Reaction of frustrated lewis pairs with ketones and esters

Article abstract of DOI:10.1002/asia.201100960

The frustrated Lewis pair (FLP) Mes₂PCH₂CH ₂B(C₆F₅)₂ (1) reacts with an enolizable conjugated ynone by 1,4-addition involving enolate tautomerization to give an eight-membered zwitterionic heterocycle. The conjugated endione PhCO-CH=CH-COPh reacts with the intermolecular FLP tBu₃P/B(C ₆F₅)₃ by a simple 1,4-addition to an enone subunit. The same substrate undergoes a more complex reaction with the FLP 1 that involves internal acetal formation to give a heterobicyclic zwitterionic product. FLP 1 reacts with dimethyl maleate by selective overall addition to the C=C double bond to give a six-membered heterocycle. It adds analogously to the triple bond of an acetylenic ester to give a similarly structured six-membered heterocycle. The intermolecular FLP P(o-tolyl)₃/B(C₆F ₅)₃ reacts analogously with acetylenic ester by trans-addition to the carbon-carbon triple bond. An excess of the intermolecular FLP tBu₃P/B(C₆F₅)₃, which contains a more nucleophilic phosphane, reacts differently with acetylenic ester examples, namely by O-C(alkyl) bond cleavage to give the {R-CO ₂[B(C₆F₅)₃]₂ ^-}[alkyl-PtBu₃⁺] salts. Simple aryl or alkyl esters react analogously by using the borane-stabilized carboxylates as good leaving groups. All essential products were characterized by X-ray diffraction. Copyright

Full text of DOI:10.1002/asia.201100960

DOI: 10.1002/asia.201100960
Reaction of Frustrated Lewis Pairs with Ketones and Esters
Bao-Hua Xu,[a] Raul Alfonso Adler Yanez,[a] Hiroshi Nakatsuka,[a, b] Masato Kitamura,[b]
Roland Frçhlich,[a] Gerald Kehr,[a] and Gerhard Erker*[a]
Dedicated to Professor Hans J. Schꢀfer on the occasion of his 75th birthday
Abstract: The frustrated Lewis pair
(FLP) Mes2PCH2CH2B(C6F5)2 (1)
1 reacts with dimethyl maleate by se-
lective overall addition to the C=C
double bond to give a six-membered
heterocycle. It adds analogously to the
triple bond of an acetylenic ester to
give a similarly structured six-mem-
bered heterocycle. The intermolecular
addition to the carbon–carbon triple
bond. An excess of the intermolecular
FLP tBu3P/BACTHUNGTRE(UNNG C6F5)3, which contains
a more nucleophilic phosphane, reacts
differently with acetylenic ester exam-
AHCTUNGTRENNUNG
reacts with an enolizable conjugated
ynone by 1,4-addition involving enolate
tautomerization to give an eight-mem-
bered zwitterionic heterocycle. The
conjugated endione PhCO-CH=CH-
COPh reacts with the intermolecular
À
ples, namely by O C
G
cleavage to give the {R-CO2[B-
À
FLP P
(o-tolyl)3/B
C
(C6F5)3]2 }[alkyl-PtBu3+] salts. Simple
FLP tBu3P/B
(C6F5)3 by a simple 1,4-ad-
gously with acetylenic ester by trans-
aryl or alkyl esters react analogously
by using the borane-stabilized carboxy-
lates as good leaving groups. All essen-
tial products were characterized by X-
ray diffraction.
dition to an enone subunit. The same
substrate undergoes a more complex
reaction with the FLP 1 that involves
internal acetal formation to give a het-
erobicyclic zwitterionic product. FLP
Keywords: 1,2-addition · 1,4-addi-
tion · esters · frustrated Lewis pairs ·
ketones
Introduction
dition to benzaldehyde yielding 4.[9] It also selectively adds
to the carbonyl group of trans-cinnamaldehyde to give
5,[13,14] leaving the conjugated carbon–carbon double bond
untouched (Scheme 1). We have now treated a series of ke-
tones and esters with the intramolecular FLP 1 and with
a choice of intermolecular FLPs of various reactivities and
found that 1,2-addition to the carbonyl group does not
always prevail in FLP chemistry. With these slightly less re-
active organic carbonyl compounds we found predominantly
different reaction modes. These reactions, some of which
lead to interesting new structural types, will be described
herein using a series of selected examples.
Frustrated Lewis pairs (FLPs), that is, non-quenched pairs
of Lewis acids and Lewis bases,[1] add to a variety of unsatu-
rated substrates, such as alkenes[2] and alkynes,[3] conjugated
dienes,[1a,4] enynes, and diynes.[5] They even add to related
nitrogen derivatives such as nitrosobenzene,[6] nitrous oxide
(N2O)[7], and nitric oxide (NO).[8] FLPs seem to usually un-
dergo 1,2-addition reactions to reactive carbonyl com-
pounds. The 1,2-addition of the intramolecular frustrated
Lewis pair Mes2PCH2CH2BACHTNUGTRENUNG(C6F5)2 (1) to phenyl isocyanate
to yield the zwitterionic six-membered heterocyclic product
2 is a typical example.[9–11] Many FLPs undergo a similar 1,2-
addition to carbon dioxide, some of them reversibly.[12] We
showed that the frustrated Lewis pair 1 undergoes a 1,2-ad-
[a] Dr. B.-H. Xu, R. A. A. Yanez, H. Nakatsuka,+ Dr. R. Frçhlich,++
Dr. G. Kehr, Prof. Dr. G. Erker
Organisch-Chemisches Institut der Universitꢀt Mꢁnster
Corrensstrasse 40, 48149 Mꢁnster (Germany)
E-mail: erker@uni-muenster.de
[b] H. Nakatsuka,+ Prof. Dr. M. Kitamura
Research Center for Materials Science and the Department of
Chemistry
Nagoya University
Chikusa, Nagoya 464-8602 (Japan)
[+] On leave to Universitꢀt Mꢁnster
++] X-ray crystal structure analyses
[
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201100960.
Scheme 1.
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Results and Discussion
We assume that compound 8 was formed in a stepwise re-
action that is probably initiated by conjugated P-addition to
yield the allenic enolate 7.[15] Subsequent tautomerization to
the exocyclic enolate may then allow ring closure by
oxygen–boron bond formation to yield the observed product
8 (Scheme 2).
FLP-Reactions with Ketones
We had recently shown that conjugated ynones may under-
go 1,4-addition of P/B-frustrated Lewis pairs.[13b,15] This is il-
lustrated by a new example. The ynone 6 reacts with the
FLP 1 to yield the eight-membered zwitterionic heterocycle
8 (isolated in 91% yield). Compound 8 is the product of an
overall 1,4-addition reaction (Scheme 2). However, the reac-
The reaction of the intermolecular FLP tBu3P/BACHTUNGTRENNUNG(C6F5)3
(10a)[7a,16,17] with the nonenolizable conjugated endione 9
takes a similar course. The reaction proceeds rapidly in di-
chloromethane at room temperature, and we have isolated
the 1,4-P/B addition product 11 in >90% yield. It features
characteristic 1H NMR resonances of the central -CH[P]-
2
CH=C- moiety at d=6.13 ppm (3JHH =10.6 Hz, JPH
=
7.1 Hz) and 4.21 ppm (3JHH =10.6 Hz, JPH =2.9 Hz), respec-
tively (Scheme 2). Compound 11 shows the NMR heteronu-
cleic resonances at d=55.3 ppm (31P{1H}) and d=À2.8 ppm
(11B{1H}), respectively.
3
The X-ray crystal structure analysis confirmed the forma-
tion of compound 11 by a 1,4-P/B-addition reaction. The
central C2-C3-C4-O4 unit is close to planar (q=7.4(4)8).
The central carbon–carbon double bond is Z-configurated.
Both the phosphorus and the boron atom feature pseudote-
trahedral coordination geometries (Figure 2).
Scheme 2.
tion sequence contains a stabilizing tautomerization on the
way as we observe the isomerized conjugated diene unit as
part of the framework of this compound [1H NMR: d=4.24,
4.21 ppm (=CH2), d=6.51 ppm (3JPH =40.1 Hz, =CH-)].
The X-ray crystal structure of compound 8 features a close
to coplanar diene moiety. The phosphorus atom is attached
to the diene carbon center C1. The boron atom of the FLP
building block is bonded to oxygen. Both the phosphorus
and the boron atoms in compound 8 feature pseudotetrahe-
dral coordination environments (Figure 1).
Figure 2. A view of the molecular structure of compound 11. Selected
bond lengths (ꢃ) and angles (8) [values taken from molecule A]: B1–O4
1.507(4) ꢃ, C1–C2 1.542(4) ꢃ, C2–C3 1.511(4) ꢃ, C3–C4 1.346(4) ꢃ, C4–
O4 1.335(3) ꢃ, O1–C1 1.218(4) ꢃ, O4–B1 1.507(4) ꢃ, P1–C2 1.890(3) ꢃ,
C2–C3–C4 126.8(3)8, C3–C4–O4 121.5(2)8, C4–O4–B1 131.4(2)8.
The reaction of the endione 9 with the intramolecular
FLP 1 took a somewhat different course. In situ-generated
1 was treated with 9 in a dichloromethane/pentane mixture.
The reaction went to completion over 24 hours to give
a close to 90% yield of product 13 (Scheme 3). The X-ray
crystal structure analysis revealed the formation of the
cyclic acetal structure. Its central five-membered heterocycle
features a C6=C7 bond adjacent to the former carbonyl
oxygen atom, which is part of the acetal structure at C4.
Boron is bonded to O3. The phosphorus atom is attached to
the carbon center C8 that marked the former Michael posi-
Figure 1. A view of the molecular structure of compound 8. Selected
bond lengths (ꢃ) and angles (8): B1–O1 1.502(2) ꢃ, C1–C2 1.338(2) ꢃ,
C1–C7 1.522(2) ꢃ, C2–C3 1.452(2) ꢃ, C3–C6 1.336(2) ꢃ, O1–C3
1.339(2) ꢃ, P1–C1 1.837(2) ꢃ, B1–O1–C3 132.0(1)8, C1–C2–C3–C6
175.2(2)8.
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Gerhard Erker et al.
atom feature pseudotetrahedral coordination geometries.
The pair of ester groups at the central bridged C2-unit is
found trans-1,2-attached at the chair-shaped, central six-
membered heterocycle. They are both positioned pseudo-
equatorially, featuring a gauche dihedral angle of C4–C3–
C6–C7: 36.6(3)8 (Figure 4). In solution we monitored heter-
Scheme 3.
tion of 9, thereby closing the annulated zwitterionic seven-
membered heterocycle to complete the bicyclic framework
of compound 13. The annulation is cis, as it is expected for
the involved ring size (Figure 3).
Figure 4. Molecular structure of the zwitterionic six-membered heterocy-
clic FLP addition product 15 to dimethylmaleate. Selected bond lengths
(ꢃ) and angles (8): B1–C6 1.686(4) ꢃ, C3–C6 1.564(4) ꢃ, P1–C3
1.867(3) ꢃ, C4–C3–C6–C7: 36.6(3)8.
onuclear NMR signals at d=28.1 (31P{1H}) and d=
À12.5 ppm (11B{1H}). The ester substituents were clearly dif-
ferentiated [1H: d=3.35, 3.04 ppm (OCH3), 13C{1H}: d=
177.8, 169.7 ppm (C=O)]. The product showed the
1H/13C{1H} NMR signals of the [P]-CH
ACTHUNTRGENNG(U CO2Me)-CH-
Figure 3. Molecular structure of compound 13. Selected bond lengths (ꢃ)
and angles (8): C4–C8 1.577(3) ꢃ, C7–C8 1.491(3) ꢃ, C6–C7 1.332(3) ꢃ,
C4–O3 1.364(3) ꢃ, C6–O5 1.368(3) ꢃ, O3–B1 1.503(3) ꢃ, O5–C4
1.477(3) ꢃ, P1–C8 1.880(2) ꢃ, C4–O3–B1 121.7(2)8, C6–O5–C4 108.6(2)8,
O3–C4–O5 112.3(2)8.
AHCTUNGTRENNUNG
(CO2Me)-[B] unit at d=44.2 (1JPC =40.8 Hz), 39.0 (br) ppm
(13C{1H}) and d=5.19, 4.03 ppm (1H), respectively. The
3
latter feature a vicinal coupling constant of JHH =12.9 Hz,
which is typical of the trans-arrangement as it was observed
in the solid state by X-ray diffraction analysis. Compound
15 showed the NMR signals of a pair of diastereotopic mesi-
tyl groups at phosphorus and a pair of diastereotopic C6F5-
substituents at boron. The hydrogen atoms at the [P]-
CH2CH2-[B] bridge were also pairwise diastereotopic (see
the Experimental Section and the Supporting Information
for details).
In solution compound 13 featured NMR signals of a pair
of diastereotopic mesityl groups at phosphorus (1H
ACHTUNGTRENNUNG
d=7.08. 6.98, 6.91, 6.88 ppm (m-Mes); 31P{1H}
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
0.0 ppm). We monitored the NMR resonances of two dis-
tinctly different phenyl substituents that are attached at the
bicyclic framework. The five-membered ring featured a set
of very typical 13C{1H} NMR resonances at d=192.8 ppm
The observed formation of the trans-15 isomer from 1 and
the cis-disubstituted olefin dimethyl maleate (actually, the
same product 15 was obtained by reacting dimethyl fuma-
rate with the FLP 1) suggests a stepwise reaction, probably
involving the ester enolate intermediate 14. It becomes rap-
[PhCO2], 98.9 ppm [=CH, 1H: d=4.96], 46.0 (1JPC
45.1 Hz) ppm [PCH], and 166.0 ppm [=CPhO].
=
À
idly stabilized by intramolecular B C bond formation to
FLP-Reactions with Esters
We first reacted the FLP 1 with dimethyl maleate and ob-
tained the six-membered heterocyclic product 15 isolated in
56% yield as a white solid. The X-ray crystal structure anal-
ysis revealed that the P/B pair had been added to the central
carbon–carbon double bond of the substrate, leaving the
ester groups untouched. Both the boron and the phosphorus
Scheme 4.
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Reaction of FLPs with Ketones and Esters
FULL PAPERS
yield the six-membered zwitterionic heterocyclic product 15
(see Scheme 4).
exhibited NMR resonances at d=15.1 ppm (31P{1H}), d=
À14.4 ppm (11B{1H}), and a set of 19F NMR resonances at
d=À130.1 (o), À162.4 (p), and À166.5 (m of C6F5), with
The reaction of the acetylenic esters 16a and 16b, respec-
tively, with the FLPs 1 or 10b,[3e] took a similar course.
Treatment of 16a with the intramolecular FLP 1 was slow
and led to a complicated mixture of products. However,
a rapid and clean reaction was achieved upon pre-activation
a small shift difference DdACTHNURGTNE(UNG m,p)=4.1 ppm typical of a newly
formed borate anion structure.[18]
The reaction of the acetylenic esters 16b with the inter-
molecular (o-tolyl)3P/BACHTUNGTRENUNG(C6F5)3 FLP (10b) took a similar
of the ester with the strong Lewis acid B
(C6F5)3. Workup
course. We isolated the regioselective 1,2-addition product
19 to the carbon–carbon triple bond with an apparently un-
touched ester functionality (see Figure 6 and Scheme 5,
after a reaction time of 24 hours at room temperature gave
the addition product 18 as a white solid. Both the X-ray
crystal structure analysis (Figure 5) and the spectroscopic
Figure 6. Molecular structure of compound 19. Selected bond lengths (ꢃ)
and angles (8): B1–C2 1.655(5) ꢃ, C1–C2 1.344(4) ꢃ, C2–C3 1.497(4) ꢃ,
C1–P1 1.795(3) ꢃ, C2–C1–P1 131.1(3)8, S(C2) 359.88, B1–C2–C1–P1
177.0(2)8.
Figure 5. Molecular structure of compound 18. Selected bond lengths (ꢃ)
and angles (8) [values taken from molecule A]: B1–C5 1.653(3) ꢃ, C4–C5
1.346(3) ꢃ, C3–C4 1.524(3) ꢃ, C5–C6 1.496(3) ꢃ, P1–C4 1.804(2) ꢃ, C2–
B1–C5 108.1(2), C4–P1–C1 105.2(1), S(C5) 359.48, S(C4) 359.88, B1–C5–
C4–P1 4.3(3)8.
path A). The X-ray crystal structure analysis showed the
À
+
bulky FLP components -BACTHNUGTRENNUG(C6F5)3 and -PACHTUGNTNER(NUGN o-tolyl)3 trans-
characterization showed that 1,2-addtion of the P/B-FLP to
the carbon–carbon triple bond of the substrate 16a had
taken place to yield the product 18 (Scheme 5, path B).
The molecular structure of 18 showed the newly formed
B1–C5 and P1–C4 bonds and a carbon–carbon double bond
inside the heterocyclic six-membered ring system, which fea-
tures a half-chair conformation. In solution, compound 18
attached at the central carbon–carbon double bond. In solu-
tion, compound 19 shows NMR features of the central unit
at d=6.37 (1H, =CH-), d=118.2 (1JPC =78.7 Hz, 13C{1H},
=CH-), and d=167.6 (br) ppm (13C{1H},=C[B]). The heter-
onuclear NMR resonances occur at d=16.6 ppm (31P{1H})
and d=À14.0 ppm (11B{1H}), respectively. We assume that
both compounds 18 and 19 were formed in closely related
two-step “Baylis–Hillman”[19]-like procedures initiated by
[15]
À
P C bond formation at the acetylenic Michael position
,
followed by trapping of the resulting reactive allenic enolate
À
intermediate by B C bond formation (Scheme 5).
The reaction of the acetylenic esters 16a and 16c
(Scheme 6) with the FLP tBu3P/BACHTNUTRGNEUNG(C6F5)3 (10a) took a differ-
ent course. Again, borane activation of the ester functionali-
Scheme 5.
Scheme 6.
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Gerhard Erker et al.
ty was necessary to achieve a clean reaction. Consequently,
treatment of 16a or 16c with an excess of 10a resulted in
the formation of the borane-stabilized acetylenic carboxyl-
ate (with the cation [MePtBu3]+). The salt 21a was isolated
from the reaction mixture in 82% yield as a white solid. It
shows a carboxylate 13C{1H} NMR signal at d=163.6 ppm
and a pair of acetylene carbon NMR resonances (d=101.2,
71.8 ppm). The corresponding 11B{1H} NMR signal of the
thane/pentane
mixture
to
yield
the
{iPrCO2[B-
AHCTUNGTRENNUNG
(C6F5)3]2}À[H5C2PtBu3]+ salt (23a) as colorless crystals in
53% yield (13C{1H} NMR: d=189.0 ppm (-CO2), 11B{1H}:
d=À1.8 ppm, 31P{1H}: d=48.9 ppm).
The X-ray crystal structure analysis of 23a shows the [eth-
ylPtBu3]+ cation and the corresponding [(C6F5)3B]2 carbox-
À
ylate anion well separated. The R-CO2[B
tures a sickle-shaped geometry (Figure 8). The ethylben-
(C6F5)3]2 unit fea-
symmetry-equivalent pair of -BACHTNUTRGNE(UNG C6F5)3 groups of the anion
occur at d=À1.0 ppm. The phosphorus 31P{1H} NMR signal
of the cation was located at d=49.4 ppm.
The X-ray crystal structure analysis of the salt 21a shows
that the newly formed [MePtBu3]+ cation was separated
from the doubly borane-stabilized acetylenic carboxylate
anion (Figure 7). The anion features an intact carbon–
Figure 8. Molecular structure of 23a. Selected bond lengths (ꢃ) and
angles (8): B1–O1 1.574(4) ꢃ, B2–O2 1.540(5) ꢃ, C1–O2 1.272(4) ꢃ, O1–
C1 1.265(4) ꢃ, B1–O1–C1 128.1(3)8, B1–O1–C1–O2 175.3(3)8, B1–O1–
C1–C2 À3.5(5)8, C2–C1–O2–B2 178.4(3)8, O1–C1–O2–B2 À0.4(6)8.
Figure 7. A view of the compound of the salt 21a. Selected bond lengths
(ꢃ) and angles (8): B1–O1 1.544(3) ꢃ, B2–O2 1.549(2) ꢃ, C1–O1
1.267(2) ꢃ, C1–O2 1.269(2) ꢃ, C2–C3 1.190(3) ꢃ, B1–O1–C1 129.5(2)8,
C1–C2–C3 177.8(2)8, C2–C3–C4 179.2(2)8, C1–O2–B2 126.9(2)8, O1–C1–
O2 116.0(2)8, B1–O1–C1–C2 1.4(3)8, B1–O1–C1–O2 À179.3(2)8.
zoate-derived salt 23b shows similar spectroscopic and struc-
tural features. It exhibits a sickle-shaped conformation of
À
the Ph-CO2[B
N
and the Supporting Information for details).
carbon triple bond with the carboxylate group at its termi-
Conclusions
nus. Both carboxylate oxygens are bonded to B
ACHTNUGRTEN(NGNU C6F5)3
groups. The carboxylate [B(C6F5)3]2 unit is close to coplanar.
The BOCOB unit at the central linear acetylenic framework
is found in a w conformation.
G
Frustrated Lewis pairs are known to undergo 1,2-addition
reactions to a variety of reactive carbonyl compounds. We
previously showed that the intramolecular FLP
The corresponding salt 21c has very similar spectroscopic
and structural data (see the Experimental Section and the
Supporting Information for details). However, different
Mes2PCH2CH2BACTHUNGETRN(NUG C6F5)2 (1), in an internal competition reac-
tion, preferred 1,2-addition to the aldehyde carbonyl func-
tionality of trans-cinnamic aldehyde over 1,4-addition or ad-
dition to the conjugated C=C bond. This seems to be differ-
ent with the conjugated ketone and ester substrates used in
this study. We have observed that 1 favored 1,2-addition to
the carbon–carbon double bonds of dimethyl maleate and
fumarate and to the carbon–carbon triple bond of acetylenic
from 21a, the compound 21c features a sickle-shaped ar-
À
rangement of the -CO2[B
N
depicted in the Supporting Information).
Subsequently, we carried out the analogous reaction of
the FLP tBu3P/BACHTUNGTRENNUNG(C6F5)3 (10a) with the saturated carboxylic
ester ethylisobutyrate (22a) and with ethyl benzoate (22b,
Scheme 7). Treatment of 22a with two equivalents of the in-
termolecular frustrated Lewis pair at room temperature for
48 hours in toluene gave an oil that separated from the solu-
tion. It was collected and crystallized from a dichlorome-
esters. Some intermolecular FLPs (e.g., Ar3P/B
ACHTNUGERTN(NGNU C6F5)3) react
similarly but the tBu3P/B(C6F5)3 FLP, which contains a more
AHCTUNGTRENNUNG
nucleophilic phosphane component, deviates from this typi-
cal behavior in favor of boron-stabilized carboxylate forma-
tion. We conclude that FLP reactions with organic carbonyl
compounds must not always involve 1,2-addition to the car-
bonyl group but may follow other reaction pathways de-
pending on both the reactivity of the carbonyl group and
the specific frustrated Lewis pair employed.
Scheme 7.
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Reaction of FLPs with Ketones and Esters
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298 K, C6D6) d=À2.7 ppm (n1/2 ~300 Hz). 31P{1H} NMR (202 MHz,
298 K, C6D6): d=25.4 ppm (n1/2 ~2 Hz). 31P NMR (202 MHz, 298 K,
C6D6): d=25.4 ppm (br t, 3JPH ~47 Hz).
Experimental Section
General Procedures. Reactions with air- and moisture-sensitive com-
pounds were carried out under argon atmosphere using Schlenk-type
glassware or in a glovebox. Solvents were dried and distilled under argon
prior to use. Dimesitylvinylphosphane (Mes2PCH=CH2) [20], bis(penta-
X-ray crystal structure analysis of 8: formula C38H34BF10OP·0.5C6H6,
M=777.49, colorless crystal 0.25ꢄ0.17ꢄ0.10 mm, a=11.3091(3), b=
13.2329(7), c=14.7771(4) ꢃ, a=115.045(3), b=110.879(2), g=
90.599(3)8, V=1837.63(12) ꢃ3, 1calc =1.405 gcmÀ3, m=1.406 mmÀ1, empiri-
cal absorption correction (0.720ꢀTꢀ0.872), Z=2, triclinic, space group
fluorophenyl)borane (HB
(C6F5)2)[21], and tris(pentafluorophenyl)borane
ACHTUNGTRENNUNG
(B
ACHTUNGTRENNUNG
benzoate were dried over CaH2 and then distilled by using vacuum trans-
fer prior to use. The following instruments were used for physical charac-
terization of the compounds: Foss–Heraeus CHNO-Rapid (elemental
analyses), Bruker Daltonics MicroTof (ESI mass spectrometry), Varian
3100 FT-IR (Excalibur Series, IR spectroscopy), and Varian UNITY plus
NMR spectrometer (1H, 599.9 MHz; 13C, 150.8 MHz; 19F, 564.4 MHz;
11B, 192.4 MHz) and Varian 500 MHz INOVA (1H, 499.9 MHz; 13C,
125.7 MHz; 19F, 470.3 MHz; 11B, 160.4 MHz). 1H NMR and 13C NMR,
chemical shift d is given relative to TMS and referenced to the solvent
signal; 19F NMR, chemical shift d is given relative to CFCl3 (external ref-
erence); 11B NMR, chemical shift d is given relative to BF3·Et2O (exter-
nal reference); and 31P NMR, chemical shift d is given relative to H3PO4
(85% in H2O, external reference). Assignments of the resonances were
supported by 2D experiments. X-ray crystal structure analysis: Data sets
were collected with a Nonius KappaCCD diffractometer. Programs used
were: data collection, COLLECT;[23a] data reduction, Denzo-SMN;[23b]
absorption correction, Denzo;[23c] structure solution, SHELXS-97;[23d]
structure refinement, SHELXL-97;[23e] and graphics, SCHAKAL.[23f]
¯
P1 (No. 2), l=1.54178 ꢃ, T=223(2) K, w and f scans, 20336 reflections
collected (Æh, Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1, 6275 independent (Rint
=
0.036) and 5804 observed reflections [Iꢁ2s(I)], 494 refined parameters,
R=0.042, wR2 =0.118, max. (min.) residual electron density 0.35 (À0.29)
eꢃÀ3, hydrogen atoms calculated and refined as riding atoms.
Preparation of compound 11. A solution of (E)-1,4-diphenylbut-2-ene-
1,4-dione 9 (41 mg, 0.20 mmol) in CH2Cl2 (3 mL) was added to a mixture
of BACHTUNRGTEN(UGN C6F5)3 (100 mg, 0.20 mmol) and PtBu3 (40 mg, 0.20 mmol) in CH2Cl2
(4 mL). The mixture was stirred at room temperature for 30 min, which
was then covered with pentane (5 mL). Colorless crystals were formed.
After storing at À358C overnight, the solid was isolated via cannula fil-
tration and washed twice with pentane (2.5 mL) to get 11 (177 mg, 93%)
as a white powder. Anal. calcd (%) for C46H39B1O2F15P1: C, 58.12; H,
4.14; found: C, 58.20; H, 4.18. 1H NMR (600 MHz, 298 K, CD2Cl2): d=
8.11 (m, 2H, o-PhA), 7.65 (m, 1H, p-PhA), 7.34 (m, 2H, m-PhA), 6.99 (m,
3
2
1H, p-PhB), 6.94 (m, 4H, o,m-PhB), 6.13 (dd, JHH =10.6 Hz, JPH =7.1 Hz,
1H, PCH), 4.21 (dd, 3JHH =10.6 Hz, 3JPH =2.9 Hz, 1H, =CH), 1.72 ppm
(d, 3JPH =14.2 Hz, 27H, CH3tBu). 13C{1H} NMR (151 MHz, 298 K,
CCDC 838026,
CCDC 838030,
CCDC 838027,
CCDC 838031,
CCDC 838028,
CCDC 838032,
CCDC 838029,
CCDC 838033,
1
CD2Cl2): d=191.9 (C=O), 163.2 (d, 3JPC =9.7 Hz, C-O), 148.0 (dm, JFC
1
~246 Hz, C6F5), 141.2 (d, 4JPC =1.8 Hz, i-PhB), 139.1 (dm, JFC ~247 Hz,
CCDC 838034, and CCDC 838048 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge
from the Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif.
1
C6F5), 136.7 (dm, JFC ~243 Hz, C6F5), 135.7 (d, 3JPC =5.5 Hz, i-PhA),
134.5 (p-PhA), 129.9 (o-PhA), 128.9 (m-PhA), 127.50 (m-PhB), 127.49 (p-
PhB), 127.0 (br, o-PhB), 123.5 (br, i-C6F5), 93.3 (d, 2JPC =5.6 Hz, =CH),
43.0 (d, 1JPC =30.9 Hz, PCH), 42.2 (d, 1JPC =23.4 Hz, PCtBu), 31.1 ppm
Preparation of compound 8: Mes2PCH=CH2 (100 mg, 0.34 mmol) and
HBACHTUNGTRENNUNG(C6F5)2 (117 mg, 0.34 mmol) were dissolved in heptane (6 mL) and
(CH3tBu). 11B{1H} NMR (192 MHz, 298 K, CD2Cl2): d=À2.8 ppm (n1/2
~
110 Hz). 19F NMR (564 MHz, 298 K, CD2Cl2): d=À132.5 (br, 2F, o-
C6F5), À161.9 (br t, 3JFF =19.7 Hz, 1F, p-C6F5), À167.1 ppm (br, 2F, m-
C6F5). 31P{1H} NMR (243 MHz, 298 K, CD2Cl2): d=55.3 ppm (n1/2 ~3 Hz).
stirred for 15 min. A solution of 3-hexyn-2-one (33 mg, 0.34 mmol) in
benzene (1 mL) was added at room temperature. After stirring for
15 min at room temperature, the reaction mixture was stored overnight
to get colorless crystals. The solid was isolated via cannula filtration and
washed twice with cold pentane (2.5 mL). Removal of all volatiles in
vacuo yielded 8 (228 mg, 91%) as a white powder. Crystals suitable for
X-ray crystal structure analysis were grown by diffusion of pentane to
a saturated toluene solution of 8 at À308C. 1H NMR (500 MHz, 298 K,
X-ray crystal structure analysis of 11: formula C46H39BF15O2P·0.5C5H12,
M=986.62, colorless crystal 0.35ꢄ0.13ꢄ0.10 mm, a=23.7983(5), b=
13.3102(2), c=28.6501(6) ꢃ, V=9075.2(3) ꢃ3, 1calc =1.444 gcmÀ3
, m=
1.445 mmÀ1, empirical absorption correction (0.632ꢀTꢀ0.869), Z=8, or-
thorhombic, space group Pna21 (No. 33), l=1.54178 ꢃ, T=223(2) K, w
and f scans, 52876 reflections collected (Æh, Æk, Æl), [(sinq)/l]=
0.60 ꢃÀ1, 15025 independent (Rint =0.055) and 13878 observed reflections
[Iꢁ2s(I)], 1212 refined parameters, R=0.043, wR2 =0.109, Flack param-
eter 0.36(2), max. (min.) residual electron density 0.54 (À0.28) eꢃÀ3, hy-
drogen atoms calculated and refined as riding atoms.
C6D6): d=6.65 (d, 4JPH =4.4 Hz, 1H, m-MesA), 6.51 (d, 3JPH =40.1 Hz,
1H, =CH), 6.51 (s, 1H, m’-MesB), 6.30 (s, 1H, m-MesB), 6.17 (d, JPH
=
4
4.4 Hz, 1H, m’-MesA), 4.24, 4.21 (each s, each 1H, =CH2), 3.35 (q, JPH
~
2
2JHH =14.8 Hz, 1H, CH2P), 2.61 (dm, 2JHH =14.8 Hz, 1H, CH2P), 2.37 (s,
3H, o-CH3MesA), 2.04 (s, 3H, o’-CH3MesB), 1.94 (s, 3H, p-CH3MesA), 1.90 (s,
3H, p-CH3MesB), 1.86 (dd, 3JPH =53.3 Hz, 2JHH =13.6 Hz, 1H, CH2B), 1.72
(m, 2H, CH2Et), 1.54 (s, 3H, o’-CH3MesA), 1.35 (s, 3H, o-CH3MesB), 1.26
Preparation of compound 13: Mes2PCH=CH2 (100 mg, 0.34 mmol) and
HBACHTUNTRGNEUNG(C6F5)2 (117 mg, 0.34 mmol) were dissolved in pentane (5 mL) and
(dd, JPH ~2JHH =13.6 Hz, 1H, CH2B), 0.68 ppm (t, 3JHH =7.2 Hz, 3H,
3
stirred for 15 min. Then a solution of (E)-1,4-diphenylbut-2-ene-1,4-dione
9 (80 mg, 0.34 mmol) in CH2Cl2 (2 mL) was added at room temperature.
The reaction mixture immediately became a light green solution which
then slowly turned to red and a white solid was simultaneously formed.
After the reaction mixture was stirred for 24 h, the solid was isolated via
cannula filtration and washed twice with cold pentane (2.5 mL). Removal
of all volatiles in vacuo yielded 13 (260 mg, 87%) as a white powder.
Crystals suitable for X-ray crystal structure analysis were grown by gas
diffusion of pentane into a solution of 13 in dichloromethane at À358C.
Anal. calcd (%) for C48H38B1O2F10P1: C, 65.62; H, 4.36; found: C, 65.06;
H, 4.21. 1H NMR (500 MHz, 213 K, CD2Cl2): d=8.18 (m, 2H, o-PhA),
7.63 (m, 1H, p-PhA), 7.53 (m, 2H, m-PhA), 7.32 (m, 2H, o-PhB), 7.15 (t,
2JPH ~3JHH =9.5 Hz, 1H, PCH), 7.10 (m, 3H, p,m-PhB), 7.08 (br, 1H, m-
MesA), 6.98 (br, 1H, m’-MesA), 6.91 (br, 1H, m-MesB), 6.88 (br, 1H, m’-
MesB), 4.96 (br d, 3JHH =9.5 Hz, 1H, =CH), 3.86, 2.99 (each br m, each
1H, PCH2), 2.89 (s, 3H, o-CH3MesA), 2.42 (s, 3H, o’-CH3MesB), 2.33 (s, 3H,
p-CH3MesA), 2.22 (s, 3H, p-CH3MesB), 1.95 (s, 3H, o-CH3MesB), 1.73 (s, 3H,
o’-CH3MesA), 1.29, 0.75 ppm (each br m, each 1H, BCH2). 13C{1H} NMR
CH3Et). 13C{1H} NMR (126 MHz, 298 K, C6D6): d=155.3 (d, JPC =7.6 Hz,
3
1
1
C-O), 149.3 (dm, JFC ~239 Hz, C6F5), 148.0 (dm, JFC ~236 Hz, C6F5),
147.6 (d, 2JPC =2.7 Hz, =CH), 145.3 (d, 2JPC =7.6 Hz, o-MesA), 142.9 (d,
2JPC =6.6 Hz, o-MesB), 142.4 (d, 4JPC =3.1 Hz, p-MesA), 141.7 (d, JPC
=
2
9.0 Hz, o’-MesB), 141.5 (d, 4JPC =2.5 Hz, p-MesB), 141.4 (d, 2JPC =11.4 Hz,
1
1
o’-MesA), 139.70 (dm, JFC ~242 Hz, C6F5), 138.5 (dm, JFC ~244 Hz,
1
1
C6F5), 137.6 (dm, JFC ~255 Hz, C6F5), 136.8 (dm, JFC ~251 Hz, C6F5),
132.39 (d, 3JPC =11.2 Hz, m-MesA), 132.36 (d, 3JPC =9.9 Hz, m’-MesB),
131.2 (d, 3JPC =9.1 Hz, m-MesB), 129.8 (d, 3JPC =12.6 Hz, m’-MesA), 126.6
(d, 1JPC =68.8 Hz, i-MesB), 123.1 (d, 1JPC =72.5 Hz, PC=), 122.2 (br, i-
C6F5), 121.4 (d, 1JPC =84.4 Hz, i-MesA), 99.5 (=CH2), 34.6 (dt, JPC
=
1
60.3 Hz, nJFC =8.3 Hz, CH2P), 29.1 (d, 2JPC =13.3 Hz, CH2Et), 24.8 (d,
3JPC =2.5 Hz, o’-CH3MesB), 24.6 (d, 3JPC =3.8 Hz, o-CH3MesB), 23.3 (m, o-
CH3MesA), 23.1 (br, CH2B), 22.5 (d, 3JPC =4.1 Hz, o’-CH3MesA), 20.5 (d,
5JPC =0.9 Hz, p-CH3MesB), 20.2 (d, 5JPC =1.1 Hz, p-CH3MesA), 13.5 ppm (d,
3JPC =9.0 Hz, CH3Et). 19F NMR (470 MHz, 298 K, C6D6): d=À128.8,
3
À130.2, À133.0, À134.6 (each br, each 1H, o-C6F5), À159.1 (t, JFF
=
3
21.0 Hz), À164.2 (t, JFF =20.5 Hz) (each 1F, p-C6F5), À164.2 (1F), À165.3
(126 MHz, 213 K, CD2Cl2): d=192.8 (d, 2JPC =1.6 Hz, PhCO2), 166.0 (d,
4
(1F), À167.1 ppm (2F) (each br, m-C6F5). 11B{1H} NMR (160 MHz,
3JPC =11.6 Hz, =CPhO), 145.6 (d, 2JPC =8.8 Hz, o’-MesA), 143.9 (d, JPC
=
&
&
&6
&
www.chemasianj.org
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

Gerhard Erker et al.
2.4 Hz, p-MesA), 143.1 (d, 4JPC =2.2 Hz, p-MesB), 141.2 (d, 2JPC =11.8 Hz,
o-MesA), 141.1 (d, 2JPC =9.6 Hz, o’-MesB), 140.8 (d, 2JPC =9.9 Hz, o-
MesB), 138.6 (d, 3JPC =4.5 Hz, i-PhB), 135.0 (d, 4JPC =4.5 Hz, i-PhA), 134.2
(p-PhA), 132.3 (d, 3JPC =10.6 Hz, m-MesB), 132.2 (d, 3JPC =11.7 Hz„ m’-
0.067) and 5418 observed reflections [Iꢁ2s(I)], 549 refined parameters,
R=0.053, wR2 =0.133, max. (min.) residual electron density 0.30 (À0.33)
eꢃÀ3, hydrogen atoms calculated and refined as riding atoms.
Method B (starting from dimethyl fumarate) A solution of dimesitylvinyl-
phosphane (100 mg, 0.34 mmol) in pentane (4 mL) and a solution of HB-
AHCTNUGTER(GNNNU C6F5)2 (117 mg, 0.34 mmol) in pentane (4 mL) were combined and
MesB, m-MesA), 132.0 (d, 3JPC =10.8 Hz, m’-MesA), 128.8 (m-PhA), 128.3
1
(o-PhA), 128.1 (p-PhB), 127.1 (m-PhB), 125.2 (o-PhB), 119.8 (d, JPC
=
1
2
68.4 Hz, i-MesB), 116.7 (d, JPC =66.7 Hz, i-MesA), 98.9 (d, JPC =8.1 Hz, =
CH), 46.0 (d, 1JPC =45.1 Hz, PCH), 26.0 (o-CH3MesA), 25.7(0) (o’-
CH3MesA), 25.6(6) (o’-CH3MesB), 25.0 (br d, 1JPC =55.2 Hz, PCH2), 23.1 (d,
stirred for 5 min under an argon atmosphere. Then dimethyl fumarate
(49 mg, 0.34 mmol)) was added to the yellow reaction solution and the
mixture was stirred for 24 h. The obtained white precipitate was isolated
via cannula filtration and washed with pentane (2ꢄ3 mL). The solid was
3JPC =4.3 Hz, o-CH3MesB), 20.9 (d, JPC =1.4 Hz, p-CH3MesA), 20.7 (d, JPC
=
5
5
0.8 Hz, p-CH3MesB), 19.7 ppm (br, BCH2) [C6F5 not listed]. 11B{1H} NMR
(160 MHz, 298 K, CD2Cl2): d=0.0 (n1/2 ~200 Hz). 19F NMR (470 MHz,
213 K, CD2Cl2): d=À131.2, À135.6 (each br, each 2F, o-C6F5), À161.6,
dried in vacuo to get 15 (154 mg, 58%) as a white powder. 1H NMR
2
(300 MHz, C6D6, 298 K): d=6.37 (m, 4H, m-Mes), 5.32 (dd, JPH
=
3
3
3
15.8 Hz, JHH =12.9 Hz, 1H, PCH), 4.16 (dd, JHH =12.9 Hz, JPH =9.5 Hz,
1H, BCH), 3.30, 2.86 (each s, each 3H, O-CH3), n.o. (PCH2), 2.17, 2.05
(each br, 12H, o-Mes), 1.85, 1.82 ppm (each s, each 3H, p-Mes), n.o.
3
À162.6 (each br t, JFF =20.4 Hz, 1F, p-C6F5), À165.3, À165.6 (each br, 2F,
m-C6F5). 19F NMR (470 MHz, 298 K, CD2Cl2): d=À131.5 (br, 2F, o-
C6F5 ), À135.5 (br, 2F, o-C6F5b), À162.5 (t, 3JFF =20.1 Hz, 1F, p-C6F5 ),
a
a
(BCH2). 11B{1H} NMR (96 MHz, C6D6, 298 K): d=À12.2 ppm (n1/2
=
À163.2 (t, 3JFF =20.3 Hz, 1F, p-C6F5b), À166.2 (m, 2F, m-C6F5b),
60 Hz). 19F{1H} NMR (282 MHz, C6D6, 298 K): d=À129.3, À131.0 (each
m, 2F, o-C6F5), À160.3 (t, 3JFF =20.8 Hz), À161.6 (t, 3JFF =20.7 Hz)(each
1F, p-C6F5), À164.9, À165.2 ppm (each m, each 2F, m-C6F5). 31P{1H}
NMR (122 MHz, C6D6, 298 K): d=29.8 ppm (n1/2 ~10 Hz).
a
À166.5 ppm (m, 2F, m-C6F5 ). 31P{1H} NMR (202 MHz, 213 K, CD2Cl2):
d=23.8 ppm (n1/2 ~20 Hz).
X-ray crystal structure analysis of 13: formula C48H38BF10O2P·0.5C5H12,
M=914.64, colourless crystal 0.25ꢄ0.18ꢄ0.11 mm, a=11.5319(7), b=
13.9590(6), c=15.2516(4) ꢃ, a=68.369(2), b=86.913(2), g=73.222(5)8,
V=2181.25(17) ꢃ3, 1calc =1.393 gcmÀ3, m=1.291 mmÀ1, empirical absorp-
Preparation of compound 18: Mes2PCH=CH2 (100 mg, 0.34 mmol) and
HBACHTUNTRGNEUNG(C6F5)2 (117 mg, 0.34 mmol) were dissolved in pentane (6 mL) and
stirred for 15 min. Then a solution of 20a (207 mg, 0.34 mmol) in CH2Cl2
(1 mL) was added at room temperature. The reaction mixture immediate-
ly became a light orange solution, in which a white precipitate was simul-
taneously formed. After the reaction mixture was stirred for 24 h, the
solid was isolated via cannula filtration and washed twice with cold pen-
tane (2.5 mL) to get 18 (208 mg, 83%) as a white powder. Crystals suita-
ble for X-ray crystal structure analysis were grown by a CH2Cl2/pentane
(1:3) solution of 18 at À308C. Anal. calcd (%) for C37H32B1O2F10P1: C,
60.02; H, 4.36; found: C, 60.37; H, 4.71. 1H NMR (500 MHz, 298 K,
¯
tion correction (0.739ꢀTꢀ0.871), Z=2, triclinic, space group P1 (No.
2), l=1.54178 ꢃ, T=223(2) K, w and f scans, 27874 reflections collected
(Æh, Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1, 7483 independent (Rint =0.046) and
6602 observed reflections [Iꢁ2s(I)], 612 refined parameters, R=0.051,
wR2 =0.149, max. (min.) residual electron density 1.03 (À0.38) eꢃÀ3, hy-
drogen atoms calculated and refined as riding atoms.
Preparation of compound 15: Method A (starting from dimethyl maleate)
A solution of dimesitylvinylphosphane (100 mg, 0.34 mmol) in pentane
(4 mL) and a solution of HBACHTUNRGTNE(UNG C6F5)2 (117 mg, 0.34 mmol) were combined
and stirred for 5 min under an argon atmosphere. Then dimethyl maleate
(42.6 mL, 0.34 mmol) was added to the yellow reaction solution and the
mixture was stirred for two days. The obtained white precipitate was iso-
lated via cannula filtration and washed with pentane (2ꢄ3 mL). The solid
was dried in vacuo to get 15 (149 mg, 56%) as a white powder. Crystals
suitable for X-ray crystal structure analysis were obtained from a solution
3
CD2Cl2): d=7.01 (d, JPH =3.8 Hz, 4H, m-Mes), 3.49 (s, 3H, OCH3), 2.85
(m, 2H, CH2P), 2.33 (s, 6H, p-CH3Mes), 2.27 (s, 12H, o-CH3Mes), 1.84 (d,
2JPH =13.6 Hz, 3H, CH3), 1.45 ppm (dm, 3JPH =27.5 Hz, 2H, CH2B).
13C{1H} NMR (126 MHz, 298 K, CD2Cl2): d=177.0 (br, BC=), 172.7 (d,
1
4
3JPC =29.5 Hz, C=O), 148.6 (dm, JFC ~239 Hz, C6F5), 144.0 (d, JPC
=
2.9 Hz, p-Mes), 143.1 (br d, 2JPC =9.3 Hz, o-Mes), 138.6 (dm, JFC
1
~246 Hz, C6F5), 137.1 (dm, JFC ~241 Hz, C6F5), 132.7 (d, 3JPC =11.0 Hz,
1
1
1
m-Mes), 125.2 (br, i-C6F5), 120.6 (d, JPC =78.0 Hz, i-Mes), 117.9 (d, JPC
=
of 15 in benzene at room temperature. ESI-MS: calculated
72.5 Hz, PC=), 51.2 (OCH3), 26.6 (d, JPC =49.2 Hz, CH2P), 23.7 (d, JPC
=
1
3
+
[C38H34BF10O4P]NH4
:
804.25,
[C38H34BF10O4P]Na+:
809.20,
804.25,
4.6 Hz, o-CH3Mes), 21.1 (d, JPC =1.4 Hz, p-CH3Mes), 20.1 (d, JPC =15.2 Hz,
CH3), 15.3 ppm (br, CH2B). 11B{1H} NMR (160 MHz, 298 K, CD2Cl2): d=
À14.4 ppm (n1/2 ~50 Hz). 19F NMR (470 MHz, 298 K, CD2Cl2): d=À130.1
5
2
[C38H34BF10O4P]K+: 825.18; found [C38H34BF10O4P]NH4
:
+
[C38H34BF10O4P]Na+: 809.20, [C38H34BF10O4P]K+: 825.18. Decomp.:
165.98C. 1H NMR (600 MHz, C6D5Br, 298 K): d=6.65 (d, 4JPH =4.2 Hz,
3
2H, m-Mesb), 6.64 (d, 4JPH =3.4 Hz, 2H, m-Mesa), 5.19 (dd, JPH
=
2
(m, 2F, o-C6F5), À162.4 (t, JFF =20.3 Hz, 1F, p-C6F5), À166.5 ppm (m, 2F,
m-C6F5). 31P{1H} NMR (202 MHz, 298 K, CD2Cl2): d=15.1 ppm (n1/2
~
15.3 Hz, 3JHH =12.9 Hz, 1H, PCH), 4.03 (dd, 3JHH =12.9 Hz, JPH
=
3
10.2 Hz, 1H, BCH), 3.35 (s, 3H, O-CH3B), 3.13, 2.45 (each m, each 1H,
PCH2), 3.04 (s, 3H, O-CH3P), 2.26, 2.19 (br, 12H, o-Mes), 2.08 (s, 3H, p-
Mesb), 2.06 (s, 3H, p-Mesa), 1.49 ppm (each m, 2H, BCH2). 13C{1H} NMR
(151 MHz, C6D5Br, 298 K): d=177.8 (d, 3JPC =19.9 Hz, C=OB)t, 169.7
(C=OP)t, 143.9 (p-Mesa), 143.3 (p-Mesb), 142.4, 141.6 (each br, o-Mes),
132.6 (d, 3JPC =11.7 Hz, m-Mesb), 132.3 (d, 3JPC =11.3 Hz, m-Mesa), 121.2
(d, 1JPC =77.7 Hz, i-Mesb), 119.3 (d, 1JPC =68.2 Hz, i-Mesa), 52.0 (O-
10 Hz).
X-ray crystal structure analysis of 18: formula C37H32BF10O2P, M=740.41,
colorless crystal 0.23ꢄ0.20ꢄ0.05 mm, a=13.0426(4), b=17.7133(7), c=
18.4101(8) ꢃ,
a=64.226(3),
b=84.329(2),
g=78.560(2)8,
empirical absorption
¯
V=
3753.6(2) ꢃ3, 1calc =1.310 gcmÀ3
,
m=1.370 mmÀ1
,
correction (0.744ꢀTꢀ0.935), Z=4, triclinic, space group P1 (No. 2), l=
1.54178 ꢃ, T=223(2) K, w and f scans, 52725 reflections collected (Æh,
CH3P), 50.8 (O-CH3B), 44.2 (d, JPC =40.8 Hz, PCH), 39.0 (br, BCH), 27.0
1
Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1
, 12918 independent (Rint =0.056) and
(d, 1JPC =44.3 Hz, PCH2), 24.5 (o-MesCH3a), 23.6 (o-MesCH3b), 20.9 (p-
10328 observed reflections [Iꢁ2s(I)], 935 refined parameters, R=0.052,
wR2 =0.145, max. (min.) residual electron density 0.25 (À0.44) eꢃÀ3, hy-
drogen atoms calculated and refined as riding atoms.
t
MesCH3), 14.8 ppm (br, BCH2) [C6F5 not listed; tentative assignment].
11B{1H} NMR (192 MHz, C6D5Br, 298 K): d=À12.5 ppm (n1/2 =80 Hz).
19F NMR (564 MHz, C6D5Br, 298 K): d=À129.0 (m, 2F, o-C6F5A), À130.7
Preparation of compound 19: A solution of ethyl propiolate (98.1 mg,
1.00 mmol) in cyclopentane (0.5 mL) was added to a suspension of B-
AHCTUNGTRENNUNG
(m, 2F, o-C6F5B), À160.0 (t, 3JFF =21.0 Hz, 1F, p-C6F5A), À161.0 (t, JFF
=
3
21.2 Hz, 1F, p-C6F5B), À164.4 (m, 2F, m-C6F5A), À164.6 ppm (m, 2F, m-
C6F5B). 31P{1H} NMR (243 MHz, C6D5Br, 298 K): d=28.1 ppm (n1/2
~
AHCTUNGTRENNUNG
10 Hz).
(1.0 mL). A brown precipitate was formed immediately. The precipitate
was collected and washed with cyclopentane (2ꢄ1 mL). After drying in
vacuo, 19 was obtained as a yellow solid (64%, 586 mg). Anal. calcd (%)
for C44H27BF15O2P C, 57.79; H, 2.98; found: C, 57.62; H, 3.22. [Solubility
of 19 in CD2Cl2 is poor; the NMR spectra at 298 K are broad] 1H NMR
X-ray crystal structure analysis of 15: formula C41H37BF10O4P·0.5C6H6,
M=864.54, colorless crystal 0.10ꢄ0.07ꢄ0.05 mm, a=9.1959(8), b=
14.9608(5), c=16.4087(14) ꢃ, a=105.957(2), b=98.971(7), g=
104.495(2)8, V=2039.2(3) ꢃ3, 1calc =1.408 gcmÀ3, m=1.383 mmÀ1, empiri-
cal absorption correction (0.874ꢀTꢀ0.934), Z=2, triclinic, space group
(600 MHz, 193 K, CD2Cl2): d=8.24 (dd,
J
PH =16.6 Hz, 3JHH =8.0 Hz,
P1 (No. 2), l=1.54178 ꢃ, T=223(2) K, w and f scans, 24511 reflections
1H), 7.67 (m, 1H), 7.59 (m, 1H), 7.29 (m, 1H) (Tolc), 7.53, 7.52, 7.38,
¯
collected (Æh, Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1, 6979 independent (Rint
=
7.32, 7.31, 7.27, 7.25, 7.23 (each 1H, Tola,b)1, 6.37 (br d, 2JPH =31.0 Hz,
Chem. Asian J. 2012, 00, 0 – 0
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
7
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Reaction of FLPs with Ketones and Esters
FULL PAPERS
1H, =CH), 3.36, 3.16 (each dq, 2JHH =10.4 Hz, 3JHH =7.1 Hz, each 1H,
CH2), 1.97 (br s, 3H, aCH3Tol), 1.83 (br s, 3H, bCH3Tol), 1.59 (br s, 3H,
cCH3Tol), 0.58 ppm (t, 3JHH =7.1 Hz, 3H, CH3) [1 from the 1 H, 13C ghsqc
experiment, without assignment]. 13C{1H} NMR (151 MHz, 193 K,
CD2Cl2): d=167.6 (=CB), 137.1, 136.2, 134.1, 134.0, 133.4, 133.2, 133.2,
132.4, 132.2, 126.6, 126.3, 126.0 (Tol)1, 120.0 (d, 1JPC =82.3 Hz, i-Tolb)2,
118.2 (d, 1JPC =78.7 Hz, =CH), 117.0 (d, 1JPC =90.4 Hz, i-Tolc)2, 114.0 (d,
1JPC =89.3 Hz, i-Tola)2, 60.8 (CH2), 12.4 ppm (CH3) [C6F6 not listed;
Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1, 9775 independent (Rint =0.036) and 9205
observed reflections [Iꢁ2s(I)], 851 refined parameters, R=0.048, wR2 =
0.137, max. (min.) residual electron density 1.21 (À0.55) eꢃÀ3, hydrogen
atoms calculated and refined as riding atoms.
Preparation of compound 21c: A solution of PtBu3 (20 mg, 0.10 mmol)
and BACTHUNRGTNE(UNG C6F5)3 (51 mg, 0.10 mmol) in pentane (10 mL) was slowly added to
a solution of 20c (69 mg, 0.10 mmol) in CH2Cl2 (2 mL). A white solid was
simultaneously formed. After stirring of the reaction mixture for 5 h, the
solid was isolated via cannula filtration and washed twice with cold
CH2Cl2/pentane (2.5 mL, 1:5) to get 21c (101 mg, 72%) as a white
powder (in CD2Cl2 solution admixed with 16c, PtBu3 and (F5C6)3B-O=
PtBu3). Crystals suitable for X-ray crystal structure analysis were grown
by a CH2Cl2/pentane (1:3) solution of 21c at À308C. (Note: Compound
21c was not stable in CD2Cl2 at À308C after 2 months). 21c: 1H NMR
(500 MHz, 298 K, CD2Cl2): d=7.47 (br m, 1H, p-Ph), 7.33 (br m, 2H, m-
Ph), 7.15 (br m, 2H, o-Ph), 2.22 (dq, 2JPH =12.0 Hz, 3JHH =7.5 Hz, 2H,
CH2), 1.59 (d, 3JPH =14.0 Hz, 27H, CH3tBu), 1.58 ppm (dt, 3JPH =14.9 Hz,
3JHH =7.5 Hz, 3H, CH3). 13C{1H} NMR (126 MHz, 298 K, CD2Cl2): d=
163.8 (C-O), 133.1 (o-Ph), 132.1 (p-Ph), 129.0 (m-Ph), 118.3 (i-Ph), 99.9
(ꢂCPh), 80.1 (ꢂCC–O)t, 39.7 (d, 1JPC =29.2 Hz, CtBu), 30.0 (CH3tBu), 12.6
t
1
2
from the 1 H, 13C ghsqc experiment, without assignment; from the 1 H,
13C ghmbc experiment]. 11B{1H} NMR (192 MHz, 193 K, CD2Cl2): d=
À14.0 ppm (n1/2 ~35 Hz). 19F NMR (564 MHz, 193 K, CD2Cl2): d=
À125.8t, À132.5 (each m, each 1F, o), À160.1 (br t, 3JFF =20.2 Hz, 1F, p),
À163.9, À165.8 (each m, each 1F, m) (C6F5), À129.4, À131.0t (each m,
3
each 1F, o), À160.9 (br t, JFF =20.4 Hz, 1F, p-C6F5), À165.8, À167.5 (each
m, each 1F, m) (C6F5), À131.3, À133.4 (each m, each 1F, o), À161.5 (br t,
3JFF =20.7 Hz, 1F, p-C6F5), À165.1, À166.2 ppm (each m, each 1F, m)
(C6F5) [t tentative assignment]. 31P{1H} NMR (243 MHz, 193 K, CD2Cl2):
d=16.6 ppm (m).
NMR scale reaction: A solution of ethyl propiolate (2.94 mg, 0.03 mmol)
in C6D6 (0.33 mL) was added to
0.03 mmol) in C6D6 (0.33 mL). This solution was added to a solution of P-
ACHTUNGTRENNUNG(o-tolyl)3 (9.13 mg, 0.03 mmol) in C6D6 (0.33 mL). After 15 min the color
a solution of BACTHUNTGENRU(GN C6F5)3 (15.4 mg,
1
2
(d, JPC =38.3 Hz, CH2), 9.9 ppm (d, JPC =6.9 Hz, CH3) [C6F5 not listed;
tentative assignment]. 11B{1H} NMR (160 MHz, 298 K, CD2Cl2) d=
À1.0 ppm (n1/2 ~120 Hz). 19F NMR (470 MHz, 298 K, CD2Cl2): d=À133.8
of the solution became pale brown. The solution was transferred to
a NMR tube and sealed under vacuum. Crystals suitable for X-ray crystal
structure analysis were obtained after storing the NMR tube for one
week at room temperature. X-ray crystal structure analysis of 19: formula
C44H27BF15O2P·2C6H6, M=1070.65, light yellow crystal 0.37ꢄ0.30ꢄ
0.20 mm, a=15.3224(5), b=19.1842(7), c=17.3717(6) ꢃ, b=102.660(2)8,
V=4982.2(3) ꢃ3, 1calc =1.427 gcmÀ3, m=1.370 mmÀ1, empirical absorption
correction (0.631ꢀTꢀ0.771), Z=4, monoclinic, space group P21/n (No.
14), l=1.54178 ꢃ, T=223(2) K, w and f scans, 41859 reflections collect-
ed (Æh, Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1, 8590 independent (Rint =0.066)
and 6360 observed reflections [Iꢁ2s(I)], 689 refined parameters, R=
0.061, wR2 =0.159, max. (min.) residual electron density 0.27 (À0.28)
eꢃÀ3, hydrogen atoms calculated and refined as riding atoms.
3
(m, 2F, o-C6F5), À160.0 (t, JFF =20.3 Hz, 1F, p-C6F5), À162.4 ppm (m, 2F,
m-C6F5). 31P{1H} NMR (202 MHz, 298 K, CD2Cl2): d=48.8 ppm (n1/2
~
2 Hz).
16c/PtBu3:1H NMR (500 MHz, 298 K, CD2Cl2): 16c, d=7.59 (m, 2H, o-
Ph), 7.48 (m, 1H, p-Ph), 7.40 (m, 2H, m-Ph), 4.27 (q, 3JHH =7.1 Hz, 2H,
3
CH2), 1.33 ppm (t, 3JHH =7.1 Hz, 3H, CH3); PtBu3: 1.29 ppm (d, JPH
=
9.7 Hz, 27H, CH3tBu). 13C{1H} NMR (126 MHz, 298 K, CD2Cl2): d=154.2
(C=O), 133.2 (o-Ph), 131.1 (p-Ph), 129.0 (m-Ph), 119.9 (i-Ph), 86.0 (ꢂ
=
CPh), 81.0 (ꢂCC O)t, 62.5 (CH2), 14.2 (CH3) [C6F5 not listed]; PtBu3: 34.6
(d, 1JPC =31.7 Hz, CtBu), 32.5 ppm (d, 2JPC =12.9 Hz, CH3tBu). 31P{1H}
NMR (202 MHz, 298 K, CD2Cl2): d=62.4 ppm (n1/2 ~2 Hz, PtBu3).
AHCTUNGTRENNUNG
(F5C6)3B-O=PtBu3: 1H NMR (500 MHz, 298 K, CD2Cl2): d=1.67 ppm
Preparation of compound 21a: Method A (one pot reaction): A solution
of PtBu3 (20 mg, 0.10 mmol) in toluene (3 mL) was added to a mixture of
BACHTUNGTRENNUNG(C6F5)3 (102 mg, 0.20 mmol, 2 equiv) and methyl but-2-ynoate (16a)
(d, 3JPH =17.4 Hz, 27H, tBu). 13C{1H} NMR (126 MHz, 298 K, CD2Cl2):
d=45.9 (d, 1JPC =14.7 Hz, PCtBu), 29.3 ppm (d, 2JPC =18.9 Hz, CH3tBu).
11B{1H} NMR (160 MHz, 298 K, CD2Cl2): d=À7.2 ppm (n1/2 ~100 Hz).
19F NMR (470 MHz, 298 K, CD2Cl2): d=À132.7 (m, 2F, o-C6F5), À162.4
(t, 3JFF =20.3 Hz, 1F, p-C6F5), À167.2 ppm (m, 2F, m-C6F5). 31P{1H} NMR
(202 MHz, 298 K, CD2Cl2): d=122.6 ppm (n1/2 ~8 Hz).
(10 mg, 0.10 mmol) in toluene (4 mL). A colorless emulsion was formed
simultaneously. Upon stirring for 3 h, the reaction mixture was stored at
room temperature for 30 min. Afterwards, the resulting oil layer was iso-
lated by removing the covered toluene phase. Crystallization of the oil
from CH2Cl2/pentane (3 mL, 1:5) at À308C gave 21a (103 mg, 78%) as
colorless crystals. 1H NMR (500 MHz, 298 K, CD2Cl2): d=1.74 (s, 3H,
CH3), 1.61 (d, 2JPH =11.3 Hz, 3H, PCH3) 1.56 ppm (d, 3JPH =14.5 Hz,
27H, MetBu). 13C{1H} NMR (126 MHz, 298 K, CD2Cl2): d=163.6 (C-O),
X-ray
crystal
structure
analysis
of
21c:
formula
C45H5B2F30O2·C30H27BF15OP·C14H32P, M=2130.77.46, colorless crystal
0.13ꢄ0.07ꢄ0.03 mm, a=12.0546(8), b=13.4978(4), c=27.7894(18) ꢃ,
a=77.017(3), b=87.962(5), g=89.439(3)8, V=4403.2(4) ꢃ3, 1calc
=
1.607 gcmÀ3, m=1.783 mmÀ1, empirical absorption correction (0.801ꢀTꢀ
1
1
¯
148.3 (dm, JFC ~242 Hz, C6F5), 140.0 (dm, JFC ~249 Hz, C6F5), 137.1
0.949), Z=2, triclinic, space group P1 (No. 2), l=1.54178 ꢃ, T=
(dm, JFC ~249 Hz, C6F5), 118.8 (br, i-C6F5), 101.2 (ꢂCCH3), 71.8 (ꢂCC–O),
1
223(2) K, w and f scans, 55640 reflections collected (Æh, Æk, Æl),
[(sinq)/l]=0.60 ꢃÀ1, 14640 independent (Rint =0.104) and 7973 observed
reflections [Iꢁ2s(I)], 1299 refined parameters, R=0.087, wR2 =0.229,
max. (min.) residual electron density 0.37 (À0.36) eꢃÀ3, hydrogen atoms
calculated and refined as riding atoms.
38.3 (d, 1JPC =31.0 Hz, CtBu), 29.3 (MetBu), 4.3 (CH3), 1.0 ppm (d, JPC
=
1
45.4 Hz, PCH3). 11B{1H} NMR (160 MHz, 298 K, CD2Cl2) d=À1.0 ppm
(n1/2 ~350 Hz). 19F NMR (470 MHz, 298 K, CD2Cl2): d=À134.0 (m, 2F, o-
C6F5), À161.1 (t, 3JFF =20.0 Hz, 1F, p-C6F5), À166.4 ppm (m, 2F, m-C6F5).
31P{1H} NMR (202 MHz, 298 K, CD2Cl2): d=49.4 ppm (n1/2 ~1 Hz).
Preparation of compound 23a: A solution of PtBu3 (40 mg, 0.20 mmol,
Method B (two stepsꢁ pathway): A solution of PtBu3 (20 mg, 0.10 mmol)
2 equiv) in toluene (3 mL) was added to a mixture of BACHTUNRGTNEUNG(C6F5)3 (102 mg,
and BACHTUNGTRENNUNG(C6F5)3 (51 mg, 0.10 mmol) in pentane (10 mL) was slowly added to
0.20 mmol, 2 equiv) and ethyl isobutyrate (22a) (12 mg, 0.10 mmol) in
toluene (4 mL). Then a colorless emulsion was slowly formed. After stir-
ring for 48 h, the reaction mixture was stored at room temperature for
30 min. Afterwards, the resulting oil layer was isolated by removing the
covered toluene phase. Subsequent fractional crystallization of the oil
from CH2Cl2/pentane (3 mL,1:5) at À308C gave 23a (71 mg, 53%) as col-
orless crystals. (Comment 1: one more equivalent or excess of PtBu3 is
a solution of 20a (61 mg, 0.10 mmol) in CH2Cl2 (2 mL). A white solid
was simultaneously formed. After stirring of the reaction mixture for 5 h,
the solid was isolated via cannula filtration and washed twice with cold
CH2Cl2/pentane (2.5 mL, 1: 5) to afford 21a (109 mg, 82%) as a white
powder. Crystals suitable for X-ray crystal structure analysis were grown
by a CH2Cl2/pentane (1:3) solution of 21a at À308C. Anal. calcd (%) for
C53H33B2F30O2P: C, 48.36; H, 2.51; found: C, 48.36; H, 2.22. X-ray crystal
structure analysis of 21a: formula C40H3B2F30O2·C13H30P·0.5C5H12, M=
1360.46, colorless crystal 0.35ꢄ0.23ꢄ0.10 mm, a=12.8051(7), b=
14.7710(3), c=15.9227(7) ꢃ, a=81.420(2), b=73.602(3), g=86.245(2)8,
V=2856.0(2) ꢃ3, 1calc =1.582 gcmÀ3, m=1.718 mmÀ1, empirical absorption
+
necessary for the formation of 23a. Comment 2: two cations, EtPtBu3
+
(38%) and HPtBu3 (12%), were detected in CD2Cl2 solution as coun-
terion). 1H NMR (500 MHz, 298 K, CD2Cl2): d=iPrC(OB
ACHTUGNRETN(NNUG C6F5)3)2: 2.68
+
3
3
(hept, JHH =6.7 Hz, 1H, CH), 0.88 (d, JHH =6.4 Hz, 6H, CH3); EtPtBu3
: 2.22 (dq, 2JPH =12.0 Hz, 3JHH =7.5 Hz, 2H, CH2), 1.61 (d, JPH =14.0 Hz,
3
correction (0.585ꢀTꢀ0.847), Z=2, triclinic, space group P1 (No. 2), l=
27H, CH3tBu), 1.59 (dt, JPH =14.6 Hz, JHH =7.5 Hz, 3H, CH3); HPtBu3
:
3
3
+
¯
1.54178 ꢃ, T=223(2) K, w and f scans, 38175 reflections collected (Æh,
5.02 (d, 1JPH =427.1 Hz, 1H, PH), 1.65 ppm (d, 3JPH =15.9 Hz, 27H,
&
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www.chemasianj.org
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

Gerhard Erker et al.
CH3tBu). 13C{1H} NMR (126 MHz, 298 K, CD2Cl2): d=iPrC(OB
ACHTNUTRGEN(UNG C6F5)3)2:
Acknowledgements
1
1
189.0 (C-O), 148.3 (dm, JFC ~243 Hz, C6F5), 140.0 (dm, JFC ~249 Hz,
1
C6F5), 137.2 (dm, JFC ~247 Hz, C6F5), 119.1 (br, i-C6F5), 35.6 (CH), 19.4
Financial support from the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industrie is gratefully acknowledged. Hiroshi Na-
katsukaꢅs stay in Mꢁnster was supported by the Mꢁnster/Nagoya DFG/
JSPS International Research Training Group/International Graduate Ex-
ternship “Complex Chemical Systems”.
(CH3); EtPtBu3+: 39.7 (d, 1JPC =29.2 Hz, CtBu), 29.9 (CH3tBu), 12.7 (d,
1
1JPC =38.4 Hz, CH2), 9.8 (d, 2JPC =6.9 Hz, CH3); HPtBu3+: 38.1 (d, JPC
=
26.7 Hz, CtBu), 30.4 ppm (CH3tBu). 11B{1H} NMR (160 MHz, 298 K,
CD2Cl2): d=À1.8 ppm (n1/2 ~450 Hz). 19F NMR (470 MHz, 298 K,
CD2Cl2): d=À133.2 (br, 2F, o-C6F5), À159.5 (br, 1F, p-C6F5), À165.9 (br,
a
2F, m-C6F5) (C6F5 ); À134.3 (br, 2F, o-C6F5), À161.1 (br, 1F, p-C6F5),
À166.7 ppm (br, 2F, m-C6F5) (C6F5b). 31P{1H} NMR (202 MHz, 298 K,
[1] Reviews: a) G. Erker, Organometallics 2011, 30, 358–368; b) D. W.
Stephan, G. Erker, Angew. Chem. 2010, 122, 50–81; Angew. Chem.
Int. Ed. 2010, 49, 46–76; c) P. P. Power, Nature 2010, 463, 171–177;
d) D. W. Stephan, Org. Biomol. Chem. 2008, 6, 1535–1539; e) D. W.
Stephan, Dalton Trans. 2009, 3129–3136; f) D. W. Stephan, S.
Greenberg, T. W. Graham, P. Chase, J. J. Hastie, S. J. Geier, J. M.
Farrell, C. C. Brown, Z. M. Heiden, G. C. Welch, M. Ullrich, Inorg.
Chem. 2011, 50, 12338-12348; g) W. E. Piers, A. J. V. Marwitz, L. G.
Mercier, Inorg. Chem. 2011, 50, 12252-12262.
[2] a) T. Voss, J.-B. Sortais, R. Frçhlich, G. Kehr, G. Erker, Organome-
tallics 2011, 30, 584–594; b) J.-B. Sortais, T. Voss, G. Kehr, R. Frçh-
lich, G. Erker, Chem. Commun. 2009, 7417–7418; c) J. S. J. McCa-
hill, G. C. Welch, D. W. Stephan, Angew. Chem. 2007, 119, 5056–
5059; Angew. Chem. Int. Ed. 2007, 46, 4968–4971; For theoretical
analysis see d) A. Stirling, A. Hamza, T. A. Rokob, I. Papai, Chem.
Commun. 2008, 3148–3150; e) Y. Guo, S. Li, Eur. J. Inorg. Chem.
2008, 2501–2505.
[3] a) C. Appelt, H. Westenberg, F. Bertini, A. W. Ehlers, J. C. Sloot-
weg, K. Lammertsma, W. Uhl, Angew. Chem. 2011, 123, 4011–4014;
Angew. Chem. Int. Ed. 2011, 50, 3925–3928; b) M. A. Dureen, C. C.
Brown, D. W. Stephan, Organometallics 2010, 29, 6422–6432;
c) M. A. Dureen, C. C. Brown, D. W. Stephan, Organometallics
2010, 29, 6594–6607; d) C. Chen, F. Eweiner, B. Wibbeling, R. Frçh-
lich, S. Senda, Y. Ohki, K. Tatsumi, S. Grimme, G. Kehr, G. Erker,
Chem. Asian J. 2010, 5, 2199–2208; e) C. Chen, R. Frçhlich, G.
Kehr, G. Erker, Chem. Commun. 2010, 46, 3580–3582; f) C. Jiang,
O. Blacque, H. Berke, Organometallics 2010, 29, 125–133; g) M. A.
Dureen, D. W. Stephan, J. Am. Chem. Soc. 2009, 131, 8396–8397;
h) T. Voss, C. Chen, G. Kehr, E. Nauha, G. Erker, D. W. Stephan,
Chem. Eur. J. 2010, 16, 3005–3008.
[4] M. Ullrich, K. S.-H. Seto, A. J. Lough, D. W. Stephan, Chem.
Commun. 2009, 2335–2337.
[5] C. M. Mçmming, G. Kehr, B. Wibbeling, R. Frçhlich, B. Schirmer, S.
Grimme, G. Erker, Angew. Chem. 2010, 122, 2464–2467; Angew.
Chem. Int. Ed. 2010, 49, 2414–2417.
[6] C. M. Mçmming, G. Kehr, B. Wibbeling, R. Frçhlich, G. Erker,
Dalton Trans. 2010, 39, 7556–7564.
[7] a) E. Otten, R. C. Neu, D. W. Stephan, J. Am. Chem. Soc. 2009, 131,
9918–9919; b) R. C. Neu, E. Otten, A. Lough, D. W. Stephan,
Chem. Sci. 2011, 2, 170–176.
[8] A. J. P. Cardenas, B. J. Culotta, T. H. Warren, S. Grimme, A. Stute,
R. Frçhlich, G. Kehr, G. Erker, Angew. Chem. 2011, 123, 7709–
7713; Angew. Chem. Int. Ed. 2011, 50, 7567–7571.
[9] P. Spies, G. Erker, G. Kehr, K. Bergander, R. Frçhlich, S. Grimme,
D. W. Stephan, Chem. Commun. 2007, 5072–5074.
1
CD2Cl2): d=48.9 ppm (n1/2 ~2 Hz), [tBu3PH+: 60.9 (n1/2 ~2 Hz, JPH
~427 Hz)].
X-ray
crystal
structure
analysis
of
23a:
formula
C40H7B2F30O2·C14H32P·0.5C5H12·CH2Cl2, M=1463.44, colorless crystal
0.45ꢄ0.25ꢄ0.20 mm, a=11.1396(3), b=14.7279(5), c=19.9358(7) ꢃ, a=
70.712(3), b=87.138(4), g=80.796(3)8, V=3047.38(17) ꢃ3, 1calc
=
1.595 gcmÀ3, m=2.441 mmÀ1, empirical absorption correction (0.406ꢀTꢀ
¯
0.641), Z=2, triclinic, space group P1 (No. 2), l=1.54178 ꢃ, T=
223(2) K, w and f scans, 40042 reflections collected (Æh, Æk, Æl),
[(sinq)/l]=0.60 ꢃÀ1, 10504 independent (Rint =0.048) and 9003 observed
reflections [Iꢁ2s(I)], 856 refined parameters, R=0.074, wR2 =0.214,
max. (min.) residual electron density 1.23 (À1.14) eꢃÀ3, cation is heavily
disordered, hydrogen atoms calculated and refined as riding atoms.
Preparation of compound 23b: A solution of PtBu3 (40 mg, 0.20 mmol,
2 equiv) in toluene (3 mL) was added to a mixture of BACHTUNRGTNEUNG(C6F5)3 (102 mg,
0.20 mmol, 2 equiv) and ethyl benzoate (22b) (15 mg, 0.10 mmol) in tolu-
ene (4 mL). Then a colorless emulsion was slowly formed. After stirring
for 48 h, the reaction mixture was stored at room temperature for
30 min. Afterwards, the resulting oil layer was isolated by removing the
covering toluene phase. Subsequent fractional crystallization of the oil
from CH2Cl2/pentane (3 mL, 1:5) at À308C gave 23b (94 mg, 68%) as
colorless crystals. (Comment 1: one more equivalent or excess of PtBu3 is
necessary for the formation of 23b. Comment 2: two anions, PhC(OB-
À
À
+
ACHTUNGTRENNUNG(C6F5)3)2 (40%) and HOBCATHUGNRTEN(NUNG C6F5)3 (10%), and two cations, EtPtBu3
+
(35%) and HPtBu3 (15%), were detected in CD2Cl2 solution. The
second anion was tentatively assigned as HOB
À
(C6F5)3
:
1H NMR
(500 MHz, 253 K, CD2Cl2): d=7.99 (br, 1H, OH). 11B{1H} NMR
(160 MHz, 253 K, CD2Cl2) d=À4.6 (n1/2 ~150 Hz). 19F NMR (470 MHz,
253 K, CD2Cl2): d=À134.9 (br, 2F, o-C6F5), À162.4 (br, 1F, p-C6F5),
À166.7 (br, 2F, m-C6F5).] 1H NMR (500 MHz, 253 K, CD2Cl2): d=
PhC(OBACHTUNGTRENNUNG(C6F5)3)2: 7.45 (m, 2H, o-Ph), 7.38 (m, 1H, p-Ph), 7.20 (m, 2H,
m-Ph); EtPtBu3+: 2.16 (dq, 2JPH =12.0 Hz, 3JHH =7.5 Hz, 2H, CH2), 1.55
(d, 3JPH =13.9 Hz, 27H, CH3tBu), 1.54 (dt, 3JPH =14.6 Hz, 3JHH =7.5 Hz,
3H, CH3); HPtBu3+: 5.02 (d, 1JPH =428.1 Hz, 1H, PH), 1.59 ppm (d,
3JPH =15.8 Hz, 27H, CH3tBu). 13C{1H} NMR (126 MHz, 253 K, CD2Cl2):
1
d=PhC(OB
G
1
1
(dm, JFC ~248 Hz, C6F5), 136.5 (dm, JFC ~255 Hz, C6F5), 132.7 (p-Ph),
132.4 (i-Ph), 128.5 (o-Ph), 127.9 (m-Ph), 118.7 (br, i-C6F5); EtPtBu3
39.2 (d, 1JPC =29.4 Hz, CtBu), 29.5 (br, CH3tBu), 12.2 (d, 1JPC =38.5 Hz,
CH2), 9.6 (d, 2JPC =6.8 Hz, CH3); HPtBu3+: 37.6 (d, 1JPC =26.9 Hz, CtBu),
29.9 ppm (CH3tBu). 11B{1H} NMR (160 MHz, 253 K, CD2Cl2): d=
À0.9 ppm (n1/2 ~800 Hz). 19F NMR (470 MHz, 253 K, CD2Cl2): d=À133.7
(br, 2F, o-C6F5), À160.0 (br, 1F, p-C6F5), À166.1 ppm (br, 2F, m-C6F5).
31P{1H} NMR (202 MHz, 253 K, CD2Cl2): d=47.5 (n1/2 ~7 Hz), [tBu3PH+:
1
59.0 ppm (n1/2 ~8 Hz, JPH ~428 Hz)].
[10] S. Moebs-Sanchez, G. Bouhadir, N. Saffon, L. Maron, D. Bourissou,
Chem. Commun. 2008, 3435–3437.
X-ray
crystal
structure
analysis
of
23b:
formula
[11] A. Stute, G. Kehr, R. Frçhlich, G. Erker, Chem. Commun. 2011, 47,
4288–4290.
C43H5B2F30O2·C14H32P·CH2Cl2, M=1461.38, colorless crystal 0.33ꢄ0.10ꢄ
0.07 mm, a=12.2191(4), b=18.4851(7), c=26.4674(8) ꢃ, b=99.132(3)8,
V=5902.5(3) ꢃ3, 1calc =1.645 gcmÀ3, m=2.523 mmÀ1, empirical absorption
correction (0.490ꢀTꢀ0.843), Z=4, monoclinic, space group P21/c (No.
14), l=1.54178 ꢃ, T=223(2) K, w and f scans, 46749 reflections collect-
ed (Æh, Æk, Æl), [(sinq)/l]=0.60 ꢃÀ1, 9651 independent (Rint =0.053)
and 6173 observed reflections [Iꢁ2s(I)], 857 refined parameters, R=
0.101, wR2 =0.333, max. (min.) residual electron density 0.80 (À0.57)
eꢃÀ3, cation is heavily disordered, hydrogen atoms calculated and re-
fined as riding atoms.
[12] a) C. M. Mçmming, E. Otten, G. Kehr, R. Frçhlich, S. Grimme,
D. W. Stephan, G. Erker, Angew. Chem. 2009, 121, 6770–6773;
Angew. Chem. Int. Ed. 2009, 48, 6643–6646; b) I. Peuser, R. C. Neu,
X. Zhao, M. Ulrich, B. Schirmer, J. A. Tannert, G. Kehr, R. Frçhlich,
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9650.
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Chem. Asian J. 2012, 00, 0 – 0
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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Reaction of FLPs with Ketones and Esters
FULL PAPERS
[14] See also: a) A. Suzuki, A. Arase, H. Matsumoto, M. Itoh, H. C.
Dureen, A. Lough, T. M. Gilbert, D. W. Stephan, Chem. Commun.
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D. W. Stephan, Chem. Commun. 2007, 5072–507.
[21] D. J. Parks, R. E. v. H. Spence, W. E. Piers, Angew. Chem. 1995, 107,
895–897; Angew. Chem. Int. Ed. 1995, 34, 809–811.
´
Brown, M. M. Rogic, M. W. Rathke, J. Am. Chem. Soc. 1967, 89,
´
5708–5709; b) H. C. Brown, M. M. Rogic, M. W. Rathe, G. W. Ka-
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H. C. Brown, A. Suzuki, S. Honma, A. Arase, M. Itoh, J. Am.
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Freiburg, 1997.
Received: November 25, 2011
Published online: && &&, 0000
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ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

FULL PAPERS
Frustrated Lewis Pairs
Bao-Hua Xu, Raul Alfonso
Adler Yanez, Hiroshi Nakatsuka,
Masato Kitamura, Roland Frçhlich,
Gerald Kehr,
Off the beaten path: Some frustrated
Lewis pairs (FLP) react with unsatu-
rated ketones and esters by means of
conjugate addition to the activated
carbon–carbon double or triple bond
to give the respective P/B addition
products. This is different from the
FLP reactivity towards, for example,
cinnamaldehyde, where 1,2-addition to
the carbonyl group is observed.
Gerhard Erker*
&&&& — &&&&
Reaction of Frustrated Lewis Pairs
with Ketones and Esters
Chem. Asian J. 2012, 00, 0 – 0
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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