Benzo/Naphtho-Anellated Dihydro-1,2-oxaphosphinines and Ring-Opening to P-Tertiary 2-Phosphanyl-1,1′-biaryl-2-ol Derivatives – Syntheses and Structures

Article abstract of DOI:10.1002/ejic.201700770

Reaction of naphthylphenol 1a and phenylnaphthol 1b, respectively, with PCl₃ in the presence of ZnCl₂ gave mixed benzo- and naphtho-anellated 6-chloro-6H-1,2-oxaphosphinines 2a and 2b. Treatment with equimolar amounts of tBuLi led to

Full text of DOI:10.1002/ejic.201700770

DOI: 10.1002/ejic.201700770
Full Paper
Asymmetric Biarylphosphanes
Benzo/Naphtho-Anellated Dihydro-1,2-oxaphosphinines and
Ring-Opening to P-Tertiary 2-Phosphanyl-1,1′-biaryl-2-ol
Derivatives – Syntheses and Structures
[
a][‡]
[a]
[a]
[a]
Piotr Wawrzyniak,
Markus K. Kindermann, Gabriele Thede, Carola Schulzke,
[b]
[a]
Peter G. Jones, and Joachim W. Heinicke*
Dedicated to Professor Dr. Marian Mikołajczyk on the occasion of his 80th birthday
Abstract: Reaction of naphthylphenol 1a and phenylnaphthol phinine 3b with oxygen in 2-position of naphthalene and the
b, respectively, with PCl in the presence of ZnCl gave mixed bulkier tBuMeP-group at the phenyl ring. Reaction of 2b with
1
3
2
benzo- and naphtho-anellated 6-chloro-6H-1,2-oxaphos- o-anisyllithium (2 equiv.) and ClSiMe led to the biarylsilyl ether
3
phinines 2a and 2b. Treatment with equimolar amounts of 5b. Further conversion with (1S)-camphanoyl chloride gave
tBuLi led to 6-tBu-substituted mixed-anellated oxaphosphinines diastereoisomers of the 2′-phosphanylbiaryl camphanate 6b.
3
a and 3b, respectively, and subsequent P–O-ring cleavage Structures were proven by characteristic multinuclear NMR
with methyllithium and quenching with ClSiMe to 2-trimethyl- spectroscopic data and for 2a and 5d by crystal structure analy-
3
silyloxy-biarylphosphanes 4a and 4b. NMR spectra indicated sis. 5b and 6b might be useful candidates for enantiomer sepa-
two data sets for 4a but only one for 4b, indicating higher ration and asymmetric transition metal catalysis.
diastereoselectivity in the ring opening of the 1,2-oxaphos-
Introduction
compounds to suppress atropisomerization and to open the
way to a diastereoselective ring-opening of benzo-naphtho-
anellated 6H-1,2-oxaphosphinines or to kinetic resolution by O-
substitution with a chiral reagent. We report here the synthesis
of 6H-1,2-oxaphosphinines with benzo- and naphtho-anella-
tion, the first examples of P-substitution and ring-opening reac-
tions of these compounds with RLi-reagents to phenylnaphthyl-
O,P compounds and the structure and configuration of the
products.
Phosphanes are among the most suitable ligands for a wide
range of homogenously transition-metal-catalyzed organic re-
[
1]
actions. The use of biarylphosphanes for this purpose has
[
2–4]
been studied intensively in the last few decades,
investigations of heterocyclic biaryl-type phosphanes have re-
mained rather scarce. The main focus was on 6H-dibenzo-
and 6H-dinaphtho[c,e][1,2]oxaphosphinines, which not only
provided access to various achiral and chiral ligands and their
use in homogeneous catalysis but also underwent ring opening
reactions to O-functionalized 1,1′-biarylphosphane ligands.
Whereas binaphthyl compounds with OR and PR substituents
in 2- and 2′-position are configuratively stable, the barriers for
the axial rotation of o,o′-biphenyl-O,P ligands are too low to
prevent atropisomerization. This raises the question whether The synthesis of the mixed benzo/naphtho-anellated 6-chloro-
the steric hindrance to rotation around the aryl–aryl-axis might 6H-1,2-oxaphosphinines 2a and 2b was achieved by thermal
already be sufficient for o,o′-substituted 1-phenylnaphthyl-O,P condensation of naphthylphenol 1a and phenylnaphthol 1b,
respectively, with PCl in the presence of anhydrous ZnCl . Pre-
whereas
[
5–7]
[
8]
[
5a,9]
Results and Discussion
2
[
2]
Synthesis
[
10]
3
2
[
a] Institut für Biochemie, Ernst-Moritz-Arndt-Universität Greifswald,
Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany
E-mail: heinicke@uni-greifswald.de
https://biochemie.uni-greifswald.de/institut/forschung/forschung-in-den-
arbeitskreisen/ordner-aks-lehrstuehle/anorganische-chemie/
b] Institut für Anorganische und Analytische Chemie, Technische Universität
Braunschweig,
cursor 1a was prepared initially by ortholithiation of methoxy-
methyl phenyl ether and Ni-catalyzed coupling with 1-bromo-
naphthalene in the presence of anhydrous MgBr yielding
2
[
11]
1
aMOM
,
followed by acid-catalyzed deprotection. For re-
[
[
peated preparations of 2a and for synthesis of 2b we optimized
the Suzuki–Miyaura-coupling of 2-bromophenol with 1-naphth-
ylboronic acid and of 2-bromonaphth-1-ol with phenylboronic
3
8023 Braunschweig, Germany
‡] Present address: Topsil Global,
6-321 Słubica B, Poland
[
12]
acid to give the products in up to 90 % yield.
The hetero-
9
cyclic chlorophosphonites 2a and 2b are sensitive to hydrolysis
and air oxidation but are thermally stable and can be separated
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejic.201700770.
Eur. J. Inorg. Chem. 2017, 3580–3586
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by high-vacuum distillation. Reaction with one equivalent of
tBuLi in pentane/toluene led quantitatively to selective substi-
tution of chloride and detection of reasonably pure crude prod-
ucts 3a and 3b, respectively. Further conversions with methyl-
lithium and subsequently with chlorotrimethylsilane furnished
the P-asymmetrically substituted 2-trimethylsiloxy-biarylphos-
phanes 4a and 4b in good to moderate yield (Scheme 1).
Notably, P–O-ring cleavage with MeLi led for 3a with tBuP at
3
1
the naphthyl group to two pairs of diastereoisomers (δ P =
20.5, –24.2 ppm), molar ratio roughly 2:1, whereas application
–
of the same procedure to 3b with tBuP at the phenyl group
provided only one pair of diastereoisomers. This may be ex-
plained by rotation of the 2-RO-phenyl group (R = Li, SiMe3)
across the 1,1′-bonded naphth-2-ylphosphane part of 4a or its
Li-precursor 4a , whereas the more bulky 2-tBuMeP-phenyl
Li
group of 4b or 4bLi is unable to surmount the barrier set up
by the benzo-fusion and the 2-substituent at opposite sides of
the RO-naphthyl fragment.
Scheme 2. Synthesis of 1-di-o-anisylphosphanylphenyl-naphthyl-silyl ether 5b
and -camphanic acid ester 6b.
Structures
The structures of the mixed benzo- and naphtho-fused 2H-1,2-
oxaphosphinines 2a,b and 3a,b were confirmed by characteris-
3
1
1
13
tic P, H and in part (2a,b) by C solution NMR spectroscopic
data. For 2a in-depth information was obtained by single-crys-
tal X-ray diffraction. Solid 2a forms twin crystals which contain
one of two possible pairs of diastereoisomers (Figure 1). The
molecules possess S ,S - and R ,R -configuration and are invers
P
ax
P ax
to each other. Phosphorus is pyramidal with an angle sum of
01.55(11)°. The 1,2-oxaphosphinine rings are non-planar and
3
display an interplanar angle of the two aryl ring planes around
the C1–C11 axis of 33.8°. This is close to the average of the
biaryl angles observed in 6-diethylamino-6-oxo-6H-dibenzo-
Scheme 1. Synthesis of benzo/naphtho-6H-1,2-oxaphosphinines 2a,b and
3a,b and ring opening to trimethylsiloxy-biarylphosphanes 4a,b.
[
6b]
[c,e][1,2]oxaphosphinine
(13.7°)
and
6-phenyl-6H-di-
[
8]
Reaction of the benzo/naphtho-anellated oxaphosphinine naphtho[c,e][1,2]oxaphosphinine–borane complex (50.7°) and
b with two equivalents of o-anisyllithium and work-up via tri- reflects a considerably stronger steric impact of naphtho-com-
2
methylsilylation provided racemic dianisyl-trimethylsiloxy- pared to benzo-anellation.
naphthylphenylphosphane 5b in good yield. To examine
The solution NMR spectra of the anellated 6H-1,2-oxaphos-
whether the configuratively more stable 1-phosphanylphenyl- phinines 2a,b and 3a,b also displayed only one phosphorus
1
13
2
-naphthol derivatives can undergo enantiomer separation by resonance and one set of H and C signals. This is consistent
esterification with a chiral acid, the silyl ether 5b was converted with two enantiomers of the four possible isomers. While the
[
13]
with nBuLi and, subsequently, with (1S)-camphanic acid chlor- barrier to inversion at phosphorus is generally high, the bar-
ide to the phosphanylbiaryl camphanic acid ester 6b rier for interconversion of the configuration at the biaryl C–C
(
Scheme 2). The solution NMR spectroscopic data reveal a axis within the six-membered ring might be sufficiently low to
roughly 1:1 mixture of two diastereoisomers with no hint of allow atropisomerization and formation of equilibrium amounts
atropisomerization to minor solution isomers as observed for of the R ,S - and S ,R -isomers in solution. To investigate this,
P
ax
1
P ax
[
10b]
31
related but sterically less hindered biphenyl compounds.
VT- P and H-NMR spectroscopic experiments were performed.
However, all attempts at separation by crystallization have In the temperature range from ca. –60 to +40 °C, however, apart
failed so far, as has growing suitable single crystals for XRD to from moderate upfield-shifts of some proton signals with tem-
ascertain whether co-crystallization occurs, as was observed for perature, neither a second signal set nor significant signal
[
10b]
some of the (1S)-camphanoyloxy-biphenylphosphanes.
broadening was detectable (see Supporting Information). This
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Figure 1. Molecular structure of 2a in the twin crystal, left with S
Å] and angles [°]: P1–C2 1.792(3), O1–P1 1.623(2), Cl1–P1 2.0835(11), C1–C11 1.474(3), C1–C2 1.388(3), C2–C3 1.415(4), C3–C4 1.356(5); C2–P1–O1 99.56(11),
O1–P1–Cl1 101.07(9).
P P
,Sax-, right with R ,Rax-configuration (ellipsoids with 50 % probability). Selected bond lengths
[
suggests that, as for dinaphtho[c,e][1,2]oxaphosphinine deriva- single crystals of the toluene solvate, grown by diffusion of di-
[
8]
tives, only the R ,S - and S ,R -stereoisomers are formed. ethyl ether into a toluene solution. Figure 2 shows the almost
P
ax
P ax
B3LYP/6-31G(d)-optimized calculations for the diastereoisomers perpendicular orientation of the naphthyl to the biaryl–phenyl
of 6-chloro-6H-dinaphtho[c,e][1,2]oxaphosphinine show about plane in the molecule (interplanar angle 88.8°), with an R-con-
7
kcal/mol lower total energy, that is, higher stability, for the figuration around the C11–C21 axis. The second molecule in
R ,R - and S ,S -diastereoisomers relative to those of the unob- the triclinic unit cell of the racemic 5b necessarily displays the
P
ax
P ax
served R ,S - and S ,R -diastereoisomers. Based on a com- S-configuration. The three o-substituted P-phenyl groups of the
P
ax
P ax
parison of bond lengths and angles a greater steric strain was depicted molecule exhibit a right turning propeller-like twist-
[
8]
anticipated in the latter isomers.
ing. The P–C22 bond is longer than P–C2 in 2a because of the
An unambiguous structure proof of the 6H-1,2-oxaphos- lack of electronegative atoms at phosphorus and the P–C angle
phinines 2a,b and 3a,b in solution was provided by characteris- sum is slightly larger [303.48(6)°]. Other bond lengths and an-
1
3
1
tic C{ H} NMR spectroscopic data. Tentative assignments (see
Scheme 1 for the numbering), based on typical chemical shift
ranges and JPC coupling constants, correlation with CH-COSY
and HH-COSY spectra (see Supporting Information) and a CH-
1
3
coupled C NMR spectrum of 2a are given in the experimental
2
part. The JPC coupling constants of C-3′ (ca. 56 Hz) are re-
2
13
markable, being considerably larger than J values for o- C
PC
[
14]
nuclei in various types of phenylphosphanes (16-31 Hz ) or
for C-3′ nuclei in 2-hydroxy- or 2-camphanoyloxybiphenyl-
phosphanes (3–6 Hz ) and 4b (6.5 Hz). The J values for
C-4′ are also somewhat increased compared to J values of
1
3
[
10]
3
PC
3
PC
1
3
2
m- C phenyl nuclei. It is assumed that the large J coupling
PC
values for C-3′ are caused by the close proximity of the P elec-
[
14]
tron lone-pair which is forced to this position by the chlorine
atom in the axial position (cf. Figure 1). C-1′ is then remote from
2
the P lone-pair and exhibits very small J couplings (0–3 Hz).
PC
The molecular structures of the mixed benzo- and naphtho-
anellated 2-trimethylsilyloxy- and (1S)-camphanoyloxy-biaryl-
phosphanes 4a and 4b–6b were likewise elucidated by charac-
3
1
1
teristic chemical shifts and coupling constants in the P,
H
1
3
and C NMR spectra. The signals were tentatively assigned by
comparison with corresponding data of 2-hydroxybiphenyl-
Figure 2. Molecular structure of (Rax)-5b in the crystal of rac-5b (ellipsoids
with 30 % probability; solvent molecule omitted). Selected bond lengths [Å]
and torsion angles [°]: P–C22 1.8353(13), P–C41 1.8398(13), P–C31 1.8416(13),
C11–C21 1.4907(17), C21–C22 1.4060(17); C12–C11–C21–C22 88.23(16), C21–
C22–P–C41 153.73(9), C21–C22–P–C31 103.26(10), C22–P–C41–C42 73.95(10),
C22–P–C31–C32 168.50(10), C31–P–C41–C42 177.73(10), C41–P–C31–C32
86.65(11).
[
10]
phosphanes
and 4b, which were analyzed by HH- and CH-
COSY spectra (see Supporting Information) and estimations of
the chemical shifts using increment methods. Detailed informa-
tion on the solid-state structure of 5b was provided by XRD of
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gles are unexceptional. The phosphorus electron lone pair is argon using a Sanyo Gallenkamp melting point apparatus and are
uncorrected.
directed roughly parallel to the bond C21–C11.
6
-Chloro-6H-benzo[e]naphtho[2,1-c]-1,2-oxaphosphinine
Chloro-6H-5-oxa-6-phospha-benzo[c]phenanthrene) (2a): 2-
Naphth-1-yl)phenol (1a) (1.77 g, 8.04 mmol) was placed in a 25 mL
(6-
(
Conclusions
flask, equipped with a reflux condenser and bubble counter at the
top. Then PCl (0.90 mL, 10.3 mmol) was added, the mixture slowly
warmed up and refluxed at a bath temperature of 140 °C until the
evolution of HCl gas stopped (about 4 h). After cooling to room
3
Mixed benzo- and naphtho-fused 6-chloro-6H-1,2-oxaphos-
phinines 2a and 2b are available by ZnCl -catalyzed condensa-
2
tion and ring-closure of 2-OH-substituted 1-phenylnaphthyl
temperature anhydrous ZnCl (14 mg, 0.1 mmol) was added. The
2
compounds with PCl . Structural data gave evidence of exclu-
3
mixture was again heated slowly (45 °C/h) up to 220 °C and stirred
at this temperature until HCl gas evolution ceased. Then excess PCl3
was removed under vacuum and the product separated by high
sive or preferred formation of R ,R - and S ,S -diastereoisomers
P
ax
P ax
(
at least for 2a). Treatment with one equivalent of RLi allows
–
5
selective substitution of chlorine. Subsequent reaction with a vacuum distillation (8 × 10 Torr/bath temperature 140–160 °C).
second equivalent of an organolithium reagent (another or the For further purification it was recrystallized from hexane yielding
0
.69 g (30 %) pale yellow twin crystals. C H ClOP (284.68): calcd.
same) opens a synthetic route to the respective 2-RO-substi-
tuted biaryl-2′-phosphanes. The reaction of the oxaphosphinine
16 10
C 67.51, H 3.54; found C 67.31, H 3.52. MS (EI, 70 eV, 25 °C): m/e
37
+
35
+
(%) = 287 (1.2), 286 (19) [M( Cl)] , 285 (9), 284 (62) [M( Cl)] , 250
2
b with oxygen at the naphthalene ring was more diastereo-
+
1
(16), 249 (100) [M – Cl] , 202 (35), 126 (12). H NMR (HH-COSY)
selective and provided only one pair of diastereoisomers. Reac-
3
4
(CDCl ): δ = 7.36 (superimp. td, J = 7–8, J = 1.4 Hz, 1 H, 5-H), 7.38
3
tion of the Me SiO-biaryl-2′-dianisylphosphane 5b with BuLi
3
3
3
4
(superimp. dbr, J = 7–8 Hz, 1 H, 3-H), 7.48 (td, J = 7–8, J = 1.6 Hz,
followed by (1S)-camphanoyl chloride furnished a diastereoiso-
meric mixture of the corresponding camphanoyloxybiarylphos-
phane 6b. The lack of any minor atropisomeric NMR signals in
3
4
4
-H), 7.60 (superimp. td, J = 6.8, J = 2 Hz, 7′-H), 7.63 (superimp.
3
4
3
3
td, J = 6.6, J = 1.7 Hz, 1 H, 6′-H), 7.73 (dd, J = 8.2, J = 10.2 Hz,
1
PH
3
4
H, 3′-H), 7.94 (superimp. dd, J = 8, J = 3.3 Hz, 1 H, 4′-H), 7.95
PH
3
4
3
solution, such as were found in related biphenyl derivatives, (superimp. dd, J = 7–8, J = 1–2 Hz, 1 H, 5′-H), 8.12 (dd, J = 7.6,
4
3
13
1
hints at a higher configurational stability and suggests that
P,OR-biaryl derivatives of this type can be used as an alternative
to binaphthylphosphane ligands in asymmetric homogeneous
transition-metal-catalyzed organic reactions. First attempts at
separation of the diastereoisomers of 6b failed, possibly be-
cause of cocrystallization, as observed already for some (1S)-
camphanoyloxybiphenylphosphanes, but further studies using
other separation methods or alternative asymmetric substitu-
ents at oxygen may overcome this problem. The paper pre-
J = 1.6 Hz, 1 H, 6-H), 8.62 (d br, J ≈ 7 Hz, 1 H, 8′-H) ppm. C{ H},
(
CH-COSY) and proton-coupled 13C NMR (75.5 MHz, CDCl ): δ =
3
3
1
21.03 (dd, JCH = 165, 7–8 Hz, CH-3), 122.84 (d, J = 5.3 Hz, no or
PC
small JCH, C -1), 123.93 (dd, J = 162, 7–8 Hz, CH-5), 124.34 (dd,
JCH = 162–163, J = 56.1 Hz, CH-3′), 126.89 (superimp. dd, JCH
q
CH
2
≈
PC
162, 6 Hz, CH-8′), 127.15 (dd, JCH = 161, 8 Hz, CH, CH-7′), 127.66
3
(dd, JCH = 161, 8 Hz, CH-5′), 128.44 (ddd, JCH = 163, 5, J = 14.3 Hz,
PC
CH-4′), 128.88 (superimpos. dt br, JCH ≈ 162, 6 Hz, CH-6′), 129.28
superimpos. s br, no or small JCH, C -4a or C -1′), 129.60 (partly
(
q
q
superimpos. dd, JCH = 162, 8 Hz, CH-4), 130.44 (partly superimpos.
sented here paves the way for such studies and subsequent dd, JCH = 163, 7 Hz, CH-6), 130.77 (no or small JCH, C -1′ or C -4a),
q
q
ligand screenings in (asymmetric) catalytic organic reactions.
132.70 (ddd, JPC = 38.5, JCH = 8, 2.6 Hz, C
mated J ≈ 8, 2 Hz, no detectable JPC, C -8a), 149.63 (dd br, J ≈
CH
q
-2′), 136.58 (d br, esti-
CH
q
2
13
1
8
, J = 6.6 Hz, C -2) ppm; δ-values and J from C{ H} measure-
PC q PC
31
ment. P NMR (CDCl ): δ = 132.2 ppm.
3
Experimental Section
5-Chloro-5H-benzo[c]-naphtho[1,2-e]-1,2-oxaphosphinine
(5-
All operations were performed under argon atmosphere. Solvents Chloro-5H-6-oxa-5-phospha-benzo[c]phenanthrene) (2b): 1-
were dried by standard techniques and freshly distilled before use. Phenyl-naphth-2-ol (1b) (3.57 g, 16.2 mmol) and PCl3 (2.0 mL,
-(Naphth-1-yl)phenol (1a) and 1-phenyl-naphth-2-ol (1b) were pre- 22.9 mmol) were slowly heated in a silicone bath and refluxed at
2
pared by Suzuki–Miyaura coupling of 2-bromophenol and naphth-
140 °C until the evolution of HCl gas ceased (about 4 h). After cool-
ing to room temp. ZnCl2 (21 mg, 0.15 mmol) was added to the
[
12]
ylboronic acid and 1-bromo-naphth-2-ol and phenylboronic acid,
[
11]
respectively, 1a also via the methoxymethyl-protected 1aMOM by
an organometallic route (for procedure and NMR spectroscopic data
see supporting information). Commercial ClSiMe and PCl were re-
mixture, the heating procedure repeated and excess PCl removed
3
–5
under vacuum (cf. above). High vacuum distillation (8.7 × 10 Torr/
bath temperature 200 °C) gave 2.45 g (53 %) of a slightly yellow
viscous liquid, which solidified on storage and was subsequently
recrystallized from hexane. C H ClOP (284.68): calcd. C 67.51, H
3
3
condensed under vacuum before use. Other chemicals were used
as purchased. NMR spectroscopic data were measured on a multi-
16 10
1
1
nuclear FT-NMR spectrometer ARX 300 (Bruker) at 300.1 ( H), 75.5
3.54; found C 67.24, H 3.62. H NMR (HH-COSY, CDCl ): δ = 7.39 (dd,
3
1
3
31
1
3
3
4
(
C), and 121.5 ( P) MHz or an AVANCE 600 (Bruker) 600.1 ( H)
J = 8.7, J = 0.7 Hz, 1 H, 3-H), 7.50 (superimp. td, J = 7.0, J = 1.2 Hz,
1 H, 6-H), 7.52 (superimp. tdd, J = 7.5, J = 2.6, J = 1.1 Hz, 4′-H),
13
3
4
4
and ( C) 151 MHz, with reference to TMS and H PO (85 %), respec-
3
4
PH
3
4
3
tively. Assignments are tentative and based on HH- and CH-COSY 7.58 (superimp. td, J = 8.4, 6.9, J = 1.5 Hz, 7-H), 7.68 (tdd, J = 7.9,
4
3
experiments of selected compounds, comparison of chemical shifts,
P-H and P–C-coupling constants (Tables S1–S4) and supplementing
increment estimations. Assignment numbers are indicated in
Scheme 1 and Scheme 2 and the Supporting Information. Mass
spectra (EI, 70 eV) were measured on a single-focusing sector field
mass spectrometer AMD40 (Intectra). Elemental analyses were de-
termined using a Leco CHNS-932 analyzer under standard condi-
tions. Melting points were determined in closed capillaries under
7.6, J = 1.5, J = 0.5 Hz, 1 H, 5′-H), 7.84 (superimp. dddd, J = 11.9,
PH
3
4
3
J = 7.5, J = 1.5, J = 0.5 Hz, 1 H, 3′-H), 7.87 (superimp. d, J = 8.7 Hz,
1 H, 4-H), 7.91 (dd, J = 7.6, J = 1.4 Hz, 1 H, 5-H), 8.23 (d br, J =
8.1 Hz, 1 H, 6′-H), 8.60 (d br, J = 8.4 Hz, 1 H, 8-H) ppm. C{ H} NMR
(CH-COSY, DEPT. CDCl ): δ = 118.86 (d, J = 7.5 Hz, C -1), 120.30 (d,
3
4
3
1
3
1
3
3
q
3
J = 1.7 Hz, CH-3), 125.11 (CH-6), 125.71 (CH-8), 127.11 (CH-7),
3
3
127.25 (d, J = 14.7 Hz) (CH-4′), 128.86 (CH-5), 129.28 ( J = 1.1 Hz,
CH-6′), 129.9 (d, 2J = 55.6 Hz, CH-3′), 130.26 (C -4a), 130.78 ( J =
4
q
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2
1
5
.1 Hz, CH-4), 130.92 ( J = 3.1 Hz, C -1′), 131.87 (C -8a), 131.95 (CH- 4J ≈ J = 0.5 Hz, 1 H, 6′-H), 8.51 (d br, J = 8.6 Hz, 1 H, 8-H) ppm;
q q
1
2
′), 135.05 (d, J = 34.7 Hz, C -2′), 147.12 ( J = 8.3 Hz, C -2) ppm. superimposed aryl proton signals assigned by comparison with
P{ H} NMR (CDCl ): δ = 128.6 ppm.
q
q
3
1
1
31
1
data of 2b (see Table S3 and Figure S3). P{ H} NMR (CDCl ): δ =
3
3
1
06.9 ppm.
ii) The solution of crude 3b was cooled to –90 °C, an ether solution
of MeLi (2.6 mL, 1.6 , 4.16 mmol) was added and the reaction
mixture warmed to room temperature overnight. NMR monitoring
indicated P-methylation with ring cleavage to the corresponding
lithium 2-phosphanylphenylnaphtholate , δ 31P = –22.9 (vbr) ppm.
2
-(tert-Butylmethylphosphanyl)naphth-1-yl-phenyl Trimethyl-
silyl Ether (4a) via 6-tert-Butyl-6H-benzo[e]-naphtho[2,1-c]-1,2-
oxaphosphinine (3a): i) A solution of tBuLi in pentane (1.8 mL,
M
1
.5
M, 2.70 mmol) was added dropwise at –90 °C to a solution of
2
a (0.764 g, 2.68 mmol) in toluene (20 mL). The mixture was
warmed slowly to room temperature with stirring overnight, giving
a pale yellow, later pale brown, solution. NMR monitoring of a sam-
ple (after removal of volatiles) indicated quantitative conversion of
Then ClSiMe (1.0 mL, 8.0 mmol) was added. After stirring for 3 h
3
the precipitate was filtered off and washed with diethyl ether. The
volatiles were removed under vacuum. Slow diffusion of hexane
into a THF solution of the viscous pale yellow residue provided
1
3
2
a to 3a. H NMR (CDCl ): δ = 0.84 (d, J = 13.0 Hz, 9 H, CMe ),
3 PH 3
3
4
3
7
3
1
.15 (td, J = 7–8, J = 1.4 Hz, 1 H, 5-H), 7.21 (d br, J ≈ 8 Hz, 1 H,
-H), 7.33 (td, J = 8.3, 7.4, J = 1.7 Hz, 1 H, 4-H), 7.48 (t, J = 8.4 Hz,
3
4
3
0.67 g (46 %) of pale yellow crystals of 4b. C H OPSi (394.56):
24 31
3
calcd. C 73.06, H 7.92; found C 73.36, H 8.14 %. MS (EI, 70 eV, 275 °C):
H, 6′-H or 7′-H), 7.51–7.57 (m, 2 H, napth-H), 7.80 (dd, J = 8.2,
+
4
J = 2.2 Hz, 1 H, 4′-H or 5′-H), 7.87 (superimp. dd, J = 7.5, 4J =
3
m/z (%) = 395 (4.5), 394 (17) [M ], 337 (11), 306 (23), 305 (100), 292
1
(
12), 249 (41), 233 (11), 146 (12), 73 (47), 57 (34). H NMR and HH-
1
1
.6 Hz, 1 H, 6-H), 7.87–7.93 (superimp. m, 1 H, 3′-H), 8.44–8.53 (m,
3
H, 8′-H) ppm. 31P{ H} NMR (CDCl ): δ = 109.0 ppm.
1
COSY (CDCl ): δ = 0.16 (s, 9 H, SiMe ), 0.90 (d, J = 12.0 Hz, 9 H,
3 3 PH
3
2
CMe ), 1.15 ( J = 5.5 Hz, 3 H, PMe), 7.06–7.11 (m, 1 H, 8-H), 7.12
d, J = 8.8 Hz, 1 H, 3-H), 7.14–7.20 (m, 1 H, 3′-H), 7.24–7.29 (super-
3
PH
ii) The solution of crude 3a was cooled to –90 °C, an ether solution
of MeLi (1.9 mL, 1.6 , 3.04 mmol) was added and the reaction
3
(
M
imp. m, 1 H, 6-H), 7.27–7.32 (superimp. m, 1 H, 7-H), 7.39–7.45 (m,
mixture warmed slowly to room temp. (12 h). NMR monitoring indi-
cated P-methylation with ring cleavage to the respective lithium 2-
3
2
H, 5′-H, 4′-H), 7.67–7.73 (m, 1 H, 6′-H), 7.76 (d, J = 8.6 Hz, 1 H, 4-
13
1
H), 7.76–7.82 (m, 1 H, 5-H) ppm. C{ H} NMR, DEPT135 and CH-
COSY (CDCl ): δ = 0.67 (SiMe ), 7.66 (d, J = 19.9 Hz, PMe), 27.48 (d,
3
1
phosphanylnaphthyl-phenolate (δ P = –21.2, –23.2, 3:2 ppm).
1
3
3
Then ClSiMe (1.0 mL, 7.9 mmol) was added. After stirring for 3 h
2
1
3
J = 15.1 Hz, PCMe ), 28.86 (d, J = 13.6 Hz, PCMe ), 120.02 (CH-3),
3
3
the precipitate was filtered off, washed with diethyl ether, and the
1
23.27 (CH-6), 125.38 (J = 2.9 Hz, CH-8), 125.94 (CH-7), 126.43 (CH-
solvent and excess ClSiMe were removed under vacuum. The resi-
3
3
5
5′), 127.88 (CH-5), 128.06 (d, J = 6.7 Hz, C -1), 128.47 (CH-4′), 128.54
q
–
due was distilled at 10 Torr/bath temperature 190 °C to give
2
3
(C -4a), 128.64 (CH-4), 131.55 ( J = 6.5 Hz, CH-3′), 132.17 ( J = 3.4 Hz,
q
6
2
77 mg (64 %) of a mixture of two diastereoisomers A and B (ca.
:1) of 4a as a viscous pale yellow liquid. (The product is oxidized
4
CH-6′), 134.56 ( J = 2.9 Hz, C -8a), 138.58 (J = 21.0 Hz, C -2′ or C -
q
q
q
31
1
1′), 144.46 (d, J = 33.5 Hz, C -1′ or C -2′), 150.15 (C -2) ppm. P{ H}
q q q
by air to a solid, which is almost insoluble in ether. Contamination
by this oxide after unintended air contact can be removed from
ether solutions of 4a by filtration to give pure 4a.) C H O PSi
NMR (CDCl ): δ = –23.1 ppm.
3
1
-(Di-o-Anisylphosphanyl)phenyl-naphth-2-yl Trimethylsilyl
Ether (5b): A pentane solution of tBuLi (12.8 mL, 1.5 , 19.2 mmol)
was added to 2-bromoanisole (3.54 g, 18.9 mmol) in diethyl ether
20 mL) at –70 °C. The mixture was warmed to room temperature.
2
4 31 4
M
(
(
394.56); found by MS (EI, 70 eV, 275 °C): m/e (%) = 395 (2.5), 394
9) [M ], 337 (7), 306 (21), 305 (100), 261 (11), 249 (36), 74 (42). H
+
1
(
NMR (CDCl ): δ = –0.28 (s, 9 H, SiMe , A), –0.09 (s, 9 H, SiMe , B),
3
3
3
After 2 h the resulting o-anisyllithium solution was added at –90 °C
to a solution of 2b (2.45 g, 8.61 mmol) in THF (30 mL), the mixture
warmed to room temp. and stirring continued overnight. Then
3
2
0
.90 (d, J = 11.7 Hz, 9 H, CMe , A, B), 1.31 (d, J = 6 Hz, 3 H,
PH 3 PH
2
3
4
Me, B), 1.33 (d, J = 5.7 Hz, 3 H, Me, A), 6.86 (dd, J = 8.0, J =
Hz, 1 H, 3-H, B), 6.97 (dd, J = 8.0, J = 1.0 Hz, 1 H, 3-H, A), 7.07
td, J = 7.5, J = 1.1 Hz, 1 H, 5-H, A), 7.10 (td, J = 7.4, J = 1 Hz, 1
H, 5-H, B), 7.24 (dd, J = 7.3, J = 1.8 Hz, 1 H, 6-H, A), 7.27 (dd, J =
.4, J = 1.7 Hz, 1 H, 6-H, B), 7.34 (superimp. tt, J ≈ 8, 7, J = 1.4 Hz,
H, 4-H, A,B), 7.37 (superimp. t, J ≈ 7.7 Hz, 1 H, 7′-H, A,B), 7.45
superimp. m, 4′-H, A,B), 7.48 (superimp. t br, J = 8.4, 8 Hz, 1 H, 6′-
H, A,B), 7.69 (dd, J = 8.5, J = 1.9 Hz, 1 H, 5′-H, A,B), 7.83 (superimp.
PH
3
4
1
(
ClSiMe (2.5 mL, 19.7 mmol) was added (10 °C). After 2 h at room
3
4
3
4
3
temp., the solvent was removed under vacuum. Dry toluene was
added (30 mL) to the residue, the insoluble lithium salt was filtered
off, and the solvent was evaporated under vacuum and warming
yielding 3.95 g (85 %) of pale yellow crude product. C H O PSi
3
4
3
4
3
4
7
1
(
3
3
33 33 3
(536.67): calcd. C 73.85, H 6.20; found C 73.61, H 6.53. Crystals of
3
4
the toluene solvate were obtained by overlayering the toluene solu-
tion with diethyl ether. Selected bond lengths and torsion angles
determined by XRD are presented in Figure 2, crystal data in
3
3
3
dd, J = 8.5, J = 6.8 Hz, 1 H, 3′-H, A, B), 7.86 (superimp. d br, J =
PH
7
.7 Hz, 1 H, 8′-H, A, B) ppm; assigned tentatively by comparison
3
1
1
with 1aMOM and other related compounds (Table S1). P{ H} NMR
CDCl ): δ = –20.5, –24.2 (integrals A:B 63:37) ppm.
+
Table 1. MS (EI, 70 eV, 230 °C): m/e (%) = 538 (3), 536 (63) [M ], 464
(
3
1
(
6), 463 (8) 448 (34), 447 (100), 401 (8), 74 (24). H NMR (CDCl ): δ =
3
rac-1-(2-tert-Butylmethylphosphanyl)phenyl-naphth-2-yl Tri-
methylsilyl Ether (4b) via 5-tert-Butyl-5H-benzo[c]-naphtho-
0.01 (s, 9 H, SiMe ), 3.43 (s, 3 H, OMe), 3.59 (s, 3 H, OMe), 6.59 (dd,
3
3
4
J = 8.2, J = 4.6 Hz, 1 H, m-H), 6.68–6.76 (m, 2 H, anisyl-H), 6.81
PH
3
4
[1,2-e]-1,2-oxaphosphinine (3b): i) A solution of tBuLi in pentane
(dd, J = 8.2, J = 4.5 Hz, 1 H, m-H), 6.82–6.90 (m, 2 H, anisyl-H),
7.02 (d, J = 8.8 Hz, 1 H, 3-H), 7.05–7.55 (m, 9 H, aryl-H), 7.70 (d,
PH
3
(
2.5 mL, 1.5 , 3.75 mmol) was added dropwise at –90 °C to a
M
3
3
13
solution of 2b (1.06 g, 3.72 mmol mmol) in toluene (20 mL). The
mixture was warmed slowly to room temperature with stirring over-
night to give a pale brown solution. NMR monitoring indicated
J = 8.8 Hz, 1 H, 4-H), 7.73 (d, J = 7.7 Hz, 1 H, aryl-H) ppm. C{H}
NMR (CDCl ): δ = 0.55 (SiMe ), 55.07, 55.36 (2s, o-OMe), 109.89 (su-
3
3
3
perimp. d, J ≤ 12 Hz, 2 CH-m), 120.30 (CH-3), 120.69, 120.96 (2s,
1
quantitative conversion of 2b to 3b. H NMR (CDCl ): δ = 0.90 (d,
CH-m′), 123.07 (CH-6), 125.30 (br., CH-8), 125.5 (br., 2 C -i), 126.06
3
q
3
3
4
3
3
JPH = 13.5 Hz, 9 H, CMe ), 7.33 (d, J = 8.8 Hz, 1 H, 3-H), 7.44 (td,
J = 8.0, 6.8, J = 1.2 Hz, 1 H, 6-H), 7.46 (tdd, J = 7.5, J = 1.8, 128.64 (CH-4), 129.05 (d, J = 6.3 Hz, C -1), 129.50, 129.55 (2s, 2 CH-
J = 1.3 Hz, 4′-H), 7.53 (td, J = 8.4, 6.8, J = 1.5 Hz, 7-H), 7.57 (td, p), 131.24 (d, J = 6.3 Hz, CH-3′), 134.05–134.25 (superimp. signals,
J = 7.9, 7.6, J = 1.5 Hz, 1 H, 5′-H), 7.63 (dddd, J = 10.6, J =
.43, J = 1.4, J = 0.5 Hz, 1 H, 3′-H), 7.78 (d, J = 8.7 Hz, 1 H, 4-H),
.87 (ddd, J = 8.0, J = 1, J = 0.5 Hz, 1 H, 5-H), 8.09 (ddd, J = 8.0,
(CH-7), 126.98, 127.38, 128.06 (CH-4′, CH-5′, CH-5), 128.19 (C -4a),
3
q
4
3
4
2
PH
q
3
4
2
4
3
3
3
2 CH-o′, C -8a, C -2′ or C -1′), 135.00 (d, J = 2.8 Hz, CH-6′), 143.16
PH
q q q
4
3
3
7
7
(d, J = 34.3 Hz, C -1′ or C -2′), 150.55 (d, J = 1.8 Hz, C -2), 161.17
q q q
3
4
3
2
2
(d, J = 16.1 Hz, C -o), 161.44 (d, J = 15.4 Hz, C -o) ppm; assignment
q
q
Eur. J. Inorg. Chem. 2017, 3580–3586
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3584
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
tentatively by comparison with data of 4b (Table S4). 31P{H} NMR
CDCl ): δ = –34.6 ppm.
Crystal Structure Analysis of 2a and 5b: A crystal of 2a was
mounted on a glass fiber in inert paraffin oil. Data were recorded
at 170 K on a STOE-IPDS 2 T diffractometer with graphite-mono-
(
3
Camphanic Acid 1-(Di-o-anisylphosphanyl)phenyl-naphth-2-yl
Ester (6b): A solution of nBuLi in hexane (0.7 mL, 1.6 , 1.1 mmol)
was added dropwise to a cold (–85 °C) solution of 5b (0.564 g,
.05 mmol) in THF (8 mL). The mixture was warmed to room tem-
chromated Mo-K -radiation (λ = 0.71073 Å). The structure was
α
M
solved by direct methods (SHELXT-2016) and refined by full-matrix
[
15]
least-squares techniques (SHELXL-2016). All non-hydrogen-atoms
were refined with anisotropic displacement parameters. All
hydrogen atoms were refined isotropically at calculated positions
using a riding model with their Uiso values constrained to 1.2 Ueq
of their pivot atoms. The structure was a racemic twin. The data
from a crystal of 5b·C H were recorded at 133 K on a Bruker SMART
1
perature and stirred for 2 h. Then, after cooling again to –85 °C, a
solution of (1S)-camphanoyl chloride (0.24 g, 1.1 mmol) in THF
(4 mL) was added, followed by warming to room temp. and removal
of the solvent under vacuum after 1 d. The product was dissolved
in toluene and LiCl extracted with water (3 × 2 mL). The organic
layer was dried with anhydrous magnesium sulfate, filtered and the
solution concentrated under vacuum to give 0.65 g (96 %) of solid
crude product, containing two pairs of diastereoisomers (ca. 1:1).
Attempts at diastereoisomer separation by crystallization from tolu-
7
8
1
000 CCD diffractometer using Mo-K -radiation (λ = 0.71073 Å). The
α
[
16]
structure was refined as above but using SHELXL-97. The toluene
molecule was well ordered. Crystal data are summarized in Table 1.
CCDC 1558150 (for 2a) and 1555546 (for 5b) contain the supple-
mentary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre.
ene/diethyl ether or toluene/hexane failed. C 0H O P (644.96):
4
37 6
1
calcd. C 74.52, H 5.78; found C 74.62, H 6.06. H NMR (CDCl ): δ =
3
0
2
6
.64, 0.70, 0.88, 0.91 (4s, 6 H, 2 9′′-Me), 1.06 (s, 3 H, 8′′-Me), 1.55–
.20 (m, 2 5′′-H, 2 6′′-H), 3.53, 3.55, 3.56, 3.57 (4s, 6 H, OMe), 6.68–
3
3
.95 (m, 6 H, anisyl-H), 7.11 (d, J = 8.8 Hz, 3-H), 7.14 (d, J = 8.8 Hz,
Supporting Information (see footnote on the first page of this
3
1
13
1
3
-H), 7.14–7.42 (m, 10 H, aryl-H), 7.81 (d, J = 8.8 Hz, 4-H), 7.84 (d,
article): Tables S1–S4 of selected H and C{ H} NMR spectroscopic
data of the new and some closely related compounds for data cor-
relation; Figures S1–S6 of HH- and CH-COSY NMR spectra of 2a, 2b,
3
31
1
J = 8.8 Hz, 4-H) ppm. P{ H} NMR (CDCl ): δ = –34.5, –35.0 (1:1)
3
ppm.
Table 1. Crystal data and structure refinement for 2a and 5b.
Compound
2a
7 8
5b C H
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
Unit cell dimensions
a [Å]
C
16
H
10ClOP
40 41 3
C H O PSi
452.50
133(2)
0.71073
triclinic
P1¯
284.66
170(2)
0.71073
orthorhombic
1 1 1
P2 2 2
7.6655(15)
9.1681(18)
18.750(4)
90
11.3939(14)
12.7531(14)
13.4758(16)
73.682(4)
b [Å]
c [Å]
α [°]
ꢀ
[°]
90
68.328(4)
γ [°]
Volume [Å ]
Z
Density (calculated) [Mg/m ]
Absorption coefficient [mm–1]
F(000)
Crystal size
ϑ range for data collection
Index ranges
90
1317.7(5)
4
1.435
0.398
584
0.45 × 0.385 × 0.28 mm
3.433 to 29.205°
–10 ≤ h ≤ 10,
88.289(4)
1740.4(4)
2
1.200
0.150
668
0.37 × 0.25 × 0.20 mm
1.67 to 30.51°
–16 ≤ h ≤ 16,
–18 ≤ k ≤ 18,
–19 ≤ l ≤ 19
31263
3
3
3
3
–
–
11 ≤ k ≤ 12,
25 ≤ l ≤ 25
Reflections collected
Independent reflections
14189
3572
10549
[
R(int) = 0.0384]
[R(int) = 0.0396]
99.4 % to ϑ = 30.00°
None
Completeness
99.7 % to ϑ = 25.24°
Numerical
Absorption correction
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2σ(I)]
0.9650 and 0.7951
Full-matrix least-squares on F
3572/0/173
2
Full-matrix least-squares on F2
10549/0/412
1.047
1.078
R1 = 0.0376,
wR2 = 0.0933
R1 = 0.0487,
wR2 = 0.1052
0.50(10)
R1 = 0.0430,
wR2 = 0.1110
R1 = 0.0720,
wR2 = 0.1232
–
R indices (all data)
Absolute structure parameter
Largest diff. peak and hole
–
3
–3
0.303 and –0.309 e Å
0.411 and –0.225 e Å
Eur. J. Inorg. Chem. 2017, 3580–3586
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© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
4
6
a, and 4b; selected NMR spectra of 1a,b, 2a,b, 3a,b, 4a,b, 5b and
b.
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Bugerenko, Zh. Obshch. Khim. 1972, 42, 93–96; b) S. D. Pastor, J. D. Spi-
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scopy and MS measurements.
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2
6
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Received: June 29, 2017
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