Soft ruthenium and hard Br?nsted acid combined catalyst for efficient cleavage of allyloxy bonds. Application to protecting group chemistry

Article abstract of DOI:10.1016/j.tet.2015.04.088

Abstract We show that a monocationic CpRu(II) complex of quinaldic acid (QAH) and a monocationic CpRu(IV)(π-allyl)QA complex catalyze efficient cleavage of the allyloxy bond in allyl ethers, allyl esters, allyl carbonates, and allyl carbamates in methanol without the need for additional nucleophiles. The only co-product is volatile allyl methyl ether, enhancing operational simplicity during isolation of the deprotected alcohols, acids, and amines. This clean and high-performance catalytic system should contribute to protecting group chemistry during the multistep synthesis of pharmaceutically important natural products. Full details of this system, including the mechanism, are reported.

Full text of DOI:10.1016/j.tet.2015.04.088

Accepted Manuscript
Soft Ruthenium and Hard Brønsted Acid Combined Catalyst for Efficient Cleavage of
Allyloxy Bonds. Application to Protecting Group Chemistry
Shinji Tanaka, Yusuke Suzuki, Hajime Saburi, Masato Kitamura
PII:
S0040-4020(15)00598-0
10.1016/j.tet.2015.04.088
TET 26691
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 12 March 2015
Revised Date: 22 April 2015
Accepted Date: 24 April 2015
Please cite this article as: Tanaka S, Suzuki Y, Saburi H, Kitamura M, Soft Ruthenium and Hard
Brønsted Acid Combined Catalyst for Efficient Cleavage of Allyloxy Bonds. Application to Protecting
Group Chemistry, Tetrahedron (2015), doi: 10.1016/j.tet.2015.04.088.
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Soft Ruthenium and Hard Brønsted Acid
Combined Catalyst for Efficient Cleavage of
Allyloxy Bonds. Application to Protecting
Group Chemistry.
Leave this area blank for abstract info.
Shinji Tanaka, Yusuke Suzuki, Hajime Saburi, Masato Kitamura*
Graduate School of Pharmaceutical Sciences, Graduate School of Science, and Research Center for Materials
Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan

1
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Tetrahedron
journal homepage: www.elsevier.com
Soft Ruthenium and Hard Brønsted Acid Combined Catalyst for Efficient Cleavage of
Allyloxy Bonds. Application to Protecting Group Chemistry.
Shinji Tanakaa, Yusuke Suzukia, Hajime Saburia, and Masato Kitamuraa
aGraduate School of Pharmaceutical Sciences, Graduate School of Science, and Research Center for Materials Science, Nagoya University, Chikusa, Nagoya
464-8601, Japan
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
We show that a monocationic CpRu(II) complex of quinaldic acid (QAH) and a monocationic
CpRu(IV)(π-allyl)QA complex catalyze efficient cleavage of the allyloxy bond in allyl ethers,
allyl esters, allyl carbonates, and allyl carbamates in methanol without the need for additional
nucleophiles. The only co-product is volatile allyl methyl ether, enhancing operational
simplicity during isolation of the deprotected alcohols, acids, and amines. This clean and high-
performance catalytic system should contribute to protecting group chemistry during the
multistep synthesis of pharmaceutically important natural products. Full details of this system,
including the mechanism, are reported.
Available online
Keywords:
Allyl Group
Deprotection
Ruthenium
Quinaldic acid
Catalysis
2009 Elsevier Ltd. All rights reserved
.
1. Introduction
Protecting groups (PGs) are the unsung heroes or heroines of
chemistry. This detail is barely acknowledged in the
retrosynthetic analysis of complicated natural and unnatural
products, but it would not be too strong to say that accomplishing
total synthesis is impossible without PGs, even in the 21st
century with its variety of highly sophisticated synthetic
methods.1 Fig. 1 illustrates the general process for the protection
of a function, A, in the conversion of B to Z. As is standard, A is
first protected by a PG (red circle), and then the function B is
subjected to a series of target reactions. Finally, A is deprotected
by the action of reagents (black sphere) to give the desired
product together with the co-product. High stability of the PG
under various reaction conditions, as well as facile and
chemoselective removal of the PG on demand, is essential.
Furthermore, easy separation of the excess reagent and
accompanying co-product from the desired product is also
required.
These requirements become even more stringent
during the synthesis of polar biomolecular compounds such as
peptides, nucleotides, and polysaccharides.
Fig. 1. Protecting group (PG) chemistry and the utility of allyl PG for
alchols in organic synthesis. i) Protection. ii) Target function
Among more than a thousand PGs invented so far, we have
revisited the allyl (All) group for protecting an alcohol as an allyl
ether, which has a structure as simple as that of an acetyl group
and has higher stability toward both acidic and basic conditions.
This chemical stability, however, often causes difficulty in
———
transformation from B to Z. iii) Deprotection. Red circle: protecting
group. Black sphere: reagent for deprotection. Black sphere in red circle:
co-product.
Corresponding author. Tel.: +0-000-000-0000; fax: +0-000-000-0000; e-mail: author@university.edu

2
Tetrahedron
deprotection or deallylation under mild conditions. As shown
evaporation. This concept catalyst would be applicable to allyl
ACCEPTED MANUSCRIPT
in Fig. 1a, the most popular approach to deprotection is Corey’s
method:2 RhCl(P(C6H5)3)3 catalyzes a 1,3-hydrogen shift of the
allyl ether to the corresponding alkenyl ether, which is then either
hydrolyzed under acidic conditions or oxidatively cleaved.
[Ir(P(C6H5)2(CH3))2(cod)]PF6 reported by van Boom in 1980
shows higher catalytic performance.3 The types of one-step
deprotection shown in Fig. 1b and Fig. 1c are simple, and many
methods have been invented on the basis of Tsuji’s Pd π-allyl
chemistry,4 Ni π-allyl chemistry,5 and Os-catalyzed oxidative
cleavage.6
esters, allyl carbonates, and allyl carbamates.
Fig. 2. Concept catalyst designed on the basis of "intramolecular redox-
mediated donor-acceptor bifunctional catalyst (Intramol-RDACat)." Ls: soft
ligating atom. Lh: hard ligating atom.
A major disadvantage common to all of these methods is that
an excess amount of acids, bases, oxidizing reagents, or reducing
reagents is required, complicating the reaction system. The ideal
approach would clearly be the “No additive, One step,” process
shown in Fig. 1b, but such a catalytic system has not been
attained. We therefore aimed to develop an optimal process that
performs direct cleavage of the allyl ether under very mild
conditions, and ultimately attained a monocationic CpRu(II)
2.2. Screening of Ls–LhH ligands
Initially, the central metal was selected as Ru(II) in
[RuCp(CH3CN)3]PF6 (1) on the basis of our finding in 2002 that
[RuCp(P(C6H5)3)(CH3CN)2]PF6 prepared from 1 and P(C6H5)3
catalyzes the allyloxy bond cleavage of allyl esters.13 The
catalyst screening was combinatorially conducted by using the
customized automated synthesizer Chemspeed,14–15 which has
five reaction blocks each containing 16 reaction vessels, and can
be used under an inert Ar atmosphere. Forty-eight commercially
available ligands L1–L48 (except for L36), used in a combination
of Ls (sp3P, sp2N, sp3N, and others) with LhH (COOH, OH, NH2,
and no proton), were screened simultaneously under the
following ideal conditions for alcohol deprotection: [C6H5-
CH2CH2OCH2CH=CH2 (C6H5CH2CH2OAll (2))] = 100 mM; [1]
= 1 mM; [Ls–LhH] = 1 mM; solvent, CH3OH; 30 °C; 3 h. The
Chemspeed system automatically mixed the CH3OH solutions of
the Ls–LhH ligands, 1, and C6H5CH2CH2OAll (2) in the reaction
vessels, and sampled the reaction mixtures in a programed way.
GC analysis was used to determine the yields of deprotected
alcohol 3 and 1,3-hydrogen shift side product 4 (column, DB-
WAX (0.25 mm x 15 m) as follows: temp., 50 °C + 10 °C/min;
tR, 6.0 min (2), 4.0 min (3), and 4.5 min (4)). Fig. 3 shows the
results. 2-Pyridinecarboxylic acid (PAH; PA indicates 2-
pyridinecarboxylate) quantitatively afforded 3. 8-Hydroxyl
quinoline derivatives also showed some acceleration effect.
Sulfides and azoles showed almost no reactivity, and phosphines
tended to isomerize the allyl group to the corresponding alkenyl
ether 4.
complex of quinaldic acid (QAH) and
a monocationic
CpRu(IV)(π-allyl)QA complex. The present article describes full
details of the screening results establishing CpRu+/QAH-
catalyzed deallylation/allylation7 and a mechanistic study of this
process.
2. Results and discussion
2.1. Catalyst design concept
We previously established a leading concept for the design of
a molecular catalyst, “intramolecular metathesis-type donor-
acceptor bifunctional catalyst” (Intramol-MDACat), via the
detailed mechanistic study of catalytic asymmetric 1,2-addition
of diorganozincs to aldehydes.8 This concept realized a new type
of asymmetric reaction including reduction,9 1,4-addition of
diorganozincs to enones,10 and others.11 Furthermore, the
Intramol-MDACat concept has been extended to “Intermol-
MDACat” and to a “soft transition metal/hard Brønsted acid-
combined catalyst” to achieve the efficient asymmetric
hydrogenation of β-keto esters.12
With this approach in mind, we designed a concept catalyst
for allyloxy bond cleavage on the basis of a “intramolecular
redox-mediated donor–acceptor bifunctional catalyst” (Intramol-
RDACat), as shown in Fig. 2. Here, the central transition metal
M(n) is coordinated by Ls–LhH (Ls, soft ligating atom; Lh, hard
ligating atom) and a monoanionic and highly electron-donative
η5 cyclopentadienyl (Cp) ligand, endowing the M complex with a
soft coordination site and a hydrogen-bond donor site. In this
soft M/hard H+ combined system, the hard oxygen atom of an
allyl ether substrate would interact with H+, while the soft C=C
double bond would coordinate to M as a η2 ligand. Enhancement
of the electrophilicity or acceptability of the allyl moiety
synergistically cooperates with the high nucleophilicity or
donicity of the CpM(n) moiety, thereby facilitating movement of
the substrate/catalyst complex to a δ+-δ–-δ+-δ–-δ+-δ– charge-
alternating transition state involving M(n) oxidation. Such
stabilization of the transition state would result in easy generation
of the corresponding π-allyl CpM(n + 2) moiety. In addition,
introduction of Cp and the bidentate property of Ls–LhH should
prevent self-aggregation of the catalyst, which often causes
catalyst deactivation. Lastly, if the π-allyl complex can react
with CH3OH, which could be used as a possible solvent, the
CpM(Ls–LhH) catalyst would be regenerated alongside liberation
of the deprotected alcohols and allyl methyl ether (CH3OAll) as
the co-product, which could be easily removed simply by
As shown in Table 1, the ligand structure–reactivity
relationship was further investigated by shortening the reaction
time to 1 h using the particularly highly reactive PAH as the
starting point (entry 1). Neither pyridine nor benzoic acid, nor a
1:1 mixture of pyridine and benzoic acid showed an acceleration
effect (entries 2–4). No reaction proceeded when the location of
COOH in PAH was changed from C(2) to C(3) or C(4) (entries 5
and 6) or when H+ was removed from PAH as PANa (sodium 2-
picolinate) or PACH3 (methyl 2-piclolinate) (entries 7 and 8).
Replacement of the carboxyl group with a hydroxymethyl or
aminomethyl group also resulted in no reaction, although a
proton is located in the same position as the carboxyl group
(entries 9 and 10). Quinoline-8-carboxylic acid, in which the
sp2N atom and H+ are located in a 1,6 manner rather than the 1,5
manner of PAH, showed no reactivity (entry 11). The presence
of an electron-withdrawing substituent at the C(4) position of the
pyridine ring of PAH tended to increase the reactivity with values
of 27% (4-CH3O), 39% (4-H), 50% (4-Cl), 54% (4-CF3), and
59% (4-NO2) (entries 1 and 12–15). Introduction of PO(OH)2
(pKa ca. 1.5) instead of COOH (pKa ca. 5.4) in PAH enhanced the
reactivity; however, further increasing the acidity by replacing
COOH with SO3H (pKa ca. –3) resulted in deceleration (entries

3
ACCEPTED MATNaUblSe C1.RIPT
Ligand structure-reactivity relationship in the
deallylation of C6H5CH2CH2OAll (2) to C6H5CH2CH2OH
(3) using [RuCp(CH3CN)3]PF6 (1)a
Entry Ligand
1
Yield %b Entry Ligand
Yield %b
0
39 (80)
11c
12
2c
0
27 (70)
3c
0
0
13
14
50 (91)
54 (95)
4c
5c
0
15
59 (96)
6c
0
0
16
17
63 (92)
24 (31)
7c
8c
9c
0
0
18
19
97 (99)
18 (48)
Fig. 3. Screening of Ls–LhH under ideal conditions of [2] = 100 mM; [1] =
1 mM; [Ls–LhH] = 1 mM; CH3OH; 30 °C; 3 h. The x-coordinate shows the
functional group of Lh moiety. "None" indicates no functional group. The
y-coordinate corresponds to Ls moiety such as sulfide, azole, amine,
pyridine, and phosphine. The vertical axis shows the % yields of the
products (light blue-colored bar for the desired phenylethyl alcohol (3), and
the purple bar for the undesired 1,3-hydrogen shift product (4). The
structures of efficient ligands were drawn in the graph. For the structures of
other ligands, see Experimentals. The numbers 1–48 in the graph
correspond to L1–L48.
10c
0
20
12 (43)
aConditions: [2] = 500 mM; [1] = [ligand] = 1 mM; solvent, CH3OH;
temperature, 30 °C; 1 h.
16 and 17) (vide infra). Fusion of a benzene ring at C(3)/C(4) or
C(4)/C(5) of PAH led to deceleration, while the most impressive
enhancement in reactivity was attained with quinaldic acid
(QAH, 2-quinolinecarboxylic acid; QA indicates 2-
quinolinecarboxy-late), in which a benzene ring is fused at C(5)
and C(6) of PAH (entries 18–20): in this case, the reaction was
completed within 1 h. The results in Table 1 clearly indicate
bValues in parentheses are obtained after 3 h.
c[2] = 100 mM.
the importance of i) a synergetic effect between the sp2N atom
and the adjacent COOH group, producing a five-membered
chelating ring with the monocationic CpRu(II) catalyst precursor;

4
Tetrahedron
ACCEPTED MANUSCRIPT
3
Table 2. Optimization of deallylation conditions using QAH/[RuCp(CH3CN)3]PF6 (1), [RuCp(η -C3H5)(QA)]PF6 (5), or
PAH/CpM precursors
Entry
Metal Precursor
Ligand
QAH
QAH
QAH
—
1, mM
100
500
1000
3000
100
100
100
100
100
100
100
100
100
100
100
100
100
S/C
100
500
1000
10000
100
100
100
100
100
100
100
100
100
100
100
100
100
Solvent
Time, h
Yield %b
>99
99c
98d
99e
99
98
82
99
99
99
99
18
0
1
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(η3-C3H5)(QA)]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[CpRu(CH3CN)3]PF6
[MoCp(CO)3]2
CH3OH
0.5
3
2
CH3OH
3
CH3OH
3
4
CH3OH
24
2
5
QAH
QAH
QAH
QAH
QAH
QAH
QAH
QAH
PAH
PAH
PAH
PAH
PAH
C2H5OH
6
i-C3H7OH
3
7
t-C4H9OH
13
6
8
1:1 CH3OH –H2O
1:1 CH3OH –DMF
1:1 CH3OH –THF
1:1 CH3OH –CH2Cl2
1:1 CH3OH –CH3CN
CH3OH
9
6
10
11
12
13
14
15
16
17
0.5
0.5
3
3
[WCp(CO)3]2
CH3OH
3
0
[FeCp(CO)3]2
CH3OH
3
0
RhCp(cod)
CH3OH
3
0
IrCp(cod)
CH3OH
3
0
aUnless specified otherwise, all of reactions were carried out at 30 °C.
bGC analysis.
c2-g scale.
dUnder a reduced pressure of 200 mmHg.
eThe pressure of the reaction system was reduced to ca. 200 mmHg for 5 min every 2 h.
ii) the acidity of the proton; and iii) the molecular orbital
coefficient of the ligand (see Mechanism).
2.3. Optimization
Table 2 showed the results of optimization of the standard
reaction (2 → 3) using QAH and 1, and other Cp metal
precursors. The QAH/1-combined system was highly reactive,
completing the reaction within 30 min (entry 1). Even with a
substrate/catalyst (S/C) ratio of 500, deprotection was achieved
in 3 h (entry 2). Under a slightly reduced pressure (200 mmHg),
the S/C ratio could be increased to 1000 (entry 3). Further
enhancement in the reactivity was realized by using a π-allyl
Fig. 4. Quantitative removal of allyl group from various allyl ethers at 30 °C
for 3 h in CH3OH with S/C ratio of 500 unless specified otherwise. aS/C =
100. bS/C = 100 and 0.5 h. All = CH2CH=CH2. Bz = COC6H5. Bn =
CH2C6H5. MOM = CH2OCH3. TBDPS = Si(t-C4H9)(C6H5)2.
complex, [RuCp(η3-C3H5)(QA)]PF6 (5), which was quantitatively
prepared as a pale yellow solid from 1, QAH, and allyl alcohol
(AllOH) in an exact 1:1:1 ratio (1 and QAH, acetone, rt, <5 min;
addition of AllOH, rt, 15 min; concentration of the mixture to
1/10 volume).7c
The complex 5 is air- and moisture-stable,
2.4. Generality
which increases operational simplicity. Even with a 0.01 mol%
of 5 (S/C = 10000), the reaction could be completed at 30 °C in
24 h by reducing the pressure to ca. 200 mmHg at 2-h intervals
(entry 4). Removal of the co-product allyl methyl ether
(CH3OAll) would force the equilibrium toward the desired
product side. In addition to CH3OH, C2H5OH and i-C3H7OH
could be used as solvents, whereas t-C4H9OH gave a lower yield
(entries 5–7). Reactivity was maintained in CH3OH containing
H2O, DMF, THF, or CH2Cl2 as a co-solvent. Using CH3CN as a
co-solvent significantly retarded the reaction (entries 8–12).
Although our investigations of the central metal were limited,
CpMo, CpW, CpFe, CpRh, and CpIr precursors—which are
known to form π-allyl complexes—were not effective under the
standard conditions using PAH (entries 13–17).
Fig. 4 summarizes the generality of the CpRu/QAH-catalyzed
deprotection of alcohols from allyl ethers.7a–7c Primary, secondary,
and tertiary alkanols, and phenol were quantitatively deprotected.
No Claisen rearrangement occurred with allyl phenyl ether. Both
allyl 4-pentenyl ether and allyl 4-pentynyl ether were quantitatively
converted to the corresponding alcohol without, respectively,
isomerization of the terminal olefin to an internal olefin or
inhibition from the terminally alkyne. Benzoate, benzyl ether,
methoxymethyl ether, and tert-butyldiphenylsilyl ether were not
affected at all, realizing selective removal of allyl group.
As shown in Fig. 5, the present catalytic allyloxy bond cleaver
could be used for allyl esters including carbonates, carboxylates,
and phosphates.7e Allyloxycarbonyl (AOC)-protected alcohols
showed much higher reactivity than other esters: a turnover
number of one million was attained by continuous removal of

5
ACCEPTED MANUSCRIPT
Fig. 5. Quantitative removal of allyl group from various allyl esters at 30
°C in CH3OH with S/C ratio of 500 unless specified otherwise. The value is
the reaction time. a10-g scale.7e b9 days with S/C ratio of 1.0 x 106. ciPrOH
instead of CH3OH. d500 mM. eS/C = 100. f88% yield.
volatile CH3OAll. For diallyl carbonates, only less substituted
allyl groups were selectively removed. Amines protected as an
N-AOC group were efficiently deprotected in the presence of a 1-
mol amount of CF3SO3H to give the corresponding ammonium
salt without any N-allylated side product.7d The effectiveness of
isolation could be amplified by salt formation. A 1-mol amount
of Nafion (SO3H equivalent), CH3SO3H, and 12 M aqueous HCl
could be used, whereas a 10-mol amount of CH3COOH was
required for efficient cleavage.
Fig. 6. Application to highly polar molecules. The deprotection yield as
well as the conditions are shown below the substrate structure.
deprotection process, a catalyst sometimes ends up as an impurity
in the final product. In this regard, a homogeneous catalyst is
disadvantageous in comparison to its heterogeneous counterpart.
The heterogeneous deallylation catalyst 6 immobilized on micro-
size spherical SiO2 particles containing Fe3O4 should be all the
more practical because it can operate in alcoholic solvents in the
absence of extra additives and the only co-product is volatile
CH3OAll. Products can be easily isolated through a simple
deprotection step, followed by magnetic separation of 6, and an
evaporation process. 3,5-U was successfully deprotected by
using the heterogeneous version of the catalyst.7h
The “No additive-One step” allyl cleaver functions smoothly
without requiring an excess amount of reducing reagents, acids,
bases, or oxidizing reagents, which often complicate the process
of isolating the products. Therefore, the CpRu/QAH-combined
catalyst can be applied to peptide synthesis and to the final
deprotection stage in the synthesis of polar biomolecular
compounds. Some examples are shown in Fig. 6. Highly multi-
functionalized molecules, such as N-Fmoc-(S)-Glu(OAll)-OtBu,
N-Fmoc-(S)-Phe-(S)-Glu(OAll)-OtBu,
N-Fmoc-(S)-Ser(OAll)-
(S)-Phe-OtBu, 2'-OAll uridine, N-AOC-(S)-Pro-OtBu, and N-
AOC-(S)-Pro-(S)-Pro-Gly-OtBu, were quantitatively deallylated
without affecting the tBu ester or Fmoc groups and without loss
of reactivity, even in the presence of a highly coordinative
peptide linkage.7a,7d,7e An RNA-related molecule—fully allyl-
protected 3,5-U—was also converted in one step to 3,5-U, which
was then isolated after (C2H5)3N addition.7f
After the

6
Tetrahedron
ACCEPTED MANUSCRIPT
2.5. Mechanism
A2B2X signal pattern of the π-allyl ligand, rather than A4X,
1
indicates that the σ-π-σ exchange in 5 is slow on the H NMR
timescale. Stereoselective generation of endo-5 can be explained
by attractive interactions between π-allyl 1,3-p orbitals and Ru
dxy* and between π-allyl 2-p* orbital and Ru dz2.13b, 16
2.5.1. NMR study and kinetics
Fig. 7 shows the step-by-step changes in the 1H-NMR
spectrum during the reaction of QAH, [RuCp(CH3CN)3]PF6 (1),
CH2=CHCH2OH (AllOH), C6H5CH2CH2OAll (2), and CH3OH in
acetone-d6 at 30 °C. When a 1-mol amount of 1 was added to a
solution of QAH, the six aromatic proton signals of QAH
completely and immediately disappeared to generate two new
sets of relatively broad signals in a 20:1 ratio (Fig. 7a and 7b).
The major set could be plausibly assigned to [RuCp(QAH)S]PF6
(7, S = CH3CN or (CD3)2CO), while the minor one might be due
to a species equilibrating with 7—for example, [RuCp(QA)S]
(8)/HPF6 or a COOH-dangling complex 9 (for supposed
structures, see Fig. 11).
The spectrum was not changed by the addition of a 1-mol
amount of C6H5CH2CH2OAll (2) into the solution of 5. When
10-mol amounts of 2 and 100-mol amounts of CH3OH were
added to 5, 70% of 2 was consumed after 12 h at 30 °C to
generate C6H5CH2CH2OH (3) and CH3OAll in a 1:1 ratio (Fig.
7d). Here, only the π-allyl complex 5 was observed, showing i)
that a π-allyl mechanism is operating; ii) that 5 is in the resting
state of the catalytic cycle; and iii) that the rate is determined at
the reductive nucleophilic attack of CH3OH on the π-allyl C(1) or
C(3) of 5 (see section 2.5.4).
Consistent with such a dynamic system, both the major and
minor signals were converted to a single set of sharp signals
when a 1-mol amount of 2 was introduced (Fig. 7c). The new
signals could be definitely assigned to the π-allyl complex
[RuCp(η3-C3H5)(QA)]PF6 (5), in which the π-allyl ligand takes
an endo conformation to Cp, as supported by the observation of
2% and 4.5% nOe enhancement between the closely located CpH
and the anti-protons HA and HA' of the π-allyl group.7b The
The 1H-NMR behavior agreed well with the kinetics shown in
Fig. 8: the reaction proceeded with a 0th-order dependence on
the initial concentration of C6H5CH2CH2OAll (2) and with a 1st-
order dependence on the initial concentration of the Ru complex
5 during the early stage of 0%–30% conversion of 2.15 Because
both 2 and CH3OAll act as an allyl donor, an excess amount of
CH3OH forced the equilibrium 2 + CH3OH ꢀ 3 + CH3OAll far to
the right side. The 0.25:0.788:0.688:9.31 ratio of 2, 3, CH3OAll,
and CH3OH observed in the 1H-NMR spectrum (Fig. 7d)
determined an equilibrium constant K of ca. 0.23, indicating that
the 2 + CH3OH side is preferred over the 3 + CH3OAll side under
the reaction conditions.
Fig. 8. Dependence of the initial rate v0 (mM/min) on [C6H5CH2CH2OAll
(2)]0 and [[RuCp(η3-C3H5)(QA)]PF6 (5)]0 in the deallylation of 2 in CD3OD
at 30 °C. (a) Plot of v0 as a function of [2]0 from 300 mM to 1000 mM ([5]0 =
1.00 mM). (b) Plot of v0 as a function of [5]0 from 0.500 mM to 2.00 mM
([2]0 = 500 mM).
2.5.2. X-ray crystallographic analysis
The π-allyl complex 5 was air- and moisture-stable and easily
crystalized from dichloromethane (yellow, prism, mp 166 °C
(dec)).7b A series of π-allyl Ru complexes of 4-X-substituted
picolinate (4-X-PA, where X = CH3O, H, Cl, CF3, and NO2) were
prepared, and the molecular structures in the crystalline state are
shown in Fig. 9. In all cases, the π-allyl ligand had a
conformation that was endo to the Cp group, being consistent
with the structure of 5 in solution. The π-allyl C(3)–Ru bond was
ca. 5% longer than the C(1)–Ru bond, albeit with a few
exceptions. This observation indicates that the rate-determining
reductive nucleophilic attack of CH3OH may occur on the C(3)
carbon.
Fig. 7.
1H-NMR behavior in the reaction of QAH with
[RuCp(CH3CN)3]PF6 (1), C6H5CH2CH2OAll (2), and CH3OH (acetone-d6,
30 °C). (a) Quinaldic acid (QAH) (10 mM). (b) 10 min after addition of 1
mol amount of 1. (c) 30 min after addition of 1 mol amount of 2. The
structure of QA moiety in the spectrum is omitted. (d) 12 h after addition of
10 mol amounts of 2 and 100 mol amounts of CH3OH. Blue sphere:
C6H5CH2CH2OH (3). Red triangle: C6H5CH2CH2OAll (2). Green square:
CH3OAll. All = CH2CH=CH2. The factor of OCH2 signal intensity of
CH3OAll for 2 was ca. 0.5.
2.5.3. Hammett plots and molecular orbital analysis
The relative reactivity of PAH for 4-X-PAH (X = CH3O, Cl,
CF3, and NO2) was investigated in the Ru-catalyzed deallylation
of 2 to 3 under the conditions of [4-X-PAH] = [1] = 1 mM; [2] =
500 mM; CH3OH; 30 °C). As shown in Fig. 10a, a stronger
electron-withdrawing ability of X led to higher reactivity, but the

7
ACCEPTED MANUSCRIPT
Fig. 10. Relationship between reactivity, LUMO energy level and acidity of
4-X-substituted picolinic acid (4-X-PAH) in deallylation of
C6H5CH2CH2OAll (2) to C6H5CH2CH2OH (3) under the conditions of [2] =
500 mM; [[RuCp(CH3CN)3]PF6 (1)] = [4-X-PAH] = 1 mM; CH3OH; 30 °C.
All = CH2CH=CH2. (a) Hammett plots of relative reactivity (log(kX/kH) as a
function of standard σ constants. (b) LUMO energy calculated at a 6-31G*
level, AtOrCo (atomic orbital coefficiency on N), and pKa (COOH) of 4-X-
PAH.
Fig. 9. Molecular structures of [RuCp(η3-C3H5)(QA)]PF6 (a) and [RuCp(η3-
C3H5)(4-X-PA)]PF6 (b–f) in the crystalline state. QAH: quinaldic acid. 4-X-
PAH: 4-X-substituted picolinic acid.
with no Intramol-RDACat ability is likely to lower the catalyst
performance of the CpRu(II)+/Brønsted acid-combined system.
This would explain our observation that replacement of COOH in
PAH with highly acidic SO3H led to low reactivity (Table 1,
entry 17).
degree of rate enhancement was not as significant as expected:
0.7 (CH3O, –0.28 (σ value)), 1 (H, 0.00), 1.4 (Cl, 0.22), 1.6 (CF3,
0.53), and 1.9 (NO2, 0.81). Hammett plots of log(kX/kH) versus
the standard σ constant for the substituent parameter exhibited
two linear free-energy relationships with a ρ value of +0.63 for X
= CH3O, H, and Cl, and +0.20 for X = Cl, CF3, and NO2,
respectively. The two-line behavior may be rationalized by the
balance between two factors: i) the π-accepting ability of the
pyridine moiety, and ii) the acidity of the carboxylic acid of 4-X-
PAH.17 In the rate-determining reductive nucleophilic attack of
CH3OH on the π-allyl ligand of [Ru(IV)Cp(η3-C3H5)(4-X-
PA)]PF6, a ligand with higher π-acceptability and a lower lowest
unoccupied molecular orbital (LUMO) level should stabilize the
transition state. This view is consistent with the LUMO
level/reactivity relationship shown in Fig. 10b, and holds even
after taking the atomic orbital coefficient (AtOrCo) of the
nitrogen atom into consideration. As the AtOrCo/LUMO value
decreases, the reactivity increases. π-Expanded QAH, which has
a LUMO level 0.6 eV lower than that of PAH (2.12 vs 1.52),
shows a reactivity that is 5–10-fold higher than PAH. At the
same time, however, a strong electron-withdrawing group with a
high σ value raises the acidity of COOH. The dibasic mono salt
[Ru(II)Cp(4-X-PAH)]PF6 may exist in equilibrium with the
neutral complex [Ru(II)Cp(4-X-PA)] and HPF6. The acidity of
COOH in [Ru(II)Cp(4-X-PAH)]PF6 would be enhanced by
coordination of the COOH oxygen atom to the mono cationic
central Ru atom, intensifying the acidity of COOH beyond
expectation from the general pKa values of PAH (ca. 5.4) and
HPF6 (ca. –20). An increase in the generation of neutral species
2.5.4. Supposed catalytic cycle
On the basis of the results of the NMR study, kinetics
experiments, structural analysis of Ru π-allyl complexes by X-
ray diffraction, Hammett plots analysis, and molecular orbital
calculation, the catalytic cycle of the present deallylation using
the [RuCp(CH3CN)3]PF6 (1)/QAH-combined system or
[RuCp(η3-C3H5)(QA)]PF6 (5) was deduced, as shown in Fig. 11.
First of all, CH3CN in 1 is easily replaced with QAH to generate
a mono cationic complex [RuCp(QAH)S]PF6 (7), which is in
equilibrium with both a neutral complex [RuCp(QA)S] (8)/HPF6
and a COOH-dangling species [RuCp(QAH)S2]PF6 (9). The
Ru(II)+/H+ in [RuCp(QAH)S]PF6 captures an allyl ether
substrate, CH2=CHCH2OR, to form the catalyst/substrate
complex 10, in which the hard ether O atom interacts with the
hard H+ ion, and the soft olefin double bond interacts with the
soft Ru atom. The hydrogen bond in 10 enhances the
electrophilicity of C(3) and C(1) in CH2=CHCH2OR, while the
electron donicity or nucleophilicity of the central Ru atom is
amplified by coordination of the carboxylate-like O atom,
electron-donative sp2N atom, and mono anionic η5 Cp ligand.
This synergetic effect realizes a charge alternation in H--O–C(1)–
C(2)=C(3)-- Ru--OCO to reduce the energy level of the transition
state. The Intramol-RDACat ability facilitates the oxidative
formation of the endo-π-allyl complex 5, liberating a deprotected
alcohol. The rate-determining reductive nucleophilic attack of

8
Tetrahedron
ACCEPTED MANUSCRIPT
4. Experimental
CH3OH on the π-allyl carbon is made easier by the lower
LUMO energy of QAH, generating 11. The CH3OAll is then
replaced with the substrate 2, thereby completing the cycle. All
elementary steps are reversible, but the presence of an excess
amount of CH3OH solvent rotates the cycle in a clockwise way.
Removal of the volatile co-product by reducing the internal
pressure or by purging the reaction mixture with an inert gas
would result in an infinite turnover number.
4.1. General
A Chemspeed ASW2000 system was used to screen ligands.
Nuclear magnetic resonance (NMR) spectra were recorded on a
JEOL JNM-ECA-600 spectrometer.
Chemical shifts are
expressed in parts per million (ppm) downfield from
tetramethylsilane or in ppm relative to CHCl3 and CHD2COCD3
(δ 7.26 and 2.05 in H NMR, and δ 77.0 and 29.8 in 13C NMR).
1
1
The signal patterns of H NMR are indicated as follows: s,
singlet; d, doublet; t, triplet; q, quartet; m, multiplet; and br,
broad signal. X-ray crystallographic analysis was conducted on a
Rigaku Saturn 70 CCD system, and the structure was solved by
direct methods using CrystalStructure crystallographic software.
Quantum chemical calculations were performed using the
Spartan 10 program implemented on an Apple iMac 3.4 GHz
intel core i7. Gas chromatography analyses were performed on a
Shimadzu GC-17A instrument. Argon (Ar) gas was purified by
passage first through a column of BASF R3-11 catalyst at 80 °C
and then through a column of granular calcium sulfate. Solvents
for the deallylation and the synthesis of Ru complexes were
dried, degassed at reflux temperature in the presence of the
following appropriate drying agents (250 mg/100 mL) under an
Ar stream for 6 h, and distilled into Schlenk flasks: calcium
hydride for iPrOH, CH2Cl2, CH3CN and CD3CN; magnesium for
C2H5OH, CH3OH and CD3OD; sodium for hexane, benzene and
benzene-d6; and MS4A for acetone, acetone-d6, (CH3)2CDOH
and (CD3)2CDOD. The solvent was degassed by three freeze–
thaw cycles before deallylation. In a similar manner, diethyl
ether, THF and THF-d8 were distilled from sodium
benzophenone ketyl (3 g/L). CDCl3 was purchased from
Cambridge Isotope Laboratories and purified by alumina column
chromatography. It was degassed by three freeze–thaw cycles
before use in the 1H NMR study. All other solvents were
obtained commercially and used without further purification
unless stated otherwise.
Details for the deallylation procedure, the results of the
allyloxy substrates in “section 2.4 on Generality,” and the NMR
data of the substrates and deprotected products have been
reported in the supporting information of previous short
communications.7
Fig. 11. Supposed catalytic cycle in deprotection of alcohols using
CpRu+/QAH-combined system. S = CH3CN, CH3OH, substrate, product, etc.
4.2. Ligand and CpM screening
3. Conclusion
4.2.1. Materials
Ligands L1–L48 shown in Fig. 3 were as follows: picolinic
acid (PAH, L1), hydroxy(pyridin-2-yl)methanesulfonic acid (L2),
quinoline-8-sulfonyl chloride (L3), 1H-imidazole-4-carboxylic
acid (L4), pyridine-2,6-dicarboxylic acid (L5), 1H-
benzo[d]imidazole-2-sulfonic acid (L6), pyridin-2-ylmethanol
In summary, the CpRuPF6-quinaldic acid catalyst described
here functions as a highly reactive and chemoselective allyloxy
bond cleaver in alcoholic solvents under very mild and
essentially additive-free conditions. The only co-product is
volatile ether. The efficiency and simplicity of the reaction
should further increase the practical utility of allyl groups for the
protection of alcohols, esters, and amines, among many other
protecting groups in organic synthesis. Furthermore, the validity
of our leading concept for designing the molecular catalyst—
namely “soft transition metal/hard Brønsted acid-combined
catalyst” or “redox-mediated donor-accepter bifunctional catalyst
(RDACat)”—has been confirmed by a series of experiments
including i) 1H-NMR spectrometry; ii) X-ray crystallographic
analyses of CpRu-π-allyl complexes of picolinic acid derivatives;
iii) Hammett plot analysis; and iv) the relationship between
LUMO levels of ligands and reactivity. The present study should
stimulate further ideas, not only for the retrosynthetic design of
pharmaceutically important natural and unnatural compounds,
but also for the continued development of molecular catalysis.18
(L7),
2-((dimethylamino)methyl)pyridin-3-ol
(L8),
(Z)-
picolinaldehyde oxime (L9), 3H-[1,2,3]triazolo[4,5-b]pyridin-3-
ol (L10), 1H-benzo[d][1,2,3]triazol-1-ol (L11), pyridin-2-ol
(L12), quinolin-8-ol (L13), 5-chloroquinolin-8-ol (L14), 8-
hydroxyquinoline-5-sulfonic acid (L15), 5-nitroquinolin-8-ol
(L16), 5-(chloro-λ5-azanyl)quinolin-8-ol hydrochloride (L17), 2-
(benzo[d]oxazol-2-yl)phenol (L18), pyridin-2-ylmethanamine
(L19), picolinamide (L20), [2,2':6',2''-terpyridin]-4'(1'H)-one
(L21),
2-(pyridin-2-yl)-1H-benzo[d]imidazole
(L22),
6-
ethoxybenzo[d]thiazole-2-sulfonamide (L23), 1H-pyrazole-1-
carboximidamide hydrochloride (L24), 2,2'-bipyridine (L25),
pyridine (L26), glycine (L27), (S)-2-amino-3,3-dimethylbutanoic
acid (L28), proline (L29), piperidine-2-carboxylic acid (L30),
piperazine-2-carboxylic acid hydrochloride (L31), 1H-indole-2-
carboxylic acid (L32), 1H-pyrrole-2-carboxylic acid (L33),
dimethylglycine (L34), methyl-L-proline (L35), 2-(diphenyl-

9
phosphanyl)acetic acid (L36), 2-(diphenylphosphanyl)benzoic
acid (L37), 2-(diphenylphosphanyl)ethan-1-ol (L38), 2-(di-
phenylphosphanyl)ethan-1-amine (L39), triphenylphosphane
(L40), tricyclohexylphosphane (L41), (2-methoxyethyl)diphenyl-
phosphane (L42), 2-(diphenylphosphanyl)-N,N-dimethylethan-1-
amine (L43), 2-(4-oxo-2-thioxothiazolidin-3-yl)acetic acid (L44),
thianthren-1-ylboronic acid (L45), 2-(thiophen-2-yl)acetic acid
(L46), benzo[b]thiophen-2-ylboronic acid (L47), and furan-2-
carboxylic acid (L48). Except for L36, all ligands were
commercially purchased and used without further purification.
L36 was synthesized according to a previously reported
method.19
coated magnetic bar was used to stir the reaction mixture. The
ACCEPTED MANUSCRIPT
typical procedure is represented by the reaction of entry 1 in
Table 1: [RuCp(CH3CN)3]PF6 (1) (1.60 mg, 3.69 ꢀmol) and
CH3OH (0.330 mL) were placed in a 20-mL Schlenk tube under
Ar stream. A 100 mM solution of PAH (0.0370 mL, 37.0 ꢀmol)
in CH3OH was added to the mixture. After standing for 30 min
at rt, the reddish brown solution was transferred into a 20-mL
Schlenk tube equipped with
a Young’s tap containing
C6H5CH2CH2OAll (2) (300 mg, 1.85 mmol) and CH3OH (3.00
mL). The yellow solution was stirred for 1 h at 30 °C. GC
analysis (conditions as above) was used to determine the yield of
C6H5CH2CH2OH (3). Instead of 1 and PAH, other CpM
precursors and ligands were used.
The ligands shown in Table 1 were as follows: benzoic acid,
nicotinic acid, isonicotinic acid, sodium picolinate, methyl
picolinate, quinoline-8-carboxylic acid, 4-methoxypicolinic acid
(4-CH3O-PAH), 4-chloropicolinic acid (4-Cl-PAH), 4-
(trifluoromethyl)picolinic acid (4-CF3-PAH), 4-nitropicolinic
acid (4-NO2-PAH), pyridin-2-ylphosphonic acid (PyPO(OH)2),
pyridine-2-sulfonic acid (PySO3H), isoquinoline-1-carboxylic
acid, isoquinoline-3-carboxylic acid, quinoline-2-carboxylic acid
(QAH). Except for PySO3H, all ligands were commercially
purchased and used without further purification. PySO3H was
prepared by a previously reported method.20
4.3. NMR experiments
A dry and Ar-filled 5-mm Young-type NMR tube was charged
with a 200-mM (CD3)2CO solution of QAH (0.500 mL, 100
µmol), and subjected to H-NMR analysis at 30 °C (Fig. 7a).
1
After degassing the mixture by two freeze/thaw cycles, a 200-
mM (CD3)2CO solution of [RuCp(CH3CN)3]PF6 (1) (0.500 mL,
100 µmol) was added to the NMR tube under Ar atmosphere.
After 10 min at 30 °C, the 1H-NMR spectrum was recorded (Fig.
7b), and then a 500-mM (CD3)2CO solution of C6H5CH2CH2OAll
(2) (0.200 mL, 100 µmol) was added. After 30 min at 30 °C, the
1H-NMR spectrum was recorded (Fig. 7c), and then 2 (162 mg,
1.00 mmol) and CH3OH (405 µL, 320 mg, 10.0 mmol) were
[RuCp(CH3CN)3]PF6 (1), [MoCp(CO)3]2, [WCp(CO)3]2,
[FeCp(CO)3]2, RhCp(cod), and IrCp(cod) were commercially
purchased. Commercial 2-propen-1-ol (AllOH) and synthetic (2-
(allyloxy)ethyl)benzene (C6H5CH2CH2OAll (2))21 were purified
by distillation and stored in a Schlenk flask under Ar.
1
added. After 12 h at 30 °C, the final H-NMR spectrum was
recorded (Fig. 7d). In a separate experiment, a 1:1 mixture of the
deprotected alcohol, C6H5CH2CH2OH (3), and the co-product,
CH3OAll, showed OCH2 signals in a ca. 1:0.5 ratio.
4.2.2. Ligand screening in Fig. 3
4.4. Kinetic experiments
The Chemspeed ASW2000 (single syringe) system was
customized for use under an inert atmosphere (see
Supplementary Data), and Chemspeed-G735 software was used
to program the screening. Five sets of reaction blocks, each
containing 16 glass vials, were heated at 120 °C for 30 min under
a reduced pressure of 200 mmHg. To each of 48 vials, ligands
L1-L48 (each 5.00 µmol) were manually added within a
glovebox, and the temperature of the five reaction blocks was
The allyl ether substrate C6H5CH2CH2OAll (2) and air- and
moisture-stable [RuCp(η3-C3H5)(QA)]PF6 (5) were used for the
kinetic study. Three stock solutions of 2 in CD3OD at 333 mM
(S-I), 556 mM (S-II), and 1.11 M (S-III), and three stock
solutions of 5 in CD3OD at 5.00 mM (C-I), 10.0 mM (C-II), and
20.0 mM (C-III) were prepared in advance, and degassed by
three freeze/thaw cycles. Five dried and Ar-filled 5-mm Young-
type NMR tubes were charged, respectively, with S-I (900 µL,
300 µmol 2), three lots of S-II (900 µL, 500 µmol 2), and S-III
(900 µL, 1.00 mmol 2), and then immersed in a dry ice/CH3OH
bath. To these tubes were added, C-I (100 µL, 0.500 µmol 5),
three lots of C-II (100 µL, 1.00 µmol), and C-III (100 µL, 2.00
µmol). Each of the five cooled S-I/C-II, S-II/C-II, S-III/C-II, S-
adjusted to 30 °C.
A 10.0 mM stock solution of
[RuCp(CH3CN)3]PF6 (1) in CH3OH (30 mL), and three 111 mM
stock solutions of C6H5CH2CH2OAll (2) (80 mL x 3) were
prepared in four 100-mL vials in a storage tray. A 500-µL
aliquot of solution 1 (5.00 µmol) was first added to each 20-mL
reaction vessel, and then the single syringe needle was subjected
to a 20-sec outside/inside rinse with CH3OH. Next, a 4.50-mL
aliquot of solution 2 (500 µmol) was added to each of the vessels.
All other reactions (L2–L48) were prepared in this way, taking
ca. 1 h. After being shaken at 30 °C for 3 h from the start point
of the first reaction (L1), the glovebox-type hood was opened,
and a 200 µL aliquot of the reaction mixture (L1) was placed in a
5-mL vial of a sampling tray, and the syringe was cleaned by a
20-sec outside/inside rinse with CH3OH. The sample was
manually frozen by using liquid N2. All other samples, which
were consecutively transferred from the corresponding reaction
vessels every 75 sec, were frozen. Gas chromatography analyses
of the samples were performed on Shimazu GC-14B and GC-
17A instruments with the following conditions: capillary column,
1
II/C-I, S-II/C-II combined systems was measured by H-NMR
with the probe temperature adjusted to 30 °C. FID was sampled
every 5 min for 3 h. The signal intensity at δ 3.77 (2H, t, J =
7.57 Hz, C6H5CH2CH2OH (3)) was plotted over time, and the rate
was determined in the 0%–30% conversion range.15 In the early
reaction stage, logarithmic plotting afforded high linearity to
determine the following initial rates: 12.2 mM/min (S-I/C-II),
12.4 mM/min (S-II/C-II), 12.6 mM/min (S-III/C-II), 8.32
mM/min (S-II/C-I), and 26.3 mM/min (S-II/C-II).
4.5. Preparation of metal complexes and X-ray crystallographic
analysis
4.5.1. [RuCp(η 3 -C3 H5 )(4-CH3 O-PA)] PF6
J&W Scientific DB-WAX (0.25 mm
x 15 m); column
temperature, 50–250 °C; rate of temperature increase, 10 °C/min;
tR 4.0 min (2) and 6.0 min (3).
A dry and Ar-filled 10-mL Schlenk flask was charged with
[RuCp(CH3CN)3]PF6 (1) (3.21 mg, 73.9 µmol), 4-CH3O-PAH
(11.3 mg, 73.8 µmol), and (CH3)2CO (7.0 mL) at rt. After the
resulting yellow solution was stirred at rt for 5 min, a 200-mM
(CH3)2CO solution of AllOH (369 µL, 73.7 µmol) was
introduced to the Schlenk flask. The resulting purple solution
was cannulated into a 5-mL tube placed in a 20-mL Schlenk
4.2.3. Ligand optimization in Tables 1 and 2
All reactions were carried out under Ar atmosphere by using a
general Schlenk technique. Schlenk flasks were dried at ca. 250
°C by using a heat gun under reduced pressure, and a Teflon-

10
Tetrahedron
ACCEPTED MANUSCRIPT
flask, and hexane (3.0 mL) was added to the Schlenk flask
5.07 (dddd, J = 11.02, 11.02, 6.89, 6.20 Hz, 1H, CHcenter), 6.43 (s,
outside the 5-mL tube. After sealing the system by using a
silicone-greased glass stopper, the whole system was kept at 5 °C
for 12 h to generate yellow prismatic crystals (32.0 mg, 63.5
µmol, 86% yield): 1H NMR ((CD3)2CO) δ 4.09 (s, 3H, OCH3),
4.23 (dd, J = 6.54, 2.75 Hz, 1H, CHsyn), 4.39 (dd, J = 6.20, 2.75
Hz, 1H, CHsyn), 4.46 (d, J = 11.02 Hz, 1H, CHanti), 4.60 (d, J =
11.02 Hz, 1H, CHanti), 4.86 (dddd, J = 11.02, 11.02, 6.20, 6.20
Hz, 1H, CHcenter), 6.36 (s, 5H, Cp), 7.40 (dd, J = 6.54, 2.75 Hz,
1H, C(5)H), 7.45 (d, J = 2.75 Hz, 1H, C(3)H), 8.81 (d, J = 6.89
Hz, 1H, C(6)H); 13C NMR ((CD3)2CO) δ 57.7, 66.3, 68.4, 97.1,
101.8, 114.2, 116.7, 152.4, 158.4, 170.8, 171.1; HRMS (ESI)
m/z: calcd for C15H16NO3Ru [M–PF6]+, 360.0174; found,
360.0174; mp 186 °C (decomposed).
5H, Cp), 8.15 (d, J = 2.07 Hz, 1H, C(3)H), 8.23 (dd, J = 5.51,
2.07 Hz, 1H, C(5)H), 9.40 (d, J = 6.20 Hz, 1H, C(6)H); 13C NMR
((CD3)2CO) δ 66.7, 70.2, 97.5, 102.2, 124.2, 126.1, 142.9 (q, J =
141.4 Hz), 152.9 (2C), 160.0, 170.2; HRMS (ESI) m/z: calcd for
C15H13F3NO2Ru [M–PF6]+, 397.9942; found, 397.9968; mp 182
°C (decomposed). Crystallographic data no. CCDC 1052809.
4.5.5. [RuCp(η 3 -C3 H5 )(4-NO2 -PA)] PF6
Conditions: [RuCp(CH3CN)3]PF6 (1) (32.0 mg, 73.7 µmol), 4-
NO2-PAH (12.4 mg, 73.8 µmol), (CH3)2CO (7.0 mL), a 200-mM
(CH3)2CO solution of AllOH (369 µL, 73.7 µmol). [RuCp(η3-
C3H5)(4-NO2-PA)]PF6 (22.2 mg, 42.8 µmol, 58% yield) as
1
yellow prismatic crystals: H NMR ((CD3)2CO) δ 4.37 (dd, J =
6.54, 2.75 Hz, 1H, CHsyn), 4.55 (dd, J = 6.20, 2.75 Hz, 1H,
CHsyn), 4.60 (d, J = 11.02 Hz, 1H, CHanti), 4.78 (d, J = 11.02 Hz,
1H, CHanti), 5.09 (dddd, J = 11.71, 11.02, 6.89, 6.20 Hz, 1H,
CHcenter), 6.46 (s, 5H, Cp), 8.43 (d, J = 2.75 Hz, 1H, C(3)H), 8.56
(dd, J = 6.20, 2.75 Hz, 1H, C(5)H), 9.53 (d, J = 6.20 Hz, 1H,
C(6)H); 13C NMR ((CD3)2CO) δ 66.8, 70.7, 97.6, 102.4, 121.0,
122.9, 154.3, 157.8, 161.1, 169.8; HRMS (ESI) m/z: calcd for
C14H13N2O4Ru [M–PF6]+, 374.9919; found, 374.9933; mp 172 °C
(decomposed). Crystallographic data no. CCDC 1052812.
Crystallographic data for the structures in this paper have been
deposited with the Cambridge Crystallographic Data Centre.
Copies of the data can be obtained, free of charge, on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44-
(0)1223-336033 or e-mail: deposit@ccdc.cam.ac.Uk). RuCp(η3-
C3H5)(4-CH3O-PA)]PF6 is available as supplementary
publication no. CCDC 1052811. Crystals of [RuCp(η3-
C3H5)(PA)]PF6,
[RuCp(η3-C3H5)(4-Cl-PA)]PF6,
[RuCp(η3-
C3H5)(4-CF3-PA)]PF6, and [RuCp(η3-C3H5)(4-NO2-PA)]PF6
were prepared in the same way.
Acknowledgments
4.5.2. [RuCp(η 3 -C3 H5 )(PA)] PF6
This work was supported by a Grant-in-Aid for Scientific
Research (No. 25410112, 24106713) and Platform for Drug
Discovery, Informatics, and Structural Life Science from the
Ministry of Education, Culture, Sports, Science and Technology
(Japan), and an Advanced Catalytic Transformation Program for
Carbon Utilization (ACT-C) from Japan Science and Technology
Agency (JST).
Conditions: [RuCp(CH3CN)3]PF6 (1) (32.0 mg, 73.7 µmol),
PAH (9.01 mg, 73.2 µmol), (CH3)2CO (7.00 mL), a 200-mM
(CH3)2CO solution of AllOH (369 µL, 73.7 µmol). [RuCp(η3-
C3H5)(PA)]PF6 (31.3 mg, 66.0 µmol, 90% yield) as yellow
1
prismatic crystals: H NMR ((CD3)2CO) δ 4.27 (dd, J = 6.54,
2.75 Hz, 1H, CHsyn), 4.45 (dd, J = 6.20, 2.75 Hz, 1H, CHsyn), 4.50
(d, J = 11.02 Hz, CHanti), 4.66 (d, J = 10.33 Hz, 1H, CHanti), 4.94
(dddd, J = 11.02, 11.02, 6.20, 6.20 Hz, 1H, CHcenter), 6.39 (s, 5H,
Cp), 7.89 (dd, J = 6.89, 6.20 Hz, C(5)H), 7.99 (d, J = 8.26 Hz,
1H, C(3)H), 8.35 (dd, J = 7.57, 7.57 Hz, 1H, C(4)H), 9.08 (d, J =
5.51 Hz, 1H, C(6)H); 13C NMR ((CD3)2CO) δ 66.4, 69.3, 97.4,
101.9, 128.9, 130.5, 142.9, 151.0, 158.2, 171.3; HRMS (ESI)
m/z: calcd for C14H14NO2Ru [M–PF6]+, 330.0068; found,
330.0090; mp 210 °C (decomposed). Crystallographic data no.
CCDC 1052813.
References and notes
1. (a) Protective Groups in Organic Synthesis, 3rd ed.; Greene, T.
W., Wuts, P. G. M., Eds.; Wiley-VCH: New York, U.S.A., 2000;
(b) Schelhaas, M.; Waldmann, H. Angew. Chem., Int. Ed. Engl.
1996, 35, 2056.
2. Corey, E. J.; Suggs, J. W. J. Org. Chem. 1973, 38, 3224.
3. (a) Oltvoort, J. J.; van Boeckel, C. A. A.; de Koning, J. H.; van
Boom, J. H. Synthesis 1981, 305; For other isomerization-based
methods, see: (b) Cadot, C.; Dalko, P. I.; Cossy, J. Tetrahedron
Lett. 2002, 43, 1839; (b) Nicolaou, K. C.; Hummel, C. W.;
Bockovich, N. J.; Wong, C.-H. J. Chem. Soc., Chem. Commun.
1991, 870; (c) Boss, R.; Scheffold, R. Angew. Chem., Int. Ed.
Engl. 1976, 15, 558; (d) Cunningham, J.; Gigg, R.; Warren, C. D.
Tetrahedron Lett. 1964, 1191.
4. (a) Vutukuri, D. R.; Bharathi, P.; Yu, Z.; Rajasekaran, K.; Tran,
M.-H.; Thayumanavan, S. J. Org. Chem. 2003, 68, 1146; (b)
Chandrasekhar, S.; Reddy, C. R.; Rao, R. J. Tetrahedron 2001, 57,
3435; (c) Honda, M.; Morita, H.; Nagakura, I. J. Org. Chem.
1997, 62, 8932; (d) Beugelmans, R.; Bourdet, S.; Bigot, A.; Zhu,
J. Tetrahedron Lett. 1994, 35, 4349.
4.5.3. [RuCp(η 3 -C3 H5 )(4-Cl-PA)] PF6
Conditions: [RuCp(CH3CN)3]PF6 (1) (32.2 mg, 74.1 µmol), 4-
Cl-PAH (11.6 mg, 73.7 µmol), (CH3)2CO (7.0 mL), a 200-mM
(CH3)2CO solution of AllOH (369 µL, 73.7 µmol). [RuCp(η3-
C3H5)(4-Cl-PA)]PF6 (37.5 mg, 60.1 µmol, 82% yield) as yellow
1
prismatic crystals: H NMR ((CD3)2CO) δ 4.29 (dd, J = 6.89,
2.75 Hz, 1H, CHsyn), 4.48 (dd, J = 6.20, 2.75 Hz, 1H, CHsyn), 4.52
(d, J = 11.02 Hz, 1H, CHanti), 4.69 (d, J = 11.02 Hz, 1H, CHanti),
5.02 (dddd, J = 11.02, 11.02, 6.89, 6.20 Hz, 1H, CHcenter), 6.41 (s,
5H, Cp), 7.96 (d, J = 2.75 Hz, 1H, C(3)H), 8.00 (dd, J = 6.20,
2.75 Hz, 1H, C(5)H), 9.05 (d, J = 6.20 Hz, 1H, C(6)H); 13C NMR
((CD3)2CO) δ 66.6, 69.6, 97.4, 102.1, 128.7, 130.4, 150.7, 152.2,
158.8, 170.3; HRMS (ESI) m/z: calcd for C14H13ClNO2Ru [M–
PF6]+, 363.9678; found, 363.9703; mp 216 °C (decomposed).
Crystallographic data no. CCDC 1052810.
5. Taniguchi, T.; Ogasawara, K. Angew. Chem., Int. Ed. 1998, 37,
1136.
6. Kitov, P. I.; Bundle, D. R. Org. Lett. 2001, 3, 2835.
7. (a) Tanaka, S.; Saburi, H.; Ishibashi, Y.; Kitamura, M. Org. Lett.
2004, 6, 1873; (b) Saburi, H.; Tanaka, S.; Kitamura, M. Angew.
Chem., Int. Ed. 2005, 44, 1730; (c) Tanaka, S.; Saburi, H.;
Kitamura, M. Adv. Synth. Catal. 2006, 348, 375; (d) Tanaka, S.;
Saburi, H.; Murase, T.; Yoshimura, M.; Kitamura, M. J. Org.
Chem. 2006, 71, 4682; (e) Tanaka, S.; Saburi, H.; Murase, T.;
Ishibashi, Y.; Kitamura, M. J. Organomet. Chem. 2007, 692, 295;
(f) Tanaka, S.; Hirakawa, T.; Oishi, K.; Hayakawa, Y.; Kitamura,
M. Tetrahedron Lett. 2007, 48, 7320; (g) Tanaka, S.; Saburi, H.;
Hirakawa, T.; Seki, T.; Kitamura, M. Chem. Lett. 2009, 38, 188;
(h) Hirakawa, T.; Tanaka, S.; Usuki, N.; Kanzaki, H.; Kishimoto,
M.; Kitamura, M. Eur. J. Org. Chem. 2009, 789–792.
4.5.4. [RuCp(η 3 -C3 H5 )(4-CF3 -PA)] PF6
Conditions: [RuCp(CH3CN)3]PF6 (1) (32.1 mg, 73.9 µmol), 4-
CF3-PAH (14.1 mg, 73.8 µmol), (CH3)2CO (7.0 mL), a 200-mM
(CH3)2CO solution of AllOH (369 µL, 73.7 µmol). [RuCp(η3-
C3H5)(4-CF3-PA)]PF6 (30.1 mg, 55.6 µmol, 75% yield) as yellow
1
prismatic crystals: H NMR ((CD3)2CO) δ 4.34 (dd, J = 6.46,
2.75 Hz, 1H, CHsyn), 4.53 (dd, J = 5.93, 2.75 Hz, 1H, CHsyn), 4.56
(d, J = 11.02 Hz, 1H, CHanti), 4.75 (d, J = 11.02 Hz, 1H, CHanti),
8. (a) Noyori, R.; Kitamura, M. Angew. Chem., Int. Ed. Engl. 1991,
30, 49–69; For the original reaction deducing Intramol-MDACat

11
concept, see: (b) Kitamura, M.; Suga, S.; Kawai, K.; Noyori, R. J.
Am. Chem. Soc. 1986, 108, 6071-6072.
Weinheim, Germany, 2012; (b) Micro Instrumentation for
ACCEPTED MANUSCRIPT
High Throughpur Experimentation and Process Intensification–a
Tool of PAT; Koch, M. V., VandenBussche, K. M., Chrisman, R.
W., Eds.; Wiley-VCH: Weinheim, Germany, 2007; (c) Principles
and Methods for Accelerated Catalyst Design and Testing;
Derouane, E.G., Parmon, V., Lemos, F., Ribeiro, F. R., Eds.;
Kluwer Academic Publishers: Dordrecht, 2002.
9. Some examples for hydrogenation: (a) Ohkuma, T.; Ooka, H.;
Hashiguchi, S.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc. 1995,
117, 2675; (b) Noyori R.; Ohkuma, T. Angew. Chem., Int. Ed.
2001, 40, 40; (c) H. Huang, T. Okuno, K. Tsuda, M. Yoshimura,
M. Kitamura, J. Am. Chem. Soc. 2006, 128, 8716–8717; (d)
Yamamura, T.; Nakatsuka, H.; Tanaka, S.; Kitamura, M. Angew.
Chem. Int. Ed. 2013, 52, 1; Transfer hydrogenation: (e)
Hashiguchi, S.; Fujii, A.; Takehara, J.; Ikariya, T.; Noyori, R. J.
Am. Chem. Soc. 1995, 117, 7562.
10. (a) Nakano, K.; Bessho, Y.; Kitamura, M. Chem. Lett. 2003, 32,
224; (b) Kitamura, M.; Miki, T.; Nakano, K.; Noyori, R. Bull.
Chem. Soc. Jpn. 2000, 73, 999.
11. Bifunctional Molecular Catalysis; Ikariya, T., Shibasaki, M., Eds.;
Springer: Heidelberg, Germany, 2011.
12. (a) Noyori, R.; Kitamura, M.; Ohkuma, T. Proc. Natl. Acad. Sci.
U. S. A. 2004, 101, 5356; (b) Kitamura, M.; Nakatsuka, H. Chem.
Commun. 2011, 47, 842. For the original reaction deducing
Intermol-MDACat, see: (c) Noyori, R.; Ohkuma, T.; Kitamura,
M.; Takaya, H.; Sayo, N.; Kumobayashi, H.; Akutagawa, S. J.
Am. Chem. Soc. 1987, 109, 5856; (d) Kitamura, M.; Ohkuma, T.;
Inoue, S.; Sayo, N.; Kumobayashi, H.; Akutagawa, S.; Ohta, T.;
Takaya, H.; Noyori, R. J. Am. Chem. Soc. 1988, 110, 629.
13. (a) Kitamura, M.; Tanaka, S.; Yoshimura, M. J. Org. Chem. 2002,
67, 4975–4977; For the first report on the utility or Cp*Ru
complex in π -allyl chemistry, see: (b) Kondo, T.; Ono, H.;
Satake, N.; Mitsudo, T.; Watanabe, Y. Organometallics 1995, 14,
1945; For the subsequent related reports, see: (c) Trost, B. M.;
Fraisse, P. L.; Ball, Z. T. Angew. Chem., Int. Ed. 2002, 41, 1059;
(d) Mbaye, M. D.; Demerseman, B.; Renaud, J.-L.; Toupet, L.;
Bruneau, C. Angew. Chem., Int. Ed. 2003, 42, 5066; (e) Burger, E.
C.; Tunge, J. A. Org. Lett. 2004, 6, 2603; (f) Hermatschweiler, R.;
Fernández, I.; Breher, F.; Pregosin, P. S.; Veiros, L. F.; Calhorda,
M. J. Angew. Chem., Int. Ed. 2005, 44, 4397.
15. For details, see supplementary data.
16. Wuu, Y.-M.; Wrighton, M. S. Organometallics 1988, 7, 1839.
17. Dictionary of Organic Compounds, 6th ed. vol. 6; Buckingham, J.,
Macdonald, F., Eds.; Chapman & Hall: London, UK, 1996.
18. Some examples of asymmetric allylation established on the basis
of RDACat concept: (a) Miyata, K.; Kutsuna, H.; Kawakami, S.;
Kitamura, M. Angew. Chem., Int. Ed. 2011, 50, 4649; Tanaka, T.
Seki, M. Kitamura. Angew. Chem., Int. Ed. 2009, 48, 8948; (c)
Seki, T.; Tanaka, S.; Kitamura, M. Org. Lett. 2012, 14, 608; (d)
Miyata, K.; Kitamura, M. Synthesis 2012, 44, 2138; (e) Kitamura,
M.; Miyata, K.; Seki, T.; Vatmurge, N.; Tanaka, S. Pure Appl.
Chem. 2013, 85, 1121.
19. Refosco, F.; Tisato, F.; Bandoli, G.; Deutsch, E. J. Chem. Soc.,
Dalton Trans. 1993, 2901–2908.
20. den Hertog, H. J.; van der Plas, H. C.; Buurman, D. J. Recueil
1958, 77, 963–972.
21. Hill, C. M.; Simmons, D. E.; Hill, M. E. J. Am. Chem. Soc. 1955,
77, 3889–3892.
Supplementary Material
Supplementary data associated with this article can be found
in the online version at dx.doi.org—j.tet.2015.XX.XXX. These
data include details of the customized Chemspeed system, the
original time-conversion curves for kinetic analysis, and the X-
ray crystallographic analyses. The X-ray diffraction data can be
obtained free of charge from the Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk—data_re-quest/cif.
14. Books for automated synthesis and catalyst screening: (a) Applied
Homogeneous Catalysis; Behr, A., Neubert, P., Eds.; Wiley-VCH:

ACCEPTED MANUSCRIPT
Supplementary Data
Soft Ruthenium and Hard Brønstead Acid Combined Catalyst for Efficient
Cleavage of Allyloxy Bonds. Application to Protecting Group Chemistry.
Shinji Tanaka, Yusuke Suzuki, Hajime Saburi, and Masato Kitamura*
Contents
1. Customized Chemspeed ASW2000
2. Time-conversion curves
3. X-ray crystallographic analyses
1

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1. Customized Chemspeed ASW2000
2

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—Continuation of Figure S1—
3

ACCEPTED MANUSCRIPT
2. Time-conversion curves
4

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3. X-ray crystallographic analyses
5

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Table S1. Crystallographic Data and Parameters for
[RuCp(η3-C3H5)(4-CH3O-PA)]PF6
C15H16F6NO3PRu
504.33
yellow, platelet
0.20 x 0.20 x 0.10
triclinic
mol formula
mol wt
crystal color, habit
3
crystal size, mm
crystal system
lattice type
space group
cell dimens
Primitive
P
–1 (#2)
a
b
, Å
, Å
11.443(5)
12.529(5)
15.231(6)
79.22(1)
72.091(13)
84.49(2)
2039.5(14)
4
c, Å
α, deg
β, deg
γ, deg
vol, Å
Z
3
–3
–1
ρ
µ
calcd, g cm
(Mo Kα), cm
1.766
9.37
diffractometer
radiation
Rigaku, Saturn
Mo Kα (l = 0.71070 Å)
graphite monochromated
54.9
2
θmax, deg
no. of reflections measured
total: 14698
Unique: 8253 (R = 0.064)
int
corrections
Lorentz-polarization
structure solution
function minimized by
refinement
no. of observations (I>3.00
no. of variables
Direct methods (SIR92)
2
Sw(|
F |–|F |)
0 c
Full-matrix least-squares on F
s(I)) 2513
562
R
0.047
0.053
1.19
a
R
w
goodness-of-fit Indicator
a
2
2 1/2
R
w
= {Σω(F |–|F |) /ΣωF } .
0 c 0
6

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(a)
(b)
Figure S4. ORTEP drawing of [RuCp(η3-C3H5)(PA)]PF6 (a) and the packing
diagram (b).
7

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Table S2. Crystallographic Data and Parameters for
[RuCp(η3-C3H5)(PA)]PF6
C14H14F6NO2PRu
474.30
yellow, prism
0.20 x 0.08 x 0.05
triclinic
mol formula
mol wt
crystal color, habit
3
crystal size, mm
crystal system
lattice type
space group
cell dimens
Primitive
P
–1 (#2)
a
b
, Å
, Å
6.939(5)
8.628(6)
13.539(9)
100.651(9)
101.600(9)
95.156(10)
776.5(9)
2
c, Å
α, deg
β, deg
γ, deg
vol, Å3
Z
ρ
µ
calcd, g cm–3
(Mo Kα), cm–1
2.028
11.884
diffractometer
radiation
Rigaku, Saturn
Mo Kα (λ = 0.71075 Å)
graphite monochromated
62.3
2
θmax, deg
no. of reflections measured
total: 7059
Unique: 4095 (R = 0.2530)
int
corrections
Lorentz-polarization
structure solution
function minimized by
refinement
no. of observations (I>3.00
no. of variables
Direct methods (SIR92)
2
Σω( F0
– Fc )
Full-matrix least-squares on F2
σ(I)) 4095
226
R
Rw
0.0952
0.2384
1.122
a
goodness-of-fit Indicator
2
2 1/2
a Rw = {Σω( F0
–
Fc ) /Σω
F
} .
0
8

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(a)
(b)
Figure S5. ORTEP drawing of [RuCp(η3-C3H5)(4-Cl-PA)]PF6 (a) and the
packing diagram (b).
9

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Table S3. Crystallographic Data and Parameters for
[RuCp(η3-C3H5)(4-Cl-PA)]PF6
C14H13F6NO2PClRu
508.75
yellow, prism
0.10 x 0.10 x 0.10
triclinic
mol formula
mol wt
crystal color, habit
crystal size, mm3
crystal system
lattice type
Primitive
space group
P−1 (#2)
cell dimens
a
b
, Å
, Å
6.969(3)
8.911(4)
14.038(7)
97.912(6)
102.973(6)
95.428(6)
834.3(7)
2
c, Å
α, deg
β, deg
γ, deg
vol, Å3
Z
ρ
µ
calcd, g cm–3
(Mo Kα), cm–1
2.025
12.68
diffractometer
radiation
Rigaku, Saturn
Mo Kα (λ = 0.71070 Å)
graphite monochromated
54.9
2
θmax, deg
no. of reflections measured
total: 5491
Unique: 3154 (R = 0.036)
int
corrections
Lorentz-polarization
structure solution
function minimized by
refinement
no. of observations (I>3.00
no. of variables
Direct methods (SIR92)
2
Σω( F0
– Fc )
Full-matrix least-squares on F
s(I)) 2218
249
R
Rw
0.074
0.077
2.37
a
goodness-of-fit Indicator
a Rw = {Σω( F0
–
Fc )2/ΣωF02}1/2.
10

ACCEPTED MANUSCRIPT
(a)
(b)
Figure S6. ORTEP drawing of [RuCp(η3-C3H5)(4-CF3-PA)]PF6 (a) and the
packing diagram (b).
11

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Table S4. Crystallographic Data and Parameters for
[RuCp(η3-C3H5)(4-CF3-PA)]PF6
C15H13F9NO2PRu
542.30
colorless, prism
0.20 x 0.15 x 0.12
monoclinic
mol formula
mol wt
crystal color, habit
crystal size, mm3
crystal system
lattice type
Primitive
space group
P21/n (#14)
cell dimens
a
b
, Å
, Å
11.306(4)
16.131(5)
13.201(4)
90.000
95.576(4)
90.000
2396.0(12)
5
1.879
c, Å
α, deg
β, deg
γ, deg
vol, Å3
Z
ρ
µ
calcd, g cm–3
(Mo Kα), cm–1
9.973
diffractometer
radiation
Rigaku, Saturn
Mo Kα (λ = 0.71075 Å)
graphite monochromated
62.1
2
θmax, deg
no. of reflections measured
total: 20141
Unique: 6879 (R = 0.1714)
int
corrections
Lorentz-polarization
structure solution
function minimized by
refinement
no. of observations (I>3.00
no. of variables
Direct methods (SHELX97)
2
Σω( F0
– Fc )
Full-matrix least-squares on F2
s(I)) 6879
262
R
Rw
0.1196
0.1247
1.658
a
goodness-of-fit Indicator
a Rw = {Σω( F0
–
Fc )2/ΣωF02}1/2.
12

ACCEPTED MANUSCRIPT
(a)
(b)
Figure S7. ORTEP drawing of [RuCp(η3-C3H5)(4-NO2-PA)]PF6 (a) and the
packing diagram (b).
13

ACCEPTED MANUSCRIPT
Table S5. Crystallographic Data and Parameters for
[RuCp(η3-C3H5)(4-NO2-PA)]PF6
C14H13F6N2O4PRu
532.32
orange, prism
0.11 x 0.08 x 0.05
monoclinic
mol formula
mol wt
crystal color, habit
crystal size, mm3
crystal system
lattice type
Primitive
space group
P21/n (#4)
cell dimens
a
b
, Å
, Å
7.274(4)
16.296(7)
14.155(7)
90.0000
93.553(6)
90.0000
1674.5(13)
3
c, Å
α, deg
β, deg
g, deg
vol, Å3
Z
ρ
µ
calcd, g cm–3
1.584
8.439
(Mo Kα), cm–1
diffractometer
radiation
Rigaku, Saturn
Mo Kα (l = 0.71070 Å)
graphite monochromated
62.4
2
θmax, deg
no. of reflections measured
total: 14220
Unique: 4814 (R = 0.1635)
int
corrections
Lorentz-polarization
structure solution
function minimized by
refinement
Direct methods (SHELX97)
Σω(|F0|–|Fc|)2
Full-matrix least-squares on F2
no. of observations (I>3.00
no. of variables
s(I)) 4814
253
R
Rw
0.0877
0.0986
1.090
a
goodness-of-fit Indicator
a Rw = {Σω(|F0|–|Fc|)2/ΣωF02}1/2.
14