHHCH3), 30.7 (d, JC,Pˆ14.5 Hz, ±C(CH3)(CH3)
3
CHHCH3), 35.9 (d, JC,Pˆ9.6 Hz, ±C(CH3)(CH3)CHHCH3),
All experiments were carried out under argon
(purity.99.998%) in previously evacuated and baked
Schlenk vessels. When the reaction mixture had to be heated
to temperatures above the boiling point of the solvent,
special pressure Schlenk tubes (glass tubes, 3£5 cm2, wall
thickness 2 mm) with screw-threaded Te¯on stoppers and
Te¯on stopcocks were used. The solvents were dried by
standard procedures, distilled and stored under argon until
used. Melting points were determined on a Mettler FP61
apparatus (heating rate 28C min21) and are uncorrected.
NMR spectra were recorded on Bruker WP200 and
2
43.1 (d, JC,Pˆ10.8 Hz, ±C(CH3)(CH3)CHHCH3), 94.7 (d,
1JC,Pˆ38.2 Hz, C-1), 98.2 (d, JC,Pˆ8.8 Hz, C-9), 122.7 (d,
2
JC,Pˆ1.2 Hz), 127.6 (s), 127.9 (s), 128.0 (s), 128.1 (s), 128.2
(s), 128.5 (s), 128.7 (s), 129.0 (s), 132.2 (s), aryl-C, 126.8
(s), 148.4 (d, JC,Pˆ2.8 Hz), C-2 and C-7, 138.7 (d,
3JC,Pˆ4.4 Hz, C-10), 140.2 (d, JC,Pˆ10.8 Hz, C-100), 189.2
2
(d, 3JC,Pˆ10.0 Hz, C-8,), 210.5 (d, 1JC,Pˆ46.8 Hz, C-10); IR
(CH2Cl2): nˆ2966 (m, CH), 1698 (vs, CO), 1594 (s), 1201
(m), 1026 (m), 836 (w); MS (EI, 70 eV): m/z (%)ˆ412
(70.3) [M]1, 397 (5.7) [M2Me]1, 383 (13.0) [M2Et]1,
342 (31.0) [M2C5H10]1, 105 (100.0) [PhCO]1, 77 (41.0)
[Ph]1, 71 (4.3) [C5H11]1; C27H25O2P (412.37 g/mol): calcd
C 78.62, H 6.11; found C 78.22, H 6.30.
1
AMX400 instruments. Chemical shifts for H and 13C are
reported in ppm relative to the solvent as internal standard;
the chemical shifts for 31P are expressed relative to external
85% orthophosphoric acid. Elemental analyses were
performed on a Perkin±Elmer Analyser 2400. IR spectra
were measured on a Perkin±Elmer 16 PC FT-IR spectro-
photometer and mass spectra were recorded on a Finnigan
MAT90 spectrometer. Compounds 131 and 332 were
prepared according to published methods.
10-(1-Methylcyclohexyl)-1,9-diphenyl-12-oxa-11-phospha-
(4c).
tricyclo[7.2.1.02,7]dodeca-2,4,6,10-tetraen-8-one
From 1000 mg oxirane (1, 3.35 mmol) and 3.35 mmol phos-
phaalkyne 3c, yield: 415 mg (28%), mp 1028C; 31P NMR
(CDCl3): dˆ268.5 (s); 1H NMR (CDCl3): dˆ0.74 (s, 3H, ±
CH3), 1.05±1.60 (m, 10H, alkyl-H), 6.81±8.21 (m, 14H,
4
aryl-H); 13C NMR (CDCl3): dˆ22.1 (d, JC,Pˆ2.9 Hz),
10-Alkyl-1,9-diphenyl-12-oxa-11-phosphatricyclo[7.2.1.02,7]
dodeca-2,4,6,10-tetraen-8-ones (4a±d). Solutions of equi-
molar amounts of oxirane 1 and the phosphaalkynes 3a±d
in 15 ml CH2Cl2 were heated for 18 h at 1508C under 5 bar
Ar overpressure. After evaporation of the solvent the residue
was dissolved in 5 ml of CH2Cl2 and subjected to ¯ash
chromatography on silica gel 60 with an n-pentane/ether
mixture (80:1) to furnish the products as pale yellow solids.
4
3
22.3 (s, JC,Pˆ2.4 Hz), 25.5 (d, JC,Pˆ9.2 Hz), 25.6 (s),
3
3
39.4 (d, JC,Pˆ13.8 Hz), 41.2 (d, JC,Pˆ15.7 Hz), 43.4 (d,
1
2JC,Pˆ9.5 Hz), alkyl-C, 94.5 (d, JC,Pˆ38.1 Hz, C-1), 97.8
(d, 2JC,Pˆ9.5 Hz, C-9), 122.8 (s), 127.6 (s), 127.8 (s), 128.0
(s), 128.1 (s), 128.2 (s), 128.6 (s), 128.7 (s), 129.1 (s), 132.4
(s), aryl-C, 126.7 (s), 148.3 (s), C-2 and C-7, 139.0 (d,
2
3JC,Pˆ4.3 Hz, C-10), 140.0 (d, JC,Pˆ10.4 Hz, C-100), 189.7
3
1
(d, JC,Pˆ9.5 Hz, C-8), 213.9 (d, JC,Pˆ46.7 Hz, C-10); IR
(CCl4): nˆ3062 (w, CH), 2930 (vs, CH), 2856 (m, CH),
1702 (vs, CO), 1677 (m), 1596 (w), 1494 (w), 1447 (s),
1282 (m), 1261 (m), 1201 (m), 1029 (m), 697 (vs); MS
(EI, 35 eV): m/z (%)ˆ438 (47.2) [M]1, 342 (40.0)
[M2C7H12]1, 105 (88.9) [PhCO]1; C29H27O2P (438.50 g/
mol).
10-tert-Butyl-1,9-diphenyl-12-oxa-11-phosphatricy-
clo[7.2.1.02,7] dodeca-2,4,6,10-tetraen-8-one (4a). From
2000 mg oxirane (1, 6.70 mmol) and 670 mg phosphaalk-
yne (3a, 6.70 mmol), yield: 2000 mg (75%), mp 968C; 31P
NMR (CDCl3): dˆ261.4 (s); 1H NMR (CDCl3): dˆ1.04 (d,
4
9H, JH,Pˆ1.2 Hz, C(CH3)3), 6.81±8.09 (m, 14H, aryl-H);
3
13C NMR (CDCl3): dˆ32.9 (d, JC,Pˆ13.0 Hz, C(CH3)3),
2
1
10-(Adamant-1-yl)-1,9-diphenyl-12-oxa-11-phospha-
(4d).
37.2 (d, JC,Pˆ13.0 Hz, C(CH3)3), 94.4 (d, JC,Pˆ37.8 Hz,
C-1), 98.0 (d, 2JC,Pˆ8.9 Hz, C-9), 122.8 (s), 127.7 (s), 127.9
(s), 128.00 (s), 128.03 (s), 128.1 (s), 128.3 (s), 128.6 (s),
129.0 (s), 132.4 (s), aryl-C, 126.7 (s), 148.3 (s), C-2 and C-7,
tricyclo[7.2.1.02,7]dodeca-2,4,6,10-tetraen-8-one
From 1000 mg oxirane (1, 3.35 mmol) and 3.35 mmol phos-
phaalkyne 3d, yield: 846 mg (52%), mp 1058C, 31P NMR
1
3
2
138.5 (d, JC,Pˆ4.0 Hz, C-10), 139.9 (d, JC,Pˆ10.4 Hz, C-
100), 189.6 (d, 3JC,Pˆ10.4 Hz, C-8), 212.5 (d, 1JC,Pˆ45.0 Hz,
C-10); IR (CCl4): nˆ2962 (s, CH), 1698 (vs, CvO), 1594
(s), 1492 (m), 1448 (w), 1446 (s), 1364 (m), 1280 (s), 1200
(s), 1184 (m), 1060 (m), 1027 (s), 836 (s); MS (EI, 70 eV):
m/z (%)ˆ398 (5.6) [M]1, 342 (2.8) [M2C4H8]1, 105 (37.6)
[Ph-CO]1, 77 (16.6) [C6H5]1, 57 (47.0) [C4H9]1; C26H23O2P
(398.43 g/mol): calcd C 78.39, H 5.78; found C 77.50, H
5.75.
(C6D6): dˆ267.8 (s); H NMR (C6D6): dˆ1.30±2.06 (m,
15H, alkyl-H), 6.75±8.43 (m, 14H, aryl-H); 13C NMR
4
(CDCl3): dˆ28.6 (d, JC,Pˆ1.6 Hz), 36.1 (s), 42.9 (d,
3
2JC,Pˆ10.4 Hz), 44.4 (s, JC,Pˆ13.3 Hz), alkyl-C, 94.6 (d,
2
1JC,Pˆ38.2 Hz, C-1), 97.6 (d, JC,Pˆ8.4 Hz, C-9), 122.8
(s), 127.6 (s), 127.9 (s), 128.0 (d, JC,Pˆ4.0 Hz), 128.0 (d,
JC,Pˆ5.2 Hz), 128.3 (s), 128.6 (s), 128.6 (s), 129.0 (s), 132.4
(s), aryl-C, 126.7 (s), 148.4 (d, JC,Pˆ1.6 Hz), C-2 and C-7,
3
2
138.9 (d, JC,Pˆ4.4 Hz, C-10), 140.0 (d, JC,Pˆ10.4 Hz,
3
C-100), 189.7 (d, JC,Pˆ10.0 Hz, C-8), 213.8 (d,
1JC,Pˆ45.8 Hz, C-10); IR (CCl4): nˆ3066 (w, CH), 2909
10-(1,1-Dimethylpropyl)-1,9-diphenyl-12-oxa-11-phospha-
tricyclo[7.2.1.02,7]dodeca-2,4,6,10-tetraen-8-one
(vs, CH), 2852 (m, CH), 1703 (m, CO), 1596 (w), 1493
(4b).

S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
6265
(w), 1448 (m), 1281 (w), 1198 (w), 1030 (w), 698 (w);
HRMS: calcd for C32H29O2P: 476.1905; found: 476.1875;
C32H29O2P (476.55 g/mol).
removed and the residue puri®ed by column chromato-
graphy with a n-pentane/ether mixture (10:1) as eluent.
yield: 282 mg (69%), mp 908C (dec.); Method B: To a solu-
tion of 350 mg of compound 5a (0.21 mmol) in 5 ml of
CH2Cl2 are added 42 ml (0.30 mmol) of triethylamine and
13 mg (0.41 mmol) of sulfur. After stirring for 2 days at
258C the solvent is removed and the residue is worked up
Synthesis of compounds 5a,b
General procedure. To a solution of 150 mg (0.38 mmol)
of the compound 4a in 5 ml of CH2Cl2 are added 70 ml
(0.50 mmol) of triethylamine and an equimolar amount of
the appropriate chalcogen. The reaction mixture is stirred
for 2 days at 258C. After evaporation of the solvent the
crude products are puri®ed by column chromatography
with an n-pentane/ether mixture (10:1) as eluent.
1
as described above. 31P NMR (CDCl3): dˆ21.5 (s); H
NMR (C6D6): dˆ1.27 (s, 9H, ±C(CH3)3), 6.89±8.26 (m,
14H, aryl-H); 13C NMR (CDCl3): dˆ31.1 (d,
3JC,Pˆ4.0 Hz, ±C(CH3)3), 36.7 (s, ±C(CH3)3), 58.8 (d,
1
1JC,Pˆ28.1 Hz, C-1), 85.0 (d, JC,Pˆ51.8 Hz, C-10), 86.6
2
(d, JC,Pˆ7.2 Hz, C-9), 127.3 (s), 128.1 (s), 128.2 (s),
128.2 (d, JC,Pˆ2.8 Hz), 128.7 (s), 128.8 (s), 128.9 (s),
129.3 (s), 129.8 (d, JC,Pˆ3.6 Hz), 129.9 (s), aryl-C, 133.8
(d, JC,Pˆ3.2 Hz), 135.2 (d, JC,Pˆ7.6 Hz), 135.5 (d,
Remark: Compound 5a cannot be obtained analytically pure
due to traces of sulfur in the product.
2
JC,Pˆ1.6 Hz) C-2, C-7, C-10, 141.5 (d, JC,Pˆ9.2 Hz, C-
100), 192.4 (s, C-8); IR (CCl4): nˆ3066 (w, CH), 2966 (m,
CH), 1709 (vs, CvO), 1596 (m), 1447 (s), 1369 (m), 1282
(m), 1263 (m), 1030 (m), 845 (m), 711 (s), 699 (s); MS (EI,
70 eV): m/z (%)ˆ463 (10.8) [M]1, 105 (28.9) [PhCO]1, 77
(50.0) [Ph]1, 57 (33.4) [C4H9]1; C26H23O2PS2 (462.57 g/
mol).
10-tert-Butyl-1,9-diphenyl-13-oxa-11-thia-12-phosphate-
tracyclo[7.3.1.02,7.010,12]trideca-2,4,6-trien-8-one
(5a).
From 150 mg phosphaalkene (4a, 0.38 mmol) and 13 mg
(0.41 mmol) of sulfur, yield: 93 mg (57%), mp 1258C
1
(dec.); 31P NMR (C6D6): dˆ265.0 (s); H NMR (CDCl3):
4
dˆ1.06 (d, 9H, JH,Pˆ0.9 Hz, ±C(CH3)3), 6.94±8.27 (m,
14H, aryl-H); 13C NMR (CDCl3): dˆ32.1 (d,
2
3JC,Pˆ6.4 Hz, ±C(CH3)3), 36.5 (d, JC,Pˆ7.2 Hz,
±
(4-Hydroxy-1-phenyl-isophosphinoline-3-yl)-phenylmetha-
none (7). A solution of the phosphaalkene 4a±c in 15 ml
toluene is heated for 3 days to 1508C. The solvent is
removed and the residue subjected to ¯ash column chroma-
tography on silica gel 60 with a n-pentane/ether mixture
(50:1) as eluent. From 1000 mg phosphaalkene (4a,
2.51 mmol), yield: 700 mg (82%), mp 1158C; 31P NMR
1
C(CH3)3), 73.2 (d, JC,Pˆ43.8 Hz, C-10), 86.9 (d,
1JC,Pˆ41.8 Hz, C-1), 88.5 (d, JC,Pˆ8.5 Hz, C-9), 124.8 (d,
2
JC,Pˆ4.4 Hz), 126.8 (s), 128.1 (s), 128.3 (s), 128.4 (s), 128.5
(s), 128.6 (s), 128.9 (d, JC,Pˆ2.0 Hz), 129.4 (d,
JC,Pˆ2.8 Hz), 129.7 (s), aryl-C, 133.7 (d, JC,Pˆ2.0 Hz),
3
137.0 (s), C-2 and C-7, 138.5 (d, JC,Pˆ6.8 Hz C-10),
1
2
144.5 (d, JC,Pˆ17.7 Hz, C-100), 193.8 (s, C-8); IR (CCl4):
(CDCl3): dˆ197.4 (s); H NMR (CDCl3): dˆ7.29±7.56
(m, 10H), 7.68±7.71 (m, 2H), 8.71±8.73 (m, 2H), aryl-H,
15.6 (s, 1H, OH); 13C NMR (CDCl3): dˆ122.7 (s), 123.3
(s), C-4a and C-8a, 125.3 (d, JC,Pˆ9.7 Hz), 126.8 (d,
JC,Pˆ4.1 Hz), 127.0 (d, JC,Pˆ5.6 Hz), 127.6 (s), 127.9 (s),
128.2 (s), 129.9 (d, JC,Pˆ8.1 Hz), 130.6 (d, JC,Pˆ10.3 Hz),
131.4 (d, JC,Pˆ3.8 Hz), 131.6 (s) aryl-C, 138.1 (d,
2JC,Pˆ10.3 Hz, C-100), 138.6 (s, C-10), 140.9 (d,
nˆ2978 (s, CH), 2869 (s, CH), 1709 (s, CvO), 1447 (m),
1264 (m), 1120 (vs), 700 (s); C26H23O2PS (430.50 g/mol).
10-tert-Butyl-1,9-diphenyl-13-oxa-11-selena-12-phos-
phatetracyclo[7.3.1.02,7.010,12]trideca-2,4,6-trien-8-one (5b).
From 150 mg phosphaalkene (4a, 0.38 mmol) and 30 mg
(0.38 mmol) of gray selenium, yield: 108 mg (59%), mp
1628C (dec.); 31P NMR (C6D6): dˆ241.4 (s,
1JP,Seˆ125.0 Hz); 1H NMR (CDCl3): dˆ1.05 (s, 9H, ±
C(CH3)3), 6.87±8.14 (m, 14H, aryl-H); 13C NMR
2
1JC,P2ˆ27.3 Hz, C-3), 164.9 (d, JC,1Pˆ38.5 Hz, C-4), 170.5
(d, JC,Pˆ10.5 Hz, C-9), 203.8 (d, JC,Pˆ32.9 Hz, C-1); IR
(CCl4): nˆ3200±2300 (bw, OH), 2946 (w, CH), 1601 (bm,
CvO), 1513 (m), 1378 (s), 1301 (m), 1272 (m), 1181 (w),
1053 (w); MS (EI, 70 eV): m/z (%)ˆ342 (100) [M]1, 265
(52.3) [M2Ph]1, 236 (7.4) [M2Ph2CHO]1, 207.1 (22.7)
[M2Ph22CHO]1, 105 (29.7) [PhCO]1, 77 (29.8) [Ph]1;
C22H15O2P (342.33 g/mol): calcd C 77.19, H 4.39; found
C 76.54, H 4.72.
3
(CDCl3): dˆ31.5 (d, JC,Pˆ6.6 Hz, ±C(CH3)3), 35.3 (d,
1
2JC,Pˆ8.0 Hz, ±C(CH3)3), 80.0 (d, JC,Pˆ53.4 Hz, C-10),
1
2
85.5 (d, JC,Pˆ42.3 Hz, C-1), 88.3 (d, JC,Pˆ2.5 Hz, C-9),
123.4 (d, JC,Pˆ4.5 Hz), 125.2 (s), 126.6 (s), 126.9 (s), 126.9
(s), 127.0 (s), 127.1 (s), 127.5 (d, JC,Pˆ2.4 Hz), 127.9 (d,
JC,Pˆ3.1 Hz), 128.4 (s), aryl-C, 132.3 (d, JC,Pˆ2.4 Hz),
3
136.3 (s), C-2 and C-7, 137.5 (d, JC,Pˆ6.9 Hz, C-10),
2
143.2 (d, JC,Pˆ17.7 Hz, C-100), 191.3 (s, C-8); IR (CCl4):
(3-Benzoyl-1-phenyl-isophosphinoline-4-yl) 2,2-dimethyl-
propanoate (9). To a cooled (2788C) mixture of 150 mg
7 (0.43 mmol) in THF is added an equimolar amount of an
n-BuLi solution (1.6 M) in n-hexane (183 ml). After stirring
this mixture at 2788C for 20 min 54 ml (0.43 mmol) of 2,2-
dimethylpropanoyl chloride (8) is added. The reaction
mixture is allowed to warm to room temperature overnight
and the reaction process is monitored by TLC. After
evaporation of the solvent the crude products are subjected
to ¯ash column chromatography with a n-pentane/ether
mixture (20:1) as eluent. yield: 75 mg (40%), mp 1458C;
31P NMR (CDCl3): dˆ185.8 (s); 1H NMR (CDCl3):
dˆ1.17 (s, 9H, ±C(CH3)3), 7.45±8.01 (m, 14H,
aryl-H); 13C NMR (CDCl3): dˆ26.8 (s, ±C(CH3)3), 39.5
nˆ3064 (w, CH), 2963 (w, CH), 1710 (vs, CvO), 1447 (m),
1280 (m), 1031 (vs), 699 (s); MS (EI, 70 eV): m/z(%)ˆ478
(48.4) [M]1, 463 (26.5)[M2CH3]1, 398 (44.5) [M2Se]1,
383 (12.7) [M2Se2CH3]1, 342 (48.6) [M2Se2C4H8]1,
105 (100.0) [PhCO]1, 77 (73.3), [Ph]1, 57 (23.2) [C4H9]1;
C26H23O2PSe (477.40 g/mol).
10-tert-Butyl-1,9-diphenyl-12-thioxo-13-oxa-11-thia-
12l5-phosphatetracyclo-[7.3.1.02,7.010,12]trideca-2,4,6-trien-
8-one (6). Method A: To a solution of 350 mg phosphaalk-
ene (4a, 0.89 mmol) in 5 ml of CH2Cl2 are added 160 ml
(1.14 mmol) of triethylamine and 86 mg (2.69 mmol) of
sulfur. After stirring for 2 days at 258C the solvent is

6266
S. G. Ruf et al. / Tetrahedron 56 (2000) 6259±6267
3
(s, ±C(CH3)3), 124.1 (d, JC,Pˆ4.6 Hz), 126.0 (d,
2JC,Pˆ9.9 Hz), 127.9 (d, JC,Pˆ1.9 Hz), 128.1 (s), 128.2 (s),
128.3 (s), 128.4 (s), 128.6 (d, JC,Pˆ4.2 Hz), 128.7 (s), 130.3
(s), 130.5 (d, JC,Pˆ2.0 Hz), 133.6 (s), aryl-C, 137.1 (s),
(6-Hydroxy-3-mesityl-10b-phenyl-10bH-isophosphino-
lino[2,1-d][1,2,4]oxazaphosphol-5-yl)phenylmethanone
(15). A solution of 125 mg isophosphinoline (7, 0.37 mmol)
in 5 ml of toluene is cooled to 2788C and 60 mg of mesityl
nitrile oxide (14, 0.37 mmol) are added. The reaction
mixture is allowed to warm to room temperature overnight.
After removal of the solvent the crude product is puri®ed by
column chromatography with a n-pentane/ether mixture
(5:1) as eluent. Yield: 151 mg (81%), mp 1068C (dec.);
1
137.6 (d, JC,Pˆ11.8 Hz), ipso-C, 140.5 (d, JC,Pˆ26.7 Hz,
C-3), 167.7 (s), 175.9 (s), C-9 and C-10, 174.2 (d,
2JC,Pˆ46.5 Hz, C-4), 195.3 (d, JC,Pˆ22.1 Hz, C-1); IR
1
(CCl4): nˆ2963 (m, ±CH), 1753 and 1711 (vs, CvO),
1665 (s), 1597 (m), 1551 (w), 1449 (s), 1261 (s),
1080 (m), 810 (w); MS (EI, 70 eV): m/z (%)ˆ426
(1.9) [M]1, 342 (9.5) [M2tBu2CO1H]1, 105 (24.4)
[PhCO]1, 77 (15.6) [Ph]1, 57 (100) [tBu]1; C27H23O3P
(426.45 g/mol).
1
31P NMR (CDCl3): dˆ4.4 (s); H NMR (CDCl3): dˆ1.50
(bs, 3H, o-CH3), 1.95 (bs, 3H, o-CH3), 2.08 (s, 3H, p-CH3),
6.35 (bs, 1H, mesityl-H), 6.63 (bs, 1H, mesityl-H), 6.93±
8.27 (m, 14H, aryl-H), 18.3 (s, 1H, OH); 13C NMR (CDCl3):
dˆ20.0 (bs, o-CH3), 20.9 (s, p-CH3), 93.1 (d,
1
(10-Hydroxy-6,7-dimethyl-4b-phenyl-5,8-dihydro-4bH-
8a-phosphaphenanthren-9-yl)-phenylmethanone (11).
A solution of the isophosphinoline 7 and a small excess of
2,3-dimethylbutadiene (10) in 15 ml of toluene is heated for
3 days to 1508C. After removal of the solvent the crude
product is puri®ed by ¯ash column chromatography with a
n-pentane/ether mixture (50:1) as eluent. From 150 mg
isophosphinoline (7, 0.43 mmol) and 43 mg diene (10,
0.50 mmol), yield: 109 mg (60%), mp 1518C; 31P NMR
(CDCl3): dˆ249.5 (s); 1H NMR (CDCl3): dˆ1.48 (s,
3H), 1.61 (s, 3H, ±H at C-12, C-13), 1.90 (m, 1H), 2.10
(m, 1H), 2.87 (m, 2H, ±H at C-5,C-8), 6.87±8.10 (m, 14H,
aryl-H), 17.8 (s, ±OH); 13C NMR (CDCl3): dˆ20.2 (s, C-
12), 21.8 (d, 3JC,Pˆ5.3 Hz, C-13), 30.3 (d, 2JC,Pˆ16.8 Hz, C-
5), 42.2 (d, 1JC,Pˆ3.9 Hz, C-4b), 45.0 (d, 1JC,Pˆ16.0 Hz, C-
1JC,Pˆ18.1 Hz), 94.3 (d, JC,Pˆ31.7 Hz), C-5 and C-10b,
127.4 (s), 127.5 (s), 127.5 (s), 127.6 (s), 127.7 (s), 127.8
(s), 127.9 (s), 128.1 (s), 129.2 (s), 129.9 (d, JC,Pˆ1.6 Hz),
131.0 (s), 133.0 (s), 128.6 (bs), 136.9 (bs), 126.0 (d,
JC,Pˆ13.3 Hz), 131.4 (s), 136.4 (s), 138.0 (d,
JC,Pˆ1.6 Hz), 138.5 (s), 139.7 (d, JC,Pˆ24.1 Hz), aryl-C,
1
160.2 (d, JC,Pˆ49.4 Hz, C-3), 178.5 (s, C-11), 197.1 (d,
2JC,Pˆ21.7 Hz, C-6); IR (CCl4): nˆ2963 (w, CH), 1601
(vs, CO), 1495 (s), 1365 (s), 1286 (m), 1262 (m), 1093
(m), 1030 (m), 850 (w), 696 (s); HRMS: calcd for
C32H26O3NP: 503.1650; found: 503.1650; C32H26O3NP
(503.53 g/mol).
Acknowledgements
1
8), 99.6 (d, JC,Pˆ20.6 Hz, C-9), 125.0 (d, JC,Pˆ1.5 Hz),
126.8 (s), C-6, C-7, 126.2 (s), 126.7 (s), 127.0 (s), 127.5
(s), 127.6 (s), 127.9 (s), 128.2 (s), 128.9 (s), 131.0 (s),
132.6 (s), 132.7 (s), 137.0 (s), aryl-C, 142.9 (d,
JC,Pˆ4.5 Hz), 145.9 (d, JC,Pˆ8.4 Hz), ipso-C, 185.2 (d,
We thank the Fonds der Chemischen Industrie for a post-
graduate grant (S. R.) and the Deutsche Forschungsge-
meinschaft (Graduate College Phosphorus as Connecting
Link between Various Chemical Disciplines) for generous
®nancial support.
2JC,Pˆ3.1 Hz, C-11), 195.0 (d, JC,Pˆ34.3 Hz, C-10); IR
2
(n-pentane): nˆ3100±2300 (bw, OH), 2926 (w, CH),
1600 (bm), 1441 (m), 1288 (m), 1223 (m), 1074 (w); MS
(EI, 70 eV): m/z (%)ˆ424 (29.9) [M]1, 342 (53.8)
[M2C6H10]1, 298 (100) [M2C6H102HCP]1, 265 (21.9)
[M2C6H102Ph]1, 105 (63.9) [PhCO]1, 77 (32.5) [Ph]1;
C28H25O2P (424.47 g/mol).
References
È
È
1. Part 150: Peters, C.; Tabellion, F.; Schroder, M.; Bergstraûer,
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1
(CDCl3): dˆ79.6 (s); H NMR (CDCl3): dˆ6.75±7.98 (m,
14H, aryl-H), 18.6 (s, 1H, OH); 13C NMR (C7D8): dˆ81.2
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3657±3665. (b) Pommeret, J. J.; Robert, A. Tetrahedron 1971,
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1
1
(d, JC,Pˆ12.1 Hz, C-12a), 100.2 (d, JC,Pˆ27.3 Hz, C-6);
122.6 (s), 123.4 (s), 127.0 (s), 125.5 (s), 125.9 (s), 127.2
(s), 127.6 (s), 128.1 (s), 128.7 (s), 128.9 (s), 129.0 (s), 129.2
(s), 129.3 (s), 132.2 (s), 132.3 (s), 134.6 (s), 136.9 (s), 139.0
(s), 139.7 (s), 140,7 (s), aryl-C, 187.7 (s, C-13), 196.4 (d,
2JC,Pˆ40.2 Hz, C-5); IR (n-pentane): nˆ3000±2400 (bw,
OH), 2966 (w, CH), 1612 (bm), 1411 (m), 1298 (m), 1249
(m), 1001 (w); MS (EI, 70 eV): m/z (%)ˆ588 (100) [M]1,
105 (2.6) [PhCO]1, 77 (2.2) [Ph]1; C28H15O4PCl4 (588.52 g/
mol): calcd C 57.14, H 2.55; found C 56.30, H 2.61.
10. (a) Ullmann, E. F.; Milks, J. E. J. Am. Chem. Soc. 1962, 84,
1315±1316. (b) Ullmann, E. F.; Milks, J. E. J. Am. Chem. Soc.
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12. Toyota, K.; Shimura, M. K.; Takahashi, H.; Yoshifuji, M.
Chem. Lett. 1994, 1927±1930.

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