α-Phosphanyl amino acids: Synthesis, structure and properties of alkyl and heterocyclic N-substituted diphenylphosphanylglycines Dedicated to Professor Dr. Dr. h.c. Manfred Scheer on the occasion of his 60th birthday

Article abstract of DOI:10.1016/j.tet.2015.05.101

N-Alkyl and N-heterocyclic substituted diphenylphosphanylglycines 1a-j were synthesized by a convenient one-pot, three-component reaction of diphenylphosphane, the corresponding primary amine and glyoxylic acid hydrate in diethyl ether. Phosphanylglycolates 2 and phosphoniobis(glycolates) 3 were detected as intermediates. In the case of steric hindrance or low basicity of the amine only 2 or mixtures of 2 and 1 are formed. Reactivity studies of selected phosphanylglycines showed facile decarboxylation and hydrolysis, oxidation and formation of coordination compounds with BH₃ or W(CO)₅. N-Alkyl derivatives (tert-butyl, n-hexyl, benzhydryl) with moderate steric hindrance reacted with Ni(COD)₂ in THF or toluene in the presence of ethylene with heating under pressure to yield highly active oligomerization catalysts, and converting the ethylene to liquid and low-molecular-weight solid ethylene oligomers (M_NMR 500-1250 g/mol) with high selectivity for linear α-olefins. Smaller N-alkyl or N-heterocyclic amino substituents at the phosphanyl acetic skeleton interfere with the ethylene conversion and deactivate the catalyst. The structures of the compounds were elucidated by solution NMR and single crystal XRD studies.

Full text of DOI:10.1016/j.tet.2015.05.101

Tetrahedron xxx (2015) 1e13
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
a-Phosphanyl amino acids: synthesis, structure and properties of
alkyl and heterocyclic N-substituted diphenylphosphanylglycines
,
Joanna Lach a, Normen Peulecke a y, Markus K. Kindermann a, Gottfried J. Palm b,
c
a,
*
€
Martin Kockerling , Joachim W. Heinicke
a
€
€
Institut fur Biochemie-Anorganische Chemie, Ernst-Moritz-Arndt-Universitat Greifswald, Felix-Hausdorff-Str. 4, D-17489 Greifswald, Germany
Institut fur Biochemie-Molekulare Strukturbiologie, Ernst-Moritz-Arndt-Universitat Greifswald, Felix-Hausdorff-Str. 4, D-17489 Greifswald, Germany
Institut fur Chemie, Anorganische Festkorperchemie, Universitat Rostock, Albert-Einstein-Str. 3a, D-18059 Rostock, Germany
b
c
€
€
€
€
€
a r t i c l e i n f o
a b s t r a c t
Article history:
N-Alkyl and N-heterocyclic substituted diphenylphosphanylglycines 1aej were synthesized by a conve-
nient one-pot, three-component reaction of diphenylphosphane, the corresponding primary amine and
glyoxylic acid hydrate in diethyl ether. Phosphanylglycolates 2 and phosphoniobis(glycolates) 3 were
detected as intermediates. In the case of steric hindrance or low basicity of the amine only 2 or mixtures
of 2 and 1 are formed. Reactivity studies of selected phosphanylglycines showed facile decarboxylation
and hydrolysis, oxidation and formation of coordination compounds with BH3 or W(CO)5. N-Alkyl de-
rivatives (tert-butyl, n-hexyl, benzhydryl) with moderate steric hindrance reacted with Ni(COD)2 in THF
or toluene in the presence of ethylene with heating under pressure to yield highly active oligomerization
catalysts, and converting the ethylene to liquid and low-molecular-weight solid ethylene oligomers
Received 17 April 2015
Received in revised form 22 May 2015
Accepted 27 May 2015
Available online xxx
Dedicated to Professor Dr. Dr. h.c. Manfred
Scheer on the occasion of his 60th birthday
Keywords:
Phosphanes
Amino acids
Three-component reactions
Nickel catalysts
(MNMR 500e1250 g/mol) with high selectivity for linear
a-olefins. Smaller N-alkyl or N-heterocyclic
amino substituents at the phosphanyl acetic skeleton interfere with the ethylene conversion and de-
activate the catalyst. The structures of the compounds were elucidated by solution NMR and single
crystal XRD studies.
Ethylene oligomerization
Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction
amino acids, their salts and esters with formaldehyde and phos-
phanes or their addition products R2PCH2OH and RP(CH2OH)2,2,8,9
Synthetic amino acids have found interest and applications in
many fields of chemistry, biochemistry and pharmacy.1 In-
troduction of a phosphanyl group into amino acids and peptides,
useful particularly as coordination site for transition metals in low
oxidation states, was accomplished by various strategies.1b,2e11
Many products were utilized for a variety of transition metal cat-
alyzed2,3 or organocatalyzed4 chemical transformations. Another
goal was the use of water soluble phosphane derivatives as carriers
for pharmaceutically interesting transition metals.5 The known
types of phosphanyl amino acids involve a) directly N-phospha-
nylated compounds, formed by reaction of the amino acids with
ClPPh2,6 b) acyclic and heterocyclic N-phosphanylmethyl de-
rivatives, prepared by condensation reactions of NeCH2OMe
substituted amino acids with secondary phosphanes7 or of free
and c) amino acids with the phosphanyl function at the a-C side
group. The latter were obtained by Pd-catalyzed coupling of sec-
ondary phosphanes with O-triflate or O-mesylate derivatives of
serine, proline or tyrosine3 or alternatively by reaction of phos-
phides with the halogenated amino acids under appropriate con-
ditions.10
a-Phosphonio-N-acyl amino acid derivatives were
reported by Mazurkiewicz et al.1b and the first N-tert-butyl and
N-aryl derivatives of glycine with a phosphanyl substituent directly
bound at the a-C atom were synthesized by us in a convenient one-
pot three-component reaction.11 Principally, the structural features
of these compounds offer the potential for formation of five-
membered P,COOꢀ or N,COOꢀ chelate complexes, to act as tripod
P,N,COOꢀ ligand or as soft-hard hybrid ligand for bimetallic com-
plexes. This prompted us to explore the scope and limits of the
three-component synthesis for a wider variety of N-substituents
and to illuminate general properties and some aspects of their re-
activity. Because of the close structural relationship to diphenyl-
phosphanylacetic acid,12 applied as phosphanylcarboxylate nickel
catalyst in the industrial ethylene oligomerization within the SHOP
* Corresponding author. Tel.: þ49 3834 864318; e-mail address: heinicke@un-
i-greifswald.de (J.W. Heinicke).
y
€
€
Current address: Leibniz-Institut fur Katalyse e. V. an der Universitat Rostock,
Albert-Einstein-Str. 29 A, 18059 Rostock, Germany.
http://dx.doi.org/10.1016/j.tet.2015.05.101
0040-4020/Ó 2015 Elsevier Ltd. All rights reserved.
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2
J. Lach et al. / Tetrahedron xxx (2015) 1e13
process,13,14 ligand screening for in situ formation of nickel catalysts
for ethylene oligomerization was also undertaken in this study.
equilibrium concentrations of sparsely soluble products in solution
remain low. NMR monitoring of the reaction with tert-butylamine
revealed that the precipitate, separated after 10 min, contained
considerable amounts of the tert-butylammonium phosphanylgly-
colate 2c, whereas a sample taken from the suspension after stirring
for 15 h displayed mainly the phosphanylglycine 1c. This shows that
the three-component synthesis of phosphanylglycines does not
proceed via a Mannich reaction with halfaminale and immonium
intermediates, as in the case of phosphanylmethylations of amines
with formaldehyde,15a but that the OH groups of GAH are stepwise
protonated and replaced with cleavage of water by the phosphane
and subsequently by the amine. The second step is slower so that
usually reaction times of 15e24 h were chosen, in the case of slow
reactions even several days. The main reason is the presence of the
COOH group that lowers the concentration of free amine, but also
steric effects or low basicity of the amine diminish the reaction rate.
If an excess of amine is used, as tested for with iPr2NH (1.6 equiv),
2. Results and discussion
2.1. Synthesis
Three-componentaminomethylations of trivalent PH-compounds
with primary or secondary amines and formaldehyde are well
known,15 but knowledge about analogous reactions with other al-
dehydes is still sparse and restricted to arylaldehydes in THF.16 The
resulting a-phosphanyl benzylamines, preferably prepared till now
by addition of R2PH or R2PMI (M]Na or Li) at benzaldimines or their
hydrochlorides, are rather unstable in solution but are stabilized by
electron-withdrawing p-nitrophenyl substituents at the
atom.17 The electron withdrawing effect of COOH suggested that
phosphanylmethylamines with a COOH group at -C also are stabi-
a-C or N
a
a
mixture of the hydrated phosphanylglycine and its salt
lized. This inspired us to develop a convenient synthesis of amino-
diphenylphosphanyl acetic acids, in the following named (diphenyl)
phosphanylglycines, by three-component one-pot condensations of
glyoxylic acid hydrate (GAH) with diphenylphosphane and primary
amines. In addition to the recently communicated condensations
with tBuNH2 and some primary aryl amines,11 a variety of linear and
branched alkyl-, arylalkyl- and heterocyclic primary amines were
used and found applicable in this reaction to give the corresponding
phosphanyl glycines 1aej. However, 1k and 1l were formed only in
minor amounts in addition to the corresponding phosphanylglyco-
lates 2k and 2l (Scheme 1). Nitrogen atoms of N-heterocyclic sub-
stituents did not interfere with the reaction as long as they did not
lower the reactivity of the primary amino group too strong, such as in
the case of, e.g. pyrimidin-2-yl amines.
(1b$0.6iPrNH2$H2O) precipitated. If 2 equiv of glyoxylic acid were
used in the three-component reaction, recently demonstrated with
tBuNH2 as amine component, organoammonium phosphanylbis(-
glycolates) 3 are formed in high yield.11c,d The analogous diethyl
ammonium salt of 3 was formed also with diethyl amine as the NH
component in good yield,18 in this case, however, even with only
1 equiv of glyoxylic acid. This shows that phosphanylbis(glycolates)
3 may also be involved in the equilibrium reactions leading to the
phosphanylglycines (Scheme 1). Disubstitution at the primary
amino group, typical for many phosphanylmethylations, was never
observed. The mono-phosphanylmethylations, known also for N-
primary
a
-amino acids such as alanine under mild conditions,19 may
-position.
thus be attributed to the presence of the COOH group in
a
Scheme 1. Three-component synthesis of N-substituted diphenylphosphanylglycines 1ael via organoammonium diphenylphosphanylglycolates 2, unless the latter are stabilized
by bulky or electron-withdrawing substituents R.
The conversions were performed in a 1:1:1 reactant ratio at room
temperature (20e24 ꢁC), best in diethyl ether by addition of the
ethereal solution of the phosphane and amine to an ethereal solu-
tion of glyoxylic acid hydrate (GAH) or reversed addition. The ma-
jority of the products precipitate in this solvent. This not only
facilitates the isolation but also increases the yield, as the
The water, liberated in the condensation into the crude reaction
mixtures, results in still minor equilibrium amounts of 2. Attempts
to remove this water from the suspensions by neutral drying agents
CaCl2 or MgSO4, introduced into the reaction encapsulated in an
immersed fritted glass, did not result in significant conversion of
the minor residual amount of 2c to 1c. Alternative efforts to remove
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J. Lach et al. / Tetrahedron xxx (2015) 1e13
3
the reaction water by distillation of wet diethyl ether, methanol or
benzene resulted in decomposition. Thus, distillation of wet
methanol from a solution of crude 1c led to the decarboxylation
product Ph2PCH2NHtBu (4c) and its salts with the anions of 2
formation of the corresponding phosphanylglycines 1hej. This
shows that the slow conversion is not caused by the presence of
a competing Lewis-basic nitrogen atom in the heterocyclic sub-
stituent but rather by the lowered basicity of the amino group,
induced by the electron withdrawing effect of the N-substituent.
Finally, it should be mentioned that attempts to synthesize N-
methyl- or N-unsubstituted diphenylphosphanylglycines by three-
component reaction with MeNH2, NH3, (Me3Si)2NH or (NH4)2CO3 as
amine component in ethereal solution also failed. It is assumed that
lack of any steric hindrance favors other condensations reactions, as
known for reactions of glyoxylic acid with ammonia, methyl amine
and ethyl amine.20
(d
31P¼ꢀ20.0/6.8) and of meso/rac-3 (
d
31P¼ꢀ19.4/26.1, 27.1). Puri-
fication of the separated crude phosphanylglycines succeeded,
however, by crystallization from dry methanol at room tempera-
ture. The crude products, in some cases monohydrates, have very
good solubility in this solvent while the majority of the methanol
solvates of 1 precipitate or crystallize from the MeOH solution with
somewhat lower solubility. Some products lost methanol on drying
under vacuum, but N-alkyl or N-arylalkyl phosphanylglycine
methanol solvates were usually stable under vacuum at room
temperature.
2.2. Properties and reactivity
2.1.1. Limitations. Whereas no limitations were observed for the
first step in the three-component condensations, the slower re-
placement of the second OH group by an amino group can be
strongly hindered, e.g. in the case of sterically demanding
substituted primary amines. Thus, in the case of 1-adamantylamine
the adamantylammonium phosphanylglycolate only converted
slowly and partly (after 3 d 10%) to the respective N-adamantyl
phosphanylglycine. In methanol, this conversion was faster but
also limited to 40% after 3 d.11d In the case of secondary amines
such as diethylamine18a or N-methylaniline,11b the second con-
densation step does not take place. Heating for thermal conden-
sation and removal of reaction water from the equilibrium is not
possible because of the generally easy decarboxylation of
phosphanylglycines.
Besides steric effects, electronic effects, i.e. low basicity of the
primary amine, also slow down or prevent the conversion of
organoammonium phosphanylglycolates to phosphanylglycines.
Thus, the reactions of 2-aminopyridine and of 2-amino-4,6-
dimethylpyrimidine with diphenylphosphane and GAH in diethyl
ether provided only 2k and 2l within 15 h, which in [D8]THF so-
lution displayed slow partial conversion to 1k and 1l (after ca. 10 h
at 22e25 ꢁC 2k:1kz45:55 and 2l:1lz80:20). Slightly higher ba-
sicity, induced by the methyl group in 3-methyl-pyridylamine or by
benzene-annulation in the quinolylamines, was sufficient to enable
Phosphanylglycines as well as phosphanylglycolates possess
two Lewis-basic substituents at the same carbon and thus behave
as P,N and P,O acetales, respectively. The presence of an intrinsic
acidic COOH group destabilizes these compounds and causes
equilibrium (Scheme 1) and in part decomposition reactions in
solution, as illustrated in the following by the solution behavior of
1b and 1c. In aqueous and D2O solution they undergo rapid acid
catalyzed replacement of the amino by an OH or OD group, yielding
quantitatively the respective organoammonium phosphanylglyco-
lates.18a Diluted aqueous bases hydrolyze slower and incomplete, as
exemplified by an NMR test of 1c. A freshly prepared solution of this
compound in D2O, containing 1 equiv of NaOD, displayed strong
phosphorus signals of sodium phosphanylglycinate and phospha-
nylglycolate and small signals of Ph2PH and Ph2PD, integral ratio ca.
45:45:4:5. After 10 d at room temperature the ratio was only
slightly shifted (ca. 40:50:5:5). Solutions of phosphanylglycines in
dry CD3OD can be stored for several days without significant de-
composition in air-tight closed NMR tubes. Only H/D exchange of
the acidic a-CH proton occurs (Scheme 2) and in CD3OD solution
leads to the disappearance of the PCHN proton signals and low-
intensity 13C multiplets with CeP and CeD coupling, in particular
in the case of stronger electron withdrawing N-(hetero)aryl
substituents.
Scheme 2. Illustration of the reactivity of 1 at room temperature.
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4
J. Lach et al. / Tetrahedron xxx (2015) 1e13
Traces of moisture and/or slight excess of amine caused various
compared to the respective phosphanes, where air oxidation also
may start by interaction with the P-lone pair.24 This prompted us to
perform some reactivity studies with selected phosphanylglycines.
The above mentioned air oxidation of phosphanylglycines in
methanol or THF solution led for 1c$MeOH to a mixture of the
phosphinoylglycine 5c and the phosphinoylglycolate 6c with 31P
equilibrium reactions. This was shown for 1b, which contains ca.
one molecule water and 0.6 equiv of excess iPrNH; minor signals for
temperature dependent equilibrium amounts of Ph2PD,
Ph2PCH(OH)COOꢀ RNH3þ and Ph2Pþ(CH(OH)COOꢀ)2 iPrNHþ3 species
were observed in the NMR spectra in CD3OD (see e.g.,
Supplementary data, Figs. S1 and S2). The sharp doublet of the
averaged methyl signals of the N-isopropyl group in pure 1b at
room temperature is strongly broadened by these reactions within
the NMR time scale and changes to two broad doublets on cooling
to ꢀ20 ꢁC (Fig. S1), indicating the non-equivalence of the two
diastereotopic methyl groups in the asymmetric compound if the
processes behind the signal averaging (CeN bond cleavage and
formation equilibria) are hindered. The presence of small equilib-
rium amounts of Ph2PH, which is rapidly attacked by oxygen, may
explain the high sensitivity of the solutions to air oxidation. In-
volvement of CD3OD or MeOH in replacing the Ph2P- or NHR-group
in solution equilibria by eOR (R]CD3 or Me) was not observed.
Phosphanylmethylacetals Ph2PCHR0OR with R0]H or aryl are
known and accessible by acid-catalyzed condensations of Ph2PH
with alcohols and aldehydes,21 but derivatives with an intrinsic
acid substituent R0]COOH are probably instable even in solution
and therefore not involved in the equilibrium reactions of phos-
phanylglycines with nucleophiles. Free equilibrium amounts of
iPrNH2, formed from the above mentioned crude 1b$0.6
iPrNH2$H2O in CD3OD solution, may partly replace the Ph2P-group,
particularly at elevated temperature (55 ꢁC). Variable temperature
(VT) 31P NMR studies of this solution showed a slight increase of the
Ph2PD integrals with the temperature at the expense of the signals
of 1b and 2b. In [D8]THF solution this trend is somewhat more
pronounced (31P integrals of Ph2PH; 1b and 2b at ꢀ20, 25, 40, 55 ꢁC:
3, 9, 13, 20; 89, 82, 78, 69 and 5, 2, 1, 1%) (see Supplementary data,
Fig. S2). A lack of H-D exchange in [D8]THF reveals the PCHN and
resonances at
d¼30.6 and 32.0 ppm. Oxidation of 1c$MeOH with
30% aqueous H2O2, due to the sensitivity to hydrolysis, led only to
6c, which was obtained in pure form also by condensation of
Ph2PHO with GAH.18a Oxidation with sulfur is a cleaner reaction
and can easily be performed in the absence of water. Reaction of
1c$MeOH and 1g$MeOH with sulfur in methanol provided the
thiophosphinoylglycines 7c and 7g$MeOH in high yields. Various
‘sulfur-protected’ thiophosphinoyl amino acid derivatives with
phosphorus bound at a more remote carbon atom than a-C have
found use in the synthesis of phosphanyl peptide transition metal
catalysts.3 This was achieved by performing synthesis and purifi-
cation of air-stable precursors under aerobic conditions and car-
rying out selective deprotection of thiophosphinoyl peptides with
Raney nickel for the final reaction with transition metal com-
pounds. The thiophosphinoylglycines 7c and 7g, however, are
similarly sensitive to hydrolysis as N-alkyl phosphanylglycines, and
this limits their handling under aerobic condition. In the presence
of moisture, 8c is obtained by hydrolysis of 7c, which was obtained
earlier by oxidation of 2c with sulfur.18a Moreover, in [D8]THF, CDCl3
and even in CD3OD solution, carbon dioxide is slowly cleaved even
at room temperature (for 7g markedly faster than for 7c), leading to
contaminations by thiophosphinoylmethylamines 9c and 9g,
respectively.
Protection of the phosphanyl group by a BH3 substituent,
a versatile tool to prevent air oxidation of phosphanes and ap-
plicable even in the presence of relatively acidic OH sub-
stituents,25,26 failed in reactions of 1bed$MeOH with excess
Me2S∙BH3 because of the facile reduction of carboxylic acids by
BH3 after primary formation of acyl boron moieties.27 However,
the increased stability of carboxylate salts towards reduction
allowed formation of a borane protected N-tert-butyl-phospha-
nylglycine derivative by reaction of crude tert-butylammonium
phosphanylglycolate 2c18a with 2.6 equiv of Me2S∙BH3 in THF at
PCHO proton doublets as well as a new singlet at
d
¼2.25, like the
new Me2CH doublets ( z1.20) it grew in intensity with the tem-
d
perature. The new singlet has a very similar chemical shift as the
methine proton in (Me2N)2CHCOOEt (
d
¼2.3322) and may thus be
attributed to equilibrium amounts of (iPr2N)2CHCOOꢀ species in
solution. Addition of 2.8 equiv of H2O to this solution increased the
content of 2b at the expense of 1b while the Ph2PH content and the
effect of increasing temperature was not markedly changed except
for a slight preference of 2b compared to 1b at higher temperature.
Use of [D8]THF instead of CD3OD for solution NMR measure-
ments is advantageous with respect to the appearance of PCHN
proton and 13C(H) NMR signals but disadvantageous with respect to
slow decarboxylation of some phosphanylglycines even at room
temperature. In the case of 1c$MeOH and 1i$MeOH, partial de-
carboxylation reached 30e40% within 1 d or prolonged 13C NMR
measurements of diluted solutions. Much stronger decarboxylation
(ꢂ70%) occurred during attempts to dissolve the phosphanylgly-
cines (i.e., 1c$MeOH and 1f to 4c and 4f) in CDCl3 with slight
warming (Scheme 2). This may be attributed to the lack of stabi-
lizing hydrogen bonds of this solvent. In the solid state the com-
pounds are somewhat more stable. Thus, substantial thermal
decarboxylation of solid 1c$MeOH starts at only 95e100 ꢁC, and the
exothermic DTA (5ꢁ/min) peak for strong decarboxylation appeared
at 114 ꢁC. This behavior is comparable to diphenylphosphanylacetic
acid, which undergoes thermal decarboxylation in the same tem-
perature range and decomposes more rapidly in diluted monomer
solutions without stabilizing hydrogen bonds to a second molecule
or a donor solvent.23
0
ꢁC. The NMR data are in accordance with the structure proposal
10c (Scheme 3). Hydrogen evolution indicated reaction of the
acidic NH/OH protons with the second equivalent of BH3, leading
to replacement of the glycolate-OH by the tert-butylamino group
and formation of an acyl borate moiety, indicated by the broad 11
B
NMR signal at
d
¼ꢀ0.7, close to that of tBuNHþ3 B(Oac)4ꢀ
(
d
¼ꢀ0.5).28
The P-bound BH3 did not attack the COO-group. The 11B resonance
appeared at
d
¼ꢀ40.5, typically for phosphane-boranes,29 the 13C
carbonyl doublet at
acetic acid anhydride and acetic acid methyl ester (
and significantly upfield from the COO resonances of 3c or free
d
¼169.2, just between the CO resonances of
d
¼167.4, 171.3)
acetic acid and acetates (
d
¼175e183).30 The substitution of the OH
by the amino group was indicated by the 13C doublet of the
a
a
-CH
-CH
carbon at
d
¼56.6, the region of the PCHN signals, while the
carbon signal of 2c is exhibited more downfield at
d
¼71.1.18a The
stabilization of 10c, however, is limited by sensitivity to hydrolysis,
like as for the related thiophosphinoyl derivative 7c. In moist THF
it is hydrolyzed with liberation of Ph2PH$BH3 (
d
31P¼2.0) and small
amounts of Ph2PH (
d
31P¼ꢀ40.0), in D2O/CD3OD it is rapidly
decomposed with formation of Ph2PD.
Finally, we studied the reaction of selected phosphanylglycines,
1c$MeOH and 1i$MeOH, with W(CO)5(THF) in THF to block the
phosphorus electron lone pair by coordination of W(CO)5 and to
determine the stability and other properties of the (phosphanyl-
glycine)W(CO)5 complexes. The N-heteroaryl-substituted complex
11i was obtained in pure form whereas the N-alkyl derivative 11c
proved less stable and was contaminated by (Ph2PH)W(CO)5
Since the reactivity of P,N-acetales towards protic solvents or
reagents is closely connected with protonation of either N or P, it
was initially assumed that blockage of the P-lone pair would in-
crease the stability of the P-substituted glycines. This is the case for
many phosphine oxides, -sulfides, -BH3 or -W(CO)5 complexes
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J. Lach et al. / Tetrahedron xxx (2015) 1e13
5
to brown complex solutions were then transferred into an auto-
clave and heated under pressure with ethylene (40e50 bar). All N-
alkyl substituted phosphanylglycines that were screened in the
batch oligomerization (1a,c,d,f) formed catalysts under these con-
ditions which became active when reaching 80e100 ꢁC (after ca.
15e20 min). The activity was low in the case of the small N-propyl
substituent but high with bulkier groups such as tBu, nHex and
benzhydryl (Table 1 entries 1e6, Fig. 1). The latter might hinder
interfering interactions of the N-donor atom with the catalyst
metal.
Scheme 3. Formation of a BH3-protected phosphanylglycine derivative.
1
(d
31P¼ꢀ13.7 (satl. d, JPW¼136.6 Hz), lit.
d
¼ꢀ14.831) despite solid
1c$MeOH was added to the THF solution of W(CO)5(THF) to prevent
decomposition of 1c in solution before complex formation. This
technique was found necessary already in our recent investigation
on hydrolytically less sensitive N-aryl phosphanylglycines (L) to
obtain the corresponding LW(CO)5 complexes in pure form.11b At-
tempts at later purification by column chromatography on silica gel
led to complete decomposition and formation of
a multi-
component mixture, which was not further analyzed. The down-
field phosphorus coordination chemical shifts Dd11L1¼23.6 and
27.3 of 11c in the crude mixture and of 11i versus 1c and 1i, re-
spectively, correspond to values typical for (Ph2PR)W(CO)5 com-
plexes32 and indicate similar net donor properties33 (Scheme 4).
Scheme 4. Formation of phosphanylglycine W(CO)5-complexes.
Whether metal phosphanylglycinate salts and P^Oꢀ-chelate
complexes with anionic phosphanylglycinate ligands are more
Fig. 1. Pressure-time plots of ethylene oligomerization catalyzed by a) 1c/Ni in THF (1),
b) 1c/Ni in toluene (3), c) 1d/Ni in toluene (4), d) 1f/Ni in toluene (2), e) 1c/Ni in tol-
uene/1-hexene (6), f) 10c/Ni in THF (5).
stable than the k
1PeW(CO)5 coordinated COOH-acidic complexes
11 and comparable to neutral P^Oꢀ- phosphanylacetate chelate
complexes is not yet clear and requires further investigations.
Nevertheless, the presence of the same PeCeC(O)O structure motif
and the importance of the phosphanylacetate nickel catalysts in the
Shell Higher Olefin Process13,14 inspired us to test the suitability of
the phosphanylglycines for generation of Ni-catalysts for ethylene
oligomerization. A variety of the new compounds was reacted with
Ni(COD)2 in THF or toluene (0e20 ꢁC). The in situ generated yellow
In THF the conversion was faster than in toluene as demon-
strated for 1c/Ni by the more rapid pressure decrease (Fig. 1 curve 1
versus 3). The N-primary n-hexyl and N-secondary benzhydryl
substituted catalysts 1d/Ni and 1f/Ni worked slightly faster than 1c/
Ni in toluene and the major part of the ethylene was converted
within 1 h. The N-2-(pyrid-2-ylethyl) and N-8-chinolyl substituted
Table 1
Oligomerization of ethylene by in situ formed phosphanylglycinate nickel catalysts
Entry
Ligand, L/Ni (mmol);
Pstart (bar), T (ꢁC), t (h)
C2H4 (g, mmol);
solvent (mL)
C2H4 conversion g (%), TON (mol/mol$h);
Wax (g);b mp. (ꢁC);
MNMR [g/mol];c
Vin/int. C]C;
Me/C]C
lower oligomersa
d (g/cm3)
1
2
3
4
5
6
7
8
1a, 0.10/0.10; 40, 100, 16
1c, 0.11/0.12; 31, 100, 15
1c, 0.10/0.11; 50, 100, 16
1d, 0.14/0.14; 50, 100, 15
1f, 0.10/0.10; 30, 100, 15
1f, 0.12/0.12; 50, 100, 15
1g, 0.1/0.1; 40, 100, 15
1i, 0.1/0.1; 40, 100/16
11.2 (399); THF 20
8.1 (289); THF 20
14.1 (503); toluene 20
15.1 (538); toluene 20
7.8 (278); toluene 20
14.1 (503) toluene 20
12.1 (431); THF 20
11.9 (424); THF 20
14 (500); toluene 20
7.6 (271); THF 20
12.2 (435); toluene
10/1-hexene 10
1.0 (9), 356; C4 38, C6 39, C8 15, C10 2; C12<1
6.9 (85), 2240; C4 30, C6 43, C8 19, C10 8
12.4 (88), 4420; n.d.
13.2 (87), 3360; C4 17, C6 24, C8 24, C10 21, C12 12
6.8 (87), 2420; C4 15, C6 23, C8 19, C10 17, C12 11
13.4 (95), 3980; C4 26, C6 25, C8 18, C10 15; C12
2.1 (17), 750; C4 17, C6 26, C8 17, C10 4, C12 1d
1.0 (8), 356; n.d.
0
d
5.2; 113e117; 0.96
10.6; 115e118; 0.94
9.8; 98e100; 0.94
6.0; 118e120; n.d.
10.4; 101e104; n.d.
0.3; 99.5; -
1230; 93:7; 1.5
900; 90:10; 1.3
510; 93:7; 1.3
1240; 95:5; 1.5
n.d.
390; 90:10; 1.3
d
0
d
9
10
11
4c, 0.10/0.11; 50, 100, 15
10c, 0.12/0.13; 29, 100, 15
1c, 0.14/0.14; 50, 100, 15
0 (inactive)
3.9 (51), 1160; n.d.
3.4 (28), 866; n.d.
d
3.2; 119e120; 0.96
0.6; 40e50; d
1250; 96:4; 1.5
n.d.
12
1c, 0.12/0.12: 50, 100, 15
12 (430); THF 15,
H2O 5
0 (inactive)
d
d
a
Solvent and lower a-olefins were separated by flash-distillation (C4 partially lost); oligomer distribution in flash distillate determined by GC (% of C2n by peak areas).
For purification of the remaining wax, see exp. section.
NMR spectra measured after swelling (24 h, 100 ꢁC) in C6D5Br at 100 ꢁC; MNMR calculated from integral ratios of proton CH2/2 and CMe3/3 signals relative to Vin/3 and CH]
b
c
CH/2 proton signals; a-to intern olefin and Me/C]C ratios determined by proton integration.
d
Unknown component (35%) with GC-retention time close to that of toluene.
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6
J. Lach et al. / Tetrahedron xxx (2015) 1e13
phosphanylglycines 1g and 1i, which at least in principal are able to
form six- and five-membered N^NeNi chelate rings, respectively,
gave only marginal conversion (entries 7,8) and led to deactivation
of the catalysts after a short time. Screening of the decarboxylation
product 4c, which did not form a catalyst, underlines the crucial
role of the COO group (entry 9), and that despite the easy thermal
decarboxylation of the ‘free’ N- or COO-protonated phosphanyl-
glycines the Ni complex catalysts must be much more thermally
stable. A similar strong increase in thermal stability to de-
carboxylation is known for diphenylphosphanylacetates compared
to diphenylphosphanylacetic acid.23 The borane-protected phos-
phanylglycine 10c forms an oligomerization catalyst with Ni(COD)2
but the conversion and reaction rate were considerably lower than
in the absence of the borane (entry 10, Fig. 1 curve 5). A test for
cooligomerization of ethylene with 1-hexene in toluene solution
failed and caused low conversion of ethylene (entry 11, curve 6).
The presence of water prevented ethylene conversion (entry 12),
possibly by hydrolytic cleavage of the ligand.
1 (
d
¼ꢀ2.2e3.1), 2 (
d
¼4.3e9), 3 (
¼ꢀ16.6 to ꢀ18.4) and of coordinated phos-
¼25.8, 11c ¼26.7, 11i ¼28.7) or oxidation
¼51.5, 7g ¼43.9) make them ideal
markers for reaction monitoring.
d
¼26e28, two signals for rac- and
meso-isomers18), 4 (
phanylglycines (10c
d
d
d
d
products (5c
d¼30.5, 7c
d
d
More information on the structures of the phosphanylglycines
in the solid state is provided by single-crystal structure analyses of
the MeOH solvates of racemic 1b and 1h (Figs. 2 and 3), grown from
their concentrated solutions in methanol. For the methanol solvate
of 1a the diffraction data were insufficient for detailed refinement.
The crystals are monoclinic and contain each four molecules in the
unit cell. The N-alkyl compounds 1a and 1b are zwitterionic with
methanol bound by hydrogen bond at the COOꢀ group. Further
inter- and intramolecular hydrogen bonds exist, as shown for 1b in
Fig. 4. The N-heteroaryl-substituted 1h exhibits free amino and
COOH groups. Bond lengths and angles of 1b and 1h display normal
values. While the CeN bond lengths and CeNeC angles in 1b cor-
respond to sp3 hybridization of the nitrogen atom, the short N1eC3
bond length and the C1eN1eC3 angle of 122.1(2) indicate that the
amino-N-atom in 1h is sp2 hybridized. In combination with the
small dihedral angle C1eN1eC3eC4 (4.776(4)ꢁ) this allows for
stabilization by conjugation of the amino group with the N-het-
The selectivity for formation of relatively short linear a-olefin
oligomers with methyl and vinyl ends, analyzed by NMR spectra of
swollen oligomers in C6D5Br at 100 ꢁC, is very similar to that re-
ported for diphenylphosphanylacetate nickel catalysts.13,14 There-
fore, a similar mechanism can be assumed for the oligomerization,
chain start with square planar hydrido- and chain growth with
alkyl-nickel(II) P^Oꢀ-chelate catalysts with the olefin coordinated in
trans-position to phosphorus and stabilization by the phosphany-
erocyclic p-system. The planar phenyl groups at the pyramidal PC3
fragment are twisted to each other to adopt the energetically most
suitable conformation.
lacetate backbone. The chain growth is terminated by b-hydride
elimination, which provides the NiH catalyst for the next catalytic
cycle. The similar working o-phosphanylphenolate P^ONi catalysts
with o-phenylene-P,O backbone, also studied in our group, were
more tolerant to water and stabilized by a-olefins and/or partially
incorporating them into the polymer chain34 but were less easily
accessible than the phosphanylglycine Ni catalysts presented here.
2.3. Structural aspects
The structure elucidation of the phosphanylglycines was based
on conclusive solution NMR data and for 1b and 1h additionally on
crystal structure analysis. Most characteristic is the doublet of the
a
-methine 13C nuclei, Pe13CHN, allowing to distinguish zwitter-
ionic N-alkyl (
heteroaryl-diphenylphosphanylglycines
phanylglycolates (PCHO,
d
¼60e65) and heterocyclic N- or COO-protonated N-
¼54e60) from phos-
ranges, from
(
d
d
¼70e75) by different
d
decarboxylated PCH2-moieties by opposite signal amplitudes in the
DEPT135 carbon NMR spectra, and from coordinated phosphanyl-,
phosphonium- or oxidized (thio)phosphinoyl phosphorus species
1
by different ranges of JPC coupling constants. The one-bond PeC
coupling constants of the N-alkyl phosphanylglycines 1aeg amount
1
to JPC¼12.3e16.5 Hz in the aprotic donor solvent [D8]THF while
these couplings are somewhat larger in the protic solvent CD3OD
(ca. 28 Hz) and for the N-heteroaryl substituted compounds 1hel
(1JPC¼18.9e25.2 Hz in [D8]THF). The PeCa coupling constants of the
BH3- and W(CO)5-coordinated compounds 10c (1JPC¼24.4) and
11c,i (1JPC¼26.1, 16.6) were found in the same range whereas the
values for diphenylphosphonium species 3 (1JPC¼51.3e57.1 Hz18),
thiophosphinoyl and phosphinoyl derivatives 7c (1JPC¼39.7 Hz), 7g
(1JPC¼59.3 Hz) and 5c (1JPC¼69.7 Hz) are considerable larger. A
similar trend was observed for the 1JPC coupling constants of the i-
Fig. 2. Molecular structure of the S-enantiomer of racemic 1b 1.43 HOCH3 in the
crystal (thermal displacement ellipsoids with 50% probability, disordered, non-
ꢀ
coordinated methanol molecule omitted for clarity). Selected bond lengths (A) and
angles (deg): P1eC1 1.890(2), P1eC6 1.834(2), P1eC12 1.834(2), C1eN1 1.494(2),
N1eC3 1.510(2), C1eC2 1.540(2); C1eP1eC12 101.38(7), C1eP1eC6 103.62(7),
C6eP1eC12 104.04(7).
3. Conclusions
phenyl carbon nuclei. Because of the asymmetric
a
-carbon atom,
N-Secondary diphenylphosphanylglycines with a wide variety
of N-substituents from primary, secondary or tertiary alkyl to N-
heteroaryl groups are available by a convenient one-pot three-
component reaction of diphenylphosphane, the corresponding
primary amine and glyoxylic acid hydrate in a 1:1:1 molar ratio at
room temperature in diethyl ether, in some cases, in methanol. The
N-alkyl compounds are zwitterionic while the N-heteroaryl de-
rivatives bear free amino and COOH groups. The reaction proceeds
the two phenyl groups are diastereoisotopic and give rise to each
two sets of phenyl signals. The proton signals are likewise in-
dicative but the ranges of the PCH proton signals of phosphanyl-
glycines and eglycolates are less clearly separated than the
respective carbon signals, and the PCH proton signals disappear in
CD3OD by H-D exchange. The 31P signals alone do not prove the
structure, but the different ranges of the phosphorus resonances of
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J. Lach et al. / Tetrahedron xxx (2015) 1e13
7
group some electron withdrawing phosphonium character, may
increase the susceptibility towards thermal decarboxylation as
known from triphenylphosphonio glycolates.1b,35 With this back-
ground it was surprising that heating of a variety of diphenyl-
phosphanylglycines with Ni(COD)2 in the presence of ethylene
furnished medium to highly active ethylene oligomerization cata-
lysts. The high selectivity for formation of linear
a-olefins with
methyl and vinyl end groups is the same as that observed in the
oligomerization with nickel diphenylphosphanylacetate chelate
complexes, suggesting that the catalysts are structurally related
and that the still unexplored P-coordinated transition metal
diphenylphosphanyl glycinates may be more stable and useful also
for other transition metal catalyzed organic transformations. The
description of the synthetic access and the properties of the title
compounds paves the way for such studies.
4. Experimental
4.1. General
All operations were carried out under nitrogen by using Schlenk
techniques. Solvents were dried and distilled before use. Diphe-
nylphosphane was synthesized by cleavage of a phenyl group from
triphenylphosphane with sodium in liquid ammonia and neutral-
ization with excess NH4Cl.36 Other chemicals were used as pur-
chased after degassing in an ultrasound bath under nitrogen.
Solutions of glyoxylic acid hydrate (GAH) in diethyl ether were
prepared in an ultrasound bath without heating. NMR spectra were
recorded on multinuclear FT-NMR spectrometers ARX300 or
Avance II (Bruker) at 300.1 (1H), 75.5 (13C), and 121.5 (31P) MHz.
Fig. 3. Molecular structure of the R-enantiomer of racemic 1h HOCH3 in the crystal
(thermal displacement ellipsoids with 50% probability). Selected bond lengths (A) and
angles (deg): P1eC1 1.923(2), P1eC12 1.831(2), P1eC18 1.832(2), C1eN1 1.440(2),
N1eC3 1.367(2), C1eC2 1.498(2); C1eP1eC18 101.84(8), C12eP1eC18 103.30(8),
C1eP1eC12 104.56(8).
ꢀ
Chemical shifts d are given in ppm and refer to tetramethylsilane for
1H and 13C and to H3PO4 (85%) for 31P or to solvent signals refer-
enced to these standards. Assignments for phenyl nuclei are
denoted by i, o, m and p, those of N-alkyl groups by a, b etc. and of
additional phenyl groups by i0, o0, m0 and p0; for assignment num-
bers in heterocyclic substituents see Scheme 1. Coupling constants
refer to JHH (1H NMR) or JPC 13C NMR) unless stated otherwise.
(
Satellite signals are abbreviated as satl. 31P integral or signal height
ratios refer to AQ¼0.33 s and D1¼2.0 s and are not strictly quan-
titative. Longer NMR measurements were carried out in melt closed
NMR tubes. (Plastic caps proved to be not air-tight and led to slow
oxidation of air sensitive phosphanylglycines and formation of
product mixtures.) Melting ranges (thermal decomposition) were
determined with a Sanyo Gallenkamp melting point apparatus,
elemental analysis with a CHNS-932 analyzer from LECO using
standard conditions.
4.2. Three-component synthesis of N-substituted
diphenylphosphanylglycines
4.2.1. Diphenylphosphanyl(propylamino)acetic acid (1a). Glyoxylic
acid hydrate (0.50 g, 5.43 mmol) was dissolved in diethyl ether
(7 mL) and added at room temperature to a solution of Ph2PH (1.0 g,
5.37 mmol) and n-propylamine (0.44 mL, 5.35 mmol) in diethyl
ether (15 mL). Precipitation started after few minutes. After stirring
overnight (z15 h) the mixture was separated, the precipitate
washed with diethyl ether and dried under vacuum to yield 1.2 g
(74%) of 1a as white powder. Crystallization from methanol fur-
nished colorless needles of 1a$MeOH, mp. 85e92 ꢁC (dec).
Figure with crude structure in the crystal see Supplementary data.
Anal. Calcd for C17H20NO2P∙CH3OH (333.36): C, 64.85; H, 7.26; N,
Fig. 4. Inter- and intramolecular hydrogen bonds (dashed lines) within and between
the molecules within crystals of 1b 1.43 HOCH3.
via organoammonium diphenylphosphanylglycolates, which, ex-
cept for very bulky or very strongly electron withdrawing N-sub-
stitutents, undergo further condensation to the title compounds. N-
Primary and N-tertiary diphenylphosphanylglycines could not yet
be obtained. Heating cannot be used to enforce the condensation
because of easy thermal cleavage of CO2. The electron-lone pair at
phosphorus, despite a much weaker base to protons than the amino
group, make the title compounds susceptible to various cleavage
reactions and lowers the stability of the diphenylphosphanylgly-
4.20. Found: C, 64.57; H, 7.31; N, 4.19. 1H NMR ([D8]THF):
d
¼0.86 (t,
3J¼7.4 Hz, 3H, CH3), 1.43 (qd, 3J¼7.2, 5JPH¼3.8 Hz, 2H, CH2), 2.45 (dt,
2J¼11.0, 3J¼7.1 Hz,1H, NCHA), 2.65 (dt, 2J¼11.0, 3J¼6.9 Hz,1H, NCHB),
4.00 (d, 2JPH¼2.8 Hz, 1H, PCH), 4.8 (vbr s, 3H, 2 OH, NH), 7.22e7.32
(m, 6H, Ph), 7.40e7.60 (m, 4H, Ph); 3.26 (s, 3H, MeOH). 13C{1H} and
cines considerably compared to classic a-amino acids. The blockage
of the P-lone pair by coordination of other electrophiles, e.g. BH3,
sulfur or transition metal fragments, which lends the phosphanyl
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8
J. Lach et al. / Tetrahedron xxx (2015) 1e13
DEPT-135 NMR ([D8]THF):
d
¼12.09 (CH3), 23.97 CH2), 52.08 (d,
to a solution of Ph2PH (1.0 g, 5.37 mmol) and tert-butylamine
(0.56 mL, 5.34 mmol) in diethyl ether (20 mL). Precipitation started
immediately. NMR monitoring of a sample filtered after 10 min
3J¼8.4 Hz, NCH2), 63.59 (d, 1J¼13.9 Hz, PCH), 128.64 (d, 3J¼6.1 Hz, 2
m-CHA), 128.73 (d, 3J¼8.3 Hz, 2 m-CHB), 129.25 (p-CHA), 129.84 (p-
CHB),133.76 (d, 2J¼17.2 Hz, 2 o-CHA),135.45 (d, 2J¼21.2 Hz, 2 o-CHB),
133.79 (d, 1J¼17.8 Hz, i-CqA), 133.91 (d, 1J¼18.2 Hz, i-CqB), 173.96
(noise level, d, 2J¼9.1 Hz, COO); 49.84 (MeOH). 31P{1H} NMR ([D8]
THF): dA¼ꢀ0.8.
displayed the phosphorus resonance in CD3OD solution at
d
¼8.0 (in
[D8]THF
d
¼6.5), corresponding to 2c.18b After stirring for 24 h the
precipitate was filtered, washed with diethyl ether and dried under
vacuum. Crystallization from a small amount of methanol furnished
1.50 g (83%) colorless needles of 1c$MeOH. Anal. Calcd for
4.2.2. Diphenylphosphanyl(isopropylamino)acetic acid (1b). A solu-
tion of Ph2PH (1.0 g, 5.37 mmol) and isopropylamine (0.46 mL,
5.40 mmol) in diethyl ether (10 mL) was added at room tempera-
ture to an ethereal solution of GAH (0.50 g, 5.43 mmol). Stirring for
24 h provided a white precipitate, which was separated by filtra-
tion, was washed twice with diethyl ether and dried in vacuum,
yielding 1.4 g (85%) of 1b as white powder. Anal. Calcd for
C
18H22NO2P∙CH3OH (347.40): C, 65.69; H, 7.54; N, 4.03. Found: C,
65.39; H, 7.57; N, 3.93. IR (KBr):
n
¼3378 (st), 2981 (st), 2874 (m),
2482 (m),1643 (vst) cmꢀ1. 1H and CHeCOSY NMR ([D8]THF, ref. THF
d
1.72):
d
¼0.95 (s, 9H, CMe3), 4.11 (d, 2JPH¼2.7 Hz, 1H, CH), 4.4e5.2
(s br, 3H, OH, NH), 7.22e7.32 (m, 6H, Ph), 7.41e7.48 (m, 2H, Ph),
7.53e7.61 (m, 2H, Ph); 3.26 (s, 3H, MeOH). 13C{1H} NMR ([D8]THF):
d
¼29.39 (s, CH3), 52.47 (d, 3J¼9.3 Hz, CMe3), 58.09 (d, 1J¼12.3 Hz,
3
C
17H20NO2P (301.32): C, 67.76; H, 6.69; N, 4.65. Found: C, 67.76; H,
PCH), 128.41 (d, 3J¼5.5 Hz, 2 m-CHA), 128.55 (d, JPC¼7.6 Hz, 2 m-
CHB), 129.00 (s, 2 p-CH), 134.21 (d, 2J¼18.3 Hz, 2 o-CHA), 135.58 (d,
2J¼21.3 Hz, 2 o-CHB), 136.80 (d, 1J¼17.2 Hz, i-CqA), 138.10 (d,
6.73; N, 4.61. Compound 1b was easily soluble in methanol and
crystallized in form of less soluble colorless needles of 1b$MeOH,
mp. 93e101 ꢁC (dec). Crystal data are compiled in Table 2, selected
1J¼18.1 Hz, i-CqB), 175.83 (d, 2J¼12.4 Hz, COOH); 49.76 (MeOH). 31
P
bond lengths and angles in Fig. 2. 1b. IR (KBr):
3386 (st), 2651 (m), 2525 (m), 2409 (m), ca. 1640 (sh), 1615 (vst)
n
¼3502 (vst, OH),
{1H} NMR ([D8]THF):
d
¼3.1. MS (EI, 70 eV, 260 ꢁC): m/z (%)¼315 (7)
[Mþ], 270 (0.5) [MþꢀCOOH], 187 (43), 186 (68) [Ph2PHþ], 185 (44),
cmꢀ1.1b$MeOHe1H NMR ([D8]THF):
d
¼0.98 (d, 3J¼6.2 Hz, 6H, CH3),
183 (53), 108 (38), 107 (81), 106 (71), 84 (25), 75 (100).
2.76 (hept d, 3J¼6.2, JPH¼0.7 Hz, 1H, CH), 4.15 (d, JPH¼3.1 Hz, 1H,
PCH), 4.4e5.6 (sbr, 2H, OH, NH), 7.23e7.33 (m, 6H, Ph), 7.47e7.62
(m, 4H, Ph); 3.26 (s, 3H, MeOH). 13C{1H} and DEPT-135 NMR ([D8]
During longer NMR measurement or storage of the solution in
[D8]THF at 22e25 ꢁC 1c$MeOH underwent slow decarboxylation,
indicated by formation of 4c (15, 40, 57% after 3 h, 1 d, 7 d by in-
tegration of 31P signals). In CDCl3 solution the decarboxylation was
faster (ca. 70% during sample preparation and slight warming for
4
2
THF):
d
¼22.13, 24.05 (CH3), 49.18 (d, 3J¼9.2 Hz, NCH), 61.20 (d,
1J¼14.1, PCHN), 128.64, 128.74 (superimposed doublets, 3J¼6.5,
8.0 Hz, 2 m-CHA, 2 m-CHB), 128.98 (p-CHA), 129.94 (p-CHB), 133.75
(d, 2J¼17.4 Hz, two o-CHA), 135.54 (d, 2J¼21.4 Hz, 2 o-CHB), 136.99
(d, 1J¼14.6 Hz, i-CqA), 138.14 (d, 1J¼18.1 Hz, i-CqB), 174.03 (d,
dissolution). 4ce1H NMR (CDCl3, 7.27):
d¼1.08 (s, 9H, CMe3), 3.31
2
(d, JPH¼1.4 Hz, 2H, PCH2N), 7.28 (br, evtl. NH), 7.32e7.37 (m, 6H,
Ph), 7.43e7.60 (m, 4H, Ph). 13C{1H} and DEPT-135 NMR (CDCl3):
2J¼12.8 Hz, COO); 49.85 (MeOH). 31P{1H} NMR in [D8]THF
d¼ꢀ0.2;
d
¼28.52 (s, CMe3), 42.54 (d, 1J¼4.6 Hz, NCH2), 51.65 (d, 3J¼10.5 Hz,
in CD3OD
d
¼ꢀ1.9.
CMe3), 128.45 (3J¼6.2 Hz, m-CH), 128.70 (s, p-CH), 132.86 (d,
2J¼18.5 Hz, o-CH), 137.41 (d, 1J¼13.3 Hz, i-C). 31P{1H} NMR (CDCl3):
4.2.3. tert-Butylamino(diphenylphosphanyl)acetic acid (1c). A solu-
tion of GAH (0.50 g, 5.43 mmol) in diethyl ether (10 mL) was added
d
¼ꢀ16.6. These NMR data are in good accordance with those of 4c,
prepared from Ph2PCH2OH and tBuNH2.37 Air oxidation led slowly
Table 2
Crystal and structure refinement data for 1b$1.43MeOH and 1h$MeOH. 1b$1.43MeOH contains two crystallographic sites, which are occupied with methanol molecules. One
position is fully occupied. The methanol molecules on this site are connected with 1b by hydrogen bonds while the other site is not fully occupied and the methanol molecule is
disordered and does not form hydrogen bonds
1b
1h
Empirical formula
Formula weight
Temperature
Wavelength
Crystal system
Space group
C
18.43H25.72NO3.43
P
C24H23N2O3P
418.41
347.13
173(2) K
0.71073 A
Monoclinic
P21/n
173(2) K
ꢀ
ꢀ
0.71073 A
Monoclinic
P21/c
ꢀ
ꢀ
Unit cell dimensions
a¼12.7797(9) A
a¼9.2122(4) A
ꢀ
ꢀ
b¼9.9828(6) A
b¼11.4288(4) A
b
¼96.112(4)ꢁ
b
¼90.505(1)ꢁ
ꢀ
ꢀ
c¼15.0121(9) A
c¼19.9939(8) A
3
ꢀ
3
ꢀ
Volume
Z
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
1904.3(2) A
4
2105.06(1) A
4
1.220 g/cm3
0.162 mmꢀ1
750
1.320 g/cm3
0.159 mmꢀ1
880
0.58ꢃ0.41ꢃ0.39 mm3
0.15ꢃ0.07ꢃ0.06 mm3
2.21e27.95ꢁ
2.71e28.26ꢁ
ꢀ16 ꢄ h<¼16,
ꢀ12 ꢄ h<¼12,
ꢀ15 ꢄ k<¼12,
ꢀ26 ꢄ l<¼25
18,663
ꢀ13 ꢄ k<¼12,
ꢀ19 ꢄ l<¼19
Reflections collected
34,165
Independent reflections
Absorption correction Max. and min transmission
Refinement method
4562 [R(int)¼0.0362]
Multiscan (SADABS) 0.9394 and 0.9117
Full-matrix least-squares on F2
4562/0/225
5213 [R(int)¼0.0559]
0.9905 and 0.9765
Full-matrix least-squares on F2
5213/0/287
Data/restraints/parameters
Goodness-of-fit on F2
1.043
0.980
Final R indices [I>2sigma(I)]
R indices (all data)
Largest diff. peak and hole
R1¼0.0464, wR2¼0.1208
R1¼0.0469, wR2¼0.0921
R1¼0.0635, wR2¼0.1289
R1¼0.0963, wR2¼0.1028
ꢀꢀ3
ꢀꢀ3
0.744e0.528 e$A
0.329e0.297 e$A
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J. Lach et al. / Tetrahedron xxx (2015) 1e13
9
to Ph2P(O)CH2NHtBu, 1H NMR(CDCl3):
d
¼1.07 (tBu), 3.40 (d,
was washed with hexane, and the residue crystallized from
methanol. Drying under vacuum gave 1.7 g (91%) white solid, mp.
121e122 ꢁC (dec). Anal. Calcd for C27H24NO2P (425.47): C, 76.22; N,
2JPH¼9.9 Hz, PCH2N), 7.20e7.87 (m, 10H, Ph); 31P NMR (CDCl3):
d¼31.1.
3.29. Found: C, 76.34; N, 3.33. 1H NMR ([D8]THF):
d
¼3.98 (d,
4.2.4. Diphenylphosphanyl(n-hexylamino)acetic acid (1d). A solu-
tion of GAH (500 mg, 5.43 mmol) in diethyl ether (10 mL) was
added to a solution of Ph2PH (1.0 g, 5.37 mmol) and n-hexylamine
(0.70 mL, 0.54 g, 5.34 mmol) in diethyl ether (20 mL). An initial
precipitate dissolved rapidly. The product precipitated slowly (2 d,
ca. 20 ꢁC), was filtered, washed with ether and dried under vacuum,
yield 1.6 g (82%) of white powder. Compound 1d was sparingly
soluble in THF or CDCl3 and decomposed on heating in these sol-
vents, but it was easily soluble in CD3OD. Crystallization from
2JPH¼2.4 Hz, 1H, PCH), 4.86 (s, 1H, NCH), 7.05e7.35 (m, 16H, Ph),
7.45e7.55 (m, 4H, Ph). 13C{1H} NMR ([D8]THF):
d
¼60.61 (d,
1J¼16.5 Hz, PCH), 67.15 (d, 3J¼9.8 Hz, NCH), 127.54, 127.74 (2 p-CH,
Ph2C), 127.77, 128.85, 128.91, 128.96 (2 o- and 2 m-C, Ph2C), 128.66
(d, 3J¼7.3 Hz, m-CA), 128.73 (d, 3J¼6.6 Hz, m-CB), 129.40 (p-CA),
129.74 (p-CB), 134.41 (d, 2J¼19.3 Hz, o-CA), 135.11 (d, 2J¼21.0 Hz, o-
CB), 136.31 (d, 1J¼15.4 Hz, i-CA), 136.75 (d, 1J¼17.3 Hz, i-CB), 143.24,
145.22 (2 i-Cq, Ph2C), 173.56 (d, 2J¼11.4 Hz, COOꢀ). 31P{1H} NMR
([D8]THF):
d
¼1.8; storage of the solution led to slow de-
a
small amount of methanol provided
a
methanol solvate
carboxylation, indicated by slowly increasing signals at
d¼ꢀ18
1d$MeOH, mp. 104e108 ꢁC (dec), which was also soluble in [D8]
THF. 1d: Anal. Calcd for C20H26NO2P (343.40): C, 69.95; H, 7.63; N,
4.08. Found: C, 70.39; H, 7.44; N, 3.96. 1d$MeOHe1H NMR ([D8]
andꢀ28.
NMR spectra of a solution of 1f in CDCl3, prepared with slight
warming (30e35 ꢁC), displayed 57%, repeated measurements after
2 d quantitative decarboxylation, leading mainly to 4f, a minor
amount of (Ph2PCH2)2NCHPh2 with very similar 31P and PCH2
proton chemical shifts as reported for (Ph2PCH2)2NPh38 and a trace
THF):
d
¼0.87 (m, 3H, CH3), 1.20e1.48 (m, 8H, CH2), 2.48 (dt, 2J¼11.0,
3J¼6.7 Hz, 1H, NCHA), 2.68 (dt, 2J¼11.0, 3J¼6.7 Hz, 1H, NCHB), 4.00
(d, 2JPH¼2.9 Hz, 1H, PCH), 7.22e7.32 (m, 6H, Ph), 7.42e7.60 (m, 4H,
Ph); 3.26 (s, 3H, MeOH), NH, OH (vbr). 13C{1H} NMR ([D8]THF):
of Ph2PH (80:17:3% by 31P integration). 4fe1H NMR (CDCl3):
2
d
¼14.40 (CH3), 23.53 (CH2), 27.82 (CH2), 30.88 (CH2), 32.67 (CH2),
d
¼2.2e2.8 (vbr. NH), 3.33 (d, JPH¼3.3 Hz, PCH2N), 4.97 (br, NCH),
50.14 (d, 3J¼8.9 Hz, NCH2), 63.60 (d, 1J¼15.2 Hz, PCH), 128.65 (d,
3J¼6.5 Hz, m-CA), 128.75 (d, 3J¼8.0 Hz, m-CB), 128.99 (p-CA), 129.86
(p-CB), 133.80 (d, 2J¼17.5 Hz, o-CA), 135.45 (d, 2J¼21.3 Hz, o-CB),
173.8 (d, 2Jz9 Hz, COO, noise level); i-Cq at noise level, 49.85
7.10e7.50 (m, 20H, 4 Ph). 13C{1H} NMR (CDCl3):
d
¼47.89 (d,
1J¼9.1 Hz, PCH2N), 68.40 (d, 3J¼11.5 Hz, NCHPh2), 127.06 (2 p0-CH),
127.39, 128.43 (4 o0-CH, 4 m0-CH), 128.21 (d, 3J¼7.2 Hz, 4 m-CH),
128.69 (2 p-CH),132.95 (d, 2J¼17.4 Hz, 4 o-CH),137.10 (d, 1J¼12.4 Hz,
(MeOH). 31P{1H} NMR ([D8]THF):
d
¼ꢀ0.7. 1H NMR (CD3OD):
d¼0.99
2
i-Cq), 143.8 (2 i0-Cq). 31P{1H} NMR (CDCl3):
d
¼ꢀ18.8.
(m, 3H, Me), 1.32e1.36 (m, 6H, 3 CH2), 1.64 (m, 2H, CH2), 3.00 (td,
(Ph2PCH2)2NCHPh2e1H NMR (CDCl3):
d
¼3.75 (br, PCH2N), Ph
3J¼8.0, JPH¼0.6 Hz, 2H, NCH2), 4.38 (br s, 0.9H, PCH), 7.28e7.35,
superimposed. 13C{1H} NMR (CDCl3):
d
¼128.21 (d, 3J¼7.2 Hz, m-
4
7.42e7.50 (m, 13H, Ph, OH, NH). 13C{1H} NMR and DEPT-135
CH), 128.63 (p-CH), 133.35 (d, 2J¼18.5 Hz, o-CH), 137.7 (d, 1Jz12 Hz,
(CD3OD):
d
¼14.26 (CH3), 23.45, 27.13, 27.34, 32.39 (CH2), 49.75
i-Cq); (PCH2N broad, within noise). 31P{1H} NMR (CDCl3):
d¼ꢀ28.8.
(NCH2), 64.90 (d, 1J¼28.1 Hz, PCH), 129.37 (d, 3J¼7.9 Hz, m-CHA),
129.98 (d, 3J¼7.9 Hz, m-CHB), 130.56 (p-CHA), 131.02 (p-CHB), 135.07
(d, 2J¼20.6 Hz, o-CHA), 135.49 (d, 2J¼22.3 Hz, o-CHB), 169.76 (COO);
4.2.7. Diphenylphosphanyl(2-pyrid-2-yl-ethylamino)acetic acid (1g).
A solution of GAH (0.35 g, 3.8 mmol) in diethyl ether (7 mL) was
added to a solution of Ph2PH (0.70 g, 3.76 mmol) and 2-(2-pyridyl)
ethylamine (0.46 g, 3.76 mmol) in diethyl ether (30 mL). After stir-
ring for 15 h the precipitate was separated, washed with a small
amount of ether and dried under vacuum to give 0.90 g (65%) white
powder. Crystallization from MeOH furnished the methanol solvate
1g$MeOH. Anal. Calcd for C21H21N2O2P∙CH3OH (396.42): C, 66.66;
H, 6.36; N, 7.07. Found: C, 66.71; H, 6.16; N, 7.08. 1H NMR and
i-Cq at noise level. 31P{1H} NMR (CD3OD):
d
¼ꢀ2.2.
4.2.5. Diphenylphosphanyl(2-methoxybenzylamino)acetic acid (1e).
A solution of Ph2PH (1.0 g, 5.37 mmol) and (2-methoxyphenyl)
methylamine (0.74 g, 5.39 mmol) in diethyl ether (10 mL) was
added at room temperature to a solution of GAH (0.50 g,
5.43 mmol) in diethyl ether. After stirring for 24 h the precipitate
was separated, washed with ether and dried to give 1.11 g (54%)
white powder. Crystallization from MeOH afforded colorless nee-
dles of 1e$0.6 MeOH. Anal. Calcd for C22H22NO3P$0.6 CH3OH
(398.62): C, 68.10; H, 6.17; N, 3.54. Found: C, 67.85; H, 5.74; N, 3.51.
H,HeCOSY ([D8]THF):
d
¼2.80e3.13 (m, 4H, CH2), 4.04 (d,
2JPH¼3.0 Hz, 1H, PCH), 5.1 (s br, 3H, NH, OH), 7.06 (ddd, 3J¼7.5, 4.8,
4J¼1.5 Hz, H-5), 7.11 (d, 3J¼7.5 Hz, H-3), 7.17e7.32 (m, 6H, Ph),
7.37e7.47 (m, 2H, Ph), 7.49e7.57 (m, 3H, H-4, Ph), 8.41 (ddd, 3J¼4.8,
4J¼1.5 Hz, 1H, H-6); 3.26 (s, 3H, MeOH). 13C{1H} NMR and DEPT-135
IR (KBr):
n
¼3540 (st, OH), 3058 (m), 2956 (m), 2496 (m), 1641 (vst),
1364 (st), 1250 (st), 750 (st) cmꢀ1
.
1H NMR ([D8]THF):
d
¼3.68 (d,
([D8]THF):
d
¼39.18 (CH2), 49.67 (d, 3J¼8.8 Hz, NCH2), 63.78 (d,
2J¼13.2 Hz, 1H, NCH2A), 3.73 (s, 3H, OMe), 3.83 (d, 2J¼13.2 Hz, 1H,
NCH2B), 4.07 (d, 2JPH¼1.8 Hz,1H, PCH), 5.32 (br s, 2.6H, NH2, 0.6 OH),
6.77e6.86 (m, 2H, 3-H, 5-H), 7.10e7.32 (m, 8H, 4-H, 6-H, Ph),
7.42e7.55 (m, 4H, Ph); 3.26 (s, 2H, 0.6 MeOH). 13C{1H} and DEPT-
1J¼15.3 Hz, PCHN), 121.55 (3-CH), 123.78 (5-CH), 128.45 (d,
3J¼6.5 Hz, 2 m-CH), 128.65 (d, 3J¼7.5 Hz, 2 m-CH), 128.81 (p-CH),
129.66 (p-CH), 133.83 (d, 2J¼18.1 Hz, 2 o-CH),135.32 (d, 2J¼21.1 Hz, 2
o-CH), 136.44 (4-CH), 137.13 (d, 1J¼19 Hz, i-Cq), 138.0 (d, 1Jz18 Hz, i-
Cq), 149.80 (6-CH), 161.31 (2-Cq), 173.89 (br, COOH); 49.77 (MeOH).
135 NMR ([D8]THF):
d
¼48.70 (d, 3J¼8.5 Hz, CH2), 55.40 (s, 2-
OCH3), 62.92 (d, 1J¼15.5 Hz, PCH), 110.78 (3-CH), 120.81 (s, 5-CH),
128.66 (d, 3J¼6.2 Hz, 2 m-CHA), 128.70 (superimp. s, 4- or 6-CH),
128.75 (d, 3J¼6.9 Hz, 2 m-CHB), 128.96 (1-Cq), 129.02 (s, 4- or 6-CH),
129.68 (p-CHA), 130.30 (p-CHB), 134.08 (d, 2J¼18.4 Hz, 2 o-CHA),
135.23 (d, 2J¼20.6 Hz, 2 o-CHB), 137.15 (d, 1J¼15.9 Hz, i-CqA), 137.80
(d, 1J¼18.3 Hz, i-CqB), 158.64 (2-Cq), 173.73 (d, 2J¼9.4 Hz, COOH);
31P{1H} NMR ([D8]THF):
d¼ꢀ0.3. (NMR spectra in CD3OD, indicating
H-D exchange from PCH to see Supplementary data.)
4.2.8. Diphenylphosphanyl(quinolin-3-ylamino)acetic acid (1h). A
solution of Ph2PH (1.0 g, 5.37 mmol) and 3-aminoquinoline (0.78 g,
5.40 mmol) in diethyl ether (10 mL) was added to a solution of GAH
(0.50 g, 5.40 mmol) in diethyl ether (10 mL). After stirring for 24 h
the precipitate was separated, washed with ether and dried under
vacuum to give 1.80 g (86%) yellow powder, mp. 130e135 ꢁC (dec).
Anal. Calcd for C23H19N2O2P (386.12): C, 71.50; H, 4.96; N, 7.25.
Found: C, 71.50; H, 4.66; N, 7.26. Crystallization from methanol
furnished yellow crystals of the methanol solvate. Crystal data of
1h$MeOH are compiled in Table 2, selected bond lengths and angles
49.84 (0.6 MeOH). 31P{1H} NMR ([D8]THF):
d
¼ꢀ0.2.
4.2.6. Benzhydrylamino(diphenylphosphanyl)acetic acid (1f). A so-
lution of GAH (403 mg, 4.38 mmol), dissolved in diethyl ether
(10 mL), was added to a solution of Ph2PH (815 mg, 4.38 mmol) and
Ph2CHNH2 (0.76 mL, 4.38 mmol) in diethyl ether (20 mL). A sticky
precipitate initially formed dissolved during stirring overnight. The
solvent and water was removed in vacuum. The remaining foam
in Fig. 3. IR (KBr):
n
¼3415 (st), 3049 (m), 2428 (wm br), 1706 (st)
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10
J. Lach et al. / Tetrahedron xxx (2015) 1e13
cmꢀ1. 1H NMR ([D8]THF):
d
¼4.94 (d, 2JPH¼9.4 Hz, 1H, PCH), 5.89 (br
114.30 (s, 5-CH), 129.03 (s, 2 p-CH), 129.16 (d, 3J¼6.6 Hz, 4 m-CH),
133.66 (d, 2J¼18.3 Hz, 4 o-CH), 138.88 (d, 1J¼15.6 Hz, 2 i-Cq), 147.81
(s, 6-CH), 147.9 (s, 4-Cq), 159.77 (br, 2-Cq). 31P{1H} NMR ([D8]THF):
3
d, JPH¼9.2 Hz, 1H, NH), 7.04 (d, 4J¼2.8 Hz, 1H, 4-H), 7.14e7.25 (m,
8H), 7.40e7.50 (m, 5H), 7.65e7.72 (m, 1H), 8.38 (d, 4J¼2.8 Hz, 1H, 2-
H); 3.15 (s, 3H, MeOH). 13C{1H} NMR ([D8]THF, DEPT-135):
d¼57.84
d¼ꢀ18.4.
(d, 1J¼18.9 Hz, PCH), 111.32 (s, 4-CH), 125.23, 126.70, 127.17 (3s, 5-
CH, 6-CH, 7-CH), 128.92 (d, 3J¼7.0 Hz, 2 m-CHA), 129.16 (d,
3J¼6.5 Hz, 2 m-CHB), 129.51 (s, p-CHA), 129.59 (s, p-CHB), 130.21 (s,
8-CH), 130.33 (s, 10-Cq), 133.67 (d, 2J¼18.8 Hz, 2 o-CHA), 135.25 (d,
2J¼21.2 Hz, 2 o-CHB), 135.90 (d, 1J¼15.9 Hz, i-CqA), 136.81 (d,
1J¼17.2 Hz, i-CqB), 142.07 (d, 3J¼6.8 Hz, 3-Cq), 143.05 (s, 9-Cq),
144.44 (s, 2-CH), 171.96 (d, 2J¼9.2 Hz, COOH); 49.78 (MeOH). 31P
4.2.11. 2-Pyridylammonium
diphenylphosphanyl(hydroxy)acetate
(2k) and diphenylphosphanyl-(pyridin-2-ylamino)-acetic acid
(1k). A solution of GAH (0.50 g, 5.43 mmol) in diethyl ether (10 mL)
was added to a solution of Ph2PH (1.0 g, 5.37 mmol) and 2-
aminopyridine (0.50 g, 5.31 mmol) in diethyl ether (15 mL). Pre-
cipitation started after few minutes. After stirring overnight the
precipitate was separated, washed with a small amount of ether
(15 h) and dried under vacuum to give 1.38 g (73%) of 2k. Anal.
Calcd for C19H19N2O3P (354.34): C, 64.40; H, 5.40; N, 7.91. Found: C,
64.35; H, 5.20; N, 7.83. In [D8]THF solution, ca. 2 h after sample
preparation), a mixture of 2k, 3k and 1k was formed, ratio ca.
13:66:17 (by 31P NMR integral. The amount of 1k increased at the
expense of 2k, after 6 h and during 10 h measuring time to 45:55
(by 13C NMR integration of the PCH signal). 2ke1H NMR ([D8]THF):
{1H} NMR ([D8]THF):
d
¼ꢀ0.6.
4.2.9. Diphenylphosphanyl(quinolin-8-ylamino)acetic acid (1i). A
solution of GAH (0.30 g, 3.26 mmol) in diethyl ether (15 mL) was
added to a solution of Ph2PH (0.60 g, 3.22 mmol) and 8-
aminoquinoline (0.46 g, 3.19 mmol) in diethyl ether (3 mL). The
yellow precipitate formed during stirring overnight was separated,
washed with ether and dried under vacuum. Crystallization from
methanol provided 0.81 g (60%) of the yellow methanol solvate,
mp. 125e130 ꢁC (dec). Anal. Calcd for C23H19N2O2P∙CH3OH
(418.14): C, 68.89; H, 5.54; N, 6.69. Found: C, 68.88; H, 5.57; N, 6.68.
d
¼5.00 (d, 1JPH¼1.8 Hz, 1H, PCH), 4.9e5.6 (s br, NH, OH), 6.46e6.52
(m, 2H, 3-H, 5-H), 7.21e7.32 (m, 6H, Ph), 7.36e7.62 (m, 5H, Ph, 4-H),
7.80 (m, 1H, 6-H); 3.26 (MeOH). 13C{1H} NMR and DEPT-135 ([D8]
IR (KBr):
([D8]THF):
n
¼3415 (st), 3049 (m), 2410 (br), 1705 (st) cmꢀ1. 1H NMR
THF):
d
¼73.41 (d, 1J¼25.4 Hz, PCHO), 110.03 (s, 3-CH), 113.54 (s, 5-
d
¼5.11 (d, 2JPH¼9.0 Hz, 1H, PCHN), 6.69 (br d, 3J¼7.4 Hz,
CH), 128.58 (d, 3J¼5.9 Hz, m-CHA), ca. 128.75 (superimposed d,
3J¼6.7 Hz, m-CHB), 129.12 (s, p-CHA), 129.21 (s, p-CHB), 134.75 (d,
2J¼19.2 Hz, o-CHA), 134.96 (d, 2J¼19.2 Hz, o-CHB), 139.49 (br, 4-CH),
144.56 (br, 6-CH), 159.55 (br, 2-Cq); i-Cq and COOH at noise level).
1H, H-7), 7.01 (br dd, J¼8.8, 1.3 Hz, 1H, NH), 7.03 (dd, 3J¼8.2,
4J¼1.0 Hz, 1H, H-5), 7.22e7.37 (m, 8H, H-3, H-6, Ph), 7.49e7.69 (2m,
4H, Ph), 8.02 (dd, 3J¼8.3, 4J¼1.7 Hz, 1H, H-4), 8.60 (dd, 3J¼4.2,
4J¼1.7 Hz, 1H, H-2); 3.25 (s, MeOH). 13C{1H} and DEPT-135 NMR
31P{1H} NMR ([D8]THF):
1ke13C{1H} and DEPT-135 NMR (D8-THF):
d
¼5.0.
(D8-THF):
d
¼57.41 (d, 1J¼22.2 Hz, PCHN), 106.42 (s, 7-CH), 115.44 (s,
d
¼54.78 (d,
5-CH), 122.13 (s, 3-CH), 128.13 (s, 6-CH), 128.93 (d, 3J¼7.4 Hz, 2 m-
CHA), 129.14 (d, 3J¼6.5 Hz, 2 m-CHB), 129.51 (s, 10-Cq), 129.62 (s, p-
CHA), 129.97 (s, p-CHB), 134.12 (d, 2J¼19.3 Hz, 2 o-CHA), 134.91 (d,
2J¼20.4 Hz, 2 o-CHB), 136.15 or 136.20 (d, 1J¼13.2 or 17.1 Hz, i-CqA),
136.26 (s, 4-CH), 136.36 or 136.41 (d, 1J¼18.4 or 14.6 Hz, i-CqB),
139.43 (s, 9-Cq), 144.24 (d, 3J¼5.0 Hz, 8-Cq), 147.69 (s, 2-CH), 171.71
(d, 2J¼7.9 Hz, COOH); 49.83 (s, MeOH). 31P{1H} NMR ([D8]THF):
1J¼20.8 Hz, PCHN), 110.15 (d, 4J¼9.3 Hz, 3-CH), 112.33 (s, 5-CH),
128.75 (superimposed d, 3J¼6.7 Hz, m-CHA), 128.92 (d, 3J¼6.6 Hz,
m-CHB), 129.40 (s, p-CHA), 129.64 (s, p-CHB), 133.74 (d br,
1J¼18.0 Hz, i-CqA), 134.28 (d, 2J¼19.7 Hz, o-CHA), 134.89 (d,
2J¼21.1 Hz, o-CHB), 137.06 (d br, 1J¼18.0 Hz, i-CqB), 137.17 (s, 4-CH),
148.16 (s, 6-CH), 158.77 (d, 3J¼4.0 Hz, 2-Cq), 172.78 (d, 2Jz9 Hz,
COOH). 31P{1H} NMR ([D8]THF):
d¼1.2.
d¼1.4.
4.2.12. 4,6-Dimethylpyrimid-2-ylammonium
diphenylphospha-
4.2.10. Diphenylphosphanyl(4-methylpyrid-2-ylamino)acetic
acid
nyl(hydroxy)acetate (2l) and detection of diphenylphosphanyl(4,6-
dimethyl-pyrimid-2-ylamino)acetic acid (1l). A solution of Ph2PH
(1.0 g, 5.37 mmol) and 4,6-dimethylpyrimidin-2-ylamine (0.66 g,
5.40 mmol) in diethyl ether (20 mL) was added to a solution of GAH
(0.50 g, 5.43 mmol) in diethyl ether (10 mL). Precipitation started
after ca. 15 h. Stirring was continued for 1 d, the precipitate sepa-
rated, washed with diethyl ether and dried under vacuum, yielding
1.46 g (74%) 2l. Anal. Calcd for C20H20N2O3P (365.37): C, 65.75; H,
5.52; N, 11.50. Found: C, 65.32; H, 5.76; N, 11.50. 1H NMR ([D8]THF):
(1j). A solution of GAH (0.50 g, 5.43 mmol) in diethyl ether (10 mL)
was added to a solution of Ph2PH (1.0 g, 5.37 mmol) and 4-methyl-
pyridin-2-ylamine (0.58 g, 5.36 mmol) in diethyl ether (15 mL).
Precipitation startet after few minutes. Filtration after stirring
overnight, washing the precipitate with ether and drying under
vacuum gave 1.60
g (84%) white powder. Anal. Calcd for
C
20H19N2O2P (350.35): C, 68.56; H, 5.47; N, 8.00. Found: C, 68.55; H,
5.55; N, 8.11. Crystallization from methanol provided colorless
needles of the methanol solvate 1j$MeOH. 1H NMR ([D8]THF):
d
¼2.16 (s, 6H, 2-Me, 6-Me), 5.04 (d, 2JPH¼2.6 Hz, 1H, PCHO), 6.22 (s
d
¼2.12 (s, 3H, CH3), 5.72 (br s, PCH), 6.29 (d, 4Jz1 Hz, 1H, 3-H), 6.33
br, 2H, NH2), 6.28 (s, 1H, 5-CH), 6.5e7.1 (extremely broad, 2H, NH/
(dd, 3J¼5.2, 4J¼0.9 Hz, 1H, 5-H), 7.23e7.32 (m, 6H, Ph), 7.43e7.56
(m, 4H, Ph), 7.82 (d, 3J¼5.2 Hz,1H, 6-H); 3.25 (s, MeOH). 13C{1H} and
OH), 7.23e7.32, 7.40e7.62 (m, 10H, Ph-H). 13C{1H} and DEPT-135
NMR ([D8]THF):
d
¼23.30 (s, 2 CH3), 75.13 (d, 1J¼24.9 Hz, PCHO),
DEPT-135 NMR ([D8]THF):
d
¼20.82 (s, CH3), 54.64 (d, 1J¼20.6 Hz,
109.36 (s, 5-CH), 128.56 (d, 3J¼7.0 Hz, m-CHA), 128.70 (d, 3J¼7.1 Hz,
m-CHB), 129.25 (s, p-CHA), 129.28 (s, p-CHB), 134.69 (d, 2J¼19.9 Hz, 2
o-CHA), 134.80 (d, 2J¼19.5 Hz, 2 o-CHB), 136.37 (d, 1J¼17.2 Hz, i-CqA),
137.42 (d, 1J¼14.8 Hz, i-CqB), 163.90 (s, 1-Cq), 167.88 (s, 4-Cq, 6-Cq),
PCH), 110.08 (s, 3-CH), 115.23 (s, 5-CH), 128.71 (d, 3J¼7.2 Hz, 2 m-
CHA), 128.86 (d, 3J¼6.6 Hz, 2 m-CHB), 129.34 (s, p-CHA), 129.56 (s, p-
CHB), 134.18 (d, 2J¼19.7 Hz, 2 o-CHA), 134.76 (d, 2J¼20.1 Hz, 2 o-
CHB), 136.94 (d, 1J¼17.3 Hz, i-CqA), 138.88 (d, 1J¼15.6 Hz, i-CqB),
147.78 (s, 6-CH), 147.92 (s, 4-Cq), 158.94 (d, 3J¼4.1 Hz, 2-Cq), 172.58
(d, 2J¼10.6 Hz, COOH); 49.75 (s, MeOH). 31P{1H} NMR ([D8]THF):
175.14 (d, 1JPC¼10.7 Hz, COOH). 31P{1H}-NMR ([D8]THF):
¼4.3.
d
In [D8]THF solution minor amounts of 1l, 3l and 4l were formed,
31P¼2.7, 26.1, ꢀ18.0; by P integration 10, 8, 2% after ca. 2 h). The
(
d
d¼2.4.
content of 1l increased to about 20% during the 13C NMR mea-
NMR spectra of 1j$MeOH in [D8]THF displayed slow de-
surement (10 h). 1le13C{1H} and DEPT-135 NMR ([D8]THF):
carboxylation at 25 ꢁC; after measuring for 12 h the 13C NMR
d
¼23.67 (s, 2 CH3), 54.85 (d, 1J¼25.2 Hz, PCHN), 110.35 (s, 5-CH),
spectrum indicates ca. 30% (by CH signal intensities) of 4j. 1H NMR
128.78 (d, 3J¼7 Hz, m-CHA), 129.03 (d, 3J¼6.7 Hz, m-CHB), 129.51 (s,
p-CHA,B), 134.43 (d, 2J¼18 Hz, 2 o-CHA), 134.56 (d, 2J¼19.9 Hz, 2 o-
CHB), 136.40 (d, 1Jz17 Hz, i-CqA), 137.77 (d, 1Jz17 Hz, i-CqB), 162.37
(s, 1-Cq), 167.63 (s, 4-Cq, 6-Cq), 172.5 (d, 1JPCz7 Hz, COOH). In-
2
([D8]THF):
d
¼2.14 (s, CH3), 4.09 (d, JPH¼3.9 Hz, PCH2N), 6.5 (vbr,
NH), 7.78 (d, 3J¼5.2 Hz, 1H, 6-H); 3-H, 5-H and phenyl proton
signals superimposed. 13C{1H} and DEPT-135 NMR ([D8]THF):
d
¼20.93 (s, CH3), 42.48 (d, 1J¼9.3 Hz, PCH2), 108.89 (s, 3-CH),
dicative for meso/rac-3l are two PCH proton doublets at
d¼5.68 and
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J. Lach et al. / Tetrahedron xxx (2015) 1e13
11
2
5.79 (each JPH¼9 Hz), typically for diphenylphosphonio-
3J¼13.8 Hz, NCH2), 64.93 (d, 1J¼59.3 Hz, PCH), 121.65 (5-CH), 123.83
(3-CH), 128.49 (d, 3J¼12.4 Hz, m-CA), 128.54 (d, 3J¼12.1 Hz, m-CB),
131.89 (d, 4J¼3.0 Hz, p-CA), 131.93 (d, 4J¼3.2 Hz, p-CB), 132.96 (d,
2J¼10.3 Hz, o-CA), 133.10 (d, 2J¼11.2 Hz, o-CB),133.60 (d, 1Jz65 Hz, i-
CA), 133.94 (d, 1J¼66.2 Hz, i-CB), 136.56 (s, 4-CH), 149.76 (s, 6-CH),
161.01 (s, 2-Cq), 169.93 (d, 2J¼4.8 Hz, COOH). 31P{1H} NMR ([D8]
bis(glycolates) 3.18a
4.3. Selected reactions of N-substituted
diphenylphosphanylglycines
4.3.1. Detection of 5c and 6c by air oxidation of 1c. A slow stream of
oxygen, generated by addition of 30% H2O2 on MnO2, was passed
through a drying tube filled with CaCl2 and introduced into a so-
lution of 1c$MeOH in methanol for 1 h. Removal of the solvent
under vacuum and NMR monitoring in CDCl3 displayed formation
of a mixture of Ph2P(O) CH(NHtBu)COOH tBuNHþ3 Ph2P(O)CH(OH)
COOꢀ (5c) and tBuNH3þ Ph2P(O)CH(OH)COO (6c), identified by
THF):
d¼43.9.
In [D8]THF solution minor amounts of the decarboxylation
product 9g were formed (ca. 25% by integration of PCH2/PCH proton
signals). 9ge1H NMR ([D8]THF):
d
¼3.62 (d, 2J¼6.7 Hz, PCH2, 25%);
other signals superimposed. 13C{1H} NMR ([D8]THF):
d
¼37.88 (s,
NCCH2), 51.18 (d, 3J¼13.4 Hz, NCH2), 52.64 (d, 1J¼64.1 Hz, NCH2),
121.70 (5-CH), 123.76 (3-CH), 129.00 (d, 3J¼11.9 Hz, 4 m-CH), 131.61
(d, 4J¼3.6 Hz, 2 p-CH), 132.31 (d, 3J¼10.2 Hz, 4 o-CH), 136.65 (4-CH);
conclusive NMR data. 5ce 1H NMR (CDCl3):
d
¼1.05 (s, CMe3), 4.22
(d, JPH¼15.6 Hz, PCHN). 13C{1H} NMR (CDCl3):
d
¼27.70 (s, Me3C),
i-Cq, 6-CH and 2-Cq superimposed. 31P{1H} NMR ([D8]THF):
d¼38.7
2
54.37 (d, 3J¼9.9 Hz, Me3C), 58.55 (d, 1J¼69.7 Hz, PCHN), 170.08 (s,
(rel intensity 15%).
COOH); aryl-C superimposed). 31P{1H} NMR (CDCl3):
d
¼30.4.
6ce1H NMR (CDCl3):
d
¼1.26 (s, CMe3), 4.84 (d, 2JPH¼5.2 Hz, PCHO).
4.3.4. [{Ph2P(BH3)CH(NHtBu)COO}3Bꢀ(OOC(tBuNH2þ)CHP(BH3)Ph2]
(10c). A solution of H3B$SMe2 in THF (1.5 mL, 1.5 mmol, 2.6 equiv)
was added slowly at 0 ꢁC to a freshly prepared solution of crude 2c
13C{1H} NMR (CDCl3):
d
¼28.00 (s, Me3C), 51.24 (s, Me3C), 71.67 (d,
1J¼79.8 Hz, PCHO), 171.68 (s, COOꢀ). 31P{1H} NMR (CDCl3):
¼32.0.
d
These values are in good accordance with recently published NMR
(
d
31P¼8.1; 200 mg, 0.58 mmol) in THF (10 mL), accompanied to
data of 6c.18a
strong evolution of hydrogen. Then, the mixture was allowed to
warm to room temperature and stirred overnight. Most of the
solvent was removed under vacuum and the residue filtered and
washed with hexane to give 190 mg (96%) white powder, mp.
116e118 ꢁC. Calcd for C72H97B5N4O8P4 (1324.51): C 65.29, H 7.38, N
4.23. Found: C 63.23 (incomplete combustion), H 7.73, N 4.35%. 1H
4.3.2. tert-Butylamino(diphenylphosphinothioyl)acetic acid (7c).
Sulfur (90.5 mg, 2.83 mmol) was added to a solution of 1c$MeOH
(893 mg, 2.57 mmol) in THF (ca. 15 mL). After stirring the mixture at
room temperature for 15 h the solvent was removed in vacuum. The
residual white foam was treated with diethyl ether to give 0.55 g
(62%) of pure 7c, mp. 106e107 ꢁC (dec). DTG/DTA (15e250 ꢁC, 5 K/
NMR (CDCl3):
d
¼0.5e3.5 (br m, ca. 12H, BH3), 1.33 (s, 36H, CMe3),
2
3
4.33 (dd, JPH¼8.2, J¼1.2 Hz, 4H, PCH), 5.61 (d, JPH¼10.5 Hz, 4H,
min, N2):
D
m117 ꢁC 12.7% (eCO2), max.exoth. 116e117 (st), max.-
NH), 7.38e7.55, 7.58e7.74, 8.19e8.28 (m, Ph, NHþ). 13C NMR
endoth. 118e120 (st) ꢁC. 7c is insoluble in D2O, soluble in methanol, in
CDCl3 and in THF. Anal. Calcd for C18H22NO2PS (347.42): C, 62.23; H,
6.38; N, 4.03. Found: C, 61.91; H, 6.36; N, 3.98%. 1H NMR (CDCl3):
(CDCl3):
d
¼25.42 (CMe3), 56.58 (d, 1J¼24.4 Hz, PCHN), 60.40 (d,
3J¼0 3.6 Hz, CMe3), 123.61 (d, 1J¼55.9 Hz, i-Cq), 125.28 (1J¼63.2 Hz, i-
Cq ), 128.74 (3J¼11.3 Hz, m-CH), 129.50 (3J¼11.0 Hz, m-CH0), 132.62
(4J¼2.6 Hz, p-CH), 132.71 (4J¼2.7 Hz, p-CH0), 133.46 (2J¼10.0 Hz, o-
CH), 133.84 (2J¼10.9 Hz, o-CH0), 169.23 (2J¼4.2 Hz, COO). 31P{1H}
d
¼1.28 (s, 9H, CMe3), 4.08 (d, 2JPH¼10.7 Hz, 1H, CH), 7.35e7.73 (m,
8H, Ph), 8.52 (m, JPH¼13.6 Hz, 2H, Ph). 13C{1H} NMR (CDCl3):
3
d
¼27.2 (CMe3), 57.3 (d, 3J¼3.4 Hz, CMe3), 57.5 (d, 1J¼39.7 Hz, PCH),
NMR (CDCl3):
d
¼25.8 (br d appearance of overlayered multiplets
128.4 (d,3J¼13.4 Hz, m-CH), 128.6 (d, 1J¼87.5 Hz, i-C), 129.0
(d,3J¼13.2 Hz, m-CH0), 129.2 (d, 1J¼85.2 Hz, i-C0), 132.1 (d,
2J¼11.3 Hz, o-CH), 132.5 (d, 4J¼3.1 Hz, p-CH), 132.8 (d, 4J¼3.1 Hz, p-
with 31Pe10B- and 31Pe11B-coupling). 11B NMR (CDCl3):
(vbr, BO4), ꢀ40.5 (br, H3BeP).
d¼ꢀ0.7
CH0), 133.0 (d, J¼10.9 Hz, o-CH0), 164.8 (s, COOꢀ). 31P{1H} NMR
4.3.5. Detection of (tert-butylamino-diphenylphosphanylacetic acid
1-P)pentacarbonyltungsten (11c). Solid 1c$MeOH (170 mg,
2
(CDCl3):
d
¼51.5.
k
Solutions of 7c in CDCl3, in [D8]THF or in CD3OD underwent slow
decarboxylation to 9c at room temperature (in CDCl3 67% after 6 d,
0.49 mmol) was added to a solution of W(CO)5THF, prepared from
W(CO)6 (380 mg, 0.85 mmol) in THF (60 mL) at 20 ꢁC by UV irra-
diation with a cooled mercury-immersion lamp (evolution of
19 mL, 0.85 mmol of CO). After stirring for 6 h at room temperature
the major part of the solvent was evaporated in vacuum. CH2Cl2
(15 mL) was added to the residual 3e5 mL, the mixture filtered and
the solution stored for 3 d at ꢀ24 ꢁC. The pale yellow crystals
(251 mg) formed were separated, washed with CH2Cl2 (5 mL) and
dried in vacuum. The NMR spectra indicated 11c, contaminated by
in [D8]THF 60% after 3 d and in CD3OD 40% after 3 d). 9ce1H NMR
2
(CDCl3):
d
¼1.11 (s, 9H, CMe3), 3.53 (d, JPH¼8.7 Hz, 2H, PCH),
7.40e7.70 (m, 6H, Ph), 7.88 (ddd, JPH¼12.9, 3J¼8.1, 3J¼1.5 Hz, 4H,
3
Ph). 13C{1H} NMR (CDCl3):
d
¼28.5 (CMe3), 51.7 (d, 3J¼13.7 Hz,
CMe3), 45.6 (d, 1J¼67.7 Hz, PCH2), 128.5 (d,3J¼12.0 Hz, 4 m-CH),
131.58 (d,2J¼10.0 Hz, 4 o-CH0), 131.63 (d, 4J¼2.0 Hz, 2 p-CH), 131.90
(d, 1J¼80.6 Hz, 2 i-C). 31P{1H} NMR (CDCl3):
¼41.9.
d
In D2O/CD3OD solution immediate deuterolysis took place to
give tBuNHþ3 Ph2P(S)CH(OH)COOꢀ (8c), identified by good accor-
dance of 1H, 13C and 31P NMR data with recently reported values.18a
(Ph2PH)W(CO)5 and a trace of h (
1-P-(Ph2PCH2NHtBu)W(CO)5 31P
NMR signal heights 65:27:8%). 11ce1H NMR (CDCl3):
d
¼0.99 (s, 9H,
3 Me), 4.27 (d, 2JPH¼10.0 Hz, 1H, PCH), 7.36e7.68 (m, 10H, 2 Ph). 13
C
3
{1H} NMR (CDCl3):
d
¼29.07 (CMe3), 52.68 (d, JPC¼10.6 Hz, CMe3),
4.3.3. Diphenylphosphinothioyl(2-pyrid-2-yl-ethylamino)acetic acid
(7g). Sulfur (32 mg, 1.0 mmol) was added to 1g$MeOH (350 mg,
0.88 mmol) in methanol (10 mL). After stirring for 24 h colorless
needles were separated, washed with a small amount of MeOH and
dried under vacuum to yield 373 mg (98%) of the methanol solvate.
Anal. Calcd for C21H21N2O2PS$CH3OH (428.48): C 61.67; H 5.88; N
59.70 (d, 1JPC¼26.1 Hz, PCH), 127.92 (d, 3J¼9.2 Hz, 2 m-CHA), 128.10
3
(d, JPC¼9.4 Hz, m-CHB), 130.04 (p-CHA), 130.57 (p-CHB), 132.81 (d,
2JPC¼9.6 Hz, 2 o-CHA), 133.12 (d, JPC¼37.0 Hz, i-CqA), 134.04 (d,
1
2JPC¼11.0 Hz, 2 o-CHB), 135.79 (d, JPC¼37.4 Hz, i-CqB), 175.27 (d,
1
2J¼9.2, COOꢀ), 197.02 (d satl, JPC¼6.7, JPW¼127.6 Hz, 4 cis-CO),
2
1
199.40 (d satl, JPC¼23.9, JPW¼143.3 Hz, trans-CO). 31P{1H} NMR
2
1
6.54. Found: C 61.62, H 5.82, N 6.55. 1H NMR ([D8]THF):
d¼2.73 (q,
(CDCl3):
d
¼26.7 (satl, 1JPW¼248 Hz).
3J¼6.3e6.7 Hz, 2H, NCCH2), 2.75e3.02 (m, 2H, NCH2), 4.50 (d,
2JPH¼13.5 Hz, 1H, PCH), 6.94e6.99 (m, 2H, aryl), 7.22e7.38, (m, 6H,
aryl), 7.41 (td 3J¼7.7, 7.6, 4J¼1.9 Hz, 1H, H-4), 7.74e7.85 (m, 2H, aryl),
7.88e7.97 (m, 2H, aryl), 8.32 (dd, 3J¼5.4, 4J¼1.9 Hz,1H, H-6). 13C{1H}
(Ph2PH-
k
1P)W(CO)5e31P{1H} NMR (CDCl3):
d
¼ꢀ12.73 (satl,
1JPW¼230 Hz); 1H NMR: PH and phenyl signals superimposed; 13C
{1H} NMR (CDCl3):
d
¼129.10 (d, 3J¼9.5 Hz, 4 m-CH), 132.32 (d,
2JPC¼11.9 Hz, 4 o-CH), 132.32 (d, JPC¼43.8 Hz, 2 i-Cq); p-CH
1
NMR ([D8]THF):
d
¼38.96 (NCCH2), 49.76 (s, MeOH), 49.57 (d,
superimposed.
(Ph2PCH2NHtBu-
k
1P)W(CO)5e31P{1H}
NMR
Please cite this article in press as: Lach, J.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.05.101

12
J. Lach et al. / Tetrahedron xxx (2015) 1e13
1
(CDCl3):
d
¼11.15 (satl, JPW¼241.5 Hz). 1H NMR (CDCl3):
d
¼1.01
squares methods on F2 (SHELXL-97).40 All non-hydrogen atoms
were refined anisotropically. H-atoms were calculated assuming
idealized geometries and refined using riding models. Crystallo-
graphic data are given in Table 2 and selected bond lengths and
angles in Figs. 2 and 3.
(CH3), 3.57 (d, 2JPH¼3.5 Hz, PCH2), phenyl signals superimposed. 13
C
NMR (CDCl3):
d
¼28.53 (CMe3), 46.43 (d, 1J¼37.1 Hz, PCH2N), 51.41
(3J¼10.6 Hz, CMe3), 128.65 (d, 3J¼9.3 Hz, 4 m-CH), 130.3 (2 p-CH),
132.22 (d, 2J¼10.6 Hz, 4 o-CH), 134.63 (d, 1J¼39.5 Hz, 2 i-Cq).
4.3.6. [Diphenylphosphanyl(quinolin-8-ylamino)acetic acid
k
1-P]
Acknowledgements
pentacarbonyltungsten (11i). Solid 1i$MeOH (431 mg, 1.03 mmol)
was added to a solution of W(CO)5(THF), prepared from W(CO)6
(363 mg, 1.03 mmol) in THF (60 mL) at 20 ꢁC, and after 6 h at room
temperature the product worked up as described for 11c to give
352 mg (48%) of 11i. Anal. Calcd for C28H19N2O7PW (710.04): C
We thank Dr. C.-Y. Guo for oligomerization screening and B. Witt
and M. Steinich for numerous NMR measurements and analyses.
Supplementary data
47.35; H 2.70; N 3.94. Found: C 47.35, H 2.55, N 3.84. 1H NMR
2
(CDCl3):
d
¼5.19 (unresolved t, JPHþ3J¼17.3 Hz, 1H, PCH), 6.78 (d,
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2015.05.101.
3J¼7.2 Hz, 1H, H-7), 6.90 (unresolved t, JþJ0z12 Hz, 1H, NH), 7.19 (d,
3J¼8.0 Hz, 1H, H-5), 7.30e7.50 (m, 8H, H-3, H-6, Ph), 7.55e7.75 (2m,
4H, Ph), 8.05 (d, 3J¼7.9 Hz, 1H, H-4), 8.64 (br, 1H, H-2). 13C{1H} and
References and notes
DEPT-135 NMR (CDCl3):
d
¼58.75 (d, 1J¼16.6 Hz, PCHN),106.68 (s, 7-
1. Recent reviews e.g. (a) Haldar, D. Curr. Org. Synth. 2008, 5, 61e80; (b) Ma-
zurkiewicz, R.; Kuznik, A.; Grymel, M.; Pazdzierniok-Holewa, A. Arkivoc 2007,
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CH), 117.07 (s, 5-CH), 121.73 (s, 3-CH), 127.27 (s, 6-CH), 128.52 (s, 10-
3
3
0
Cq ), 128.70 (d, J¼9.6 Hz, 2 m-CHA), 128.72 (d, J¼9.2 Hz, 2 m-CHB),
130.91 (s, p-CHA), 130.97 (s, p-CHB), 132.78 (d, 1J¼36.9 Hz, 2 i-Cq),
132.70 (d, 2J¼11.9 Hz, 2 o-CHA), 132.94 (d, 2J¼11.7 Hz, 2 o-CHB),
135.87 (s, 4-CH), 138.45 (s, 9-Cq), 142.40 (d, 3J¼6.3 Hz, 8-Cq), 147.61
(s, 2-CH), 172.43 (d, 2J¼6.3 Hz, COOH), 196.29 (d, 2J¼6.8 Hz, 4 cis-
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2. (a) Kellner, K.; Tzschach, A.; Nagy-Magos, Z.; Marko, L. J. Organomet. Chem. 1980,
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A freshly prepared solution or suspension of 1 (ca. 0.1 mmol) in
THF (10 mL) or toluene (10 mL) was added at 0 ꢁC to a freshly
prepared solution of Ni(COD)2 (ca. 0.1 mmol) in THF. For the
screening in THF/water (15:5 mL) and in THF/1-hexene, re-
spectively, each the THF amount was used to prepare the pre-
catalyst mixture, followed by addition of the water or 1-hexene.
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stainless steel autoclave, equipped with a powerful magnetic stir-
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10ꢀ1 Torr into a cooling trap (ꢀ96 ꢁC). Solid residue was treated for
1 d with MeOH/conc. hydrochloric acid (1:1), washed repeatedly
with methanol and dried under vacuum. The solids were charac-
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(acquisition time 4.9e5.4 s, delay 1.0 s, reference p-CH of solvent
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