Efficient addition reaction of dibutylphosphane oxide with alkynes: New mechanistic proposal involving a duo of palladium and Br?nsted acid

Article abstract of DOI:10.1002/adsc.201000758

The addition reaction of dibutylphosphane oxide [Bu₂P(O)H] with alkynes proceeds efficiently in the presence of palladium-chelating phosphane-Br?nsted acid catalyst systems. Terminal alkynes afford branched-structured products selectively. On the other hand, the same reaction using monodentate phosphane ligands or the reaction run in the absence of a Br?nsted acid affords a much lower yield. A mechanistic study has revealed that Br?nsted acids (XOH) interact with oxygen in MP(O)R ₂ species (M=Pd, Pt) through hydrogen bonding to transform them to ionic M⁺←PR₂(OH?O^-X) species, which was confirmed by NMR spectroscopy and X-ray crystallography. The phosphane-like PR₂(OH?O^-X) moiety is coordinatively labile, as substantiated by the ligand exchange reaction with tert-butyl isocyanide. A new mechanism that accommodates these observations has been proposed to rationalize the enhancement of catalytic activity and the regioselectivity induced by the Br?nsted acid.

Full text of DOI:10.1002/adsc.201000758

COMMUNICATIONS
DOI: 10.1002/adsc.201000758
Efficient Addition Reaction of Dibutylphosphane Oxide with
Alkynes: New Mechanistic Proposal Involving a Duo of
Palladium and Brønsted Acid
Jun Kanadaa and Masato Tanakaa,*
a
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259-R1-13 Nagatsuta, Midori-ku, Yokohama 226-8503,
Japan
Fax : (+81)-45-924-5279; e-mail: m.tanaka@res.titech.ac.jp
Received: October 9, 2010; Revised: December 25, 2010; Published online: April 12, 2011
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.201000758.
Abstract: The addition reaction of dibutylphos-
phane oxide [Bu2P(O)H] with alkynes proceeds ef-
ficiently in the presence of palladium-chelating
phosphane–Brønsted acid catalyst systems. Terminal
alkynes afford branched-structured products selec-
tively. On the other hand, the same reaction using
monodentate phosphane ligands or the reaction run
in the absence of a Brønsted acid affords a much
lower yield. A mechanistic study has revealed that
We and other groups have reported a series of
ꢀ
metal complex-catalyzed addition reactions of H
[3]
ꢀ
P(O) bonds across C C unsaturated linkages. As far
as the palladium-catalyzed reaction of dialkylphos-
phane oxides is concerned, there is only one paper
published by Toffano and co-workers, disclosing the
first examples of the reactions with alkynes.[3u,4] How-
ever, the only phosphane oxide they used was a five-
membered cyclic one, which might be more reactive
than plain dialkylphosphane oxides if we take account
of the exceptionally high reactivity of five-membered
cyclic hydrogen phosphonates as compared with di-
methyl or diethyl phosphonates.[5] In addition, the
yields of the adducts were not very high (31–63%
1H NMR yields). Thus, the process has remained to
be further improved in order to generalize the syn-
thetic applicability. In this paper we wish to report a
high-yielding general procedure for the addition of di-
ꢀ
Brønsted acids (XOH) interact with oxygen in M
P(O)R2 species (M=Pd, Pt) through hydrogen
!
bonding to transform them to ionic M+ PR2
ACHTUNGTRENNUNG
CHTUNGTRENNUNG
labile, as substantiated by the ligand exchange reac-
tion with tert-butyl isocyanide. A new mechanism
that accommodates these observations has been
proposed to rationalize the enhancement of catalyt-
ic activity and the regioselectivity induced by the
Brønsted acid.
ꢁ
alkylphosphane oxides to C C triple bonds by using
palladium-chelating phosphane–Brønsted acid catalyst
systems (Scheme 1).
Some time ago, one of us reported that the palladi-
um-catalyzed addition of Ph2P(O)H with terminal al-
kynes afforded linear compounds as major products,[6]
while the same reaction run in the presence of a cata-
lytic quantity of Ph2P(O)OH under otherwise identi-
cal conditions furnished branched-structured prod-
Keywords: alkynes; Brønsted acids; homogeneous
catalysis; hydrogen bonding; palladium; phosphory-
lation
Although metal complex-catalyzed reactions assisted
by Brønsted acids (XOH) have long been known, the
role of Brønsted acids is usually to generate hydrido-
metal species or to take part in a cascade process
comprising metal-catalyzed and acid-catalyzed reac-
tions.[1] Homogeneous catalysis where more intimate
metal-acid cooperation plays an indispensable role is
still rare.[2]
Scheme 1. Addition of dibutylphosphane oxide with alkynes.
890
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 890 – 896

Efficient Addition Reaction of Dibutylphosphane Oxide with Alkynes
Scheme 2. Tentative mechanism proposed in ref.[7] to rationalize the regiochemical reversal induced by addition of a small
quantity of Ph2P(O)OH in PdL2-catalyzed addition reaction of diphenylphosphane oxide.
ucts.[7] In the mechanistic study on the latter catalysis,
Table 1. Performance of Brønsted acid (XOH) in addition
reaction of dibutylphosphane oxide to 1-octyne.[a]
Ph2P(O)Pd[OP(O)Ph2]ACHTNURTGENUNG
(dmpe)[8] was isolated and this
complex was found to display basically the same per-
formance affording the branched products as the cata-
lyst generated in situ from Me2PdACTHNUTRGNEU(GN dmpe) and
Ph2P(O)OH [and also Ph2P(O)H present as reagent].
On the basis of these findings, a tentative mechanism
XOH
[3,5-(CF3)2C6H3]2P(O)OH
Ph2P(O)OH
(p-t-BuC6H4)2P(O)OH
4-toluic acid
Time
[h]
Yield of
Selec.
[%][c]
3aA [%][b]
G
G
1
1
1
3
3
88
75
39
40
67
94
97
95
80
93
that
involves
phosphopalladation
between
Ph2P(O)Pd[OP(O)Ph2]L2 and the alkyne was pro-
posed (Scheme 2) although convincing evidence to
substantiate the phosphopalladation was lacking. With
these previous observations in mind, the present find-
ing of the addition of dialkylphosphane oxides being
made efficient prompted us to revisit the role of the
acid, which also will be disclosed in the present paper.
In a reaction to confirm the necessity of a Brønsted
acid, an ethylbenzene (2.0 mL) solution of 1-octyne
2,3,5,6-F4-4-toluic acid
[a]
Run using 1-octyne 1a (1.00 mmol), HP(O)Bu2 2A
(1.00 mmol), CpPd
(h3-allyl) (5 mol%), dppe (5 mol%),
AHCTUNGTRENNUNG
and X-OH (5 mol%) in 2.0 mL toluene at 1108C for 1 h
under nitrogen. Conversion of 2A was 100%.
Determined by H NMR spectroscopy.
Selec.=100ꢁ3aA/ACTHNUTRGNEU[GN 3aA+(E)-4aA+(Z)-4aA].
[b]
[c]
1
(1a, 1.00 mmol) and Bu2P(O)H (2A, 1.00 mmol) was lar, is an indispensable prerequisite for efficient catal-
heated in the presence of Pd
(dba)2 (5 mol%), ysis.[10] Thus, in the reactions using 1-octyne 1a
dppben[8] (5 mol%) and Ph2P(O)OH (5 mol%) at (1.00 mmol), HP(O)Bu2 2A (1.00 mmol), Pd
(dba)2
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
1308C for 1 h and the resulting mixture was evaporat- (5 mol%), and Ph2P(O)OH (5 mol%) in 2.0 mL tolu-
ed. 1H NMR analysis of the residue dissolved in ene at 1108C for 3 h, the performance of phosphane
CDCl3 using p-dimethoxybenzene as internal standard ligand decreased in the following order: dppe
revealed the formation of 2-dibutylphosphinyl-1- (1H NMR yield of 3aA=86%)>dppben (80%)>
octene (3aA) in 92% yield. Very interestingly, another dppen (53%)=dppp (53%)>PPhMe2 (23%)>dppxy
similar reaction run in the absence of Ph2P(O)OH (20%)>dppb (18%)>PPh2Me (8%)>PPh3 (~0%)>
under otherwise the same conditions resulted in only PMe3 (0%).
5% yield, clearly indicating the dramatically enhanced
catalytic performance induced by the addition of dition reactions of dibutylphosphane oxide with vari-
Ph2P(O)OH. ous alkynes using [3,5-(CF3)2C6H3]2P(O)OH as acid
After these trial experiments, we ran a series of ad-
Besides Ph2P(O)OH, other Brønsted acids also en- and dppe or dppben as ligand (Table 2). Although the
hanced the activity as shown in Table 1.[9] When the reactions were not optimized, all aliphatic and aro-
reaction was run at 1108C for 1 h using Pd-dppe-acid matic alkynes (entries 1–8) afforded satisfactory
catalyst systems, [3,5-(CF3)2C6H3]2P(O)OH, the most yields. The formation of other regio- and stereoiso-
strongly acidic one among those examined, was the mers appeared to be negligible in these reactions on
best performing (88% yield) while the less acidic the basis of NMR spectroscopy of the crude products
Ph2P(O)OH and the even less acidic (p-tert-bu- run before chromatographic separation. However, a
tylC6H4)2P(O)OH gave lower yields (75 and 39%, re- small quantity of a by-product that had come from
spectively). In another set of reactions (1108C, 3 h), double bond isomerization appeared to be formed in
2,3,5,6-tetrafluoro-4-toluic acid afforded a 67% yield entries 4 and 5. Cyclohexen-1-ylethyne (1g), a conju-
while the use of plain 4-toluic acid resulted in a 40% gated enyne, also reacted normally only at the triple
yield. Note, however, that these results do not neces- bond and the double bond remained intact (entry 9).
sarily indicate that stronger acids are always better. In the reaction of methyl 5-hexynoate (1h), double
What we have to think for successful addition is to bond isomerization of 3hA took place somewhat ex-
use an acid that matches the nature of a particular tensively to form another isomer in 19% yield, but
phosphane oxide (vide infra).
the ester group was not deteriorated under the condi-
Another set of trial experiments shows that the use tions (entry 10). In view of our previous results,[7] the
of chelating phosphanes, dppe and dppben in particu- new recipe is also envisioned to tolerate other func-
Adv. Synth. Catal. 2011, 353, 890 – 896
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
891

Jun Kanada and Masato Tanaka
COMMUNICATIONS
Table 2. Addition reactions of dibutylphosphane oxide with
In our mechanistic study, we examined the reactivi-
various alkynes.[a]
ty of Me2Pd
diphenylphosphane oxide, in comparison with the re-
activity of Me2Pd(dmpe) reported previously (vide
supra).[7] When Me2Pd
(dppe) was treated with diphe-
nylphosphinic acid (1 equiv.) at 198C for 3 h,
MePd[OP(O)Ph2](dppe) (5) was isolated in 52% yield
ACHTUNGTRENN(UNG dppe) with diphenylphosphinic acid and
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
Entry 1x, R1 =, R2 =
Ligand Yield of 3xA [%][b]
dppe 95 (86)
dppben 84
dppben 86 (74)
after recrystallization (Scheme 3) and was character-
ized by X-ray diffraction.[11] However, further treat-
ment of the product with diphenylphosphane oxide
(1 equiv.), as opposed to our expectation on the basis
of our previous observation using MePd[OP(O)Ph2]
1
1a, n-C6H13, H
1a
1b, t-Bu, H
1c, PhCH2, H
1c
2
3[c]
4
dppe
66
ACHUTNGRENU(NG dmpe), did not form Ph2P(O)Pd[OP(O)Ph2]ACHTUNGTRENNUNG(dppe),
5
dppben 70 (57)
dppben 86 (70)
dppben 80 (68)
dppben 77 (68)
but the product appeared to be a hydrogen-bonded
6
7
1d, p-t-BuC6H4, H
1e, Ph, H
1
ionic complex 6. Its structure was supported by H
and 31P NMR spectroscopy. FAB-MS analysis also dis-
played satisfactory data for [MePd[P(OH)Ph2]
8
1f, p-FC6H4, H
9
1g, 1-cyclohexenyl, H dppben 96 (81)
1h, MeOOC
1i, Ph, Ph
AHCTUNGTRENNUNG
(dppe)]+ and [Ph2P(O)O]ꢀ, although we were unable
10
ACHTUNGTRENNUNG
11[e]
to obtain crystalline material suitable for an X-ray dif-
fraction study. The conversion from 5 to 6 is some-
what intuitive. It may involve coordination of
PPh2(OH) and dissociation of Ph2P(O)Oꢀ.[12] Howev-
[a]
Run using alkyne 1x (1.00 mmol), HP(O)Bu2 2A
(1.00 mmol), CpPd
(h3-allyl) (5 mol%), ligand (5 mol%)
and [3,5-(CF3)2C6H3]2P(O)OH (5 mol%) in 2.0 mL ethyl-
AHCTUNGTRENNUNG
benzene at 1308C for 30 min under nitrogen. Conversion er, the mechanism is uncertain at this stage. In anoth-
of 2A was 100%.
Determined by H NMR spectroscopy. The figures in pa-
rentheses are isolated yields.
Solvent volume=3.0 mL.
Yield of a mixture of 3hA (79%) and methyl (E)-5-dibu-
tylphosphinyl-4-hexenoate (19%).
Reaction time=21 h.
er reaction, we treated Me2Pd
Ph2P(O)H, which afforded MePd[P(O)Ph2]
Further treatment of 7 with Ph2P(O)OH also gave 6,
but not Ph2P(O)Pd[OP(O)Ph2](dppe).
With these unexpected results in hand, we attempt-
ed to synthesize HPd[P(O)Ph2](dmpe) in order to
gain more realistic view on the reactivity of its Pd
P(O)Ph2 moiety toward Ph2P(O)OH. However, an at-
tempted reaction to synthesize it starting with
ACHTUNGTRENNUNG
[b]
1
AHCTUNGTRENNUNG
[c]
[d]
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
[e]
ꢀ
tional groups. Finally, diphenylethyne (1h), an internal (PhCH=CH2)Pd
alkyne, also conformed to the reaction to give a forded only Pd[P(OH)Ph2]
nearly quantitative yield although a longer reaction tallization).[12] On the other hand, we could isolate its
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
time was required (entry 11).
platinum analogue HPt[P(O)R2]ACTHNGUTERNNU(G dmpe) (8-R; R=Ph,
Scheme 3. Sequential treatment of Me2Pd
vice versa.
ACHTUNGTNER(NUNG dppe) with diphenylphosphinic acid followed by diphenylphosphane oxide and
892
asc.wiley-vch.de
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 890 – 896

Efficient Addition Reaction of Dibutylphosphane Oxide with Alkynes
p-t-BuC6H4, adamantyl) by mixing PtACTHNURGTNE(NUG cod)2, dmpe
(1 equiv.) and R2P(O)H (1 equiv.) in toluene, benzene
or THF at 20~408C for 0.5~17 h. These complexes
were fully characterized by NMR spectroscopies, ele-
mental analysis/HR-MS and also by X-ray diffraction
for 8-Ph.[11]
As we anticipated, these complexes, including the
one derived from dialkylphosphine oxide, also display
hydrogen bonding interaction with phosphinic acids.
Thus, when HPt[P(O)Ph2]ACTHNUTRGENUGN(dmpe) (8-Ph) was treated
with 1 equiv. of diarylphosphinic acids [Ar2P(O)OH;
Figure 2. Molecular structure of 9-Ad-[3,5-(CF3)2C6H3].
Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms and solvated CH2Cl2 molecule are omitted
for clarity.
Ar=Ph, p-t-BuC6H4, 3,5-(CF3)2C6H3], the 31P NMR
ꢀ
signals arising from Pd P(O)Ph2, which appeared at
67.3 ppm (dd) for starting 8-Ph, was downfield shifted
and broadened, indicative of generation of ionic hy-
dridoplatinum complexes (9-Ph-Ar) (Figure 1).
1H NMR spectra of these complexes exhibited a
Figure 1 suggests that the hydrogen bonding inter-
(broad) singlet signal due to the proton participating action appears more distinct when a larger quantity of
ꢀ
in the O H···O hydrogen bonding in the range of an acid is added as shown by addition of 2 equivalents
8.62–14.4 ppm. Also, a ddd signal accompanied by a of Ph2P(O)OH and also when the acidy is higher as
satellite band due to 195Pt (997–1034 Hz) was found in substantiated
by
the
addition
of
[3,5-
ꢀ
a ꢀ2.64–ꢀ2.32 ppm range, assignable to H Pt. These (CF3)2C6H3]2P(O)OH (1 equiv.). More decisive evi-
spectral features indicate that the resulting species dence came from the treatment of the complex
retain their structural integrity except the hydrogen HPt[P(O)Ad2]
ACHTUNGTRENNUNG
bonding.
Very interestingly, ionic species 9-Ad-[3,5-
(CF3)2C6H3] is significantly labile in terms of substitu-
tion/dissociation
PAd2A[OH···OP(O)
of
ACHTUNGTRENNUNG
its
phosphane-like
G
N
upon treatment with tert-butyl isocyanide (7.0 equiv.
in total of incremental additions) at 178C for 3 h, 9-
Ad-[3,5-(CF3)2C6H3] was consumed nearly completely
to generate the species [HPt
[OP(O)(3,5-
C
(dmpe)]+
2ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
In view of these results, when a Brønsted acid
XOH is present, we can think of an alternate mecha-
nistic possibility, such as the one depicted in
Scheme 4, in which key steps are dissociation/substitu-
tion of the PR2ACTHNUTRGNEUNG
(OH···OX)ꢀ ligand resulting in facile
Figure 1. 31P NMR spectral change in the Pt P(O)Ph2 region
upon addition of diarylphosphinic acids to the complex
ꢁ
coordination of the C C triple bond (step ii), hydro-
palladation (step iii), recoordination of the
ꢀ
HPt[P(O)Ph2]
N
PR2ACTHUNGETRNNUG
(OH···OX)ꢀ ligand (step iv), liberation of XOH
Adv. Synth. Catal. 2011, 353, 890 – 896
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
893

Jun Kanada and Masato Tanaka
COMMUNICATIONS
Scheme 4. Alternate mechanism of Pd-chelating phosphane-Brønsted acid-catalyzed addition of secondary phosphane oxide
with alkynes.
from hydrogen bonding (step v) and reductive elimi- ry, weaker ones (entries 2–4) were better performing
nation (step vi).[16]
and the best one was tert-butylphenylphosphinic acid,
This mechanistic proposal can rationalize the effi- the least acidic among the four. These results clearly
cient addition of dialkylphosphane oxides disclosed in indicate that acidity is an important factor, but not
the present paper and also the following two puzzling the only factor that dictates the catalytic activity irre-
ꢀ
observations in the Pd Ph2P(O)OH-catalyzed addi- spective of the structure of phosphane oxides. In a
tion of diphenylphosphane oxide; (1) the enhanced scenario based on the acidity, elemental step i (pre-
activity and (2) the provenance of the regiochemical sumably step ii also) in Scheme 4 is envisioned to be
reversal (i.e., selective formation of branched struc- facile when the acidity is high. However, a strong acid
tured products) induced by the addition of is not likely to readily dissociate the hydrogen bond-
Ph2P(O)OH. Given that a coordinatively labile ionic ing interaction at step v, a prerequisite for reductive
palladium species is generated, an alkyne molecule is elimination, suggesting that stronger acids are not
envisioned to interact with ionic palladium species
more readily than with neutral four-coordinate spe-
Table 3. Effect of acids in the reaction of 1-octyne with tert-
butylphenylphosphane oxide.[a]
cies and is likely to undergo Markovnikov addition
due to the more protonic nature of the cationic “hy-
dridopalladium” species.
Finally it is of importance in consideration of the
extension of the recipe to other phosphane oxides
that we have to seek the best Brønsted acid for a par-
ticular phosphane oxide, as already mentioned. As we
have reported in a previous paper, Ph2P(O)OH ap-
peared to be the best acid among the acids screened
as far as diphenylphosphane oxide is concerned.[7]
The present paper has already disclosed that [3,5-
(CF3)2C6H3]2P(O)OH, a stronger acid, is the best one
for Bu2P(O)H, a more basic phosphane oxide. How-
ever, a stronger acid is not necessarily better perfom-
ing, depending on the structure of the phosphane
oxide reagent. Table 3 shows that, in the reaction of
tert-butylphenylphosphane oxide, strongly acidic [3,5-
(CF3)2C6H3]2P(O)OH (entry 1) afforded the lowest
yield among the four acids examined. On the contra-
Entrya)
X-OH
[3,5-(CF3)2C6H3]2P(O)OH
p-CH3C6F4COOH
(p-t-BuC6H4)2P(O)OH
Yield of 3aB[b]
1
2
3
4
G
E
25
63
68
72 (60)
(t-Bu)PhP(O)OH
[a]
Run using 1-octyne 1a (1.00 mmol), (t-Bu)PhP(O)H 2B
(1.00 mmol), CpPd
and X OH (5 mol%) in 2.0 mL ethylbenzene at 1308C
A
ꢀ
for 4 h under nitrogen.
Determined by H NMR spectroscopy. The figure in pa-
[b]
1
rentheses is the isolated yield.
894
asc.wiley-vch.de
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 890 – 896

Efficient Addition Reaction of Dibutylphosphane Oxide with Alkynes
(24), 215 (27), 201 (100), 187 (19), 161 (14) 104 (10); HR-
MS: m/z=272.2265, calcd. for C16H33OP: 272.2269.
always better than weaker ones. As a separate scenar-
io, we may have to consider the steric effect of the
phosphane oxide and acid since the displacement/dis-
sociation (step ii) and recoordination (step iv) of the
PR2ACHTUNGTRENNUNG
(OH···OX)ꢀ ligand are also likely to be affected
Acknowledgements
by its steric demand. Although we have not scruti-
nized the steric aspect seriously, we believe that we
have to seek for an optimum match between the
phosphane oxide and the acid, in terms of their elec-
tronic and steric factors.
This work was supported by a Grant-in-Aid for Scientific Re-
search on Priority Areas (No. 18065008) and by a G-COE
research fellowship to J.K. from MEXT, Japan.
In summary, this communication reports the suc-
cessful addition of dibutylphosphane oxide to alkynes,
both terminal and internal. A new mechanism com-
prising intimate cooperation of palladium and Brønst-
ed has also been proposed to rationalize the enhance-
ment of the catalysis and the branch selectivity. Full
details will be reported shortly.
References
[1] Selected examples for palladium: a) B. M. Trost, D. C.
Lee, J. Am. Chem. Soc. 1988, 110, 7255; b) B. M. Trost,
Acc. Chem. Res. 1990, 23, 34; c) H. Alper, N. Hamel, J.
Am. Chem. Soc. 1990, 112, 2803; d) I. Kadota, A. Shi-
buya, Y. S. Gyoung, Y. Yamamoto, J. Am. Chem. Soc.
1998, 120, 10262; e) I. Kadota, ; L. M. Lutete, A. Shi-
buya, Y. Yamamoto, Tetrahedron Lett. 2001, 42, 6207;
f) M. A. Kazankova, I. V. Efimova, A. N. Kochetkov,
V. V. Afanasꢂev, I. P. Beletskaya, P. H. Dixneuf, Synlett
2001, 497; g) K. Sorimachi, M. Terada, J. Am. Chem.
Soc. 2008, 130, 14452. See also for metal-acid bifunc-
tional heterogeneous catalysis: h) P. Meriaudeau, C.
Naccache, Catal. Rev. 1997, 39, 5; i) H. Du, C. Fair-
bridge, H. Yang, Z. Ring, Appl. Catal. A 2005, 294, 1.
[2] a) L. K. Vo, D. A. Singleton, Org. Lett. 2004, 6, 2469;
b) J.-R. Kong, M.-Y. Ngai, M. J. Krische, J. Am. Chem.
Soc. 2006, 128, 718; c) V. Belting, N. Krause, Org. Lett.
2006, 8, 4489; d) V. Komanduri, M. J. Krische, J. Am.
Chem. Soc. 2006, 128, 16448; e) S. Mukherjee, B. List,
J. Am. Chem. Soc. 2007, 129, 11336; f) E. Hu, X. Xu, J.
Zhou, W.-J Liu, H. Huang, J. Hy, L. Yang, L.-Z. Gong,
J. Am. Chem. Soc. 2008, 130, 7782.
[3] a) M. Tanaka, Top. Curr. Chem. 2004, 232, 25, and the
references cited therein; b) L.-B. Han, C.-Q. Zhao, M.
Tanaka, Patent WO 2002/064604, 2002; c) L.-B. Han, C.
Zhang, M. Tanaka, Patent WO 2003/097654, 2003;
d) A. N. Reznikov, M. V. Sokolova, N. K. Skvortsov,
Russ. J. Gen. Chem. 2004, 74, 1461; e) L.-B. Han, C.
Zhang, H. Yazawa, S. Shimada, J. Am. Chem. Soc.
2004, 126, 5080; f) P. Ribiꢃre, K. Bravo-Altamirano,
M. I. Antczak, J. D. Hawkins, J.-L. Montchamp, J. Org.
Chem. 2005, 70, 4064; g) A. I. Kuramshin, A. A. Niko-
laev, R A. Cherkasov, Mendeleev Commun. 2005, 15,
155; h) L.-B. Han, Y. Ono, H. Yazawa, Org. Lett. 2005,
7, 2909; i) N. Ajellal, C. M. Thomas, J.-F. Carpentier,
Adv. Synth. Catal. 2006, 348, 1093; j) Q. Xu L-.B. Han,
Org. Lett. 2006, 8, 2099; k) N. Dobashi, K. Fuse, T.
Hoshino, J. Kanada, T. Kashiwabara, C. Kobata, S. K.
Nune, M. Tanaka, Tetrahedron Lett. 2007, 48, 4669;
l) M. Niu, H. Fu, Y. Jiang, Y. Zhao, Chem. Commun.
2007, 272; m) A. N. Reznikov, N. K. Skvortsov, Russ. J.
Gen. Chem. 2007, 77, 1170; n) S. K. Nune, M. Tanaka,
Chem. Commun. 2007, 2858; o) Review: I. P. Belet-
skaya, M. M. Kabachnik, Mendeleev Commun. 2008,
18, 113, and their previous papers cited therein; p) K.
Barta, G. Franciꢄ, W. Leitner, G. C. Lloyd-Jones, I. R.
Shepperson, Adv. Synth. Catal. 2008, 350, 2013; q) N.
Ajellal, E. Guillevic, C. M. Thomas, R. Jackstell, M.
Experimental Section
Typical Procedure for a Catalytic Reaction and
Isolation of Products: Addition Reaction of 1-Octyne
(1a) with Dibutylphosphane Oxide (2A) using
CpPd
phenyl]phosphinic Acid
ACHTUNGTRENNUNG ACHTUNGTRENN[UGN 3,5-di(trifluoromethyl)-
(h3-allyl), Dppe and Bis
To a dried 25-mL Schlenk tube containing CpPd
(10.6 mg, 0.05 mmol), dppe (19.9 mg, 0.050 mmol), bis
di(trifluoromethyl)phenyl]phosphinic acid (24.5 mg,
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
0.05 mmol) and dibutylphosphine oxide (2A, 162 mg,
1.00 mmol) were added toluene (2.0 mL) and 1-octyne (1a,
147 mL, 1.00 mmol) under nitrogen at room temperature.
The Schlenk tube was then heated in an oil bath kept at
1308C and the mixture was stirred for 30 min. Evaporation
of the solvent yielded the crude mixture, which was added
to a solution of p-dimethoxybenzene (internal standard,
22.7 mg 0.164 mmol) in CDCl3 (5.0 mL). NMR analysis of
the mixture revealed that 2-dibutylphosphinyl-1-octene
(3aA) was formed in 95% yield together with by-products
such as (E)-1-dibutylphosphinyl-1-octene (E)-4aA in 3%
1
yield and traces of others. After H NMR measurement, the
solution was evaporated and the residue was subjected to
column chromatography on silica gel (CH2Cl2/methanol=
90/1) to allow isolation of 3aA; yield: 86%; colorless oil; bp
1
728C/0.01 mmHg (Kugelrohr). H NMR (400 MHz, CDCl3):
d=5.91 (dd, JH,P =18.8 Hz, J=1.2 Hz, 1H, trans-PC=CH),
5.69 (dd, JH,P =36.4 Hz, J=1.2 Hz, 1H, cis-PC=CH), 2.04
(dt, JH,P =8.8 Hz, J=7.2 Hz, 2H, PCCH2), 1.76–1.20 [m,
20H, CH3ACHTUNGTRENNUNG(CH2)4 +2PAHCTUNGTREN(NGUN CH2)3CH3], 0.87–0.80 (m, 9H,
3CH3); 13C{1H} NMR (75 MHz, CDCl3): d=142.8 (d, J=
79.3 Hz, PC=C), 127.0 (d, J=5.8 Hz, PC=CH2), 31.5 (=
CCH2CH2CH2), 31.0 (d, J=10.7 Hz, =CCH2CH2CH2), 28.8
[=CACHTUNGTRENNUNG(CH2)3CH2], 27.6 (d, J=5.6 Hz, =CCH2CH2CH2), 27.4
(d, J=66.8 Hz, 2C, 2PCH2), 24.0 (d, J=14.3 Hz, 2C,
2PCH2CH2CH2), 23.3 (d, J=3.9 Hz, 2C, 2PCH2CH2CH2),
22.4 [=C
(CH2)3CH3]; 31P{1H} NMR (162 MHz, CDCl3): d=42.2; IR
(neat):): n=1163 (nP O), 1635 cmꢀ1 (nC C); MS (EI, 70 eV,%
ACHTUNGTRENNUNG(CH2)4CH2], 13.9 [=CACHTUGNTRENN(UGN CH2)5CH3], 13.5 [2C, 2P-
ACHTUNGTRENNUNG
=
=
relative intensity): m/z=272 (M+, 7), 257 (8), 243 (25), 229
Adv. Synth. Catal. 2011, 353, 890 – 896
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
895

Jun Kanada and Masato Tanaka
COMMUNICATIONS
Beller, J.-F. Carpentier, Adv. Synth. Catal. 2008, 350,
431; r) B. K. Alnasleh, W. M. Sherrill, M. Rubin, Org.
Lett. 2008, 10, 3231; s) J. Kanada, K.-i. Yamashita, S. K.
Nume, M. Tanaka, Tetrahedron Lett. 2009, 50, 6196;
t) V. P. Ananikov, L. L. Khemchyan, I. P. Beletskaya,
Synlett 2009, 2375; u) A. Duraud, M. Toffano, J.-P.
Fiaud, Eur. J. Org. Chem. 2009, 4400; v) Q. Xu, L.-B.
Han, J. Organomet. Chem. 2011, 696, 130, and the ref-
erences cited therein.
2002, 346; g) E. Galardon, S. Ramdeehul, J. M. Brown,
A. Cowley, K. K. Hii, A. Jutand, Angew. Chem. 2002,
114, 1838; Angew. Chem. Int. Ed. 2002, 41, 1760;
h) J. H. Kirchhoff, M. R. Netherton, I. D. Hills, G. C.
Fu, J. Am. Chem. Soc. 2002, 124, 13662; i) G. Mann, Q.
Shelby, A. H. Roy, J. F. Hartwig, Organometallics 2003,
22, 2775; j) M. O. Shulyupin, G. Francio, I. P. Belet-
skaya, W. Leitner, Adv. Synth. Catal. 2005, 347, 667;
k) F. Barrios-Landeros, J. F. Hartwig, J. Am. Chem.
Soc. 2005, 127, 6944; l) D. B. Grotjahn, Y. Gong, L. Za-
kharov, J. A. Golen, A. L. Rheingold, J. Am. Chem.
Soc. 2006, 128, 438; m) A. G. Sergeev, A. Spannenberg,
M. Beller, J. Am. Chem. Soc. 2008, 130, 15549.
[4] Cu-catalyzed addition of dibenzylphosphane oxide has
also been reported. See ref.[3l]
[5] L.-B. Han, F. Mirzaei, C.-Q. Zhao, M. Tanaka, J. Am.
Chem. Soc. 2000, 122, 5407.
[6] L.-B. Han, N. Choi, M. Tanaka, Organometallics 1996,
15, 3259.
[7] L.-B. Han, R. Hua, M. Tanaka, Angew. Chem. 1998,
110, 98; Angew. Chem. Int. Ed. 1998, 37, 94.
.
[10] We have reported that chelating phosphanes serve as
efficient and branch-selective ligands in the palladium-
catalyzed addition reactions of Ph2P(O)H and
PhACTHNUTRGNEUNG
(EtO)P(O)H with terminal alkynes. See refs.[3k,3n]
[11] CCDC 795289, CCDC 795290 and CCDC 795291 con-
tain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[8] The following abbreviations are used in this communi-
cation;
(CH2)2PPh2, dppen=cis-Ph2PCH=CHPPh2, dppp=
Ph2P(CH2)3PPh2, dppb=Ph2P(CH2)4PPh2, dppben=
dmpe=Me2P
G
dppe=Ph2P-
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
1,2-(Ph2P)2C6H4, dppxy=1,2-(Ph2PCH2)2C6H4.
[12] Secondary phosphine oxides exist in two tautomeric
[9] In the experiments listed in Table 1, Table 2 and
ꢀ
isomers, P(=O)H and P OH, the former being domi-
Table 3, CpPdACHTUNGTRENNUNG
(h3-allyl) was used as precatalyst in con-
nant in the equilibrium. See: a) W. J. Bailey, R. B. Fox,
J. Org. Chem. 1963, 28, 531; b) W. J. Bailey, R. B. Fox,
J. Org. Chem. 1964, 29, 1013; c) L. A. Hamilton, P. S.
Landis, in: Organic Phosphorus Compounds, (Eds.:
G. M. Kosolapoff, L. Maier), Wiley, New York, 1972,
Vol. 4, Chapter 11.
junction with a chelating phosphane and a Brønsted
acid. It is well established that, upon treatment with
phosphane ligands, CpPdACHTNUTGRNEUNG
(h3-allyl) generates Pd(0)-
phosphane complexes with extrusion of allylcyclopenta-
diene and its isomers. For the chemistry between CpPd-
ACHTUNGTRENNUNG
(h3-allyl) and phosphane ligands, see: a) V. Harder, H.
[13] Solvated with a CH2Cl2 molecule.
[14] Another species was also formed. See the Supporting
Information.
[15] Treatment of 9-Ad-[3,5-(CF3)2C6H3] with acetonitrile
(540 equiv.) in CDCl3 at 178C did not induce any reac-
tion to the complex.
[16] Somewhat related chemistry with a cationic Pd-dmpe
complex has been documented. See: J. Ledford, C. S.
Shultz, D. P. Gates, P. S. White, J. M. DeSimone, M.
Brookhart, Organometallics 2001, 20, 5266.
Werner, Helv. Chim. Acta 1973, 56, 549; b) D. M.
Norton, E. A. Mitchell, N. R. Botros, P. G. Jessop,
M. C. Baird, J. Org. Chem. 2009, 74, 6674. This in situ
procedure has been often utilized in the synthesis of
and catalysis by palladium(0) complexes. For selected
examples, see: c) P. Leoni, Organometallics 1993, 12,
2432; d) S. R. Stauffer, N. A. Beare, J. P. Stambuli, J. F.
Hartwig, J. Am. Chem. Soc. 2001, 123, 4641; e) V. P. W.
Bohm, W. A. Herrmann, Chem. Eur. J. 2001, 7, 4191;
f) T. Matsumoto, T. Kasai, K. Tatsumi, Chem. Lett.
896
asc.wiley-vch.de
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2011, 353, 890 – 896