Conversion of dibenzoxaphosphinines into 2-hydroxybiphenyl-2′- ylphosphane ligands and their BH3 adducts: The O-H δ+...Hδ--B hydrogen-hydrogen bond

Article abstract of DOI:10.1002/ejoc.201001242

Chlorodibenz[c,e][1,2]oxaphosphinine 1_Cl reacted with bulky organolithium compounds R¹Li (R¹ = tBu, mesityl) under mild conditions to yield organodibenz[c,e][1,2]oxaphosphinines 1 _R¹, which underwent

Full text of DOI:10.1002/ejoc.201001242

FULL PAPER
DOI: 10.1002/ejoc.201001242
Conversion of Dibenzoxaphosphinines into 2-Hydroxybiphenyl-2Ј-ylphosphane
Ligands and Their BH3 Adducts: The O–Hδ+···Hδ––B Hydrogen–Hydrogen
Bond
Piotr Wawrzyniak,[a] Markus K. Kindermann,[a] Joachim W. Heinicke,*[a] and
Peter G. Jones*[b]
Keywords: P ligands / Boranes / Dihydrogen bonds / Biaryls / Phosphorus heterocycles / Phosphane ligands
Chlorodibenz[c,e][1,2]oxaphosphinine 1Cl reacted with
bulky organolithium compounds R1Li (R1 = tBu, mesityl) un-
der mild conditions to yield organodibenz[c,e][1,2]oxaphos-
phinines 1R1, which underwent ring-opening metathesis with
less bulky organolithium compounds R2Li. After O-trimethyl-
silylation, 2-(trimethylsilyloxy)biphenylylphosphanes 2 were
were unable to undergo O-acylation. Acylation of 5 followed
by borane protection afforded O-acyloxybiphenylylphos-
phane–borane adducts, as demonstrated by the formation of
compounds 7a and 8a. X-ray crystal structure analyses
revealed intermolecular O–H···H–B hydrogen–hydrogen
bonds; for compound 6b the average H···H distance is 1.90 Å,
isolated. Reaction of 1Cl with R2Li followed by silylation pro- whereas for 6e a three-centre O–H···H2B interaction (av.
vided symmetrically P-substituted compounds 2. The forma-
tion of compounds 3 and 4 demonstrated the facile hydrolysis
and oxidation of 1R1, the formation of compound 5cox indi-
cated the sensitivity of 2 to hydrolysis and air oxidation.
Methanolysis of 2 provided the free hydroxybiphenylylphos-
phanes 5 (for further modification by O-acylation), which
were converted into air-stable borane adducts 6. The latter
H···H 2.25 Å) was observed, which is still shorter than twice
the van der Waals radius for hydrogen (2.4 Å). To the best of
our knowledge this is the first report on hydrogen–hydrogen
bonds in functionally substituted phosphane–boranes and
may explain the low reactivity at the OH group. Only on
stronger heating was hydrogen evolved.
group and a hydrogen-bonding motif.[4] However, the effect
of the o-hydroxy group on biarylylphosphane-based transi-
tion-metal catalysts has only been sparingly investigated
and proved to be variable. We observed blockage of the
hydrogenation activity of Rh complexes under mild condi-
tions but tolerance and high-yielding Rh-catalysed hydro-
formylation of vinyl and allyl acetate under pressure and at
an elevated temperature.[5] The OH group has also been
used to couple biarylylphosphane ligands to soluble poly-
mer supports to provide efficient palladium catalysts for the
Suzuki–Miyaura coupling of aryl chlorides,[6] to resolve
racemic 2-hydroxybinaphthylylphosphanes by column
chromatography of diastereoisomeric O-camphorsulfo-
nates[7] and to synthesize asymmetric O-camphanoyl deriv-
atives, which, after enantiomer separation by crystalli-
zation, allowed Rh-catalysed hydrogenation of N-(1-phen-
ylvinyl)acetamide with excellent yields and moderate ees.[8]
Coupling with chlorodibenzoxaphosphorinane gave a bi-
phenylylphosphanylphosphinite ligand that formed a stable
P,P-chelate PtCl2 complex.[9a] Stable chiral O-phosphite
derivatives, valuable ligands for hydroformylation catalysts,
have so far been synthesized by stereoselective reduction
Introduction
Among the wide variety of ligands studied in transition-
metal catalysis, biarylylphosphanes have attracted consider-
able interest in the last decade. Various applications with
several different transition metals have been studied, but the
most striking results were obtained with palladium catalysts
with bulky and basic dialkylphosphanyl derivatives, which
provide greatly improved activity in a large number of car-
bon–carbon and carbon–heteroatom coupling reactions.
Additional substituents, including alkoxy or amino donor
groups, at the ortho position of the adjacent aryl group were
found to improve the performance of these catalysts fur-
ther.[1,2] 2-Hydroxybiarylylphosphanes[3–10] have received
much less attention in this respect. Axial chiral 2-hydroxybi-
naphthylylphosphanes[3] are useful organocatalysts in the
asymmetric aza-Morita–Baylis–Hillman reaction as a result
of the concomitant action of the nucleophilic phosphanyl
[a] Institut für Biochemie–Anorganische Chemie, Ernst-Moritz-
Arndt-Universität Greifswald,
Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany
Fax: +49-3834-864377
E-mail: heinicke@uni-greifswald.de
of asymmetric 2-hydroxybiarylylphosphane oxides.[11]
A
[b] Institut für Anorganische und Analytische Chemie, Technische
Universität Braunschweig,
potential alternative route to asymmetric derivatives is the
diastereoselective O-acylation of 2-hydroxybiphenylylphos-
phanes with asymmetric electrophiles, which provides suf-
Hagenring 30, 38106 Braunschweig, Germany
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001242.
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FULL PAPER
ficient steric bulk to prevent rotation around the C–C axis, treatment with acid (aqueous H2SO4) or by O-trimethyl-
whereas this still occurs in the 2-hydroxy derivatives. As a silylation failed. Only mixtures were obtained in diethyl
first step in this direction we have begun to study bulkily ether or THF or under forced conditions at an elevated
substituted 2-hydroxybiphenylylphosphanes and the protec- temperature in toluene or xylene. Similarly, an attempt to
tion of air-sensitive derivatives by complexation with BH3. convert 1Cl with 2 equiv. of mesityllithium did not lead to
Surprisingly, the reactivity of the hydroxy group was the expected (hydroxybiphenylyl)dimesitylphosphane in tol-
strongly diminished. We report here on the synthesis of uene/diethyl ether at room temperature. Under mild condi-
these compounds and the detection of B–H···H–O hydro- tions – slow addition of R1Li and low temperature – con-
gen–hydrogen bonds.
trolled monosubstitution took place and furnished the tert-
butyl- and mesityldibenzoxaphosphinines 1tBu and 1Mes
,
respectively, in good yields. Excess organolithium reagent,
necessary to complete substitution of chloride (monitored
by NMR), was scavenged by reaction with chlorotrimethyl-
silane. The products were purified by vacuum distillation.
An attempt to introduce a second tert-butyl group at the
phosphorus atom by heating a solution of 1tBu and tBuLi
in toluene under microwave irradiation (6 min, 100 W, ca.
100 °C) led to partial conversion of 1tBu (Ͻ40%) and the
formation of a mixture. The main product after O-trimeth-
ylsilylation displays a 31P NMR signal at δ = 21.5 ppm, but
was neither obtained in the pure form nor identified. More
satisfactory were the conversions of dibenzoxaphosphinines
1tBu and 1Mes with less bulky organolithium reagents R2Li
such as methyl- or p-tolyllithium, although they too needed
controlled reaction conditions to provide defined products.
Whereas treatment of 1tBu with methyllithium at room
temperature or at –30 °C gave mixtures of products, ad-
dition at –90 °C and slow warming to 20 °C led to clean
ring-opening metathesis. The resulting lithium 2-oxybiphen-
ylylphosphanes, which display broad phosphorus reso-
nances in the 31P NMR spectra, were silylated with excess
chlorotrimethylsilane to afford the silyloxybiphenylylphos-
phanes 2a,b (Scheme 1). The compounds were easily sepa-
rated from LiCl and unconsumed ClSiMe3 and purified by
high-vacuum distillation to give yields of about 60%. Both
compounds displayed two sharp phosphorus signals, which
indicates a sufficiently high barrier to rotation around the
C–C axis to generate two pairs of diastereoisomers (ca. 93:7
for 2a and ca. 60:40 for 2b). Analogous conversion of 1Mes
with methyllithium and subsequent silylation provided 2c
Results and Discussion
Synthesis
For the synthesis of 2-hydroxybiarylylphosphanes three
routes have been established: (i) the monophosphinoylation
of BINOL triflates with diorganophosphane oxides fol-
lowed by hydrolysis and reduction of the phosphinoyl
group, usually used for axial chiral derivatives,[3,4] (ii) ether
cleavage of dibenzo- or dinaphthofuran with lithium in
THF and coupling with chlorodiorganophosphanes,[5–7]
(iii) reaction of chlorodibenzoxaphosphinine 1Cl with excess
Grignard reagent.[9,10] In a patent, coupling of 1Cl with
organolithium compounds has been claimed.[12] Although
phenols, alcohols and amines allow selective monosubstitu-
tion of benzo- or naphtho-annulated chloro-1,2-oxaphos-
phinines to yield catalytically valuable heterocyclic annu-
lated oxaphosphinine ligands,[13–15] reactions with organo-
metallic reagents seem to be less selective. Phenylmagne-
sium bromide and 1Cl gave a mixture of mono- and disub-
stituted products; only the bulky 2,4,6-triisopropylphenyl-
magnesium bromide underwent clean monosubstitution.[9b]
We supposed that the increased reactivity of organolithium
compounds compared with Grignard compounds would
force disubstitution and allow the synthesis of 2-hydroxybi-
phenylylphosphanes with bulky substituents at the phos-
phorus atom and decided to follow this fourth route. How-
ever, several attempts to prepare di-tert-butyl(2-hydroxybi-
phenylyl)phosphane by the reaction of 1Cl with excess tert-
butyllithium (up to 2.5 equiv.) and subsequent workup by
1
Scheme 1. Conversion of dibenzoxaphosphinine 1Cl to 1R and to (trimethylsilyloxy)biphenylylphosphanes 2: R1 = tBu, R2 = Me (a) and
pTol (b); R1 = mesityl, R2 = Me (c); R1 = mesityl, R2 = tBu (d); 2R2 = Me (e), 2-anisyl (f), 2,4-dimethoxyphenyl (g).
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2-Hydroxybiphenyl-2Ј-ylphosphane Ligands and Their BH3 Adducts
in 67% yield with a diastereoisomer ratio of around 1:1. Reactivity
The ring-opening reaction of 1Mes with the bulky but highly
reactive tBuLi proceeded nearly quantitatively in THF by
The dibenzoxaphosphorinanes 1 are sensitive to hydroly-
addition at a very low temperature and slow warming (–100 sis and air oxidation. For compound 1tBu hydrolysis resulted
to 20 °C), as indicated by a broad phosphorus resonance at in the secondary phosphane oxide 3, whereas oxidation fur-
δ = –3.5 ppm. Subsequent silylation gave around 80% crude nished the cyclic phosphinate 4. The 31P NMR spectra dis-
2d (by 31P NMR spectroscopy), isolated in 40% yield after play similar chemical shifts for the major and minor dia-
high-vacuum distillation (diastereoisomer ratio ca. 1:1). The stereoisomers of 3 (δ = 43.8 and 58.9 ppm) and for 4 (δ =
alternative route, reaction of the bulky 1tBu with the less 45.3 ppm), but the compounds can easily be distinguished
1
reactive mesityllithium and silylation, failed to give this by the large JPH coupling constant for 3 in the proton-
compound. Attempts to induce enantioselective ring-open- coupled phosphorus NMR spectrum, which is lacking in 4.
ing metathesis of 1tBu with MeLi or pTolLi in the presence Detailed structural information on 3 has been provided by
of (–)-sparteine to select one of the two asymmetric phos- a crystal structure analysis (see below).
phane configurations failed. The diastereoisomer ratio re-
mained unchanged.
Hydrolysis or methanolysis of the 2-(trimethylsilyloxy)bi-
phenylylphosphanes 2 furnished 2-hydroxybiphenylylphos-
For comparison, and to lower the number of isomers af- phanes 5 (Scheme 2). Methanolysis was found to be advan-
ter O-acylation with chiral acids,[8] the reactivity of 1Cl tageous for product isolation[5] and was therefore preferred.
towards some less bulky organolithium compounds R2Li For the alkyl-aryl and dialkyl derivatives 2a–c and 2e, the
was studied. Treatment with 2 equiv. of methyllithium, 2- reaction proceeded at room temperature and was complete
methoxy- or 2,4-dimethoxyphenyllithium led to substitu- after storage of the solution overnight. For the diaryl deriv-
tion of the chloride and ring-opening metathesis to give, atives, heating at reflux in methanol was required (1–4 h for
after treating the lithium salts with excess ClSiMe3, the 2- 2f; 1–2 d for 2g); the low solubility of the products 5f and
(trimethylsilyloxy)biphenylylphosphanes 2e–g. NMR analy- 5g caused them to be deposited in pure form. The synthesis
ses showed analogous behaviour for phenyllithium. After of hydroxybiarylylphosphanes via the silyl ethers and their
hydrolysis, the phosphorus resonance (δ31P = –12.1 ppm) methanolysis circumvented problems in direct workup with
of the known 2-hydroxybiphenyl-2Ј-yldiphenylphosphane[9] aqueous acids associated with phosphonium or phenolate
was observed. 31P NMR monitoring of the conversion of salt formation if the pH was not optimally adjusted. The
1Cl with p-tolyllithium in a 1:1 molar ratio showed that the ambiphilic behaviour of the phosphanes with phenolic
reaction of non-bulky lithium reagents did not proceed se- OH groups towards aqueous bases and acids has been
2
lectively to 1R by substitution of chlorine but resulted in a studied in more detail for 2-[(alkyl)(phenyl)phosphanyl]-
mixture of mono- and disubstituted products (δ = 84.0, phenols.[16]
–13.3, –15.3 ppm). It may be reasoned that after replace-
The P-alkyl-P-aryl- and P,P-dialkyl-substituted trimeth-
ment of chlorine by an organic substituent the basicity of ylsilyloxy- and hydroxybiphenylylphosphanes were oxidized
oxygen is increased and coordination of LiR favoured, in air to varying extents to form the corresponding phos-
which then leads to competing reactions at the P–O bond phane oxides. Thus, 5a in ethereal solution was completely
2
of 1R and partial disubstitution, as also observed in reac- oxidized on contact with air overnight, as indicated by 31P
tions of 1Cl with PhMgBr in a 1:1 molar ratio.[9b]
NMR monitoring (5aOx: δ = 57.6 and 53.1 ppm). Detailed
Scheme 2. Formation of 2-hydroxybiphenylylphosphane–boranes 6a–c,e and 8a.
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structural information has been provided by an X-ray crys- atom. For the more nucleophilic aliphatic OH groups the
tal structure analysis of the phosphane oxide 5cOx (see be- effect will be less pronounced. Support for the donor prop-
low), similarly formed by oxidation of 5c with air.
erties of the coordinated BH3 group is provided by the short
An efficient and general method for preventing aerial distances between hydrogen atoms of the borane and the
oxidation of the phosphane ligands is to form the borane hydroxy proton observed in single crystals of 6b (ca. 1.88
adducts. Various functional groups are tolerated,[2,17] even and 1.93 Å, see below), which lie in the normal range of
the acidic OH group in 2-phosphanylphenols[18] or the “dihydrogen bonds” (1.75–1.95 Å[20]), and also related close
COOH group in 2-(diphenylphosphanyl–borane)propionic H···H contacts in 6e (2.24 and 2.26 Å), which are less than
acid.[19] BH3 can be removed by treatment with strong twice the van der Waals radius of the hydrogen atom
amine bases at room temperature or by heating.[17] For (2.4 Å).
transition-metal catalytic applications that tolerate BH3 or
need it for reduction or as a Lewis acid, the borane adducts
can also be used directly, because transition metals usually
bind more strongly to phosphane ligands and replace BH3.
Structural Aspects
Thus, in screening tests of the oligo- or polymerization of
The structures of the compounds were determined by
ethylene we observed high activity of nickel catalysts,
multinuclear NMR spectroscopic data, elemental analysis
formed in situ from [Ni(1,5-cod)2] and the borane adducts
and HRMS and in more detail for 3, 5cOx, 6b and 6e by X-
of 2-(diphenyl- or dicyclohexylphosphanyl)phenol, and no
ray crystal structure analysis. The accordance of the pro-
marked influence of the borane additive on the selectivity,
1
posed structures with the H and 13C NMR spectroscopic
molecular weight and microstructure of the polymers.[18d]
data was confirmed by assignment of the partly superim-
The useful properties of phosphane–boranes prompted us
posed signals in the rather complex spectra of representative
to convert the P-alkyl-P-aryl- and P,P-dialkyl-substituted
compounds of 1, 2 and 6 and for 7f through H–H and C–
2-hydroxybiphenylylphosphanes into the borane adducts
H COSY experiments. C–H COSY spectra of 1Mes and 6b
in the aryl range are depicted in Figures 1 and 2. Apart
from the typical upfield region of the phenoxy protons 3-H
6a–c and 6e. This occurs quantitatively by treatment with
a slight excess of H3B·SMe2 in dichloromethane at room
temperature. After removal of the volatiles in vacuo, minor
and 5-H in the spectra of the dibenzoxaphosphinine 1Mes
,
contamination by an SMe2 adduct was observed. Purifica-
tion was achieved by crystallization from methanol, which
gave 6a, 6b and 6e in high yields, whereas attempts to crys-
tallize the compounds from dichloromethane, tetra-
hydrofuran, diethyl ether, hexane or toluene failed. Ethanol
or acetonitrile also allowed crystallization. Compound 6c,
prepared from crude 5c, could not be obtained in crystalline
form and was purified by column chromatography on silica
gel to yield a viscous oil. Initial gas evolution on contact
with silica gel may be caused by excess H3B·SMe2; the ad-
ducts 6 were found to be stable to silica gel. They can be
handled in air and stored for months without decomposi-
tion; only on stronger heating (130–145 °C) does decompo-
sition occur with evolution of dihydrogen. A disadvantage
with respect to O-functionalization is that the reactivity of
the OH group is also strongly reduced, which seems not to
be the case in phosphane–boranes with aliphatic hydroxy
groups. These are known to undergo various reactions.[2,17]
Attempts at esterification of 6a with the highly reactive ace-
tyl chloride failed under various conditions, in diethyl ether
at room temperature or in THF at reflux in the presence of
anhydrous NaHCO3 or KHCO3 to trap HCl and uncon-
verted phenolate. Acetylation of 5a with CH3COCl/
NaHCO3 to give 7a (68% yield), and subsequent reaction
with H3B·SMe2 in dichloromethane was necessary to obtain
2-acetoxybiphenylylphosphane–borane 8a. A possible ex-
planation for the lower reactivity of the OH group of the
phosphane–borane 6a relative to the unprotected phos-
phane 5a is that the negatively charged borane in HO-bi-
the carbon doublet with JPC = 23.8 Hz, assigned to C-3Ј,
and the relatively strong downfield shifts of 6-H and 6Ј-H,
despite upfield C-6 and C-6Ј carbon signals, are characteris-
tic. The latter is indicative of planar or only slightly twisted
biphenyl systems and can be attributed to the steric proxim-
ity by fixation through the six-membered P–O ring. After
ring-opening, the planes of the biphenyl rings are strongly
twisted, which causes considerable upfield shifts of the 6-H
and 6Ј-H signals in compounds of type 2–8.
δ–
aryl-PR2δ+···BH3 favours interactions with the carbonyl
Figure 1. C–H COSY NMR spectrum of 1Mes (aryl range; assign-
ment numbers as shown for compound 2 in Scheme 1; 3ЈЈ for m-
group of the acetyl chloride and thus suppresses the usual
reaction with the weakly nucleophilic phenol(ate) oxygen CH of the mesityl group).
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2-Hydroxybiphenyl-2Ј-ylphosphane Ligands and Their BH3 Adducts
an additional a water molecule; see packing figure in the
Supporting Information) or BH3, which represent classic
O···H–O and non-classic B–H···H–O hydrogen bonds,
respectively. The P–C, P=O, C–C and C–O bonds have nor-
mal bond lengths and angles. The structure determination
of the secondary 2-hydroxybiphenylylphosphane oxide 3
(Figure 3) shows it to be a racemate of the diastereoisomer
SPRbiphenyl in the solid state, crystallizing in the triclinic
¯
space group P1 as a deuteriobenzene trisolvate. The other
diastereoisomer is presumably less stable and converts to
the more stable isomer by rotation around the C–C axis.
The biphenyl interplanar angle is 68°. Two molecules are
connected with an inversion symmetry (see the Supporting
Information) by linear hydrogen bonds between the P=O
and hydroxy group [D–H···A 172.2(6)°]. In addition, every
unit cell contains six molecules of the solvent C6D6. The
three independent C6D6 molecules are connected either to
one molecule of 3 through a C–H···π interaction [C3–
H3B···Cent(C51–C56) 2.73 Å, normalized] or in a tape of
mutually perpendicular molecules (C31–C36 and C41–C46,
interplanar angle 72°) parallel to the a axis with no short
Figure 2. C–H COSY NMR spectrum of 6b (aryl range).
The P–C coupling constants of the carbon nuclei in the C–H···π contacts (Ͻ3 Å) but with incipient face-to-edge or
P-phenyl ring are not comparable with the rotation- edge-to-edge contacts. There is no ring stacking. The angles
averaged coupling constants of phenylphosphanes but vary around the phosphorus atom range from 102.7(5)° [C1–P–
strongly for the two ortho and meta positions of 2–8. For H02] to 113.3(5)° [C1–P–H02] and thus correspond to a
oxybiphenylylphosphanes 2 and 5, the 2JP-C1Ј coupling con- slightly distorted tetrahedron.
2
3
stants are much larger than JP-C3Ј, and even JP-C6Ј is
3
somewhat larger, whereas JP-C4Ј is zero or very small. For
2
the borane adducts 6, however, JP-C3Ј is much larger than
2JP-C1Ј and JP-C4Ј is considerably larger than JP-C6Ј. The
3
3
carbon nuclei Cq-2Ј (ipso to the phosphorus atom) are
1
clearly distinguished by strongly increased JP-C coupling
constants in the spectra of the borane adducts. Finally, it
should be mentioned that the 2-hydroxybiphenylylphos-
phanes 5f and 5g with two equal o-methoxy-substituted aryl
groups display only one broad (5f) or sharp (5g) phospho-
rus signal at room temperature. The proton signals, particu-
larly of the dimethoxyphenyl group of 5g, are strongly
broadened, which hints at dynamic processes on the NMR
timescale, probably rotation around the P–C bond, in-
terconversion of the two rotamers with the 2-methoxy
groups on the same or opposite sides. The protons of the
biaryl part appear as sharp multiplets, but the 6-H and in
particular the 3Ј-H signal are strongly shifted upfield in
comparison to those of other 2-hydroxybiphenylylphos-
phanes because of the influence of the o-OMe group.
Figure 3. Molecular structure of 3. Ellipsoids are drawn at the 50%
probability level. C6D6 molecules have been omitted for clarity. Se-
lected bond lengths [Å] and angles [°]: P–O1 1.5026(9), P–C11
1.8042(13), P–C1 1.8239(14), P–H02 1.28(1); O1–P–C11 111.57(6),
O1–P–C1 112.79(6), C11–P–C1 109.11(6)°.
The P-tertiary 2-hydroxybiphenylylphosphane oxide 5cox
The structures of the 2-hydroxybiphenylylphosphane ox- (Figure 4) crystallizes as a hemihydrate in the monoclinic
ides 3 and 5cOx, formed by (slow) hydrolysis of 1tBu in moist space group C2/c; it is a racemate of the diastereoisomer
benzene and hydrolysis and air oxidation of 2c, respectively, SPSbiphenyl in the solid state (in solution the C–C rotation
were determined by X-ray crystallography. Furthermore, barrier is low). The biphenyl interplanar angle is 90°. The
single crystals of the 2-hydroxybiarylylphosphane–boranes water molecule lies with its oxygen on a two-fold axis and
6b and 6e were grown, and the resulting crystal structure connects four molecules of 5cox through classic hydrogen
analyses delivered additional structural information not de- bonds, two through the 2-hydroxy groups [H···A 1.91(2) Å,
ducible from the NMR analyses. Common features in both D···A 2.6976(13) Å, D–H···A 173(2)°] and two directed
types of compounds are the twisted ring planes of the two towards the O=P group [H···A 1.78(2) Å, D···A
connected phenyl rings, typical of biaryl compounds, and 2.6475(13) Å, D–H···A 176(2)°], thus forming hydrogen-
the formation of hydrogen bonds between the OH hydrogen bonded tapes parallel to the c axis (see the Supporting In-
atom and the phosphorus substituents, O (in 5cox through formation).
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are slightly lengthened to 1.16 Å. The O–Hδ+···Hδ– angles
are very approximately linear (168, 150°), whereas the B–
Hδ–···Hδ+ angles are both 119°.
Figure 4. Molecular structure of the P-oxide of 5cOx. Ellipsoids are
drawn at the 30% probability level. Selected bond lengths [Å] and
angles [°]: P–O 1.5036(10), P–C1 1.7939(14), P–C31 1.8200(13), P–
C12 1.8217(13); O2–P–C 109.18–110.60(6), C1–P–C12 103.91(6),
C1–P–C31 115.24(6), P–C12–C11 125.17(10), P–C12–C13
115.42(10).
Figure 5. Molecular structures of the R,R (left) and S,S diastereo-
isomers (right) in the asymmetric unit of 6b. Ellipsoids are drawn
at the 50% probability level. Selected bond lengths [Å] and angles
[°]: P1–B1 1.938(2), P2–B2 1.931(2), P1–C31 1.8069(18), P1–C12
1.8325(18), P1–C38 1.8773, P2–C31Ј 1.8073(18), P2–C12Ј
1.8251(18), P2–C38Ј 1.890(3); B1–P1–C12 111.52(9), B1–P1–C31
The 2-hydroxybiphenylylphosphane–borane 6b forms a
racemate of the diastereoisomer RPRbiphenyl, crystallizing in
the orthorhombic space group Pna21 with one R,R and one
S,S molecule in the asymmetric unit (Figures 5 and 6). The
molecules are very similar, with an r.m.s. deviation of a le- 115.31(9), B1–P1–C38 108.98(9), C31–P1–C38 103.83(10).
ast-squares fit of 0.02 Å; the biphenyl interplanar angles are
both 76°. The P–C bond lengths are similar to those of the
related borane-free tert-butyl(2-hydroxybiphenylyl)phenyl-
phosphane[5] but the angles C12–P1–C31 and C12–P1–C38
are somewhat larger [105.82(8) and 111.12(10) vs. 101.89(9)
and 103.18(10)°], because the BH3 substituents have re-
placed the lone-electron pairs. The P–B bonds of 6b are
slightly longer than in Ph3P–BH3 (1.917 Å)[21] and Me3P–
BH3 (1.901 Å[22]), which may be associated with an O–
H···H–B hydrogen–hydrogen bond to the neighbouring mo-
lecule leading to the formation of chains of molecules.
Chains in the regions z = 0, 1/2, etc. are composed only of
molecule 1 and those at z = 1/4, 3/4, etc. of molecule 2.
Furthermore, adjacent molecules in the chains are related
by y-axis translation, and thus each chain is formed from
molecules of only one enantiomer. The average hydrogen–
hydrogen bond length H···H is 1.90 Å (Table 1), which is
significantly less than twice the van der Waals radius for hy-
drogen (2.4 Å) and lies at the lower end of the 1.7–2.2 Å
range attributed to “dihydrogen bonds”. The H–B bonds cated as thick dashed lines.
Figure 6. Unit cell of 6b. The hydrogen–hydrogen bonds are indi-
Table 1. Hydrogen–hydrogen bond lengths and angles in 6b.[a]
Bond
Length [Å]
Bond
Angle [°]
O1–H1
O2–H2
H01–H1B_$1
H02–H2B_$1
B1–H1A, B1– H1C, B2–H2A, B2–H2C
B1–H1B, B2–H2B
0.92(2)
0.92(2)
1.93(3)
O1–H01–H1B_$1
O2–H02–H2B_$1
H01–H1B_$1–B1_$1
H02–H2B_$1–B2_$1
C22–O1–H01
168(3)
150(3)
119(2)
119(2)
105(2)
105(2)
1.88(3)
1.09–1.11
1.17(2), 1.16(2)
C22Ј–O2–H02
[a] Operator for generating equivalent atoms: $1: x, y – 1, z.
598
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 593–606

2-Hydroxybiphenyl-2Ј-ylphosphane Ligands and Their BH3 Adducts
In the monoclinic crystals of the 2-hydroxybiphenylyl-
phosphane–borane 6e (Figure 7), with a higher donor
strength and a lack of steric hindrance and asymmetry at
the phosphorus atom, the P–B bond is somewhat shorter
than in 6b. The biphenyl interplanar angle is 80°. Hydro-
gen–hydrogen bonds (Table 2, Figures 7 and 8) are still
formed but are three-centre O–H···H2B interactions and
therefore longer than in 6b, which correspond to the longest
values defined for two-centre “dihydrogen bonds”. The
bridging mode is reminiscent of bridging bonds in metal
BH4 complexes except that here the metal atom is replaced
by the protic hydrogen atom. The OH bond in 6e is 0.1 Å
shorter than in 6b, consistent with a weaker hydrogen–hy-
drogen bond. The molecules are connected through glide
planes to form chains, vertical in Figure 8, parallel to (101).
Figure 8. Unit cell of 6e. The hydrogen–hydrogen bonds are indi-
cated by thick dashed lines. View direction is perpendicular to
(101).
For N–H functional amine–borane adducts, the influ-
ence of dihydrogen bonds on the crystal packing and reac-
tivity in solution has been known for some years[20] and
has stimulated extensive studies on the role of “dihydrogen
bonds” in transition-metal hydride chemistry and catalysis
and for use in hydrogen storage.[23] The structures of the 2-
hydroxybiphenylylphosphanes 6b and 6e, in particular the
relatively short H···H distance in the P-alkyl-P-aryl-hy-
droxybiphenylylphosphane 6b, and the unexpectedly low re-
activity of the hydroxy group of 6a show that phosphane–
boranes with acidic hydroxy groups are also able to form
such hydrogen–hydrogen bonds.
Figure 7. Molecular structure of 6e. Ellipsoids are drawn at the
50% probability level. Selected bond lengths [Å] and angles [°]: P–B
1.9165(13), P–C1 1.8045(11), P–C2 1.8133(12), P–C11 1.8222(10),
C12–C21 1.4924(14), C11–C12 1.4087(14), C11–C13 1.4038(14),
other C–C biphenyl bonds 1.3854–1.3994(14–18); B–P–C1
114.35(6), B–P–C2 111.56(6), B–P–C11 111.58(6), C(1)–P–C(2)
102.50(6), C(1)–P–C(11) 110.56(5), C(2)–P–C(11) 105.59(5).
Conclusions
Under defined conditions chlorodibenz[c,e][1,2]oxaphos-
phinine 1Cl reacted with bulky organolithium compounds
R1Li (R1 = tBu, mesityl) selectively with replacement of
chlorine. Attempts at disubstitution with excess tBuLi failed
in our hands under various conditions, whereas ring-open-
ing metathesis with less bulky organolithium compounds
R2Li occurred easily. Reactions of 1Cl with 1 equiv. of R2Li
did not proceed selectively, being associated with a prefer-
ence for P–O bond cleavage after replacement of chlorine
by an organic substituent. With 2 equiv. of R2Li, however,
clean disubstitution was achieved. Workup by O-trimethyl-
silylation proved to be advantageous with various 2-hy-
droxyarylphosphanes because of the ambiphilic properties
of these compounds. The trimethylsilyl group was easily re-
moved with methanol in most cases, particularly if at least
one P-alkyl group was present. The 2-hydroxybiphenylyl-
phosphanes have low barriers to rotation around the C–C
axis in contrast to O-acyl derivatives and are thus potential
candidates for kinetic resolution by diastereoselective O-
acylation with suitable chiral acid derivatives or for enanti-
omer separation by crystallization (cf. ref.[8]). Air-stable 2-
Table 2. Hydrogen–hydrogen bond lengths and angles in 6e.[a]
Bond
Length [Å] Bond
Angle [°]
O–H01
0.81(2)
O–H01–H2_$1
O–H01–H3_$1
H01–H2_$1–B_$1
H01–H3_$1–B_$1
161(2)
150(2)
90(1)
H01–H2_$1
H01–H3_$1
B–H1
B–H2
B–H3
2.26(3)
2.24(3)
1.15(2)
1.16(2)
1.11(2)
93(1)
[a] Operator for generating equivalent atoms: $1: x + 1/2, –y +
3/2, z + 1/2.
Eur. J. Org. Chem. 2011, 593–606
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
599

P. Wawrzyniak, M. K. Kindermann, J. W. Heinicke, P. G. Jones
FULL PAPER
3
4
H), 7.25 (td, J = 7.7, J = 1.6 Hz, 1 H, 5-H), 7.32–7.42 (m, 2 H,
hydroxybiphenylylphosphane–borane adducts are expected
to facilitate these operations but are unsuitable for this pur-
pose as a result of a strongly diminished reactivity of the
OH group towards O-acylation. Acylation must thus be
performed before borane protection. The reason for this pe-
culiar behaviour of 2-hydroxybiphenylylphosphane–bo-
ranes can be seen in terms of their unusual structures. Crys-
tal structure analyses revealed that the 2-hydroxybiphen-
ylylphosphane–boranes are new examples of compounds
with an unconventional “dihydrogen bond” between a pro-
tic and a hydridic hydrogen atom, polar enough to display
this short H···H distance but not enough to decompose at
ordinary temperature with the evolution of dihydrogen. At
3
4
4-H, 4Ј-H), 7.49 (m, 1 H, 5Ј-H), 7.79 (dd, J = 7.8, J = 1.6 Hz, 1
H, 6Ј-H), 7.89 (br. d, 3J = 8 Hz, 1 H, 6-H) ppm. 31P{1H} NMR
(CDCl3): δ = 106.4 ppm. MS (EI, 70 eV, 120 °C): m/z (%) = 257
(4), 256 (23) [M]+, 200 (45), 199 (100), 151 (20), 57 (4). C16H17OP
(256.28): calcd. C 74.99, H 6.69; found C 75.25, H 6.37.
Hydrolysis and Air Oxidation of 1tBu to 3 and 4: Treatment of 1tBu
in CDCl3 with water led to 3, which, as a result of hindered rotation
at 25 °C, forms a major and minor diastereoisomer (ca. 75:25).
31P{1H} NMR (CDCl3): δ = 43.8 (major), 58.9 (minor) ppm; inten-
sity ratio ca. 4:1; proton coupling led to doublets (1JPH ≈ 487 Hz)
3
1
with further splitting (“quint”, J ≈ 16 Hz). H NMR (CDCl3): δ
3
3
= 0.91 (d, JPH = 17.1 Hz, 1/4ϫ9 H, CMe3), 0.94 (d, JPH
=
1
16.5 Hz, 3/4ϫ9 H, CMe3), 6.93 (d, JPH = 488 Hz, 3/4 H, HP=O),
a higher temperature, however, the compounds decompose 7.00 (d, JPH = 465 Hz, 1/4 H, HP=O), 6.86 (td, 3J = 7.4, 4J =
1
1.2 Hz, 5-Hma), 7.01 (td, 5-Hmi), 7.06–7.16 (td and dd, 2 Hma/mi),
7.19–7.3 (m, 2 H), 7.35–7.50 (m, 1 H), 7.54–7.68 (m, 1 H), 7.91
with the formation of B–O bonds, which can easily by
cleaved by alcohols, providing a route for the deprotection
of the ligands.
3
3
4
(ddd, JPH = 10.8, J = 7.7, J = 1.2 Hz, 1 H, 3Ј-Hma) ppm. From
a concentrated solution of 1tBu in moist C6D6 single crystals of 3
deposited in the NMR tube. Crystal data are compiled in Table 3.
Selected bond lengths and angles are presented in Figure 3. Slow
diffusion of air into a plastic-capped NMR sample for 6 d led to
complete air oxidation and the formation of 4: 31P{1H} NMR
(CDCl3): δ = 45.3 ppm; the proton-coupled multiplet appears as a
Experimental Section
General: All reactions were carried out under argon by using stan-
dard Schlenk techniques. Solvents were dried and freshly distilled
before use. Me3SiCl was recondensed in vacuo. 6-Chloro-6H-di-
benz[c,e][1,2]oxaphosphinine (1Cl) was synthesized according to a
literature procedure.[24] Other chemicals were purchased. NMR
spectroscopic data were recorded with a Bruker multinuclear FT-
NMR ARX 300 spectrometer at 300.1 (1H), 75.5 (13C) and
121.5 MHz (31P) or a Bruker Avance 600 spectrometer at 600.1
(1H) and 150 MHz (13C). Chemical shifts are given as δ values with
reference to TMS and H3PO4 (85%). Coupling constants of the 1H
NMR spectra refer to JHH and those of 13C NMR spectra to JPC
unless indicated otherwise. Doublets of doublets, which by similar
coupling constants appear as distorted triplet, are indicated as t
with two similar J values. Further doublet or multiple fine splitting
is indicated by td or tm. Assignments of the biphenyl ring atoms
are as indicated in Scheme 1 with those of the P-phenyl ring de-
noted by primes. For dibenzoxaphosphinines the same assignment
numbers are used. External phenyl groups are indicated by i, o, m
and p or, if substituted, by 1ЈЈ etc. Assignments are based on 2D
experiments (C–H and H–H COSY) of selected compounds and
are supported by DEPT-135 analyses, for other compounds they
are tentative. Mass spectra (EI, 70 eV) were recorded with an Intec-
tra AMD40 single-focusing sector field mass spectrometer and
HRMS spectra with a MAT95 (EI, 70 eV) spectrometer. Elemental
analyses were determined by using a LECO CHNS-932 analyser
under standard conditions. A Sanyo Gallenkamp melting-point ap-
paratus was used to determine melting points, for air-sensitive sub-
stances in a closed capillary under nitrogen.
1
“sept” (3JPH = 16 Hz) with fine splitting. H NMR (CDCl3): δ =
3
1.54 (d, JPH = 16.5 Hz, CMe3), 7.15–7.23 (dt, 2 H), 7.25–7.40 (m,
1 H), 7.45–7.60 (tm, 1 H), 7.65–7.75 (tm, 1 H), 7.85–8.05 (m, 3 H)
ppm.
6-Mesityl-6H-dibenz[c,e][1,2]oxaphosphinine (1Mes): A solution of
tBuLi (16.0 mL, 1.5 m, 23.9 mmol) in pentane was added at –30 °C
to a solution of bromomesitylene (3.60 mL, 23.9 mmol) in tetra-
hydrofuran (15 mL). After stirring at room temperature for 2 h, the
resulting mesityllithium was added in small portions at –30 °C to
a solution of 1Cl (5.1 g, 21.7 mmol) in toluene (35 mL). A yellow
mixture was formed, which was stirred at room temperature over-
night. Because NMR monitoring indicated incomplete conversion
of 1Cl, a second portion of mesityllithium was prepared and added
at –30 °C. After stirring at room temperature for 1 d, excess chloro-
trimethylsilane (10 mL, 80 mmol) was added (ca. 0 °C) to trap un-
converted organolithium reagent. The mixture was allowed to react
at 20 °C for 2 h, and then the precipitate was filtered off and
washed with diethyl ether. The solvent was removed in vacuo to
yield the crude product as a yellow viscous liquid. High-vacuum
distillation at 160–170 °C/10–5 mbar gave 3.64 g (53%) of 1Mes as
1
white solid (m.p. 82–85 °C). H NMR, H–H COSY (CDCl3): δ =
2.26 (s, 3 H, 4ЈЈ-Me), 2.36 (2 s, 6 H, 2ЈЈ,6ЈЈ-Me), 6.84 (dd, J = 2.5,
3
0.7 Hz, 2 H, 3ЈЈ-H), 6.97 (br. d, J = 7.6 Hz, 1 H, 3-H), superim-
3
3
4
5
posed 6.98 (tdd, J ≈ JPH = 7–8, J = 1.4, J = 0.5 Hz, 1 H, 3Ј-
H), 7.06 (td, 3J = 7.8, 7.4, J = 1.3 Hz, 1 H, 5-H), 7.19 (td, J = 8,
7.3, J = 1.7 Hz, 1 H, 4-H), 7.20 (tt, J = 7.5, 7.4, J = 1, JPH
0.7 Hz, 1 H, 4Ј-H), 7.36 (td, J = 7.6, 7.5, J = 1, JPH = 0.5 Hz, 1
4
3
4
3
4
5
=
3
4
5
6-tert-Butyl-6H-dibenz[c,e][1,2]oxaphosphinine (1tBu): A solution of
tBuLi in pentane (12.7 mL, 1.5 m, 19.0 mmol) was added dropwise
to a solution of 1Cl (4.46 g, 19.0 mmol) in toluene (30 mL) at
–30 °C, which led to formation of a precipitate. (Fast addition and
3
4
H, 5Ј-H), 7.69 (dt, J = 7.5, J = 1.3, J = 1.2 Hz, 1 H, 6Ј-H), 7.72
(dd, J = 7.8, J = 1.8 Hz, 1 H, 6-H) ppm. 13C{1H} NMR, C–H
3
4
COSY (CDCl3): δ = 21.13, 22.15, 22.39 (Me), 120.55 (d, 3J =
higher temperatures gave product mixtures.) After the addition was 2.6 Hz, C-3), 123.05 (C-5), 123.32 (d, 3J = 1.6 Hz, C-6Ј), 125.05
3
2
complete, the reaction mixture was warmed to room temperature
and stirred overnight. Then the precipitate was separated, and the
filtrate was removed in vacuo. The residue was distilled at 130–
140 °C/10–2 mbar in a distillation apparatus with an air-cooled con-
(br., C-6), 125.25 (d, J = 8.1 Hz, Cq-1), 127.90 (d, J = 23.8 Hz,
3
C-3Ј), 127.98 (d, J = 5.3 Hz, C-4Ј), 129.54 (br., C-5Ј), 129.76 (C-
4), 130.19 (d, 3J = 2.7 Hz, 2 C-3ЈЈ), 131.75 (d, 1J = 33.3 Hz, Cq-
2Ј), 134.57 (d, 3J = 9.4 Hz, Cq-1ЈЈ), 135.91 (d, 2J = 22.6 Hz, Cq-1Ј),
2
4
densation tube, diameter 10 mm. Colourless crystals deposited in
141.17 (Cq-4ЈЈ), 144.32 (d, J = 18.6 Hz, 2 Cq-2ЈЈ), 152.37 (d, J =
this tube, yield 3.1 g (64%), m.p. 88–90 °C. H NMR (CDCl3): δ = 2.6 Hz, Cq-2) ppm. 31P{1H} NMR (CDCl3): δ = 110.5 ppm. MS
1
3
0.88 (d, JPH = 13.0 Hz, 9 H, CMe3), 7.04 (br. d, 3J = 8, 4J =
(EI, 70 eV, 90 °C): m/z (%) = 319 (19), 318 (100) [M]+, 317 (93),
3
3
4
1.2 Hz, 1 H, 3-H), 7.07 (td, J ≈ JPH = 7–8, J = 1.5 Hz, 1 H, 3Ј- 316 (16), 216 (38), 199 (57), 151 (36), 119 (49), 91 (20), 77 (11), 41
600
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 593–606

2-Hydroxybiphenyl-2Ј-ylphosphane Ligands and Their BH3 Adducts
(20). C21H19OP (318.35): calcd. C 79.23, H 6.02; found C 79.06, H
6.09.
136.61 (d, 1J = 20.9 Hz, Cq-2Ј), 136.67, 137.33 (Cq-pAB), 137.47 (d,
1J = 20.5 Hz, Cq-2Ј), 146.21 (d, 2J = 30.6 Hz, Cq-1ЈB), 146.92 (d,
2J = 34.3 Hz, Cq-1ЈA), 152.04 (Cq-2B), 152.37 (Cq-2A) ppm. 31P{1H}
NMR (CDCl3): δ = 6.7, 5.5 ppm (A/B ca. 60:40). MS (EI, 70 eV,
90 °C): m/z (%) = 421 (3), 420 (2) [M]+, 363 (16), 332 (14), 331
(66), 309 (31), 308 (37), 275 (41), 252 (70), 251 (28), 199 (35), 195
(100), 181 (73), 106 (41), 74 (48). C26H33OPSi (420.20): calcd. C
74.25, H 7.91; found C 73.98, H 8.15.
2Ј-[tert-Butyl(methyl)phosphanyl]-2-(trimethylsilyloxy)-1,1Ј-biphenyl
(2a): A solution of methyllithium in diethyl ether (8.1 mL, 1.6 m,
13.0 mmol) was added dropwise at –80 °C to a solution of com-
pound 1tBu (3.015 g, 11.8 mmol) in THF (35 mL). The mixture was
warmed to room temperature and stirred overnight to complete the
conversion. Then chlorotrimethylsilane (1.65 mL, 13 mmol) was
added dropwise. After stirring for 5 h, the precipitate was separated
by filtration, the solvent removed from the filtrate, and the residue
distilled at 100–120 °C/9ϫ10–6 mbar to give 2.28 g (56%) of a
colourless viscous liquid. 1H NMR, H–H COSY (CDCl3, ref.
solv.): δ = –1.32 (s, 9 H, SiMe3), 0.90 (d, 3J = 11.8 Hz, 9 H, CMe3),
2Ј-[Mesityl(methyl)phosphanyl]-2-(trimethylsilyloxy)-1,1Ј-biphenyl
(2c): A solution of MeLi in diethyl ether (7.8 mL, 1.6 m, 12.5 mmol)
was added to a solution of 1Mes (3.59 g, 11.3 mmol) in THF
(35 mL) cooled to –90 °C. The reaction mixture was warmed to
room temperature. After stirring at room temperature overnight,
chlorotrimethylsilane (3.3 mL, 26 mmol) was added. The reaction
mixture was stirred for 5 h, the precipitate was filtered off, the sol-
vent removed in vacuo, and the product distilled at 160–170 °C/
1.2ϫ10–5 mbar to yield 3.07 g (67%) as a colourless viscous liquid.
2
3
1.38 (d, J = 5.4 Hz, 3 H, PMe), 6.99 (br. d, J = 8.0 Hz, 1 H, 3-
3
H), 7.09 (br. t, J = 7.3 Hz, 1 H, 5-H), 7.23–7.31 (m, 2 H, 6Ј-H, 6-
3
4
3
H), 7.33 (td, J = 8.0, 7.3, J = 1.6 Hz, 1 H, 4-H), 7.43 (td, J ≈ 7,
4J = 1.7 Hz, 1 H, 5Ј-H), 7.44 (td, J ≈ 7, J = 1–2 Hz, 1 H, 4Ј-H),
7.63 (ddd, 3JPH = 3.8, 3J ≈ 7, 4J = 1.7 Hz, 1 H, 3Ј-H) ppm. 13C{1H}
NMR, C–H COSY (CDCl3): δ = 0.07 (SiMe3), 6.23 (d, 1J =
21.2 Hz, PMe), 27.06 (d, 2J = 14.5 Hz, CMe3), 29.42 (d, 1J =
12.6 Hz, CMe3), 119.91 (C-3), 121.10 (C-5), 126.16 (C-5Ј), 128.33
3
4
2
1H NMR (CDCl3): δ = 0.04, 0.07 (2 s, 9 H, SiMe3), 1.42 (d, J =
2
5.1 Hz, 1.5 H, PMe), 1.49 (d, J = 5.7 Hz, 1.5 H, PMe), 2.04, 2.08
(2 s, 6 H, 2ЈЈ,6ЈЈ-Me), 2.19, 2.23 (2 s, 3 H, 4ЈЈ-Me), 6.45 (d, 3J =
8.1 Hz, 0.5 H, 3-H), 6.61 (v br. s, 2 H, 3ЈЈ-H), 6.71 (v br. s, 1 H),
3
2
3
3
(C-4), 128.37 (C-4Ј), 130.53 (d, J = 5.6 Hz, C-6Ј), 131.26 (d, J =
3.6 Hz, C-3Ј), 131.43 (C-6), 135.20 (d, 3J = 5.6 Hz, Cq-1), 137.07
(d, 1J = 20.3 Hz, Cq-2Ј), 146.21 (d, 2J = 33.3 Hz, Cq-1Ј), 151.82
(Cq-2) ppm. 31P{1H} NMR (CDCl3): δ = –20.5, –25.1 ppm; rel.
intensity 93:7. MS (EI, 70 eV, 90 °C): m/z (%) = 344 (3) [M]+, 328
(7), 309 (17), 287 (14), 256 (20), 255 (100), 252 (27), 199 (84), 195
(44), 183 (28), 181 (29), 57 (26). C20H29OPSi (344.50): calcd. C
69.73, H 8.48; found C 70.14, H 8.46.
6.80 (d, J = 8 Hz, 0.5 H, 3-H), 6.90 (t, J = 7.7, 7.3 Hz, 0.5 H, 5-
H), 7.00–7.15 (m, 2 H, aryl), 7.21–7.38 (m, 3 H, aryl), ca. 7.10 (m,
0.5 H, aryl) ppm. 31P{1H} NMR (CDCl3): δ = –38.2, –39.4 ppm
(A/B ca. 1:1). MS (EI, 70 eV, 90 °C): m/z (%) = 407 (13), 406 (42)
[M]+, 405 (26), 318 (25), 317 (100), 213 (8), 199 (13). C25H31OPSi
(406.57): calcd. C 73.85, H 7.69; found C 73.66, H 7.80.
Hydrolysis and Air Oxidation of 2c to 5cox: Attempts at crystalli-
zation of 2c in various solvents by layering with hexane failed under
inert conditions, whereas crystals of 5cox were formed from a sam-
ple allowed to stand in an open beaker with contact to air and
moisture. Crystal data are compiled in Table 3. Selected bond
lengths and angles are displayed in Figure 4.
2Ј-[tert-Butyl(p-tolyl)phosphanyl]-2-(trimethylsilyloxy)-1,1Ј-biphenyl
(2b): A solution of p-tolyllithium was prepared by dropwise ad-
dition of tBuLi solution (12.7 mL, 1.5 m in pentane, 19.0 mmol) at
–70 °C to p-bromotoluene (3.25 g, 19.0 mmol) dissolved in diethyl
ether (20 mL) and stirring at room temperature for 3 h. The re-
sulting solution was added at –90 °C to a solution of 1tBu (4.4 g,
17.2 mmol) in THF. The mixture was warmed to room temperature
and stirred overnight. Then chlorotrimethylsilane (2.55 mL,
20 mmol) was added dropwise. After stirring for 5 h, the precipitate
was filtered off and the solvent removed in vacuo. The crude prod-
uct was purified by high-vacuum distillation at 160–180 °C/
10–6 mbar to give 4.16 g (57%) of a colourless viscous liquid. The
Detection of 2Ј-[tert-Butyl(mesityl)phosphanyl]-2-(trimethyl-
silyloxy)-1,1Ј-biphenyl (2d): A solution of tBuLi in pentane
(2.7 mL, 1.5 m, 4.05 mmol) was added dropwise to a solution of
1Mes (1.138 g, 3.58 mmol) in THF (10 mL) cooled to –100 °C. Re-
sidual tBuLi in the dropping funnel was rinsed with n-hexane
(10 mL) and added to the reaction mixture, which then was
warmed to room temperature. The colour changed from pale-
brown after the addition to red at –70 °C. After stirring at room
temperature overnight, NMR monitoring showed a broad 31P sig-
nal for the ring-cleavage product and a small sharp signal for unre-
acted 1Mes, conversion Ͼ95%. Excess ClSiMe3 (2.0 mL, 15.7 mmol)
was added and the mixture stirred overnight. The colour turned
slowly to pale-yellow. Then the precipitate was filtered off, the sol-
vent removed in vacuo, and the product distilled at 180–200 °C/
1
diastereoisomer ratio A/B was ca. 60:40 (by tBu H NMR integra-
tion). 1H NMR, H–H COSY (CDCl3, ref. solv.): δ = –0.08, 0.09 (2
s, 60:40, 9 H, SiMe3AB), 1.02 (d, 3J = 12.2 Hz, 5.4 H, CMe3A), 1.10
3
(d, J = 12.4 Hz, 3.6 H, CMe3B), 2.34 (br. s, 3 H, p-Me), 6.61 (br.
3
3
d, J = 7.2 Hz, 0.4 H, 6-HB), 6.70 (br. t, J = 7.5, 7.3 Hz, 0.4 H, 5-
HB), 6.84, 6.85 (2 d, 3J = 7.8 Hz, 1 H, 3-HAB), 7.02 (superimposed
t, 5-HA), 7.02–7.12 (m, 2 m-HB, 2 o-HA), 7.13–7.30 (m, 4-HB, 2 o-
HB, 6Ј-HA, 4-HA, 6-HA, 6Ј-HB), 7.27–7.42 (m, 5Ј-HA, 4Ј-HB, 5Ј-
1
10–5 mbar to yield 0.68 g (40%) of a colourless viscous liquid. H
NMR (CDCl3): δ = 0.04, 0.07 (2 s, 9 H, SiMe3), 1.315 (d, 3J =
12.6 Hz, 4.5 H, PCMe3), 1.32 (d, 3J = 12.9 Hz, 4.5 H, PCMe3),
1.90, 1.93 (2 br. s, 6 H, 2ЈЈ,6ЈЈ-Me), 2.15, 2.21 (2 s, 3 H, 4ЈЈ-Me),
3
HB, 4Ј-HA), 7.44–7.50 (br. t, 2 o-HA), 7.58 (br. d, J = 6.9 Hz, 0.6
H, 3Ј-HA), 7.85 (br. m, 0.4 H, 3Ј-HB) ppm. 13C{1H} NMR, C–H
COSY, DEPT (CDCl3): δ = 0.27 (SiMe3A), 0.47 (SiMe3B), 21.15
(br., p-Me), 28.83 (d, 2J = 15.1 Hz, CMe3A), 28.89 (d, 2J = 15.7 Hz,
CMe3B), 30.52 (d, 1J = 17.3 Hz, CMe3B), 31.48 (d, 1J = 16.8 Hz,
CMe3A), 119.05 (C-3B), 119.63 (C-3A), 120.06 (C-5B), 120.75 (C-
5A), 126.23 (C-5ЈB), 126.27 (C-5ЈA), 127.48 (C-4ЈB), 128.14 (C-4B),
128.26–128.38 (m, 2 m-CHAB, C-4A, C-4ЈA), 130.51 (d, 3J = 6.8 Hz,
C-6ЈA), 131.5 (superimposed, C-6ЈB), 131.57 (superimposed, C-6A),
132.40 (d, 3J = 4.6 Hz, C-6B), 133.40 (superimposed d, 2J =
3
4
3
4
6.02 (dd, J = 7.4, J = 1.7 Hz, 0.5 H, 3-H), 6.30 (dd, J = 8, J =
3
4
1 Hz, 0.5 H, 3-H), 6.30 (superimposed td, J = 7–8, J = 1 Hz, 0.5
H, 5-H), 6.53 (br. s, 1 H, 3ЈЈ-H), 6.63 (br. s, 1 H, 3ЈЈ-H), 6.74, 6.86
(2 d, J = 7–8 Hz, 6-H) superimposed by 6.70–7.10 (m, 4-H, 3Ј-H
3
3
or 6ЈH), 7.15–7.40 (m, 4Ј-H, 5Ј-H), 7.93 (br. d, J = 7.4 Hz, 1 H,
6Ј-H or 3ЈH) ppm. 31P{1H} NMR (CDCl3): δ = –1.4, –2.9 ppm
(A:B ca. 1:1).
3
17.7 Hz, 2 o-CHA, C-3ЈB), 133.58 (superimposed d, J ≈ 9 Hz, Cq-
2Ј-(Dimethylphosphanyl)-2-(trimethylsilyloxy)-1,1Ј-biphenyl (2e): A
solution of MeLi in diethyl ether (24 mmol, 15 mL, 1.6 m) was
added dropwise to a solution of compound 1Cl (2.57 g, 11.0 mmol)
in diethyl ether/THF (10:7 mL) at –90 °C. The mixture was warmed
2
2
1B), 134.17 (d, J = 19.2 Hz, 2 o-CHB), 134.92 (d, J = 3.2 Hz, C-
1
3ЈA), 135.12 (superimposed d, J ≈ 19 Hz, Cq-iB), 135.20 (superim-
posed br. d, 4J ≈ 7 Hz, Cq-1A), 135.12 (d, 1J = 21.6 Hz, Cq-iA),
Eur. J. Org. Chem. 2011, 593–606
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
601

P. Wawrzyniak, M. K. Kindermann, J. W. Heinicke, P. G. Jones
FULL PAPER
to room temperature, stirred overnight, and chlorotrimethylsilane
(22 mmol, 2.8 mL) was added slowly. After stirring for 4 h, the pre-
cipitate was separated by filtration, the solvent removed from the
filtrate, and the residue distilled at around 90 °C/10–4 mbar to give
1.28 g (39%) of a colourless viscous liquid 2e. H NMR (CDCl3):
δ = 0.06 (s, 9 H, SiMe3), 1.19 (br. s, 3 H, PMeA), 1.28 (br. s, 3 H,
Air Oxidation: An ethereal solution of 5a was stirred with air con-
tact for about 12 h. NMR measurement showed oxidation to the
corresponding phosphane oxide. 31P{1H} NMR (CDCl3): δ = 53.1,
1
3
57.6 ppm (20:80). H NMR (CDCl3): δ = 0.94 (d, JPH = 15.4 Hz,
1
3
2
CMe3ma), 1.08 (d, JPH = 14.9 Hz, CMe3mi), 1.84 (d, JPH =
2
14.7 Hz, Memi), 1.85 (d, JPH = 12.0 Hz, Mema), 6.80–7.60 (8 H,
3
4
3
PMeB), 6.96 (br. dd, J = 8.0, J = 1.1 Hz, 1 H, 3-H), 7.08 (td, J
aryl) ppm.
4
3
4
= 7.4, J = 1.2 Hz, 1 H, 5-H), 7.30 (superimposed dd, J ≈ 7.2, J
2Ј-[tert-Butyl(methyl)phosphanyl]-2-hydroxy-1,1Ј-biphenyl–Borane
(6a): Reaction of excess H3B·SMe2 in dichloromethane (6.1 mL,
1 m, 6.1 mmol) with 5a (1.64 g, 6.02 mmol) in CH2Cl2 (20 mL) at
–80 to 20 °C (4 h), removal of the solvent in vacuo, and crystalli-
zation from methanol furnished 1.69 g (98%) of colourless crystals,
m.p. 141–144 °C (decomposition), with a diastereoisomer ratio A/
B of ca. 75:25 (based on 1H NMR integration). 1H NMR (CDCl3):
δ = 0.1–1.2 (v. br., 3 H, BH3), 1.02 (superimposed d, 2JPH ≈ 11 Hz,
3
= 1.6 Hz, 1 H, 6-H), 7.24–7.30 (m, 1 H, 6Ј-H), 7.32 (td, J = 8.0,
7.4, 4J = 1.8 Hz, 1 H, 4-H), 7.39 (td, J ≈ 7.5, 4J = 1.6 Hz, 1 H,
3
3
4
5Ј-H or 4Ј-H), 7.43 (m, J ≈ 7.4, J = 1.7 Hz, 1 H, 4Ј-H or 5Ј-H),
7.63 (ddd, JPH = 3.8, 3J = 6.9, 4J = 1.7 Hz, 1 H, 3Ј-H) ppm.
3
13C{1H} NMR (CDCl3): δ = 0.20 (SiMe3), 14.05 (d, J = 14.1 Hz,
1
PMe), 15.15 (d, 1J = 13.8 Hz, PMe), 119.70 (C-3), 120.94 (C-5),
127.16, 127.60 (br.), 128.57, 128.77 (br. C-4, C-4Ј, C-6, C-5Ј),
2
3
130.24 (d, J = 5.3 Hz, C-6Ј), 131.19 (d, J = 2.6 Hz, C-3Ј), 133.91
3
2.3 H, PMeA), 1.06 (d, JPH = 13.8 Hz, 9 H, CMe3AB), 1.15 (d,
3
1
(d, J = 5.6 Hz, Cq-1), 141.11 (d, J = 15.1 Hz, Cq-2Ј), 144.40 (d,
2J = 29.3 Hz, Cq-1Ј), 152.45 (Cq-2) ppm. 31P{1H} NMR (CDCl3):
δ = –53.6 ppm. HRMS (EI): calcd. for C17H23OPSi+ (302.1250);
found 302.1253.
3
2JPH = 9.9 Hz, 0.7 H, PMeB), 4.69 (s, 1 H, OH), 6.916 (dd, J =
8.1, 4J = 1 Hz, 3-HA), 6.92 (dd, 3J = 8.1, 4J = 1 Hz, 3-HB), 6.96
4
3
4
(td, 3J = 7.5, J = 1.2 Hz, 5-HB), 6.97 (td, J = 7.5, J = 1.2 Hz, 5-
3
4
3
HA), 7.07 (dd, J = 7.5, J = 1.8 Hz, 0.25 H, 6-HB), 7.15 (dd, J =
7.5, J = 1.8 Hz, 0.75 H, 6-HA), 7.22–7.27 (m, 1 H, 6Ј-HAB), 7.31
4
2Ј-(Di-o-anisylphosphanyl)-2-(trimethylsilyloxy)-1,1Ј-biphenyl (2f):
A solution of tBuLi (20 mL, 1.5 m in pentane, 30.0 mmol) was
added at –78 °C to a solution of o-bromoanisole (3.72 mL,
30.0 mmol) in diethyl ether (25 mL). After stirring for 2 h at room
temperature the solution of o-anisyllithium was added dropwise at
–90 °C to a solution of 1Cl (3.187 g, 13.6 mmol) in THF (35 mL).
The reaction mixture was warmed to room temperature and stirred
overnight. Then ClSiMe3 (4.0 mL, 31.5 mmol) was added, and, af-
ter stirring at 20 °C for 2 h and filtration, the solvent was removed
in vacuo. The crude product was purified by crystallization from
diethyl ether/hexane (3:1) to afford 6.28 g (95%) of colourless crys-
tals, m.p. 121–123 °C. 1H NMR (CDCl3): δ = 0.02 (s, 9 H, SiMe3),
3.62 (s, 6 H, 2ЈЈ-OMe), 6.73 (ddd, 3J = 7.6, 3JPH = 4.3, 4J = 1.8 Hz,
2 H, 3ЈЈ-H), 6.76–6.86 (br. m, 6 H, 5ЈЈ-H, 3-H, 5-H, 6ЈЈ-H), 6.99–
7.04 (vbr. d, 1 H, 6-H), 7.03 (ddd, 3J = 7.7, 3JPH = 3.8, 4J = 1.1 Hz,
3
4
3
(td, J = 8.1, 7.4, J = 1.7 Hz, 1 H, 4-HB), 7.32 (td, J = 8.1, 7.4,
4J = 1.7 Hz, 1 H, 4-HA), 7.49–7.61 (m, 2 H, 4Ј-HAB, 5Ј-HAB), 8.07
3
3
4
5
(ddt, JPH = 12.7, J = 7.1, J ≈ J = 1.0–1.5 Hz, 0.25 H, 3Ј-HB),
3
3
4
5
8.16 (ddt, JPH = 12.7, J = 7.1, J ≈ J = 1.0–1.5 Hz, 0.75 H, 3Ј-
HA) ppm. 31P{1H} NMR (CDCl3): δ = 33.8 (pseudo-d), ca. 32
(shoulder) ppm. MS (EI, 70 eV, 20 °C): m/z (%) = 286 (7) [M]+,
256 (8), 255 (52), 215 (8), 199 (38), 118 (15), 93 (100), 67 (28).
C17H24BOP (286.16): calcd. C 71.35, H 8.45; found C 71.02, H
8.70.
2Ј-[tert-Butyl(p-tolyl)phosphanyl]-2-hydroxy-1,1Ј-biphenyl (5b): A
solution of 2b (2.11 g, 5.02 mmol) in methanol (10 mL) was heated
at reflux for 7 h. The solvent and Me3SiOMe were removed in
vacuo to yield 1.74 g (100 %) of colourless crystals, m.p. 127–
133 °C, with a diastereoisomer ratio A/B of ca. 50:50. 1H NMR
(CDCl3): δ = 1.08 (d, 3J = 12.8 Hz, 4.5 H, CMe3), 1.17 (d, 3J =
12.7 Hz, 4.5 H, CMe3), 2.30, 2.33 (2 s, 3 H, p-Me), 4.88 (br., 0.5
4
1 H, 3Ј-H), 7.12 (td, 3J = 7–8 Hz, J = 1.8 Hz, 1 H, 4-H), 7.19 (td,
4
3J = 7.5, 7.1, J = 1.7 Hz, 1 H, 4Ј-H or 5Ј-H), 7.24–7.31 (m, 3 H,
3
4
2 4ЈЈ-H, 6Ј-H), 7.33 (td, J = 7.5, 7.3, J = 1.3 Hz, 1 H, 5Ј-H or 4Ј-
H) ppm. 13C{1H} NMR (CDCl3): δ = 0.36 (SiMe3), 55.48 (br.,
OMe), 110.0 (vbr., 2 C-3ЈЈ), 119.25, 120.30 (C-3, C-5), 120.69 (st,
2 C-5ЈЈ), 126.82, 127.70, 128.28 (C-4Ј, C-4, C-5Ј), 129.71 (st, 2 C-
3
H, OH), 5.18 (br., 0.5 H, OH), 6.41 (br. d, J = 7.4 Hz, 0.5 H, 3-
3
3
H), 6.59 (br. t, J = 7.3 Hz, 0.5 H, 5-H), 6.84 (br. d, J = 7.5 Hz,
0.5 H, 3-H), 6.90–7.30 (m, 6.5 H), 7.30–7.52 (m, 3 H), 7.68 (ddd,
3
4
3J = 7.3, JPH = 3.8, J = 1.1 Hz, 0.5 H, 3Ј-H), 7.92 (m, 0.5 H, 3Ј-
H) ppm. 31P{1H} NMR (CDCl3): δ = 6.87, 7.01 ppm (A/B ≈ 50:50).
MS (EI, 70 eV, 345 °C): m/z (%) = 348 (9) [M]+, 332 (22), 331 (100),
291 (15), 283 (14), 275 (56), 272 (11), 199 (63), 183 (16), 182 (10),
151 (11), 74 (17). HRMS (EI): calcd. for C23H25OP+ 348.1643;
found 348.1645.
3
2
4ЈЈ), 130.76 (d, J = 5.6 Hz, C-6Ј or C-3Ј), 131.87 (d, J = 4.6 Hz,
1
C-3Ј or C-6Ј), 133.16 (d, J = 6.8 Hz, Cq-2Ј), 133.96 (C-6), 134.29
(st br., 2 C-6ЈЈ), 145.01 (d, 2J = 31.9 Hz, Cq-1Ј), 152.57 (Cq-2),
161.29 (d, 2J = 16.2 Hz, 2 Cq-2ЈЈ) ppm; Cq-1 and Cq-1ЈЈ signals
superimposed. 31P{1H} NMR (CDCl3): δ = –33.7 (br.) ppm. MS
(EI, 70 eV, 20 °C): m/z (%) = 487 (18), 486 (100) [M]+, 398 (27), 397
(94), 351 (4), 108 (4), 74 (12). HRMS (EI): calcd. for C29H31O3PSi+
486.1780; found 486.1778.
2Ј-[tert-Butyl(p-tolyl)phosphanyl]-2-hydroxy-1,1Ј-biphenyl–Borane
(6b): Reaction of excess H3B·SMe2 in dichloromethane (0.52 mL,
1 m, 0.52 mmol) with 5b (178 mg, 0.51 mmol) in CH2Cl2 (5 mL) at
–80 to 20 °C (4 h), removal of the solvent in vacuo, and crystalli-
zation from methanol furnished 175 mg (95%) of colourless crys-
tals, m.p. 135–139 °C (decomposition), with a diastereoisomer ratio
2Ј-[tert-Butyl(methyl)phosphanyl]-2-hydroxy-1,1Ј-biphenyl (5a): A
solution of 2a (4.594 g, 13.3 mmol) in methanol (15 mL) was
heated at reflux for 7 h. Removal of the solvent and MeOSiMe3 in
vacuo gave 3.60 g (100%) of colourless crystals, m.p. 93–94 °C, with
1
1
a diastereoisomer ratio A/B of ca. 80:20 based on H NMR inte-
A/B of ca. 56:44 (based on H NMR integration). Single crystals
gration of Me signals. 1H NMR (CDCl3): δ = 0.81, 0.815 (2 d, 3JPH
studied by X-ray structure analysis displayed a 1:1 ratio. Crystal
data are displayed in Table 3. Selected bond lengths and angles are
2
= 12.4 Hz, 9 H, CMe3), 1.26 (d, JPH = 5.3 Hz, 0.75 H, PMeB),
2
1
1.35 (d, JPH = 4.2 Hz, 2.25 H, PMeA), 5.6 (br. s, 1 H, OH), 6.98
presented in Figure 5. H NMR, H–H COSY (CDCl3): δ = 0.50–
3
4
3
3
(td, J = 7.5, J = 1.2 Hz, 1 H, 5-H), 7.00 [d, J ≈ 8 Hz (sh), 1 H,
1.80 (v. br. m, 3 H, BH3), 1.36 (d, JPH = 13.7 Hz, 4 H, CMe3B),
3
4
3
3-H], 7.14 (dd, J = 7.5, J = 1.4 Hz, 1 H, 6-H), 7.23–7.35, 7.39–
7.48 (2 m, 4 H, 4,4Ј,5Ј,6Ј-H), 7.54 (m, ΣJ = 12.3 Hz, 0.8 H, 3Ј-HA),
7.62–7.7 (m, 0.2 H, 3Ј-HB) ppm. 31P{1H} NMR (CDCl3): δ =
–19.3, –24.7 ppm (A/B ≈ 80:20). For analytical characterization as
the borane adduct, see below.
1.41 (d, JPH = 13.9 Hz, 5 H, CMe3B), 2.34 (1.3 H, p-CH3B), 2.42
(1.7 H, p-CH3A), 4.67 (s, 0.54 H, OHA), 4.73 (s, 0.44 H, OHB), 6.37
3
4
3
4
(dd, J = 7.6, J = 1.6 Hz, 6-HA), 6.49 (dd, J = 8.1, J = 0.7 Hz,
3-HB), 6.51 (td, 3J = 7.6, 7.4, 4J = 0.9 Hz, 5-HA), 6.67 (dd, 3J =
8, 4J = 1 Hz, 3-HA), 6.69 (td, 3J = 7.5, 4J = 0.9 Hz, 5-HB), 6.99
602
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Eur. J. Org. Chem. 2011, 593–606

2-Hydroxybiphenyl-2Ј-ylphosphane Ligands and Their BH3 Adducts
(superimposed td, 3J ≈ 7.8, 4J = 1.6 Hz, 4-HB), 7.00–7.10 (m, 4-
o-CB), 152.35 (C-2A), 152.98 (C-2B) ppm. 31P{1H} NMR (CDCl3):
δ = 9.8 (br. m, B), 12.5 (br. m, A); trace impurity signal at δ =
–39.5 ppm. MS (EI, 70 eV, 345 °C): m/z (%) = 348 (0.3) [M]+, 334
3
4
HA, 4 m-HAB), 7.19 (dd, J = 7.6, J = 1.6 Hz, 6-HB), 7.24 (ddd,
4
4
4
3J = 7.5, JPH = 3.4, J = 1.7 Hz, 6Ј-HB), 7.32 (ddd, 3J = 7.5, JPH
4
3
3
= 3.4, J = 1.7 Hz, 6Ј-HA), 7.39 (dd, J = 8.1, JPH = 5.4 Hz, 2 o- (27), 316 (26), 317 (94), 199 (19), 119 (18), 105 (27), 74 (100).
HA), 7.43 (dd, 3J = 8.0, JPH = 5.4 Hz, 2 o-HB), 7.51–7.63 (m, 4
C22H26BOP (348.23): calcd. C 75.88, H 7.53; found C 75.63, H
3
H, 4Ј-HAB, 5Ј-HAB), 8.10–8.18 (m, 3Ј-HB), 8.21–8.29 (m, 3Ј-HA) 7.67.
ppm. 13C{1H} NMR, C–H COSY (CDCl3): δ = 21.26 (p-MeB),
2-Hydroxy-2Ј-(dimethylphosphanyl)-1,1Ј-biphenyl (5e): Compound
2e (959 mg, 3.17 mmol) was dissolved in methanol (15 mL) and
21.37 (p-MeA), 27.23 (d, 2J = 2.3 Hz, CMe3A), 27.57 (d, 2J =
2.2 Hz, CMe3B), 31.66 (d, 1J = 31.1 Hz, CMe3A), 32.28 (d, 1J =
31.0 Hz, CMe3B), 114.89 (C-3A), 116.66 (C-3B), 119.36 (C-5AB),
stirred at room temperature overnight. Then the solvent was re-
1
moved in vacuo to yield 728 mg (100%) of a colourless solid. H
1
3
124.33 (d, J = 54.1 Hz, 2 Cq-iAB), 127.37 (d, J = 9.1 Hz, C-4ЈA),
127.41 (d, 3J = 9.1 Hz, C-4ЈB), ca. 127.4 (superimposed Cq-1A),
127.51 (d, 3J ≈ 4 Hz, Cq-1B), 128.38 (d, 3J = 10.3 Hz, 2 C-mA),
128.50 (d, 3J = 10.2 Hz, 2 C-mB), 128.82 (C-4A), 129.04 (C-4B),
NMR (CDCl3): δ = 1.12 (br. s, 3 H, PMeA), 1.19 (br. s, 3 H, PMeB),
3
4
5.15 (v. br. s, 1 H, OH), 6.99 (td, J = 7.4, J = 1.2 Hz, 1 H, 5-H),
3
4
5
3
7.00 (br. dd, J = 8, J = 1.6, J ≈ 0.4 Hz, 1 H, 3-H), 7.17 (ddd, J
4
5
= 7.4, J = 1.8, J ≈ 0.3 Hz, 1 H, 6-H), 7.23–7.27 (m, 1 H, 6Ј-H),
1
4
129.27 (br. d, J ≈ 52 Hz, Cq-2ЈA), 130.36 (d, J = 2.3 Hz, C-5ЈB),
7.30 (td, 3J = 8.2, 7.3, J = 1.7 Hz, 1 H, 4-H), 7.40 (m, J ≈ 7.5, 4J
4
3
4
1
130.83 (d, J = 2.2 Hz, C-5ЈA), 130.6 (superimposed d, J ≈ 59 Hz,
Cq-2ЈB, tentatively), 132.12 (C-6B), 132.90 (d, 2J = 8.5 Hz, C-oB),
133.25 (d, 3J = 7.2 Hz, C-6ЈA), 133.79 (d, 2J = 8.8 Hz, C-3ЈA),
3
4
= 1.6 Hz, 1 H, 5Ј-H or 4Ј-H), 7.44 (m, J ≈ 7.5, J = 1.6 Hz, 1 H,
3
3
4
4Ј-H or 5Ј-H), 7.55 (ddd, JPH = 3.7, J = 6.9, J = 1.7 Hz, 1 H,
3Ј-H) ppm. 31P{1H} NMR (CDCl3): δ = –49.7 (br.); trace impurity
phosphane oxide signal at δ = 41.0 ppm. For the analytical charac-
terization as a borane adduct, see below.
3
2
134.15 (d, J = 7 Hz, C-6ЈB), 134.16 (d, J = 8.8 Hz, C-oA), 134.63
2
2
(d, J = 8.6 Hz, C-3ЈB), 140.53 (d, J = 2.5 Hz, Cq-1ЈB), 140.91 (d,
2J = 2.5 Hz, Cq-1ЈA), 141.80 (d, 4J = 5.7 Hz, Cq-pA), 141.98 (d, 4J =
5.5 Hz, Cq-pB), 151.33 (Cq-2B), 152.87 (Cq-2A) ppm. 31P{1H} NMR
(CDCl3): δ = 33.0 (pseudo-d, A), 35.1 (pseudo-d, B); trace impurity
signal at δ = 7.04 ppm. MS (EI, 70 eV, 150 °C): m/z (%) = 363 (5),
362 (17) [M]+, 348 (7), 332 (21), 331 (100), 291 (11), 275 (59), 272
(10), 200 (8), 199 (66), 183 (23), 151 (11), 57 (15). C23H28BOP
(362.25): calcd. C 76.26, H 7.79; found C 75.94, H 7.72.
2-Hydroxy-2Ј-(dimethylphosphanyl)-1,1Ј-biphenyl–Borane (6e): A
solution of H3B·SMe2 in dichloromethane (3.5 mL, 1 m,
3.50 mmol) was added at –60 °C to a solution of 5e (728 mg,
3.16 mmol) in the same solvent (10 mL). The mixture was warmed
to room temperature and stirred overnight. Then the solvent was
removed in vacuo and the product crystallized from methanol to
yield 700 mg (91%) of colourless crystals, m.p. 128–131 °C (decom-
position). Crystal data are displayed in Table 3. Selected bond
lengths and angles are presented in Figure 7. 1H NMR, H–H
COSY (CDCl3): δ = 0.15–1.20 (v. br. pseudo-q, 3 H, BH3), 1.27 (d,
2JPH = 10.5 Hz, 3 H, PMeA), 1.29 (d, 2JPH = 10.5 Hz, 3 H, PMeB),
2-Hydroxy-2Ј-[mesityl(methyl)phosphanyl]-1,1Ј-biphenyl (5c) and the
Borane Adduct 6c: The silyl ether 2c (2.12 g, 5.21 mmol) was heated
at reflux in methanol (15 mL) for 4 h. Then the solvent was re-
moved in vacuo, the residual crude 5c dissolved in CH2Cl2 (10 mL),
the solution cooled to –80 °C, and a solution of H3B·SMe2 in
dichloromethane (6.0 mL, 6.0 mmol) added. After warming to
room temperature, the mixture was stirred for 4 h to complete the
reaction. Then the solvent was evaporated and the product purified
by column chromatography on silica gel with CH2Cl2/hexane (1:1)
to yield 0.83 g (46%) of a viscous liquid product. The NMR spectra
indicate a diastereoisomer ratio A/B of 67:33 to 62:38 based on 1H
3
4
4.69 (s, 1 H, OH), 6.98 (br. dd, J = 8.0, J = 1.0 Hz, 1 H, 3-H),
3
4
3
7.00 (td, J = 7.5, 7.6, J = 1.0 Hz, 1 H, 5-H), 7.16 (dd, J = 7.5,
4J = 1.8 Hz, 6-H), 7.28 (ddd, J ≈ 7.2, JPH ≈ 2.7, J = 1.7 Hz, 1
3
4
4
3
4
H, 6Ј-H), 7.34 (td, J = 8.1, 7.6, J = 1.8 Hz, 1 H, 4-H), 7.51 (tt,
3J = 7.5, 4J ≈ JPH = 1.7 Hz, 1 H, 4Ј-H), 7.57 (tt, 3J = 7.4, 4J ≈
4
5JPH = 1.6 Hz, 1 H, 5Ј-H), 8.10 (ddd, JPH = 13.8, J = 7.4, J =
3
3
4
1.6 Hz, 1 H, 3Ј-H) ppm. 13C{1H} NMR, C–H COSY (CDCl3): δ
1
NMR integration and 13C NMR intensities of related signals. H
1
1
= 12.36 (d, J = 39.9 Hz, PMeB), 13.70 (d, J = 39.3 Hz, PMeA),
115.93 (C-3), 120.20 (C-5), 127.16 (d, 3J = 2.8 Hz, Cq-1), 128.61
2
NMR (CDCl3): δ = 0.50–1.80 (v. br. m, 3 H, BH3), 1.77 (d, JPH
2
= 9.7 Hz, 2 H, PMeA), 1.82 (d, JPH = 9.5 Hz, 1 H, PMeB), 2.12
3
1
(d, J = 12.1 Hz, C-4Ј), 130.37 (C-4), 130.55 (d, J = 49.9 Hz, Cq-
2Ј), 131.07 (C-6), 131.50 (d, 4J = 2.4 Hz, C-5Ј), 132.06 (d, 3J =
6.3 Hz, C-6Ј), 134.99 (d, 2J = 17.2 Hz, C-3Ј), 140.15 (d, 2J = 1.7 Hz,
Cq-1Ј), 152.86 (Cq-2) ppm. 31P{1H} NMR (CDCl3): δ = 6.8
(pseudo-q) ppm. MS (EI, 70 eV, 300 °C): m/z (%) = 244 (6) [M]+,
243 (6), 241 (15), 214 (16), 213 (100), 183 (14), 151 (8). C14H18BOP
(244.08): calcd. C 68.89, H 7.43; found C 68.84, H 7.20.
(4 H, o-CH3A), 2.15 (2 H, o-CH3B), 2.22 (2 H, p-CH3A), 2.24 (1 H,
p-CH3B), 4.52 (s, 0.65 H, OHA), 4.57 (s, 0.35 H, OHB), 6.52 (br. d,
3
4
3J = 5 Hz, 0.65 H, 3-HA), 6.54 (td, J = 7.5, J = 1.1 Hz, 0.65 H,
5-HA), 6.63–6.73 (m, 3.35 H, 5-HB, 6-HAB, 2 m-HAB), 6.80 (br. d,
3
4
3J = 8.1 Hz, 0.35 H, 3-HB), 7.07 (td, J = 7.5, J = 1.7 Hz, 0.63 H,
4-HA), 7.13 (ddd, 3J ≈ 7, 4JPH ≈ 4, 4J ≈ 1 Hz, 0.37 H, 6Ј-HB), 7.17–
7.24 (m, 1 H, 6Ј-HA, 4-HB), 7.45–7.56 (m, 2 H, 4Ј-HAB, 5Ј-HAB),
3
7.71–7.80 (m, 0.38 H, 3Ј-HB), 7.97–8.08 (m, JPH = 13.8 Hz, 0.62
2-(Di-o-anisylphosphanyl)-2-hydroxy-1,1Ј-biphenyl (5f): Compound
H, 3Ј-HA) ppm. 13C{1H} NMR (CDCl3): δ = 15.40 (d, 1J = 2f (0.730 g, 1.5 mmol) was heated at reflux in methanol (20 mL)
42.0 Hz, PMeB), 16.05 (d, 1J = 41.7 Hz, PMeA), 20.74 (p-MeA),
20.80 (p-MeB), 23.37 (d, 3J = 5.4 Hz, o-MeB), 23.51 (d, 3J = 5.5 Hz,
o-MeA), 115.04 (C-3A), 116.27 (C-3B), 119.59 (C-5B), 119.72 (C-
for 1 week. Then the precipitate formed during heating was sepa-
rated by filtration at room temperature, washed with a small
amount of methanol and dried in vacuo to yield 0.338 g (54%) of
1
1
1
5A), 123.60 (d, J = 52 Hz, Cq-iB), 123.71 (d, J = 52.0 Hz, Cq-iA),
white crystals, m.p. 160–161 °C. H NMR (CDCl3): δ = 3.61, 3.77
3
3
126.59 (d, J = 3.2 Hz, Cq-1A), 127.0 (d, J = 3 Hz, Cq-1B), 128.5 (2 s, each 3 H, 2ЈЈ-OMe), 6.53 (v. br. t, 1 H, 3ЈЈ-H), 6.78–6.93 [partly
(d, J = 10 Hz, C-4ЈB), 128.56 (d, J = 11.3 Hz, C-4ЈA), 129.34 (s,
3
3
3
4
resolved superimposed multiplets: 6.79 (td, J = 7.4, J = 1.1 Hz),
4
3
4
C-4A), 129.42 (s, C-4B), 130.36 (d, J = 2.2 Hz, C-5ЈB), 130.67 (br. 6.83 (br. t), 6.88 (td, J = 7.4, J = 1.1 Hz), 7 H, aryl], 7.02–7.09
4
s, 2 m-CH), 130.80 (C-6A), 130.81 (d, J = 2.3 Hz, C-5ЈA), 131.45 (m, 2 H, aryl), 7.20 (td, 3J = 8.2, 7.3, 4J = 1.8 Hz, 1 H, aryl), 7.27–
2
3
3
4
(d, J = 10.5 Hz, C-3ЈB), 132.09 (d, J = 6.6 Hz, C-6ЈA), 132.62 (d,
7.39 (m, 4 H, aryl), 7.48 (td, J = 7.3, J ≈ 1 Hz, 1 H, aryl) ppm.
31P{1H} NMR (CDCl3): δ = –32.0 (br.) ppm. MS (EI, 70 eV): m/z
4J = 7.7 Hz, C-6ЈB), 133.39 (d, J = 14.6 Hz, C-3ЈA), 134.59 (d, J
2
1
= 53.0 Hz, Cq-2ЈA), 134.65 (d, J = 53 Hz, Cq-2ЈB), 139.71 (d, J = (%) = 415 (15) [M]+, 414 (8), 398 (30), 397 (100), 381 (6), 367 (5),
1
2
3.8 Hz, Cq-1ЈB), 139.97 (d, 2J = 7.2 Hz, Cq-1ЈA), 140.43 (p-CA),
140.90 (p-CB), 142.47 (d, 2J = 9.3 Hz, o-CA), 143.50 (d, 2J = 9.5 Hz,
351 (9). C26H23O3P (414.43): calcd. C 75.35, H 5.59; found C 75.41,
H 5.76.
Eur. J. Org. Chem. 2011, 593–606
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
603

P. Wawrzyniak, M. K. Kindermann, J. W. Heinicke, P. G. Jones
2-[Bis(2,4-dimethoxyphenyl)phosphanyl]-2-hydroxy-1,1Ј-biphenyl ratio A/B Ͼ 75:25), trace impurity signals at δ = 51.6, 50.3 ppm
FULL PAPER
(5g) via Silyl Ether 2g: A solution of tBuLi (3.20 mL, 1.5 m in hex-
ane, 4.74 mmol) was added dropwise at –70 °C to 1-bromo-2,4-di-
methoxybenzene (0.68 mL, 4.74 mmol) dissolved in diethyl ether
(10 mL), and the mixture was stirred at 20 °C for 2 h. The turbid
solution of 2,4-dimethoxyphenyllithium was added at –80 °C to a
solution of 1Cl (506 mg, 2.16 mmol) in diethyl ether (10 mL). The
reaction mixture was warmed to room temperature and stirred
overnight. Then ClSiMe3 (0.62 mL, 4.89 mmol) was added. After
2 h at room temperature, the precipitate was filtered off and the
solvent removed in vacuo to give crude viscous liquid 2g. This was
dissolved in excess methanol (20 mL) and heated at reflux for 6 h
to complete the methanolysis of the silyl ether (NMR control). The
precipitate formed was separated and dried in vacuo to give 370 mg
(2:1, phosphane oxides). MS (EI, 70 eV, 80 °C): m/z (%) = 313 (1)
[M – 1]+, 256 (16), 255 (88) [M – OC(O)Me]+, 215 (16), 200 (17),
199 (100) [M – OC(O)Me – C4H8]+, 183 (13), 151 (9), 74 (17), 57
(21), 43 (22). C19H23O2P (314.36): calcd. C 72.59, H 7.37; found C
72.68, H 7.61.
2-Acetoxy-2Ј-[tert-butyl(methyl)phosphanyl]-1,1Ј-biphenyl–Borane
(8a): Reaction of H3B·SMe2 in dichloromethane (4.38 mL, 1 m,
4.38 mmol) with 7a (1.312 g, 4.17 mmol) in CH2Cl2 (5 mL) at –70
to 20 °C overnight, removal of the solvent in vacuo and purification
by column chromatography on silica gel by using dichloromethane/
n-hexane (1:1) as eluent furnished 0.406 g (30 %) of pure 8a as
colourless crystals, m.p. 92–96 °C. Diastereoisomeric ratio A/B
1
based on H NMR integration and 13C NMR intensities of sepa-
1
(36%) of white crystals, m.p. 175–176 °C. H NMR (CD2Cl2): δ =
1
rated related signals ca. 80:20–85:15. H NMR (CDCl3): δ = 0.15–
3.62, 3.73, 3.77, 3.80 (br. s, each 3 H, 2ЈЈ,4ЈЈ-OMe), 5.94 (d, J =
3.5 Hz, 1 H, OH), 6.38 (br. s, 2 H, 3ЈЈ-H), 6.40–6.50 (br. m, 3 H, 2
2
1.20 (v. br. m, 3 H, BH3), 0.99 (superimposed d, JPH = 11–12 Hz,
3 H, PMe), 1.03 (d, 3JPH = 13.7 Hz, 7.2 H, PCMe3A), 1.07 (d, 3JPH
3
5ЈЈ-H, 6ЈЈ-H), 6.65 (br. dd, 3J = 8.1, JPH = 4.5 Hz, 6ЈЈ-H), 6.84
= 13.7 Hz, 1.8 H, PCMe3B), 1.84 (s, MeA), 1.97 (s, MeB), 7.11 (d,
3
4
3
4
(td, J = 7.4, 7.3, J = 1.1 Hz, 1 H, 5-H), 6.92 (dd, J = 7.5, J =
3
3J = 8.0 Hz, 1 H, 3-H), 7.10–7.20 (m, 2 H, 5-H, 6-H), 7.32 (dd, J
3
4
1.8 Hz, 1 H, 6-H), 6.97 (dd, J = 8.1, J = 1.1 Hz, 1 H, 3-H), 7.03
(ddd, JPH = 3.7, J = 6.9, J = 1.7 Hz, 1 H, 3Ј-H), 7.23 (td, J =
8.1, 7.4, J = 1.8 Hz, 1 H, 4-H), 7.23 (dd, J = 7.3, J = 1.5 Hz, 1
4
= 7.5, JPH = 11.6 Hz, 1 H, 6Ј-H), 7.40–7.49 (m, 3 H, 4-H, 4Ј-H,
3
3
4
3
5Ј-H), 7.98–8.11 (m, 3JPH ≈ 13 Hz, 1 H, 3Ј-H) ppm. 13C{1H} NMR
4
3
4
1
1
(CDCl3): δ = 5.40 (d, J = 36.5 Hz, PMeA), 7.81 (d, J = 37.0 Hz,
3
4
H, 6Ј-H), 7.30 (td, J = 7.5, J = 1.4 Hz, 1 H, 5Ј-H or 4Ј-H), 7.45
2
PMeB), 20.16 (MeA), 20.58 (MeB), 25.72 (d, J = 2.5 Hz, CMe3A),
3
4
(td, J = 7.4, 7.5, J = 1.3 Hz, 1 H, 4Ј-H or 5Ј-H) ppm. 13C{1H}
25.76 (superimposed d, 2J = 4.7 Hz, CMe3B), 29.76 (d, 1J =
NMR (CD2Cl2): δ = 55.62, 55.90, 56.12 (2ЈЈ,4ЈЈ-OMe), 98.46, 98.73
1
32.6 Hz, CMe3A), 29.99 (d, J = 32.1 Hz, CMe3B), 122.41 (C-3A),
1
(2 br. s, C-3ЈЈ), 105.77 (2 C-5ЈЈ), 115.0 (br. d, J ≈ 10 Hz, Cq-1ЈЈ),
122.91 (C-3B), 125.40 (d, 1J = 48.9 Hz, C-2ЈA), 125.68 (C-5A), 126.3
116.2 (br. d, 1J ≈ 10 Hz, Cq-1ЈЈ), 117.03 (C-3), 120.83 (C-5), 128.57,
129.43, 129.92 (C-4, C-4Ј, C-5Ј), 130.23 (d, 3J = 6.0 Hz, Cq-1),
131.16 (d, 3J = 1.8 Hz, C-3Ј), 131.44 (d, 3J = 6.1 Hz, C-6Ј), 134.12,
(d, 1J = 49 Hz, C-2ЈB), 126.32 (C-5B), 127.0 (superimposed d, J Ͼ
3
9 Hz, C-4ЈB), 127.08 (d, 3J = 12.3 Hz, C-4ЈA), 129.47 (C-4B), 129.57
(C-4A), 129.91 (C-1B), 130.27 (d, 3J = 2.3 Hz, C-1A), 130.83 (C-
6A), 133.8 (br., C-5ЈB), 134.89 (d, 4J = 2.5 Hz, C-5ЈA), 131.57 (d, 3J
= 6.5 Hz, C-6ЈB), 132.12 (d, 3J = 6.1 Hz, C-6ЈA), 132.71 (C-6B),
136.03 (d, 2J = 16.9 Hz, C-3ЈAB), 140.32 (C-1ЈA), 141.59 (C-1ЈB),
148.07 (C-2B), 148.99 (C-2A), 168.84 (C=OA), 169.29 (C=OB) ppm.
31P{1H} NMR (CDCl3): δ = 33.5 (br., A and B unresolved) ppm.
MS (EI, 70 eV, 100 °C): m/z (%) = 328 (0.2) [M]+, 314 (0.7), 285
(0.7), 283 (3.5), 267 (5.5), 256 (19), 255 (100), 215 (8), 199 (51), 183
(13), 179 (6), 151 (6), 103 (9), 57 (14). C19H26BO2P (328.19): calcd.
C 69.53, H 7.99; found C 69.67, H 8.13.
1
135.14 (2 br. s, C-6ЈЈ), 134.54 (C-6), 137.33 (d, J = 11.7 Hz, Cq-
2
4
2Ј), 143.88 (d, J = 35.1 Hz, Cq-1Ј), 152.88 (d, J = 1.2 Hz, C-2),
161.81, 162.33, 162.53 (superimposed br. d and s, C-2ЈЈ, C-4ЈЈ)
ppm. 31P{1H} NMR (CD2Cl2, ref. ext. CDCl3): δ = –34.4 ppm. MS
(EI, 70 eV, 135 °C): m/z (%) = 474 (16) [M]+, 473 (9), 458 (27), 457
(100), 243 (11), 215 (11), 199 (14), 197 (15), 170 (28). C28H27O5P
(474.48): calcd. C 70.88, H 5.74; found C 70.99, H 5.46.
2-Acetoxy-2Ј-[tert-butyl(methyl)phosphanyl]-1,1Ј-biphenyl (7a):
NaHCO3 (0.764 g) was added to a solution of 5a (0.248 g,
0.91 mmol) in diethyl ether (10 mL) followed by dropwise addition
of acetyl chloride (0.13 mL, 1.82 mmol). After stirring the mixture
overnight, the precipitate was filtered off, the filtrate was washed
with water (3ϫ2 mL), and the organic layer dried with Na2SO4.
Solvent evaporation in vacuo yielded 0.195 g (68%) of the pure
product as a viscous liquid. Diastereoisomeric ratio A/B based on
1H NMR integration and 13C NMR intensities of separated related
2-Acetoxy-2Ј-(di-o-anisylphosphanyl)-1,1Ј-biphenyl (7f): A solution
of nBuLi (1.5 mL, 1.6 m solution in hexane, 2.40 mmol) was added
dropwise to a solution of 2f (1.113 g, 2.29 mmol) in toluene
(15 mL) at –78 °C. The reaction mixture was warmed to room tem-
perature. After 2 h, a solution of acetyl chloride (0.17 mL,
2.40 mmol) in diethyl ether (5 mL) was added at –78 °C, and stir-
ring was continued at room temperature overnight. The precipitate
was then filtered off, and the solution was washed with water and
dried with MgSO4. After solvent evaporation, a yellow viscous li-
quid was formed that crystallized after addition of dichlorometh-
ane with 2/3CH2Cl2 per molecule. 1H NMR, H–H COSY (CDCl3):
δ = 1.91 (s, 3 H, Me), 3.62, 3.66 (s, 6 H, 2ЈЈ-OMe), 5.30 (s, 1.3 H,
1
3
signals ca. 70:30. H NMR (CDCl3): δ = 0.85 (d, JPH = 12.0 Hz,
3
6.3 H, CMe3A), 0.86 (d, JPH = 12.2 Hz, 2.7 H, CMe3B), 1.29 (d,
2JPH = 5.5 Hz, 0.9 H, PMeB), 1.32 (d, 2JPH = 5.3 Hz, 2.1 H, PMeA),
1.85 (s, MeA), 2.04 (s, MeB), 7.11 (dm, 3J = 8.0 Hz, 1 H, 3-H),
7.19–7.25 (m, 1 H, 5-H), 7.27–7.36 (m, 2 H, 6Ј-H, 6-H), 7.36–7.44
(m, 3 H, 4-H, 5Ј-H, 4Ј-H), 7.55–7.65 (m, 1 H, 3Ј-H) ppm. 13C{1H} 0.67 CH2Cl2), 6.70–6.77 (br. m, 2 H, 6ЈЈ-H), 6.77–6.88 (br. m, 4 H,
NMR (CDCl3): δ = 6.36 (d, 1J = 18.9 Hz, PMeB), 6.57 (d, 1J =
3ЈЈ-CH, 5ЈЈ-CH), 7.05 (dt, J = 8.0, J ≈ JPH = 0.5–0.8 Hz, 1 H,
3
3
4
3
19.8 Hz, PMeB), 20.35 (MeA), 20.69 (MeB), 26.85 (d, 2J = 14.0 Hz, 6Ј-H), 7.07 (dd, 3J = 8.1, J = 1.4 Hz, 1 H, 3-H), 7.09–7.13 (super-
2
1
CMe3B), 27.03 (d, J = 14.3 Hz, CMe3A), 28.98 (d, J = 12.9 Hz,
CMe3B), 29.41 (d, 1J = 12.3 Hz, CMe3A), 121.63 (C-3A), 122.56 (C-
3B), 124.71 (C-5B), 125.51 (C-5A), 126.79, 127.98, 128.16, 128.49,
imposed “d”, 2 H, 5-CH, 6-CH), 7.21 (d, 1 H, 3Ј-H), 7.22 (t, 1 H,
5Ј-H), 7.29 (tm, 2 H, 4ЈЈ-H), 7.31 (t, 1 H, 4-H), 7.34 (t, 1 H, 4Ј-H)
ppm. 13C{1H} NMR, C–H COSY (CDCl3): δ = 20.63 (Me), 55.40,
55.54 (2 s, OMe), 110.10, 110.18 (2 s, 2 C-3ЈЈ), 120.65 (s, 2 C-5ЈЈ),
3
128.82 (C-5ЈAB, C-4ЈAB, C-4AB), 129.74 (d, J = 5.2 Hz, C-3ЈB),
130.50 (d, 3J = 6.4 Hz, C-3ЈA), 131.13 (d, 2J = 3.6 Hz, C-6A), 131.52
(C-6ЈAB), 132.10 (d, 2J = 2.9 Hz, C-6B), 133.66 (d, 3J = 7.6 Hz, Cq-
122.24 (s, C-3), 125.23 (C-5), 125.01 (d, JPC = 15.2 Hz, 1 Cq-i),
1
1
125.67 (d, JPC = 13.2 Hz, 1 Cq-i), 127.51 (s, C-5Ј), 128.05 (s, C-
3
1
2
1A), 134.59 (d, J ≈ 5 Hz, Cq-1B), 136.06 (d, J = 6.5 Hz, Cq-2ЈA),
136.32 (br., Cq-2ЈB), 144.48 (d, 2J = 33.3 Hz, C-1ЈA), 144.40 (d, 2J =
33 Hz, C-1ЈB), 147.67 (C-2A), 148.14 (C-2B), 168.59 (C=OA), 169.77
(C=OB) ppm. 31P{1H} NMR (CDCl3): δ = –21.4, –25.5 (intensity
4Ј), 128.43 (s, C-4), 129.71 (d, JPC = 5.3 Hz, C-3Ј), 129.82 (br. s,
4
2 C-4ЈЈ), 131.70 (d, JPC = 3.7 Hz, C-6), 133.86 (s, C-6Ј), 134.11
3
1
(br. s, 2 C-6ЈЈ), 134.67 (d, JPC = 6.8 Hz, Cq-1), 136.49 (d, JPC
=
2
2
12.1 Hz, Cq-2Ј), 143.26 (d, J = 31.7 Hz, C-1Ј), 161.28 (br. d, JPC
604
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 593–606

2-Hydroxybiphenyl-2Ј-ylphosphane Ligands and Their BH3 Adducts
Table 3. Crystallographic data.
3·3C6D6
5cOx·1/2H2O
6b
6e
Empirical formula
Mt
T [K]
C34H19D18O2P
526.72
133(2)
C22H24O2.5
359.38
133(2)
P
C23H28BOP
362.23
133(2)
C14H18BOP
244.06
133(2)
λ [Å]
0.71073
0.71073
monoclinic
C2/c
0.71073
orthorhombic
Pna21
14.5556(12)
8.8905(8)
31.443(3)
90
90
90
4069.0(6)
8
1.183
0.71073
monoclinic
P21/n
9.9297(4)
8.5673(4)
16.1589(7)
90
98.124(1)
90
1360.85(10)
4
1.191
0.18
520
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
triclinic
¯
P1
9.8433(8)
12.5272(11)
13.1816(11)
70.398(4)
86.451(4)
71.655(4)
1451.7(2)
2
23.110(2)
11.0977(11)
14.9704(15)
90
99.779(3)
90
3783.6(6)
8
1.262
γ [°]
V [Å3]
Z
ρcalcd. [Mg/m3]
μ [mm–1]
F(000)
1.227
0.12
544
0.16
1528
0.14
1552
Crystal size [mm]
θ range [°]
Index ranges
0.34ϫ0.28ϫ0.26
1.64–28.28
–13ՅhՅ13
–16ՅkՅ16
–17ՅlՅ17
20782
0.3ϫ0.2ϫ0.2
1.79–30.51
–32ՅhՅ32
–15ՅkՅ15
–21ՅlՅ21
21939
0.35ϫ0.25ϫ0.15
1.30–30.51
–20ՅhՅ20
–12ՅkՅ12
–44ՅlՅ44
69887
0.35ϫ0.20ϫ0.15
2.27–30.51
–13ՅhՅ14
–12ՅkՅ12
–23ՅlՅ23
17388
Collected reflections
Independent reflections
R(int)
7173
0.062
5768
0.055
12413
0.047
4143
0.042
Completeness to φ = 30.00° [%]
Data/restraints/parameters
GOF on F2
Final R indices
[I Ͼ 2σ(I)]
99.6
7173/0/345
0.98
R1 = 0.0394
wR2 = 0.0905
R1 = 0.0675
wR2 = 0.0997
0.44/–0.30
99.9
5768/0/243
1.04
R1 = 0.0463
wR2 = 0.1139
R1 = 0.0621
wR2 = 0.1216
0.45/–0.26
100.0
12413/9/510
1.00
R1 = 0.0398
wR2 = 0.0954
R1 = 0.0585
wR2 = 0.1028
0.44/–0.20
99.8
4143/0/172
1.06
R1 = 0.0376
wR2 = 0.0966
R1 = 0.0459
wR2 = 0.1013
0.51/–0.20
R indices
(all data)
Largest difference peak/hole [e/Å3]
= 18.1 Hz, Cq-2ЈЈ), 148.06 (Cq-2), 169.59 (C=O) ppm. 31P NMR
(CDCl3): δ = –34.3 (br.) ppm. MS (EI, 70 eV, 345 °C): m/z (%) =
5cOx, 6b and 6e and description of the oligo/polymerization of eth-
ylene by catalysts formed in situ from [Ni(cod)2] and 2-hydroxy-
456 (1) [M]+, 427 (2), 398 (32), 397 (100), 367 (6), 151 (14), 229 (4), phenylphosphane–boranes.
199 (15), 44 (19), 43 (17). C28H25O4P (456.15): calcd. C 73.67, H
5.52; for the 2/3CH2Cl2 solvate C 67.10, H 5.15; found C 66.93, H
5.35.
Acknowledgments
Crystal Structure Analyses: Crystals of 3, 5cOx, 6b and 6e were
We thank B. Witt for NMR, W. Heiden for MS and Dr. G. Fischer
mounted on glass fibres in inert oil. Data were recorded at low
temperature with a Bruker SMART 1000 CCD diffractometer by
using Mo-Kα-radiation (λ = 0.71073 Å). No absorption corrections
were applied. Selected bond lengths and angles for 6b are presented
in Figures 3–5 and 7 and in Tables 1 and 2, and crystal data are
presented in Table 3. The structures were solved by direct methods
and refined by full-matrix least squares on F2.[25] The hydrogen
atoms of the BH, PH and OH groups were refined freely. Methyl
H atoms were included as rigid idealized methyl groups. Other H
atoms were included by using a riding model. Special features: for
6b, the Flack parameter refined to 0.04(6). Sets of O–H, B–H (hy-
drogen-bonded) and B–H (not hydrogen-bonded) distances were
restrained equal. CCDC-784400 (3), -784401 (5cOx), -784402 (6b)
and -784403 (6e) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
(Ludwig-Maximilians-University of München) for HRMS mea-
surements.
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