Interaction of tris(3-Hydroxymethyl)phosphine with cinnamic acids

Article abstract of DOI:10.1080/10426507.2012.736102

Phosphonium zwitterions of the known type R3P⁺CH(Ar)CH2CO2 ^- (II) are obtained as a racemic mixture in moderate yield via a 1:1 reaction of cinnamic acids (Ar = phenyl, or substituted phenyl) with [HO(CH2)3]3P in acetone at room temperature under Ar. The products are characterized by elemental analysis, ³¹P{¹H}-, ¹H-, and ¹³C{¹H}-NMR spectroscopies, and mass spectrometry, although they contain a minor coproduct formed via neutralization of the positive and negative charges of II with the respective acid and phosphine reactants (see Experimental Section). In CD3OD, the monodeuterated salts R3P⁺CH(Ar)CH(D)CO2 ^- are formed as a mixture of diastereomers with d.r. values of ～2 to 8, depending on substituent groups present in the organic acid; in these studies, 2-HO-cinnamic acid is the most reactive, and β-methylcinnamic acid is the least reactive.

Full text of DOI:10.1080/10426507.2012.736102

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Phosphorus, Sulfur, and Silicon and the
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Interaction of Tris(3-
Hydroxymethyl)Phosphine with Cinnamic
Acids
Dmitry V. Moiseev a b , Brian R. James a & Aleksey V. Gushchin b
a Department of Chemistry , University of British Columbia ,
Vancouver , British Columbia , Canada
b Department of Organic Chemistry , Lobachevsky State University of
Nizhny Novgorod , Nizhny Novgorod , Russia
Accepted author version posted online: 24 Oct 2012.
To cite this article: Dmitry V. Moiseev , Brian R. James & Aleksey V. Gushchin (2013): Interaction of
Tris(3-Hydroxymethyl)Phosphine with Cinnamic Acids, Phosphorus, Sulfur, and Silicon and the Related
Elements, 188:6, 678-690
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Phosphorus, Sulfur, and Silicon, 188:678–690, 2013
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2012.736102
INTERACTION OF TRIS(3-HYDROXYMETHYL)PHOSPHINE
WITH CINNAMIC ACIDS
Dmitry V. Moiseev,1,2 Brian R. James,1
and Aleksey V. Gushchin2
1Department of Chemistry, University of British Columbia, Vancouver, British
Columbia, Canada
2Department of Organic Chemistry, Lobachevsky State University of Nizhny
Novgorod, Nizhny Novgorod, Russia
GRAPHICAL ABSTRACT
−
Abstract Phosphonium zwitterions of the known type R3P+CH(Ar)CH2CO2 (II) are ob-
tained as a racemic mixture in moderate yield via a 1:1 reaction of cinnamic acids (Ar = phenyl,
or substituted phenyl) with [HO(CH2)3]3P in acetone at room temperature under Ar. The
1
1
products are characterized by elemental analysis, 31P{ H}-, 1H-, and 13C{ H}-NMR spectro-
scopies, and mass spectrometry, although they contain a minor coproduct formed via neutraliza-
tion of the positive and negative charges of II with the respective acid and phosphine reactants
−
(see Experimental Section). In CD3OD, the monodeuterated salts R3P+CH(Ar)CH(D)CO2
are formed as a mixture of diastereomers with d.r. values of ∼2 to 8, depending on substituent
groups present in the organic acid; in these studies, 2-HO-cinnamic acid is the most reactive,
and β-methylcinnamic acid is the least reactive.
Keywords (3-Hydroxypropyl)phosphine; cinnamic acids; phosphobetaine; diastereomeric
ratio
INTRODUCTION
Investigations into transition metal-catalyzed hydrogenation of lignin and lignin
model compounds1 led to the discovery that water-soluble (hydroxyalkyl)phosphines (and
their phosphonium salt precursors) are excellent bleaching and brightness stabilization
agents for wood pulps.2 Subsequent investigations have shown that this ability results from
interaction of the nucleophilic phosphine with conjugated C C C O moieties present
within lignin chromophores,3 and our group has reported on such phosphine interactions
Received 23 August 2012; accepted 23 September 2012.
We thank the Natural Sciences and Engineering Council of Canada for financial support via a Discovery
Grant.
Address correspondence to Brian Robert James, Department of Chemistry, University of British Columbia,
Vancouver, BC V6L 1Z1, Canada. E-mail: brj@chem.ubc.ca
678

TRIS(3-HYDROXYMETHYL)PHOSPHINE AND CINNAMIC ACIDS
679
with aromatic aldehydes,4 aromatic and cinnamic alcohols,5 α,β-unsaturated aldehydes,6
and quinones.7
This present work describes the interaction of [HO(CH2)3]3P, i.e. tris(3-
hydroxypropyl)phosphine, abbreviated as THPP, with cinnamic acids, which are precursors
of monolignols that subsequently polymerize to lignins.8 Our previous investigations
have shown that THPP has less bleaching ability than tris(hydroxymethyl)phosphine
(HOCH2)3P,2 but is less prone to side-reactions that can complicate studies with the hy-
droxymethyl phosphine: the (α-hydroxy)phosphine tends to lose aldehyde with formation
of the P–H functionality, which is reactive toward unsaturated organics.6c,9,10
Reactions of phosphines with α,β-unsaturated carbonyl compounds typically occur
via nucleophilic attack of the phosphorus on the activated C C bond, with formation
of phosphabetaines (e.g., the I → II reaction of Scheme 1 discussed below). Examples
include aqueous reactions of (m-NaSO3C6H4)3P and (m-NaSO3C6H4)Ph2P with acrylic,
methacrylic, crotonic, and itaconic acids,11 and reactions of Ph3P with methacrylic, cin-
namic, and p-methoxycinnamic acids in CHCl3.12 Kinetic and mechanistic details of the
PPh3/α,β-unsaturated carboxylic acids systems in acetic acid, alcohol media, and aprotic
solvents have recently been published.13
Scheme 1
RESULTS AND DISCUSSION
A 1:1 reaction of THPP with cinnamic acid (Ia) in acetone at room temperature (r.t.,
∼295 K) under Ar precipitated over 24 h a white, hygroscopic solid that is a mixture of
two products. The major one is the zwitterionic phosphabetaine IIa, formed as a racemic
mixture via nucleophilic attack of the phosphine at the β-C atom of Ia (Scheme 1). The
1
31P{ H} spectrum of the solid in D2O revealed a singlet at δP = 38.3, consistent with
1
a phosphonium species4,5,6a,b,d,7 such as IIa. The H data (see Section Experimental) are
consistent with the structure, with the α- and β-protons generating an MABX spin system
that is well simulated (Figure 1). The γ -, δ- and ε-protons of the THPP moiety (multiplets
centered at δH = 2.34, 1.77, 3.67, respectively) are downfield-shifted of those of free THPP
(multiplets at δH = 1.47, 1.63, 3.60, respectively), and form the same pattern as those
reported for other THPP-derived phosphonium salts.4,5,6b,7 The β-C atom of IIa appears in
1
the 13C{ H} spectrum as a doublet at δC = 37.7 (1JPC = 44 Hz). The ESI-MS (in MeOH)
shows the major peak corresponding to the protonated form of IIa and a minor peak due to
protonated THPP. The elemental analysis of the mixture is consistent with the formulation
of II because the coproduct (see below) is of the same formulation.

680
D. V. MOISEEV ET AL.
1310 1300 1290 1280 1270 1260 1250 1240 1230 1220
960 950 940 930 920 910 900 890 880 870
Hz
Hz
1
Figure 1 Experimental (top) and simulated (bottom) H spectra for the α- and β-protons of IIa in D2O; there
is one MABX spin system with 3JMA = 11.4, 3JMB = 4.3, 2JAB = 15.7, 2JXM = 15.0, 3JXA = 8.0, and 3JXB
=
8.4, where X is the P-atom; HM, HA, and HB resonances at 1269.2, 922.7, and 893.3 Hz, respectively; spectral
half-width = 1.8 Hz.
The minor product is thought to be the intermolecular phosphonium salt IIIa formed
via neutralization of positive and negative charges of IIa with the anion of Ia and protonated
THPP, respectively. IIIa is not detected in the solution NMR spectra because it decomposes
into IIa and the reactants Ia and THPP, which then form the intermolecular phosphonium
1
salt IV (Scheme 2), as judged by the H-spectral data. Multiplets for the γ -, δ-, and
ε-protons of the THPP moiety, which will be averaged signals due to proton exchange
between the cinnamate and THPPH+, are centered at δH = 2.45, 1.95, 3.74, respectively,
and are downfield-shifted from those of IIa and THPP; the α-H of IV is seen as a doublet
at δH = 6.57 (3JHH = 16.2 Hz) while the β-H is hidden by the Ph signals. The 1H data show
that IV is formed initially in 17% yield, but then slowly disappears due to conversion into
IIa (Scheme 2).
Scheme 2
Cinnamic acids Ib–h react similarly with THPP to afford IIb–h, and the correspond-
1
ing byproduct IIIb–h again in ∼15%−25% yield. The 31P{ H} shifts of IIc–h (δP
=
38.3−38.0), and the 1H and 13C{ H} resonances of the THPP and acid moieties, are similar
1
to those of IIa. For IIb, formed from 2-HO-cinnamic acid, compared to these similar data,

TRIS(3-HYDROXYMETHYL)PHOSPHINE AND CINNAMIC ACIDS
681
1
the 31P{ H} singlet is at lower field (δP = 39.3), the β-C atom is seen as a broad singlet
(vs. a doublet) at a higher field (δC = 31.2), and the β-proton appears as a broad triplet (vs.
a ddd) at significantly lower field (δH = 4.60). Such features of IIb are likely due to an
ortho-effect of the HO-group of the aromatic ring, which could form a resonance structure
with the phosphonium cation via a five-member cyclic ring.
A 1:1 reaction of Ia with THPP in CD3OD ([THPP] = [Ia] = 0.1 mol/L, r.t., Ar)
affords the monodeuterated salt IIa–D as a mixture of diastereomers (Scheme 3). Moni-
toring the reaction by the NMR spectrometry revealed the following features: immediately
1
observed in the reaction mixture is a broad 31P{ H} singlet for the THPP species at δP =
−25.6, which is downfield-shifted from the sharp singlet of THPP (δP = −29.5) recorded
1
separately. [In H2O, the 31P{ H} singlets vary with pH from δP –29.6 for THPP to +17.0
for THPP+H (pKa ∼7.2); broad signals at intermediate pH values result from averaging
of these resonances due to fast proton exchange between the two species;14 in CD3OD,
compared to the D2O system, the THPPH+/THPP equilibrium will favor more the neutral
species and thus the δP = −25.6 value seems appropriate for the equilibrium between
these two species]. The respective δH = 6.49 and 7.65 doublets of the α- and β-protons
of Ia in the mixture are slightly upfield-shifted of those of Ia (δH = 6.48 and 7.68) that
were also recorded separately. These data indicate that an acid–base interaction of THPP
and Ia in methanol first forms the intermediate species IV. Over hours (cf. see Figure 4
1
below), the broad 31P{ H} THPP singlet is replaced by a sharp singlet at δP = 38.7 signal,
corresponding to the P atom of IIa–D.
Scheme 3
The α- and β-protons of the two diastereomers of IIa–D appear in the 1H spectrum as
two overlapping three-spin systems that are readily simulated using a d.r. of ∼2.0 (Figure
2). Formation of the corresponding monodeuterated stereoisomers was observed for all the
cinnamic acids, and in most systems the d.r. was ∼2. For Ib (2-HO-cinnamic acid), the 1H
patterns for the α- and β-protons of IIb–D (Figure 3) imply a d.r. value of ∼5; the α- and
β-protons of the major isomer appear as a doublets of doublets at δH = 2.96 (3JHH = 6.4;
3JPH = 11.8 Hz) and δH = 4.60 (3JHH = 6.4; 2JPH = 15.4 Hz), respectively.
The reaction rates of the cinnamic acids depend on substituents in the aromatic ring.
1
Figure 4 illustrates consumption of the acids, according to integration values in the H
spectra, in a set of reactions ([THPP] = [acid] = 0.1 mol/L, CD3OD, r.t., Ar). The reaction
rates decrease in the order: Ib (2-HO-cinnamic acid) > Ic > Ia > Ie > If ≈ Id ≈ Ig ≈ Ih,
the last four being naturally occurring cinnamic acids containing the 4-OH group.8,15
The r.t. reactions with α- and β-methylcinnamic acids (Ii and Ij, respectively) are
very slow and required heating (Scheme 4). The isolated IIi and IIj products were viscous,
and satisfactory elemental analyses were not obtained, C and H analyses were both ∼0.7%
higher than the calculated values. However, the NMR data are consistent with the for-
mulations. An NMR-scale, 1:1 reaction of Ii in CD3OD at 60◦C was monitored by the

682
D. V. MOISEEV ET AL.
Scheme 4 [In IIj, the -carbon is a non-chiral centre with diastereomeric (anisochronous) protons]
1
31P{ H} NMR and, after 7 days, 85% of THPP had reacted. The two diastereomers of
the monodeuterated phosphobetaine IIi–D were seen at δP = 38.1 and 37.6 with relative
intensities 1.0:7.5, respectively. The 1H doublet of the β-H (δH = 7.67; 4JHH = 1.5 Hz) of
the reactant Ii was replaced by two overlapping doublets at δH = 3.92 and 3.85 (ratio 1:8),
31
which collapsed into singlets in the 1H{ P} spectrum (2JPH ≈ 15 Hz); the Me resonance
4
of Ii at δH = 2.08 (d, JHH = 1.5 Hz) was gradually replaced by a doublet at δH = 1.06
(4JHH = 1.2 Hz) and a singlet at δH = 1.00 in a respective ratio of 8:1.
The same reaction was carried out in MeOH in order to compare the 1H NMR spectra
of IIi–D and IIi. After 7 days of reaction at 60◦C, the MeOH was removed in vacuo and
1
the residue was redissolved in CD3OD where it remains as IIi. Integration in the 31P{ H}
Figure 2 Experimental (top) and simulated (bottom) 1H pattern for the α- and β-protons of IIa–D in CD3OD;
there are two three-spin systems (abbreviated MBX and MAX, where X is the P-atom: 2JHD is neglected) using
3
2
3
a ratio of 2.0. For the major isomer: JMB = 4.9, JXM = 15.2, and JXB = 11.9; HM and HB resonances at
1286.4 and 868.6 Hz, respectively. For the minor one: 3JMA = 9.3, 2JXM = 15.0, and 3JXA = 11.6; HM and HA
resonances at 1286.8 and 876.6 Hz, respectively. Spectral half-width = 2.3 Hz.

TRIS(3-HYDROXYMETHYL)PHOSPHINE AND CINNAMIC ACIDS
683
Figure 3 Experimental 1H NMR pattern for the α- and β-protons of IIb–D in CD3OD.
spectrum gave a d.r. of 7.5, while the 1H pattern of the α- and β-protons of IIi (Figure 5)
consists of two MAXY3 spin systems. The major isomer is well simulated using JMA
5.5, JMX = 15.4, JAX = 5.0, JAY = 7.0, JYX = 1.0, JMY = 0, and ꢀMA = 217.0 Hz.
=
Thus, the α-Me group affects both the reactivity of the acid and the stereoselectivity
of the product. The lower reactivity of Ii versus Ia likely results from the electron-donating
Me group reducing the electrophilicity of the β-C atom. The higher d.r. for IIi–D (7.5 vs.
∼2 for IIa–D) could be a result of the steric effect of the Me-group in an intermediate
stage. Worth noting is that interaction of Ph2PH with α-methylcinnamaldehyde affords
Ph2PCH(Ph)CH(Me)CHO as a mixture of diastereomers with predominantly (S,S)- and
(R,R)-chirality (d.r. ∼20, after isolation).10
Figure 4 Relative concentration of cinnamic acids in the 1:1 reaction with THPP (r.t., Ar, CD3OD) versus time;
data determined from integrations of the α-proton signal of the acid and the β-proton signal of the phosphobetaine
product. (Color figure available online).

684
D. V. MOISEEV ET AL.
Figure 5 Experimental 1H NMR pattern for the α- and β-protons of IIi in CD3OD.
The β-methylcinnamic acid (Ij) reacts with THPP much more slowly than does
Ii, only 40% of IIj–D (δP = 43.7) being generated in CD3OD at 60◦C over 11 days
(Scheme 4), presumably due to the steric effect of the Me at the β-position, where the
phosphine attacks; IIj–D is formed as a diastereomeric mixture with d.r. ∼2 (the same as
31
for IIa–D), as estimated by integration within the 1H{ P} spectrum. Figure 6 shows the
1H pattern for the α-protons of the non-deuterated product IIj in CD3OD; in this three-spin
ABX system (X is the P-atom), the diastereotopic α-protons are anisochronous by 14.2 Hz,
the whole pattern being well simulated by using JAB = 15.5, JAX = 8.5, and JBX = 17.0 Hz.
In D2O, the α-protons are anisochronous by 141.5 Hz and each proton is seen as a simple
doublet of doublets with JAB = 15.2, JAX = 11.0, and JBX = 6.0 Hz. Of note, the coupling
constants of the α-protons to the P-atom in IIj are different, whereas in IIa they are equal
(JXA = JXB = 8.3 Hz); this is likely due to more restricted rotation about the α−β bond
1
in IIj caused by the steric effect of the β-Me. In the 31P{ H} spectrum of IIj in D2O,
the coproduct (IVj, see Scheme 2) is seen as a broad resonance at δP = ∼14, which is
reasonable considering the chemical shift value of [DO(CH2)3]3PD+ in D2O (δP = 17.0,
Figure 6 Experimental 1H NMR pattern for the α-protons of IIj in CD3OD.

TRIS(3-HYDROXYMETHYL)PHOSPHINE AND CINNAMIC ACIDS
685
1
t, JPD = 75 Hz);4,13 the corresponding THPPH+/THPP equilibria in H2O was discussed
above.
The reaction of 3,4-(MeO)2-cinnamic acid (Ie) with THPP in D2O at r.t. under Ar
for 24 h generated the monodeuterated salt IIe-D in 85% NMR-yield (d.r. ∼1.3), with
the remaining 15% being present as THPPH+(cinnamate−) (IV-e); in the corresponding
reaction in CD3OD, the d.r. was ∼2. A parallel 1:1 reaction of the sodium salt of this acid
(V) with THPP in D2O occurs very slowly (Scheme 5) and, after 1 day, a low intensity
1
31P{ H} singlet at δP = 38.2 was seen and attributed to the monodeuterated salt (VI-D1).
1
A
31P{ H} resonance of THPP seen at δP = –29.1, and 1H signals at δH = 1.43, 1.60, and
3.58 for the associated γ -, δ-, and ε-protons, are close to those recorded for the neutral
THPP, implying that IVe is not formed. Heating the reaction mixture to 60◦C resulted in
slow consumption of the THPP, with the α- and β-protons of VI-D1 now being detected
as multiplets (cf. Figures 3 and 4) centered at δH = 2.90 and 4.10, respectively; these are
slightly upfield to those for the salt IIe–D (δH = 2.95 and 4.16, respectively), reflecting
somewhat higher electron density on these protons in VI-D1 vs. those in IIe–D. This must
result from a balance between relative electrostatic effects of the two ionic P+ . . . −OD and
CO2− . . . Na+ sites. The γ -protons of VI-D1 are detected at δH = 2.24 (see Scheme 1 for
labeling of protons). In the course of the reaction, the α-, β- and γ -protons are exchanged
with deuterons, and replacement of each of the β- and γ -proton results in an upfield-shift
1
of the 31P resonance of VI by ∼0.1 ppm. After 5 days, the 31P{ H} resonance attributed
1
to the deuterated product VI-D10 was detected at δP = 37.5, and the H spectrum of the
mixture showed no resonances for the α-, β-, or γ -protons, while the δ- and ε-protons of
VI-D10 were seen at δH = 1.67 and 3.61. The presence of the Na+ prevents formation of a
zwitterionic structure, similar to that of II. In aqueous media, after the attack of THPP on
the C C bond of V, the phosphonium VI-D1 cation “acquires” the OD− counterion which,
as a strong base, leads to exchange of the β- and γ -protons adjacent to the P-atom via ylide
intermediate species,4,6a and replacement of the acidic α-protons via acid–base interaction.
Scheme 5
CONCLUSIONS
As part of studies on the interaction of pulp constituents with tertiary phosphines,
which is relevant in pulp bleaching, [HO(CH2)3]3P is shown to react with cinnamic acids
(1:1) to form in moderate yield phosphonium zwitterions of a known type, in this case
[HO(CH2)3]3P+CH(Ar)CH2CO2− (II). In acetone, the zwitterions precipitate with a minor
product formed via neutralization of the ionic charges of II with the reactant acid and
phosphine, but in aqueous solution this is slowly converted to II. The corresponding
reactions in CD3OD generate the diastereomers [HO(CH2)3]3P+CH(Ar)CH(D)CO2− with

686
D. V. MOISEEV ET AL.
d.r. values that depend on substituent groups present in the organic acid. The reactivity of
the cinnamic acids decreases in the order: 2-HO-cinnamic acid > 3-HO-cinnamic acid >
cinnamic acid > 3,4-(MeO)2-cinnamic acid > ferulic acid ≈ caffeic acid ≈ sinapic acid
≈ p-coumaric acid > α-methylcinnamic acid > β-methylcinnamic acid, all the naturally
occurring acids having similar reactivity; a Me substituent at the C C bond reduces the
reactivity dramatically.
EXPERIMENTAL
General. All cinnamic acids were purchased from Aldrich and were used without
purification. Tris(3-hydroxypropyl)phosphine (an oil, >80%)4 was purchased from Strem
and was also used without purification. The sodium salt of 3,4-dimethoxycinnamic acid
was prepared by neutralization of the acid with NaOH. Regular distilled water and D2O
were saturated with Ar for 3 h under stirring. CD3OD (Cambridge Isotope Laboratories)
was used as received. Organic solvents were dried over the appropriate agents, distilled
under N2, degassed, and saturated with Ar. The NMR spectra were recorded on a Bruker
1
1
AV300 spectrometer at 300 K (300 MHz for H; 121 MHz for 31P{ H}; 75 MHz for
13C{ H}). A residual deuterated solvent proton (relative to external SiMe4) and external
1
85% aq H3PO4 were used as references (br = broad, s = singlet, d = doublet, t = triplet,
1
and m = multiplet; J values are given in Hertz). The H spectra simulated by using the
gNMR version 4 program, with J values to 0.3 Hz. Elemental analyses were performed
using a Carlo Erba 1108 analyzer. Mass spectrometry was performed on a Bruker Esquire
Electrospray (ESI) ion-trap instrument with samples dissolved in MeOH or H2O, with
positive ion polarity, scanning from 100−1000 m/z.
Preparation of [HO(CH2)3]3P+CH(Ph)CH2CO2 (IIa). A solution of THPP
−
(70 mg, 0.34 mmol for 100% purity) and cinnamic acid (50 mg, 0.34 mmol) in O2-free
acetone (3 mL) was kept at r.t. for 24 h. The white product was filtered off, washed with
acetone (∼1 mL), and dried in vacuo. Yield 82 mg (68%). Anal. Calcd. for C18H29O5P
1
(356.39 g/mol): C 60.66, H 8.20. Found: C 60.3, H 8.1%. 31P{ H} NMR (D2O), δ = 38.3 s.
1H NMR (D2O), δ = 7.58−7.43 (m, 5H, C6H5), 4.23 (ddd, 1H, PCH, 2JPH 15.2, 3JHH 11.2,
3JHH 4.6 − see Figure 1), 3.67 (t, 6H, CH2OH, 3JHH 6.0), 3.16−2.91 (m, 2H, CH2CO2 −
2
3
see Figure 1), 2.34 (dt, 6H, PCH2, JPH 12.7, JHH 8.5), 1.89−1.65 m (6H, PCH2CH2).
1
3
2
13C{ H} NMR (D2O), δ = 177.6 (d, CO2, JPC 16), 133.3 (d, ipso-C, JPC 6), 131.0 (d,
m-C, 4JPC 2), 130.6 (d, p-C, 5JPC 3), 130.3 (d, o-C, 3JPC 5), 62.4 (d, CH2OH, 3JPC 17), 37.7
(d, PCH, 1JPC 44), 37.0 (s, CH2CO2), 25.1 (d, PCH2CH2, 2JPC 4), 15.7 (d, PCH2, 1JPC 48).
ESI-MS (MeOH): m/z 209.0 (5%) [THPP + H]+, 357.1 (100%) [M + H]+. According to
NMR data (see text), the solid contains 17% of the byproduct IIIa.
[HO(CH2)3]3P+CH(2-HOC6H4)CH2CO2− (IIb). The procedure used follows that
given for IIa except that 100 mg (0.48 mmol) of THPP and 78 mg (0.48 mmol) of 2-HO-
cinnamic acid were used; 150 mg of a white solid (84%) were isolated. Anal. Calcd. for
C18H29O6P (372.39 g/mol): C 58.06, H 7.85. Found: C 58.4, H 7.7%. 31P{ H} NMR (D2O),
1
δ = 39.3 s. 1H NMR (D2O), δ = 7.38−7.27 (m, 2H), 7.07−6.95 (m, 2H), 4.60 (br t, 1H,
PCH), 3.60 (t, 6H, CH2OH, 3JHH 6.0), 3.14−2.87 (m, 2H, CH2CO2), 2.32 (dt, 6H, PCH2,
2JPH 12.9, 3JHH 8.2), 1.84−1.61 (m, 6H, PCH2CH2). 13C{ H} NMR (D2O), δ = 177.9 (d,
1
CO2, 3JPC 15), 155.9 (d, o-C-OH, 3JPC 5), 131.6 (d, p-C, 5JPC 2), 130.7 (br s), 122.6 (d, JPC
1), 120.4 (d, ipso-C, 2JPC 5), 117.4 (d, JPC 2), 62.5 (d, CH2OH, 3JPC 17), 36.6 (s, CH2CO2),
31.2 (br s, PCH), 25.1 (d, PCH2CH2, 2JPC 4), 16.1 (d, PCH2, 1JPC 48). ESI-MS (MeOH):

TRIS(3-HYDROXYMETHYL)PHOSPHINE AND CINNAMIC ACIDS
687
m/z 209.2 (10%) [THPP + H]+, 373.3 (100%) [M + H]+. The solid contains 15% of the
byproduct IIIb.
[HO(CH2)3]3P+CH(3-HOC6H4)CH2CO2− (IIc). The procedure used follows that
given for (IIb); 152 mg of a white solid (85%) was isolated. Anal. Calcd. for C18H29O6P
1
(372.39 g/mol): C 58.06, H 7.85. Found: C 57.7, H 7.5%. 31P{ H} NMR (D2O), δ = 38.3 s.
1H NMR (D2O), δ = 7.30 (t, 1H, 3JHH 7.8), 6.96−6.81 (m, 3H), 4.11 (ddd, 1H, PCH, 2JPH
3
3
3
15.2, JHH 11.0, JHH 4.6), 3.59 (t, H, CH2OH, JHH 6.0), 3.06−2.81 (m, 2H, CH2CO2),
2.25 (dt, 6H, PCH2, 2JPH 12.5, 3JHH 8.3), 1.79−1.54 (m, 6H, PCH2CH2). 13C{ H} NMR
1
(D2O), δ = 177.2 (d, CO2, 3JPC 16), 157.9 (d, m-C-OH, 4JPC 2), 134.9 (d, ipso-C, 2JPC 5),
132.4 (d, m-C, 4JPC 2), 122.2 (d, o-C, 3JPC 5), 117.5 (d, p-C, 5JPC 3), 117.1 (d, o-C, 3JPC 5),
62.3 (d, CH2OH, 3JPC 17), 37.5 (d, PCH, 1JPC 44), 36.7 (s, CH2CO2), 25.1 (d, PCH2CH2,
2JPC 4), 15.7 (d, PCH2, 1JPC 48). ESI-MS (MeOH): m/z 209.2 (9%) [THPP + H]+, 373.3
(100%) [M + H]+. The solid contains 12% of the byproduct IIIc.
[HO(CH2)3]3P+CH(4-HOC6H4)CH2CO2− (IId). The procedure used follows that
given for (IIb); 147 mg of a white solid (83%) was isolated. Anal. Calcd. for C18H29O6P
(372.39 g/mol): C 58.06, H 7.85. Found: C 58.4, H 7.5%. 31P{ H} NMR (D2O), δ = 38.1 s.
1
1H NMR (D2O), δ 7.30 (m, 2H), 6.96 (m, 2H), 4.14 (ddd, 1H, PCH, 2JPH 15.3, 3JHH 11.0,
3JHH 4.6), 3.64 (t, 6H, CH2OH, JHH 6.0), 3.07−2.84 (m, 2H, CH2CO2), 2.28 (dt, 6H,
3
PCH2, JPH 12.7, JHH 8.3), 1.85−1.61 (m, 6H, PCH2CH2). 13C{ H} NMR (D2O), δ =
177.3 (d, CO2, 3JPC 16), 157.7 (d, p-C-OH, 5JPC 3), 131.7 (d, o-C, 3JPC 4), 124.4 (d, ipso-C,
2JPC 6), 117.7 (s, m-C), 62.3 (d, CH2OH, 3JPC 17), 37.0 (s, CH2CO2), 36.9 (d, PCH, 1JPC
2
3
1
2
1
44), 25.1 (d, PCH2CH2, JPC 4), 15.7 (d, PCH2, JPC 48). ESI-MS (MeOH): m/z 209.1
(52%) [THPP + H]+, 373.3 (100%) [M + H]+. The solid contains 17% of the byproduct
IIId.
[HO(CH2)3]3P+CH[3,4-(MeO)2C6H3]CH2CO2 (IIe). The procedure used fol-
−
lows that given for (IIb) except that 100 mg (0.48 mmol) of 3,4-(MeO)2-cinnamic acid
was used; 135 mg of a white solid (68%) was isolated. Anal. Calcd. for C20H33O7P
1
(416.44 g/mol): C 57.68, H 7.99. Found: C 57.3, H 8.4%. 31P{ H} NMR (D2O), δ = 38.1 s.
2
3
1H NMR (D2O), δ = 7.09−6.96 (m, 3H, C6H3), 4.16 (ddd, 1H, PCH, JPH 15.0, JHH
10.8, 3JHH 4.6), 3.88 (s, 3H, CH3O), 3.83 (s, 3H, CH3O), 3.62 (t, 6H, CH2OH, 3JHH 6.0),
2
3
3.09−2.83 (m, 2H, CH2CO2), 2.29 (dt, 6H, PCH2, JPH 12.3, JHH 8.3), 1.82−1.59 (m,
6H, PCH2CH2). 13C{ H} NMR (D2O), δ = 177.5 (d, CO2, 3JPC 16), 150.1 (d, p-C-OMe
1
3
2
3
and m-C-OMe, JPC 2), 125.8 (d, ipso-C, JPC 6), 123.2 (d, o-C, JPC 5), 113.8 (d, m-C,
4JPC 2), 113.6 (d, o-C, 3JPC 5), 62.3 (d, CH2OH, 3JPC 17), 57.2 (s, OCH3), 57.1 (s, OCH3),
37.4 (d, PCH, 1JPC 43), 37.1 (s, CH2CO2), 25.1 (d, PCH2CH2, 2JPC 4), 15.7 (d, PCH2, 1JPC
48). ESI-MS (MeOH): m/z 209.2 (100%) [THPP + H]+, 417.4 (95%) [M + H]+. The solid
contains 20% of the byproduct IIIe.
[HO(CH2)3]3P+CH(4-HO-3-MeO-C6H3)CH2CO2− (IIf). The procedure used fol-
lows that given for IIb except that 93 mg (0.48 mmol) of ferulic acid was used; 90 mg of
a white solid (47%) was isolated. Anal. Calcd. for C19H31O7P (402.42 g/mol): C 56.71,
H 7.76. Found: C 56.4, H 7.9%. 31P{ H} NMR (D2O), δ = 38.0 s. 1H NMR (D2O), δ =
1
7.04−6.88 (m, 3H, C6H3), 4.14 (ddd, 1H, PCH, 2JPH 15.4, 3JHH 11.0, 3JHH 4.8), 3.91 (s,
3H, CH3O), 3.65 (t, 6H, CH2OH, 3JHH 5.9), 3.09−2.84 (m, 2H, CH2CO2), 2.32 (dt, 6H,
PCH2, JPH 12.3, JHH 8.3), 1.84−1.61 (m, 6H, PCH2CH2). 13C{ H} NMR (D2O), δ =
2
3
1
3
5
4
177.5 (d, CO2, JPC 16), 149.4 (d, p-C, JPC 2), 147.0 (d, m-C-OMe, JPC 3), 125.2 (d,
ipso-C, 2JPC 6), 123.3 (d, o-C, 3JPC 5), 117.6 (d, m-C, 4JPC 2), 114.3 (d, o-C, 3JPC 4), 62.4
3
1
(d, CH2OH, JPC 17), 57.4 (s, OCH3), 37.3 (d, PCH, JPC 45), 37.0 (s, CH2CO2), 25.1

688
D. V. MOISEEV ET AL.
(d, PCH2CH2, 2JPC 5), 15.7 (d, PCH2, 1JPC 48). ESI-MS (MeOH-H2O): m/z 209.2 (20%)
[THPP + H]+, 403.3 (100%) [M + H]+. The solid contains 20% of the byproduct IIIf.
[HO(CH2)3]3P+CH[3,4-(HO)2C6H3]CH2CO2− (IIg). The procedure used follows
that given for IIb except that 87 mg (0.48 mmol) of caffeic acid was used; 112 mg of a
yellowish solid (60%) was isolated. Anal. Calcd. for C18H29O7P (388.39 g/mol): C 55.66,
1
H 7.53. Found: C 54.9, H 8.0%. 31P{ H} NMR (D2O), δ = 38.0 s. 1H NMR (D2O), δ =
2
3
3
7.01−6.81 (m, 3H, C6H3), 4.06 (ddd, 1H, PCH, JPH 15.0, JHH 10.8, JHH 4.8), 3.64 (t,
6H, CH2OH, 3JHH 6.0), 3.03−2.81 (m, 2H, CH2CO2), 2.29 (dt, 6H, PCH2, 2JPH 12.7, 3JHH
8.5), 1.85−1.60 (m, 6H, PCH2CH2). 13C{ H} NMR (D2O), δ = 177.6 (d, CO2, 3JPC 16),
1
146.2 (overlapping p-C-OH and m-C-OH), 125.1 (d, ipso-C, 2JPC 6), 122.7 (d, o-C, 3JPC 5),
118.2 (s, m-C), 117.7 (d, o-C, 3JPC 4), 62.3 (d, CH2OH, 3JPC 16), 37.0 (d, PCH, 1JPC 44),
36.9 (s, CH2CO2), 25.1 (d, PCH2CH2, 2JPC 4), 15.7 (d, PCH2, 1JPC 48). ESI-MS (H2O):
m/z 209.2 (17%) [THPP + H]+, 389.2 (100%) [M + H]+. The solid contains 20% of the
byproduct IIIg.
[HO(CH2)3]3P+CH[4-HO-3,5-(MeO)2C6H2]CH2CO2− (IIh). The procedure used
follows that given for IIb except that 107 mg (0.48 mmol) of sinapic acid was used; 118 mg
of a yellowish solid (57%) was isolated. Anal. Calcd. for C20H33O8P (432.44 g/mol): C
55.55, H 7.69. Found: C 55.4, H 7.3%. 31P{ H} NMR (D2O), δ = 38.1 s. 1H NMR (D2O), δ
1
= 6.72 (d, 2H, C6H2, 4JPH 2.3), 4.14 (ddd, 1H, PCH, 2JPH 15.2, 3JHH 11.2, 3JHH 4.6), 3.90
3
(s, 6H, CH3O), 3.65 (t, 6H, CH2OH, JHH 6.0), 3.10−2.86 (m, 2H, CH2CO2), 2.19 (dt,
6H, PCH2, 2JPH 12.3, 3JHH 8.5), 1.70−1.45 (m, 6H, PCH2CH2). 13C{ H} NMR (D2O), δ
1
= 177.5 (d, CO2, 3JPC 16), 149.7 (d, m-C, 4JPC 3), 136.1 (d, p-C, 5JPC 3), 124.6 (d, ipso-C,
2JPC 6), 107.9 (s, o-C), 62.4 (d, CH2OH, 3JPC 16), 57.9 (s, OCH3), 37.8 (d, PCH, 1JPC 44),
36.8 (s, CH2CO2), 25.1 (d, PCH2CH2, 2JPC 5), 15.8 (d, PCH2, 1JPC 48). ESI-MS (MeOH):
m/z 209.2 (70%) [THPP + H]+, 433.4 (100%) [M + H]+. The solid contains the byproduct
IIIh (20%).
[HO(CH2)3]3P+CH(Ph)CH(Me)CO2− (IIi). The procedure used follows that given
for IIb except that 79 mg (0.48 mmol) of α-methylcinnamic acid was used and the reaction
mixture was heated at 60◦C for 2 days; ∼90 mg of a white, viscous solid (∼50%) was
isolated. 31P{ H} NMR (D2O), δ = 37.4 s (major diastereomer), δ = 37.9 s (minor): d.r.
1
= 10. 1H NMR (D2O), δ = 7.55−7.29 (m, 5H, C6H5), 3.89 (dd, 1H, PCH, 3JHH 8.9, 2JPH
3
14.5), 3.60 (t, 6H, CH2OH, JHH 5.8), 3.24 (m, 1H, CHMe), 2.45−2.25 (m, 6H, PCH2),
1.78−1.58 (m, 6H, PCH2CH2), 1.27 (d, 3H, CHCH3, JHH 6.9). 13C{ H} NMR (D2O),
3
1
3
2
3
δ = 180.3 (d, CO2, JPC 10), 132.0 (d, ipso-C, JPC 5), 129.9 (d, o-C, JPC 4), 129.6 (d,
4
5
3
m-C, JPC 2), 129.2 (d, p-C, JPC 3), 61.1 (d, CH2OH, JPC 17), 43.5 (s, CH2CO2), 43.1
(d, PCH, 1JPC 43), 24.1 (d, PCH2CH2, 2JPC 5), 16.8 (d, CH3, 3JPC 5), 16.4 (d, PCH2, 1JPC
48). ESI-MS (MeOH): m/z 371.1 [M + H]+; Mcalcd 370.2. The solid contains 25% of the
byproduct IIIi.
Reaction of THPP and β-methylcinnamic acid in methanol. This reaction was
performed according to the procedure described above except for that the reaction mixture
was heated at 60◦C for 11 days in MeOH. After removal of MeOH, a white residue was
washed three times with acetone and dried overnight in vacuo. Th−e resulting viscous-like
1
solid was dissolved in D2O. [HO(CH2)3]3P+C(Me)(Ph)CH2CO2 (IIj): 31P{ H} NMR
(D2O), δ = 43.5 s. 1H NMR (D2O), δ = 7.60−7.35 (m, 5H, C6H5), 3.58 (t, 6H, CH2OH,
2
3
2
3JHH 6), 3.35 (dd, 1H, CHAHB, JHH 15.2, JPH 11.0), 2.87 (dd, 1H, CHAHB, JHH 15.2,
3JPH 6.0), 2.35−2.17 (m, 6H, PCH2), 2.02 (d, 3H, CH3, JPH 18), 1.72−1.43 (m, 6H,
2
PCH2CH2). 13C{ H} NMR (D2O), δ = 175.4 (d, CO2, 3JPC 17), 136.2 (d, ipso-C, 2JPC 5),
1

TRIS(3-HYDROXYMETHYL)PHOSPHINE AND CINNAMIC ACIDS
689
129.5 (d, m-C, 4JPC 3), 128.4 (s, p-C), 127.5 (d, o-C, 3JPC 5), 61.1 (d, CH2OH, 3JPC 16),
42.1 (s, (CH2CO2), 40.8 (d, PCH, 1JPC 39), 24.4 (d, PCH2CH2, 2JPC 5), 17.1 (s, CH3), 14.1
(d, PCH2, 1JPC 46).
NMR investigation of the 1:1 reaction of THPP with cinnamic acids in CD3OD.
In a glove-box, THPP (24.0 mg, 0.115 mmol) and an acid (0.115 mmol; cinnamic acid
17.0 mg, 2-, 3-, 4-HO-cinnamic acid 18.9 mg, 3,4-(MeO)2-cinnamic acid 24.0 mg, ferulic
acid 22.3 mg, caffeic acid 20.7 mg, sinapic acid 25.8 mg, α-, β-methylcinnamic acid
18.6 mg) were dissolved in CD3OD (1 g, 1.12 mL). The mixture was stirred for 5 min at
r.t., when 0.7 mL of the solution was transferred into a J-Young NMR tube under Ar; the
NMR spectra were then recorded periodically.
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