Oxaphospholes and bisphospholes from phosphinophosphonates and α,β-unsaturated ketones

Article abstract of DOI:10.1002/chem.201302014

The reaction of a {W(CO)₅}-stabilized phosphinophosphonate 1, (CO)₅WPH(Ph)-P(O)(OEt)₂, with ethynyl- (2 a-f) and diethynylketones (7-11, 18, and 19) in the presence of lithium diisopropylamide (LDA) is examined. Lithiated

Full text of DOI:10.1002/chem.201302014

DOI: 10.1002/chem.201302014
Oxaphospholes and Bisphospholes from Phosphinophosphonates and
a,b-Unsaturated Ketones
[
a]
[a]
[a]
[b]
Anna I. Arkhypchuk, Andreas Orthaber, Viorica Alina Mihali, Andreas Ehlers,
[
b]
[a]
Koop Lammertsma, and Sascha Ott*
Abstract: The reaction of a {W(CO) }-
stabilized phosphinophosphonate 1,
rated oxaphospholes 14, 15, 24, and 25.
Diacetylenic ketones 10 and 11, with
two aromatic acetylene substituents,
react with lithitated 1 to form exclu-
sively ethenyl-bridged bisphospholes 16
and 17. Mechanisms that rationalize
the formation of all heterocycles are
presented and are supported by DFT
calculations. Computational studies
suggest that thermodynamic, as well as
kinetic, considerations dictate the ob-
served reactivity. The calculated reac-
tion pathways reveal a number of
almost isoenergetic intermediates that
follow after ring opening of the initially
formed oxadiphosphetane. Bisphos-
phole formation through a carbene in-
termediate G is greatly favored in the
presence of phenyl substituents, where-
as the formation of cumulene-decorat-
ed oxaphospholes is more exothermic
for the trimethylsilyl-containing sub-
strates. The pathway to the latter com-
pounds contains a 1,3-shift of the group
that stems from the acetylene terminus
of the ketone substrates. For silyl sub-
stituents, the 1,3-shift proceeds along a
smooth potential energy surface
through a transition state that is char-
acterized by a pentacoordinated silicon
center. In contrast, a high-lying transi-
5
(
CO) WPH(Ph)ꢀP(O)
A
H
U
G
R
N
N
(OEt) ,
with
5
2
ethynyl- (2a–f) and diethynylketones
(
7–11, 18, and 19) in the presence of
lithium diisopropylamide (LDA) is ex-
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
ACHTUNGTRENNUNG
amined. Lithiated 1 undergoes nucleo-
philic attack in the Michael position of
the acetylenic ketones, as long as this
position is not sterically encumbered
by bulky (iPr) Si substituents. Reaction
3
of all other monoacetylenic ketones
with lithiated 1 results in the formation
of 2,5-dihydro-1,2-oxaphospholes 3 and
4
. When diacetylenic ketones are em-
ployed in the reaction, two very differ-
ent product types can be isolated. If at
least one (Me) Si or (Et) Si acetylene
tion state TS
A
H
U
G
R
N
U
G
of 37 kcal
R=Ph
ꢀ
1
mol is found when the substituent is
a phenyl group, thus explaining the ex-
perimental observation that aryl-termi-
nated diethynylketones 10 and 11 ex-
3
3
Keywords: cumulenes
·
density
terminus is present, as in 7, 8, and 19,
an anionic oxaphosphole intermediate
can react further with a second equiva-
lent of ketone to give cumulene-deco-
functional calculations · domino re-
actions · phosphaorganic chemistry ·
reaction mechanisms
clusively form bis ACHUTNGRENNUGp hos ACHTUNGTRENNGNUp holes 16 and 17.
Introduction
aromaticity is reflected in a relatively modest “nucleus-inde-
pendent chemical shift” (NICS) value of ꢀ5.3 compared to
[2]
Known for 60 years through the pioneering work of Wittig
that of its N-analogue, that is, pyrrole (NICS=ꢀ15.1). As
the P center remains outside the p-conjugation paths, it
allows fine tuning of the optical properties of the whole
system by chemical modifications such as metal coordina-
tion, oxidation, or addition of electrophiles (formation of
[1]
and Geissler, phospholes have experienced a remarkable
renaissance over the last decade. The interest is fuelled by
the tetrahedral nature of the phosphorous center and the re-
sulting low aromaticity of the heterocycle. Phospholeꢀs low
[3–6]
phosphonium salts) on the heteroatom.
The electronic
impact that the chemically modified P center has on the ad-
[
a] A. I. Arkhypchuk, Dr. A. Orthaber, V. A. Mihali, Dr. S. Ott
Department of Chemistry, ꢁngstrçm Laboratories
Uppsala University, Box 523, 751 20 Uppsala (Sweden)
E-mail: sascha.ott@kemi.uu.se
[4,7]
jacent p system has been coined the “doping effect”.
An-
nelation of (hetero)aromatic ring systems enables additional
[8]
ways to modify the electronics of phospholes. The possibil-
[
b] Dr. A. Ehlers, Prof. K. Lammertsma
ity to tune their electronic properties, and thus their absorp-
tion and emission behavior over a large range makes phos-
Department of Chemistry and Pharmacochemistry
VU University Amsterdam, de Boelelaan 1083
1
081 HV Amsterdam (The Netherlands)
ACHTUNGTRENNUNGp holes targets for applications in organic electronic devices,
such as OLEDs, and as dyes within organic solar cells.
[9]
[10]
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201302014.
From a synthetic viewpoint, early routes to phospholes
were typically based on reactions between dilithium salts
ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co.
KGaA. This is an open access article under the terms of the Creative
Commons Attribution-NonCommercial-NoDerivs License, which per-
mits use and distribution in any medium, provided the original work
is properly cited, the use is non-commercial and no modifications or
adaptations are made.
[11]
and dichlorophosphines or the addition of phosphines to
[12,13]
acetylenes, followed by formation of the heterocycle.
Most of these procedures suffer from restrictions regarding
13692
ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 13692 – 13704

FULL PAPER
the substrate structure and do not allow large variation of
the substituents on the final product.
{W(CO) }-coordinated phosphinophosphonate 1 was chosen
for this study.
5
The development of the so-called Fagan–Nugent synthetic
[
14]
strategy in 1988 gave new life to phosphole chemistry.
Reaction of phosphinophosphonate 1 with monoacetylenic
ketones: In the majority of cases, the reaction of 1 with
monoacetylenic ketones does not produce the, perhaps ex-
pected, phosphaalkenes, but instead results in the formation
of 1,2-oxaphospholes. As shown in the reaction between
ethynyl methyl ketones 2a–c,f or ethynyl phenyl ketones
2d,e with 1 (Scheme 1 and Table 1), it is clear that the acety-
lene terminus directs the reaction outcome.
This methodology, based on treating acetylenes with an acti-
vated zirconocene complex followed by quenching of the
newly formed zirconium metallacycle by phosphorus di-
chloride, allowed the preparation of large libraries of target
[15]
structures. The biggest drawback of the method, the low
selectivity when asymmetrically substituted acetylenes are
used, was overcome by simply linking the two reacting acet-
ylenes through an inert bridge. This modification resulted in
[16]
not only increased selectivity, but also improved yields.
The versatility and elegance of the method made it possible
to introduce a large variety of substituents at the 2- and 5-
positions of the phosphole ring and at the phosphorus
[9,17]
center.
Yet, despite the flexibility of the Fagan–Nugent method,
it is not suitable for preparing heterophospholes like oxa-
[18,19]
phospholes,
which represent one of the biggest classes
of phosphorus-containing molecules. Recently, benzannelat-
ed 1,3-oxaphospholes drew much attention due to their in-
[20]
triguing luminescent properties.
1,2-Oxaphospholes have
Scheme 1. Reaction of 1 with monoacetylenic ketones. i) Lithium diiso-
propylamide (LDA; 1.1 equiv), ꢀ308C, 30 min, then 2 (1 equiv), 1 h at
been addressed in a few instances, but remain an almost un-
explored type of phosphorus-containing heterocycle due to
the absence of reliable synthetic approaches.
Herein, we present a synthetic strategy to convert readily
available phosphinophosphonates and ethynylketones into
ꢀ
508C; ii) MeOH (10 equiv), ꢀ508C, 30 min. a: R=CH
3
, R’=TMS;
[21]
b: R=CH
3
, R’=TES; c: R=CH
, R’=TIPS.
3
, R’=Ph; d: R=Ph, R’=Ph; e: R=Ph,
R’=TES; f: R=CH
3
1,2-oxaphospholes. The prepared 1,2-oxaphospholes are
Table 1. Product yields for the reaction of 1 with monoacetylenic ke-
highly substituted and thus offer the possibility for rich
follow-up chemistry. Furthermore, it is shown that introduc-
tion of a second acetylene into the ketone substrate initiates
subsequent chemistry and leads to the formation of oxa-
phospholes with appended cumulene frameworks or conju-
gated bisphospholes. The reaction outcome is determined by
the substituents at the remote acetylene termini. We show
that these reactions are of general applicability and can be
used for the preparation of a variety of oxaphospholes and
bisphospholes. The reaction sequences are followed by in
situ FTIR spectroscopy using the stretching vibrations of the
tungsten-coordinated CO ligands as sensitive reporters. Re-
action mechanisms that rationalize all transformations are
proposed and key steps are supported by DFT calculations.
tones.
[a]
Entry
R
R’
Combined yield [%]
products 3 and 4
Yield [%]
product 6
A
B
C
D
E
F
CH
CH3
CH
Ph
Ph
3
TMS
TES
Ph
Ph
TES
TIPS
38
35
33
45
43
0
0
0
0
0
0
3
CH
3
65
[
a] Reaction outcome can be directed to either 3 or 4 by appropriate
choice of workup procedure as demonstrated for the reaction of 18 with
1
(Scheme 6, Table 3).
With its very bulky (iPr) Si (TIPS) substituent at the ace-
3
tylene terminus, ketone 2 f reacts with lithiated 1 (abbreviat-
ed as 1Li) as expected to produce phosphaalkene 5 f, which
is, however, unstable and can only be isolated as its metha-
nol-addition product. Two stereocenters at the former car-
Results and Discussion
Phosphinophosphonates are well-established reagents in the
bonyl carbon atom and the phosphorus center give rise to
[22]
31
so-called phospha-Wittig–Horner reaction,
that is, the P
two diastereomeric products in a ratio of 3:2 (d
A
H
U
G
R
N
U
G
[23]
analogue of the Horner–Wadsworth–Emmons reaction.
and 134.3 ppm). If less sterically demanding acetylene termi-
As such, they convert simple aldehydes and ketones to the
corresponding phosphaalkenes. Stabilization of phosphino-
phosphonates, as well as phosphaalkene products, is ensured
ni, such as (Et) Si (TES) in ketones 2b,e or phenyl in ke-
3
tones 2c,d, are used, the reaction proceeds very differently
and 2,5-dihydro-1,2-oxaphospholes 3b–e and 4c–e are ob-
tained as the sole products. Compounds 3 and 4 only differ
in the phosphonate group at C4 of the oxaphosphole, which
can be removed by basic workup (see below). Oxaphosp-
III
either by bulky substituents at P or the coordination of
metal fragments to the same center. The latter strategy
III
allows for a larger substrate scope at P and therefore a
3
1
holes 3 exhibit characteristic P NMR chemical shifts for
Chem. Eur. J. 2013, 19, 13692 – 13704 ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
13693

S. Ott et al.
compounds with silyl groups at C5 (3a,b,e; d=132 ppm),
whereas those with a phenyl substituent (3c,d) resonate at
d=149.6 ppm. For compounds 4b–e, the P NMR spectra
by LDA-promoted abstraction of a proton from 1 to form
intermediate A. Subsequent [2+2] cycloaddition with the
acetylene unit of the ketone results in intermediate B; this
cycloaddition is prevented if the substituent at the acetylene
is too bulky, as in 2 f. Ring opening of B gives intermedia-
te C, which can be depicted in several isomeric forms. One
3
1
feature AB coupling patterns with typical doublets at chemi-
3
cal shifts of d=161.5 and 16.0 ppm ( J =35 Hz) for hetero-
PP
3
cycle 4e and approximately 152 and 15 ppm ( J =28 Hz)
PP
for compounds 4c,d. The molecular structure of compound
of these, C , stems from rotation around the newly formed
B
3
e was confirmed by X-ray diffraction analysis of single
CꢀC bond and engages in an intramolecular nucleophilic
attack that results in the formation of heterocycle D. Hy-
drolysis during aqueous workup gives rise to products 3a–e
and 4c–e. The reactions with ketones 2a–e exclusively
follow the pathway depicted in Scheme 2. No traces of phos-
crystals obtained by slow evaporation of a solution in pen-
tane (Figure 1).
AHCTUNGTRENNUNGp ha ACHTNURTGENNUNGa l ACTHUNGTRENNGNUk enes that would arise from the usual phospha-Wittig–
Horner reaction could be detected even when the reaction
was quenched at low temperatures with MeOH or 1,3-buta-
diene.
Reaction of 1 with diacetylenic ketones:
Symmetric ketones: Having identified an exclusive pathway
for the preparation of 1,2-oxaphospholes, we were prompted
to investigate the reactivity of diacetylenic ketones. The re-
action of symmetric ketones 7–11 with 1 proved to be very
complex and highly dependent on the acetylene termini
(
Scheme 3 and Table 2).
Figure 1. Crystal structure of compound 3e (ellipsoids set to 50% proba-
bility). All protons are omitted for clarity except for those at the oxa-
phosphole. Only one of the possible two phenyl ring positions at phos-
phorus is presented.
In the solid state, the TES group at C5 resides in the steri-
cally least demanding position, trans to the P-phenyl sub-
stituent. In general, it seems that it is the systemꢀs desire to
avoid steric clashes between the P-bound phenyl group and
the bulky C5 substituent that determines the formation of
only one diastereomer for 3b–e and 4c–e. Supporting this
notion, two diastereomeric products can be observed when
the steric bulk of C5 is decreased, as in trimethylsilyl
(
TMS)-substituted 3a, which can be isolated as both trans
31
and cis isomers (d ACHTUNGTRENNUNG( P)=132.0 and 140.8 ppm, respectively)
in a 5:1 ratio.
Scheme 3. Reaction of 1 with symmetric diacetylenic ketones. i) BuLi
1.1 equiv), ꢀ308C, 30 min; ii) 9 (1.05 equiv), ꢀ788C, 30 min; iii) 2,3-di-
methylbuta-1,3-diene (10 equiv), ꢀ788C to RT, 1 h; iv) 7 or 8 (2 equiv),
788C to ꢀ308C, 1.5 h; v) 10 or 11 (1.05 equiv), ꢀ508C, 1.5–2 h.
Formation of 3a–e and 4c–e can be explained by the
mechanism presented in Scheme 2. The sequence is initiated
(
ꢀ
Table 2. Yields of products in the reaction of 1 with symmetric di
enic ketones.
ACHTUNGTRENNUNGa ce ACHTUNGTRENNUNGt yl-
AHCTUNGTRENNUNG
3
1
III
31
V
3
Ketone
R
Product Yield
d
A
H
U
G
R
N
N
d
A
H
U
G
R
N
U
G
J
PP
[
%]
A
H
U
G
R
N
U
G
A
H
U
G
E
N
N
[ppm]
[Hz]
7
8
9
1
1
TMS
TES
TIPS
Ph
14
15
13
16
7
168.2
167.5
9.7
38.4
37.2
6.4
6.8
–
13.6
13.4
59
63
–
38
32
57
35
38
50
0
1
thiophene 17
Scheme 2. Mechanism for the formation of complexes 3 and 4.
13694
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Oxaphospholes and Bisphospholes
FULL PAPER
Scheme 4. Proposed mechanism of the formation of 14 and 15.
In analogy to monoacetylenic ketones, substrates with
very bulky substituents at the acetylene termini, such as the
TIPS groups in 9, exhibit the traditional phospha-Wittig be-
havior and afford thermally unstable phosphaalkenes such
as 12, which were detected in situ by P NMR spectroscopy
and trapped with 1,3-butadiene to give compounds like 13.
For the ketones with smaller silyl substituents, such as TES
or TMS, the only observed reaction products are cumulenes
charge, it can also be represented as G , which exhibits car-
B
bene character. It is this latter resonance form that enables
the carbene dimerization to generate K. Hydrolysis of K
during workup affords the final products 16 and 17.
3
1
Asymmetric ketones: To differentiate between the reactivity
of dissimilarly substituted diacetylenes, as well as to obtain
mechanistic insights by determining the rate- and product-
determining steps, a series of reactions with asymmetrically
disubstituted ketones were performed. Thus, ketones 18,
which carries phenyl and TIPS groups at the acetylene ter-
mini, and 19, having instead phenyl and TES groups, were
reacted with 1 (Scheme 6 and Table 3).
14 and 15, respectively.
The first steps in the mechanism for the formation of cu-
mulenes 14 and 15 are identical to those depicted in
Scheme 2. Due to the presence of a second acetylene unit,
intermediate D can be described by additional resonance
structures D and D (Scheme 4). Of these, D is an allenyl
As expected, the acetylenic TIPS group prevents [2+2]
cycloaddition in the early stages of the reaction. It is then
not surprising that 1Li attacks the phenyl-terminated acety-
B
C
C
anion that can engage in nucleophilic attack on a second
ketone to form intermediate E. This adduct can undergo a
1,3-silyl shift to give F, in which the newly formed OSiR3
can function as a leaving group to generate the observed cu-
mulenes 14 and 15. Quenching of the reaction mixture with
MeOH at low temperature allowed the isolation of proto-
nated intermediate F.
Changing the termini at the acetylenes from silyl groups
to aromatic groups alters the reactivity of the system dra-
matically. The only compounds that can be detected from
the reaction of 1 with bis(phenylethynyl)ketone 10 and
bis(2-thiophenylethynyl)ketone 11 are bisphospholes 16 and
17, which are isolated as bright-orange and -red solids in 38
and 50% yield, respectively. Both compounds are character-
3
1
ized by two doublets in their P NMR spectra at approxi-
mately d=37 and 13 ppm, respectively, with coupling con-
3
stants of around J =32 Hz. The proposed mechanism for
PP
the formation of 16 and 17 is presented in Scheme 5. Again,
the first steps, up to intermediate C, are identical to those in
Schemes 2 and 4. Of the different representations of C, CC
contains a formal negative charge at the phosphorus center
that enables a 5-exo attack at the carbon atom of the second
acetylene unit to form intermediate G . Although this inter-
A
mediate can be described as GA with a localized negative
Scheme 6. Reaction of 1 with asymmetric diacetylenic ketones 18 and 19.
Scheme 5. Proposed mechanism for the reaction between aryl-substituted ketones and 1.
Chem. Eur. J. 2013, 19, 13692 – 13704 ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
13695

S. Ott et al.
Table 3. Products yields for the reaction of 1 with asymmetric diacetylen-
ic ketones.
Executing the reaction of 1Li with ketone 19 results in
the selective formation of the corresponding oxaphospholes
3
1
III
31
V
3
31
31
3
Ketone
Ratio
Product
Yield
%]
d
A
H
U
G
R
N
U
G
d
A
T
N
T
E
N
N
J
PP
2
2
2 (d
ACHTUNGTNREUNNG( P)=150.0 ppm) and 23 (d ACHTUNGTRNENUNG( P)=156.0 (d, JPP =
[
A
H
U
G
R
N
N
A
H
U
G
R
N
U
G
[Hz]
III
V
8 Hz, P ) and 11.7 ppm (d, J=28 Hz; P )) with their ratio
[
[
[
[
[
[
a]
b]
a]
a]
b]
c]
18
18
18
19
19
19
1:1
1:1
1:2
1:1
1:1
1:2
20
21
20
22
23
24
37
30
31
10
27
–
150.0
155.9
150
150.1
156.0
150.7
–
27
–
again dependent on the workup (see above). Evidently, also
in this case, 1Li attacks the phenyl acetylene rather than the
TES acetylene. It is important to note that 22 and 23 were
the exclusive products when the starting materials were
used in an equimolar ratio. This indicates that the formation
of the oxaphosphole is faster than the nucleophilic attack of
12.4
–
–
11.7
6.0
6.2
–
28
43
43
150.5
[
a] Reaction was quenched by addition of water at ꢀ508C. [b] Reaction
intermediate D on a second equivalent of the ketone. Thus,
C
was quenched by direct application to a silica gel column. [c] Reaction
was quenched by direct application on silica after 1.5 h; only the red frac-
tion was collected and concentrated to obtain crude products for
if the ratio between ketone 19 and compound 1 was in-
creased to 2:1, the only detectable product was cumulene
24, which is, however, unstable under the reaction condition
and tends to polymerize on workup. Nevertheless, the
3
1
P NMR spectroscopy. Two isomers for complex 24 were found.
3
1
P NMR spectrum of the characteristically bright-red crude
3
1
lene of 18 to give oxaphospholes 20 (d
and 21 (d
A
H
U
G
E
N
N
( P)=150.0 ppm)
reaction mixture indicates the presence of two isomeric
31
3
III
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
( P)=155.9 (d, J =27 Hz, P ) and 12.4 ppm (d,
forms of 24 with chemical shifts of d=150.7 (d, J =43 Hz,
PP
PP
V
III
V
J=27 Hz; P )), which differ only in the presence or absence
of the phosphonate group. This reaction behavior is identi-
cal to that described for the monoacetylenic ketones in
Scheme 1. It is noteworthy that the ratio of 20 to 21 depends
on the pH during workup. Quenching the reaction mixture
by filtration through a plug of (acidic) silica gives only 21,
whereas aqueous (basic) workup at ꢀ508C leads to loss of
the phosphonate group and the formation of 20. The molec-
ular structure of 21 was confirmed by X-ray diffraction anal-
ysis of single crystals obtained by evaporation of a solution
in CH Cl at ꢀ308C (Figure 2).
P ) and 6.0 ppm (d, J=43 Hz; P ) for the first isomer and
3
III
V
d=150.5 (d, J =43 Hz, P ) and 6.2 ppm (d, J=43 Hz; P )
PP
for the second. The presence of two isomers can be expect-
ed based on the cis/trans isomers of the butatriene system.
Reaction with two different ketones: If intermediate D with a
reactive appended acetylene moiety can indeed be formed
selectively, it should also be possible to subsequently react it
with a second, different diacetylenic ketone. This hypothesis
was tested by successively adding two different ketones to
1Li in a one-pot procedure (Scheme 7).
2
2
Scheme 7. Stepwise reaction of 1 with two different ketones.
Thus, one equivalent of ketone 19 was first added to 1Li
at ꢀ788C. After stirring the resulting dark-red solution for
3
0 min, one equivalent of ketone 8 was added and the reac-
tion mixture was allowed to warm to ꢀ108C. Direct quench-
ing of the reaction mixture on silica gel allowed the isolation
of 25 as the sole product. Other cumulenes that would arise
from scrambling of the ketones were not observed, nor were
any oxaphospholes of type 22 or 23. The exclusive formation
of 25 convincingly illustrates the control that is possible
during the reaction sequence, allowing the selective intro-
duction of different substituents at C5 of the oxaphosphole
and at the acetylene termini.
Figure 2. Crystal structure of compound 21 (ellipsoids set to 50% proba-
bility). All protons are omitted for clarity except for those at the oxa-
phosphole ring.
The TIPS group in 18 not only prevents the [2+2] cyclo-
addition at its adjacent acetylene in the reaction with 1Li,
but also prevents subsequent chemistry in 20 and 21. Even if
the ratio between 18 and 1 is changed from 1:1 to 1:2, no
formation of cumulene-type products is observed, thus sup-
porting the notion that nucleophilic attack of the respective
NMR studies
3
1
31
D intermediate (Scheme 4) on a second molecule of ketone
P NMR studies: The P chemical shifts of all compounds
are summarized in Tables 2, 3, and 4. Those of oxaphos-
C
is not viable with TIPS groups at the acetylene terminus.
13696
www.chemeurj.org ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2013, 19, 13692 – 13704

Oxaphospholes and Bisphospholes
FULL PAPER
3
1
Table 4. P NMR chemical shifts and coupling constants for oxaphosp-
holes.
3
1
31 III
31
V
1
Compound
d
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
( P)
Compound
d
A
H
U
G
R
N
U
G
)
d
A
H
U
G
R
N
U
G
J
PP
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[ppm]
A
H
U
G
R
N
U
G
A
H
U
T
E
N
N
[Hz]
3
3
3
3
3
2
2
a
b
c
d
e
0
2
132.0
132.0
149.6
149.6
132.8
150.0
150.1
–
–
–
–
–
–
–
–
4c
4d
4e
21
23
153.0
151.2
161.5
156.0
156.0
15.8
14.8
16.0
12.4
11.7
28
28
36
27
27
pholes 3, 20, and 22 are at around d=150 ppm, whereas that
for the C5-phenyl-substituted 3e resonates at higher field
V
(
d=132 ppm). The presence of a P substituent at C4 in 4,
2
1, and 23 (resonating at d=12–16 ppm) causes a downfield
III
shift of the P resonance. The cumulene substituent in 14,
V
15, and 25 induces an upfield shift of the P resonance of
approximately d=6 ppm, enabling the unambiguous identi-
fication of these compounds from the crude reaction mix-
tures.
1
13
H and C NMR studies: Because oxaphospholes are still
1
13
rather rare heterocycles, we report their H and C NMR
spectroscopic signatures in detail (Figure 3 and Table 4).
3
The H proton in 3 and 4 is featured as a multiplet due to
2
3
3
JHP (ca. 4–8 Hz) and J (3–4 Hz) or J (ca. 3 Hz) cou-
HH
HP
3
plings, respectively. The chemical shift of the C carbon
atom in compounds bearing a phenyl group is generally de-
shielded compared to that of the silyl-substituted deriva-
1
III
tives. J
C3PIII
coupling constants of the P center are in the
range of 7–11 Hz for the compounds with R’=Ph and 2–
Hz for those with R’=TES. For silyl-substituted cumu-
6
lenes 14 and 15 this coupling constant was not detected,
Figure 3. Summary of the chemical shifts and carbon–phosphorus and
proton–carbon coupling constants for ring carbon atoms and protons.
whereas it is 4 Hz for the phenyl-substituted analogue. Cou-
3
V
pling between the C and P atoms is generally 9–13 Hz and
is independent of the ring substitution pattern. Another
1
3
characteristic resonance in the C NMR spectra of 4, 21,
4
and 23 is observed for the C carbon atom, which has a
1
rather large J
C4PV
coupling constant of up to 200 Hz. The
5
presence of acetylene substituents at C in 20–23 gives rise
to an upfield shift of approximately d=15 ppm compared to
those of the other oxaphospholes.
Scheme 8. Reaction followed by in situ FTIR spectroscopy.
Reaction monitoring by in situ IR spectroscopy: The CO
stretching vibrations of the P-bound {W(CO) } fragment
5
provide convenient spectroscopic handles to detect chemical
transformations at the W-coordinated phosphorous center.
We examined the behavior of the carbonyl vibrational fre-
quencies by following the reaction of 1 and 10 to form bis-
ACHTUNGTRENNUNGp hos ACHTUNGTRENNUNGp hole 16 by in situ FTIR spectroscopy (Scheme 8 and
Figure 4).
dition of ketone 8, 1Li is consumed within 5 min with con-
comitant emergence of several very broad bands, most
ꢀ
1
prominently at n˜ CO =2080, 1940, 1880, and 1840 cm . The
multiple vibrational frequencies indicate high complexity of
the reaction mixture and the formation of various side prod-
ucts, which could not, however, be isolated. The IR spec-
trum of the reaction mixture remains in essence unchanged,
even after quenching with water. Absorptions that result
Compound 1 exhibits two absorptions in the typical car-
ꢀ
1
bonyl region at n˜ CO =2080 (w) and 1950 cm (s; Figure 4).
ꢀ
1
Upon treatment with BuLi, new bands appear at n˜ =2060,
from bisphosphole 16 at n˜ CO =2077 and 1936 cm can be
observed in the reaction mixture and are identical to those
of the purified product (inset Figure 4).
CO
ꢀ
1
1
920, and 1875 cm , while those of 1 disappear within min-
utes, indicating the fast and complete lithiation of 1. On ad-
Chem. Eur. J. 2013, 19, 13692 – 13704 ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
13697

S. Ott et al.
Figure 4. In situ IR spectra obtained during the reaction of 1 (a;
3 mm in THF at ꢀ508C) with BuLi (l), followed by addition of 10
43 mm) before (g) and after (c) quenching with water at the same
4
(
temperature. Inset: overlay of the final crude IR spectrum and that of
purified 16 (thick line).
Calculations: The reaction mechanism proposed to explain
the observed products was scrutinized by using DFT calcula-
tions. In particular, insights were sought into the reasons
why aryl groups at the acetylene termini give rise to bis-
phospholes, whereas silyl groups promote cumulene-deco-
rated oxaphosphole formation. To reduce computational
time, the following modifications were made: ethyl groups
in the phosphonate were substituted by methyl groups, the
transition metal was changed to chromium, and functional
groups at the acetylenic termini that do not participate in
the immediate reaction were changed to hydrogen atoms.
Scheme 9 summarizes all (model) intermediates with R
being either Ph or TMS; in the text this is identified as sub-
scripts, that is, DR=Ph and DR=TMS, respectively. For simplici-
ty, the PꢀP bond cleavage (B!C) and the carbene dimeri-
Scheme 9. General mechanism for the reaction of 1 with diacetylenic ke-
tones.
CC reveal that C is less favorable by at least 1.4 and
A
ꢀ
1
zation (G!K), can be considered irreversible, while all
other intermediates are presumably in equilibrium. This as-
sumption focuses the calculations on the distinguishing fac-
tors of C and the conversion of C to D and on to F and the
dimerization to form K via G.
2.2 kcalmol for phenyl and TMS substitution, respectively.
However, no clear conformational preference could be
found for either CB or CC that would depend on the sub-
stituents. This prompted us to investigate subsequent steps
of the suggested mechanism.
First, we investigated whether there is a conformational
preference for intermediate C that depends on the substitu-
ent R (Table 5), and whether such a preference could ex-
plain the product selectivity. Namely, conformer CC fore-
casts phosphole formation (G), whereas CB is more similar
to D. DFT calculations on the three conformers C , C , and
Phosphole formation (C !G) is slightly endothermic for
C
both the phenyl- and silyl-substituted derivatives (by 4.9 and
ꢀ
1
8.7 kcalmol , respectively), whereas oxaphosphole forma-
tion (C !D) is energetically favored by 6.2 and 17.1 kcal
B
ꢀ
1
mol , respectively (Table 6). Assuming that intermedia-
tes C, D, and G are in equilibrium, the G!D transforma-
A
B
ꢀ
1
Table 5. Relative B3LYP/6-31G* energies of the intermediates C for R=
Ph and R=TMS.
Table 6. Relative B3LYP/6-31G* energies (in kcalmol ) for the cycliza-
tions and dimerizations.
Entry
C
A
C
B
C
C
C
A
C
B
C
C
R
C
C
!G
C
B
!D
G’!K’
D’!E’
TS
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(D’!E’)
R
TMS
0
TMS
ꢀ2.4
TMS
ꢀ2.2
Ph
0
Ph
ꢀ1.4
Ph
ꢀ1.5
TMS
Ph
8.7
4.5
ꢀ17.1
ꢀ17
ꢀ27
ꢀ12
ꢀ
1
DE [kcalmol
]
ꢀ6.2
ꢀ23
ꢀ17
+10
13698
www.chemeurj.org ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2013, 19, 13692 – 13704

Oxaphospholes and Bisphospholes
FULL PAPER
Figure 5. Reaction coordinate for the formation diacetylenic cumulenes 14/15.
ꢀ
1
tion is thus calculated to be downhill by 24.2 kcalmol for
ꢀ
1
the TMS-substituted derivative, but by only 9.6 kcalmol
for the Ph-substituted derivative. Put differently, the forma-
tion of DR=TMS is greatly favored, whereas GR=Ph, although
endothermic, may still be accessible under the experimental
conditions.
Scheme 10. Structures of simplified model compounds for the dimeriza-
Next, the energetics of the nucleophilic attack of D on a
second ketone (D!E) and the subsequent 1,3-R shift (R=
TMS or Ph) was investigated by using the simplified struc-
tures D’, E’, and F’ in Figure 5. The transition-state energies
for the nucleophilic attack towards the diacetylenic ketone
tion of G’ to form bisphospholes.
the TMS- and phenyl-substituted compounds by 17 and
ꢀ
1
23 kcalmol , respectively. The dimerization step, G’!K’, is
thus more exothermic for the phenyl- than for the TMS-sub-
stituted case, which somewhat explains the preferred bi-
sphosphole formation for phenyl-substituted compounds.
In conclusion, the differences in the reactivity for the
compounds with two different substituents mainly originate
from the final silyl or phenyl migration converting inter-
mediate E into F. The phenyl migration proceeds through a
high-energy transition state that is inaccessible at low tem-
peratures, whereas the silyl shift proceeds without a signifi-
cant barrier. On the other hand, the bisphosphole formation
is much more exothermic for the phenyl substituent
(
TS ACHTUNGTRENNUNG( D’–E’)) were found to be low lying irrespective of the
substituents, suggesting reversibility of this elemental step.
Interestingly, there is a distinct difference in the stationary
points E’R=Ph and E’R=TMS. Whereas the former shows the
expected twisted arrangement of the phenyl substituent, the
latter involves the formation of a SiꢀO bond and thus a pen-
tacoordinated Si center with one methyl group and the O
atom in the axial positions. In this case, the almost isoener-
getic transition state of the TMS migration resembles a
[24,25]
“Berry-pseudorotation”,
which brings the O atom into
an equatorial position and the terminal allene C atom into
the elongated axial position that promotes the bond rupture.
In contrast, the transition state for the phenyl migration TS-
ꢀ
1
(ꢁ20 kcalmol ) than for the TMS-containing compound
ꢀ
1
(ꢁ10 kcalmol ). Moreover, the C !G transformation is
C
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(E’–F’)
is a typical 1,3-shift of significantly higher
thermodynamically more costly for R=TMS than for R=
R=Ph
energy with a relative barrier of approximately 37 kcal
Ph (Table 6).
ꢀ
1
mol . Thermodynamic considerations of the final elimina-
tion result in the TMS-substituted reaction being exothermic
UV/Vis spectroscopic and electrochemical characterization:
The electronic absorption properties of selected compounds
are summarized in Table 7. Cumulenes 15 and 25 are bright-
red compounds with longest-wavelength absorption maxima
at 470 and 460 nm, respectively. It is interesting to note that
introduction of a phenyl substituent instead of a TES group
ꢀ
1
by 16 kcalmol , whereas the Ph-substituted reaction is
ꢀ
1
slightly endothermic (+2 kcalmol ).
Bisphosphole formation (G!K) was theoretically inves-
ACHTUNGTRENNUNGt igated by using the simplified structures presented in
Scheme 10, and was found to be energetically favorable for
Chem. Eur. J. 2013, 19, 13692 – 13704 ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
13699

S. Ott et al.
[
a]
Table 7. Electronic absorption spectra of compounds 15–17 and 25.
are observed for 15 and 25 at around ꢀ1.4 V are presumably
localized on the p-conjugated portions of the compounds, as
they are almost identical to the values reported for perace-
ꢀ
1
ꢀ1
3
Compound
cumulenes
lmax [nm] (e [m m ꢃ10 ])
15
303 (47.3), 322 (47), 342 (47.2), 470 (86)
300 (19), 334 (13.6), 460 (14.4)
316 (16.6), 445 (7.3)
[27]
2
5
tylenic butatriynes. The effect that the oxaphospholes in
5 and 25 have on the electronic properties of the com-
bisphospholes
16
1
1
7
329 (21.7), 484 (11.8)
pounds is thus comparable to that imposed by two addition-
al acetylene substituents.
[
2 2
a] Measured in CH Cl .
Bisphospholes 16 and 17 are oxidized at relatively mild
potentials of 0.43 and 0.35 V, respectively, with the presence
of the electron-rich thiophene unit in 17 being responsible
on the C3 carbon atom of oxaphosphole 25 leads to a hypso-
chromic shift of 10 nm (compared to 15) and a large reduc-
tion in the extinction coefficient. Comparison of the optical
for a cathodic shift of 80 mV. In comparison, {W(CO) }-co-
5
ordinated 2,5-bis ACHUTNGRNENUG( thienyl)phosphole has an oxidation poten-
[9c]
properties with those of a peracetylenic butadiyne (l
=
tial of 0.70 V. In the cathodic scan, electrochemically re-
versible one-electron reductions are observed at ꢀ2.00 and
ꢀ1.87 V for 16 and 17, respectively. It is thus interesting to
note that the thiophene substituents in 17 shift both the re-
duction and oxidation potentials to smaller absolute values.
This result is consistent with the UV/Vis spectrum that
shows 17 to have the lowest energy absorption maximum of
this series.
max
[26]
4
24 nm)
maxima of 15 and 25 are bathochromically shifted by about
0 nm. It is thus clear that the lowest energy absorptions are
reveals that the longest wavelength absorption
4
not isolated within the cumulene-based p system, but rather
extend over the entire oxaphosphole unit.
The lowest-energy absorption maxima of bisphospholes
16 and 17 differ by approximately 40 nm, indicating a size-
able contribution of the peripheral thiophene substituents to
the compoundsꢀ frontier molecular orbitals. The absorptions
at 445 and 484 nm for 16 and 17, respectively, are consider-
ably redshifted compared, for example, to 2,5-bis-
Conclusion
[9c]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(thienyl)phosphole (l =412 nm) , indicating that the un-
We have shown that phosphinophosphonate 1 reacts prefer-
entially in the Michael-addition position of acetylenic ke-
tones. The observed behavior is fundamentally different to
that of classical Horner–Wadsworth–Emmons reactions,
which react in a 1,2-fashion and convert acetylenic ketones
max
saturated ethylene bridge between the two phosphole units
mediates a certain degree of delocalization.
The electrochemical behavior of the compounds was stud-
ied by cyclic voltammetry and the results are summarized in
Table 8. Simple oxaphospholes 20 and 23 with acetylene
[28]
to the corresponding alkenes.
The reactivity of 1 can,
however, be changed to the usual attack at the carbonyl
carbon atom by the presence of sterically demanding
(
iPr) Si termini on the acetylenes. In all other cases, 1 reacts
3
Table 8. Electrochemical properties of compounds 15, 16, 17, 20, 23, and
[
a]
with monoacetylenic ketones 2a–e to afford highly function-
alized 2,5-dihydro-1,2-oxaphospholes 3 and 4. The presented
approach provides reliable access to this rather rare class of
heterocycles.
2
5.
Compound Reduction Ecp [V]
Oxidation Epa [V]
[
c]
[b]
cumulenes
15
ꢀ1.81
ꢀ1.67
ꢀ2.38
ꢀ2.34
–
ꢀ1.40
ꢀ1.35
ꢀ2.00
ꢀ1.87
–
0.94
0.96
0.43
0.35
1.27
1.12
1.36
–
1.03
1.14
–
[
b]
2
5
bisphospholes
16
Inclusion of a second acetylene in the ketone substrate
promotes further reactivity of the system. Diacetylenic ke-
tones that contain at least one silyl substituent as an acetyl-
ene terminus also form 2,5-dihydro-1,2-oxaphospholes,
which react further with a second equivalent of ketone to
form an appended cumulene framework. The reaction se-
quence allows a high degree of control as the two diacetyl-
enic ketones can be added successively and substituents at
the oxaphosphole and the cumulene can thus be introduced
selectively. Completely different reactivity is observed when
both acetylene moieties of the diethynylketones are termi-
nated by aromatic groups. In this case, ethenyl-bridged bis-
1
7
oxaphospholes 20
2
3
–
–
–
[
a] Measured for 1 mm solutions of the analyte in CH
2
Cl
2
(0.1m
ꢀ
1
NBu
4
PF
6
), glassy C electrode, n=100 mVs . All potentials are given
c+/0
versus F . [b] Peak is reversible, reported value corresponds to E1/2
pa +Epc)/2. [c] Measured for a 0.6 mm solution due to low solubility of
the complex.
=
(
E
substituents at C5 are inert to reductive processes within the
solvent window and feature only one irreversible oxidation
+
/0
at a potential of 1.27 and 1.12 V versus Fc , respectively.
The difference of 150 mV arises from the presence of the
phosphonate group in 23, which seems to contribute to the
compoundsꢀ HOMOs and shifts the potential cathodically.
Expanding the p system further by inclusion of the cumu-
lene portion in 15 and 25 shifts the oxidation potential fur-
ther cathodically by another 160 and 180 mV, respectively,
compared to that of 23. Reversible reductive processes that
A
H
U
G
R
N
U
G
ACHTUNGTRENNUNpG holes are formed.
pounds are identical, but diverge after the ring-opening of a
putative oxadiphosphetane intermediate. DFT computation-
al studies suggest that many of the initial reaction intermedi-
ates are in equilibrium and that bisphosphole formation is
significantly more exothermic for ketone substrates with ar-
omatic acetylene termini. Moreover, the formation of cumu-
13700
www.chemeurj.org ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2013, 19, 13692 – 13704

Oxaphospholes and Bisphospholes
FULL PAPER
1
1
lenic oxaphospholes is highly favored for silyl-terminated
ethynylketones. In contrast to the easily accessible 1,3-silyl
shift to form cumulenes, the corresponding putative phenyl
shift proceeds through a large relative barrier that complete-
ly inhibits the aryl migration while the silyl rearrangement is
greatly favored.
C
6
D
6
): d=198.4 (d, J=26 Hz), 196.3 (d, JPW =126, JPC =7 Hz), 154.4 (d,
J=6 Hz), 146.5 (d, J=26 Hz), 129.5 (d, J=2 Hz), 128.3 (d, J=9 Hz),
1
4
25.5 (d, J=12 Hz), 102.0 (d, J=3 Hz), 39.2 (d, J=5 Hz), 15.1 (d, J=
Hz), 7.5 (s), 3.3 ppm (d, J=2 Hz); HRMS (solution in CHCl with addi-
COO): m/z calcd for C42 Ag: 1341.03996
[2M+Ag] ; found: 1341.04221.
3
tion of AgCF
3
50 2 2 2
H O12Si P W
+
Oxaphospholes 3c and 4c: Prepared from 1 (0.31 g, 0.55 mmol) and
ketone 2c (0.08 g, 0.55 mmol). Final compounds were obtained after
chromatography by using diethyl ether (1%) in pentane as eluent to give
pure 3c (R
f
=0.11; 0.016 g, 5%) followed by pure diethyl ether to give 4e
Experimental Section
(R =0.46, 0.11 g, 28%) as white solids.
f
3
1
1
Compound 3c: P NMR (121 MHz, CDCl
3
): d=149.6 ppm ( JPW
=
1
General: All reactions were performed under argon by using modified
287 Hz); H NMR (300 MHz, CDCl
3
): d=7.56–7.52 (m, 3H; Ph), 7.47–
Schlenk techniques. Diethyl ether and THF were freshly distilled from
7.33 (m, 3H; Ph), 7.30–7.27 (m, 3H; Ph), 7.20–7.17 (m, 1H; Ph), 5.09
1
13
31
2
3
sodium/benzophenone prior to use. H, C, and P spectra were record-
ed on a JEOL Eclipse+ and a Varian Mercury+ operating at proton fre-
quencies of 400 and 300 MHz, respectively. Chemical shifts are reported
(dd, JHP =18, JHH =3 Hz, 1H; HC=), 4.26–4.21 (m, 1H; HCPh),
1
3
2.19 ppm (brs, 3H; =CCH ); C NMR (75 MHz, CDCl ): d=198.7 (d,
3
3
J=29 Hz), 194.8 (d, J=8 Hz), 158.3 (d, J=7 Hz), 142.9 (d, J=30 Hz),
138.4 (d, J=5 Hz), 130.2 (d, J=2 Hz), 129.2 (d, J=3 Hz), 129.0 (d, J=
5 Hz), 128.6 (d, J=9 Hz), 128.0 (d, J=4 Hz), 126.4 (d, J=12 Hz), 103.7
(s), 59.8 (d, J=11 Hz), 15.9 ppm (d, J=3 Hz); IR (CH Cl ): n˜ =2306,
1
13
in ppm and referenced internally to residual solvent peaks ( H, C) or
externally to aqueous H PO (85%). High-resolution mass spectral analy-
3
4
ses (HRMS) were performed on a high resolution and FTMS+pNSI
mass spectrometer (OrbitrapXL). Ketones 2a–f were prepared following
literature procedures (for references please see the Supporting Informa-
tion).
2
2
ꢀ
1
2076, 1946, 1605, 1198, 1118 cm ; HRMS (solution in MeOH/CHCl3
with addition of AgCF
3
COO): m/z calcd for C21
H
15
O
6
PWAg: 684.91665
+
[
M+Ag] ; found: 684.91528.
X-ray data: CCDC-848398 (3e) and CCDC-933297 (21) contain the sup-
plementary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif. A summary of the data can be
found in Table SI1 of the Supporting Information.
31
3
Compound 4c: P NMR (121 MHz, CDCl
J
3
): d=153.0 (d,
JPP =28,
1
III
3
V
1
PW =293 Hz; P ), 15.8 ppm (d,
CDCl ): d=7.53–7.49 (m, 4H; Ph), 7.44–7.41 (m, 1H; Ph), 7.39–7.34 (m,
H; Ph), 7.28–7.23 (m, 2H; Ph), 4.26–4.23 (m, 1H; HCPh), 3.71–3.56 (m,
JPP =28 Hz, P ); H NMR (300 MHz,
3
3
2
3
2 3 2 3
H; OCH CH ), 3.35–3.15 (m, 2H; OCH CH ), 2.54 (dd, JHP =2, 1 Hz,
3H; =CCH ), 0.90 (dt, J =7, J =7 Hz, 3H; OCH CH ), 0.77 ppm (t,
3 HH HP 2 3
JHH =7 Hz, 3H; OCH CH ); C NMR (CDCl ): d=198.0 (d, J=30 Hz),
194.3 (d, JCW =126, JCP =8 Hz), 170.2 (dd, J=32, 8 Hz), 141.6 (d, J=
29 Hz), 137.1 (d, J=5 Hz), 130.5 (d, J=2 Hz), 129.2 (s), 129.1 (s), 128.7
(d, J=9 Hz), 128.2 (d, J=3 Hz), 126.2 (d, J=12 Hz), 105.7 (d, J=
00 Hz), 61.5 (d, J=5 Hz), 61.1 (d, J=5 Hz), 60.8 (dd, J=10, 7 Hz), 16.3
d, J=3 Hz), 15.9 (d, J=7 Hz), 15.5 ppm (d, J=8 Hz); IR (CH Cl ): n˜ =
307, 2078, 1950, 1630, 1137 cm ; HRMS (solution in MeOH/CHCl ): m/
3
4
General procedure for the reaction of 1 with monoacetylenic ketones:
Compound 1 (1 equiv) was dissolved in THF (5–15 mL) and the solution
was cooled to ꢀ208C. Subsequently, LDA (1 equiv, 2m in THF/heptanes)
was added dropwise and the reaction mixture was stirred for 20 min.
After this time, the solution was cooled to ꢀ788C and the ketone
3
13
2
3
3
1
1
(
1.05 equiv in THF) was added dropwise. The reaction mixture was stir-
2
red for 1.5 h at ꢀ508C and directly poured onto a silica gel plug and
washed with THF. After removal of all volatile compounds, the residue
was subjected to column chromatography to give the final product.
(
2
2
2
ꢀ1
3
+
z calcd for C25
24 9 2
H O P WNa: 737.03026 [M+Na] ; found: 737.02821.
Oxaphosphole 3a: Prepared from 1 (0.15 g, 0.26 mmol) and ketone 2a
Oxaphospholes 3d and 4d: Prepared from 1 (0.24 g, 0.43 mmol) and
ketone 2d (0.09 g, 0.43 mmol). Compound 4d was obtained by filtration
(
(
0.04 g, 0.27 mmol). The final compound was obtained as a colorless oil
0.04 g, 38%, mixture of two isomers in a 4:1 ratio) after chromatography
(
0.09 g, 27%) as a white solid after treating the crude mixture with pure
diethyl ether. “Procedure” Chromatography of the residue by using
CH Cl (20%) as eluent gave 3d (0.05 g, 18%) as a white solid.
Compound 3d: P NMR (121 MHz, CDCl
by using CH
2
Cl
P NMR (161 MHz, CDCl
400 MHz, CDCl ): d=7.42–7.39 (m, 2H; Ph), 7.35–7.30 (m, 3H; Ph),
2 f
(10%) in pentane as eluent (R =0.57). Major isomer:
3
1
1
1
3
): d=132 ppm ( JPW =277 Hz); H NMR
2
2
(
4
3
3
1
1
3
3
5
3
): d=149.6 ppm ( JPW
=
.81 (ddq,
J
PH =18,
J
HH =4,
J
HH =1 Hz, 1H; HC=), 2.36–2.34 (m, 1H;
), 0.26 ppm (s, 9H; TMS);
3
): d=198.6 (d, J=26 Hz), 196.1 (d, J=7 Hz),
1
3
4
4
4
289 Hz); H NMR (300 MHz, CDCl
2H; Ph), 7.60–7.33 (m, 13H; Ph), 5.86 (dd,
3
): d=7.84 (dd,
J
HH =8,
J
J
HH =2 Hz,
HH =4 Hz, 1H;
HH =4 Hz, 1H; HCPh); C NMR
HCP), 2.03 (dd, JHP =3, JHH =1 Hz, 3H; CH
3
3
3
1
3
J
HP =18,
C NMR (100 MHz, CDCl
2
3
13
HC=), 4.46 ppm (dd,
75 MHz, CDCl
J
HP =5,
J
1
9
54.8 (d, J=7 Hz), 146.2 (d, J=26 Hz), 129.5 (d, J=2 Hz), 128.2 (d, J=
Hz), 125.5 (d, J=12 Hz), 101.9 (d, J=3 Hz), 42.5 (d, J=4 Hz), 15.6 (d,
(
3
): d=198.5 (d, J=29 Hz), 194.8 (d, J=8 Hz), 158.4 (d,
3
1
J=7 Hz), 142.3 (d, J=30 Hz), 138.0 (d, J=5 Hz), 130.3 (d, J=2 Hz),
129.7 (s), 129.3 (d, J=3 Hz), 129.1 (d, J=5 Hz), 128.8 (s), 128.7 (d, J=
9 Hz), 128.2 (d, J=4 Hz), 126.4 (d, J=13 Hz), 125.6 (s), 102.5 (s),
60.1 ppm (d, J=11 Hz); IR (CH Cl ): n˜ =2077, 1947, 1712, 1144,
J=4 Hz), ꢀ1.7 ppm (d, J=2 Hz); Minor isomer: P NMR (161 MHz,
1
1
CDCl
3
): d=140.8 ppm ( JPW =274 Hz); H NMR (400 MHz, CDCl
3
): d=
3
3
7
.51–7.48 (m, 2H; Ph), 7.45–7.43 (m, 3H; Ph), 4.78 (ddq, JPH =19, JHH =
4
4
2
J
,
J
HH =1 Hz, 1H; HC=), 3.08–3.06 (m, 1H; HCP), 2.10 (dd,
J
HP =3,
2
2
ꢀ
1
3
13
1024 cm
AgCF COO): m/z calcd for C26
48.93386.
Compound 4d: P NMR (121 MHz, CDCl
;
HRMS (solution in MeOH/CHCl3 with addition of
HH =1 Hz, 3H; CH
3
), ꢀ0.22 ppm (s, 9H; TMS); C NMR (100 MHz,
+
3
H
17
O
6
PWAg: 748.93196 [M+Ag] ; found:
CDCl
3
): d=199.2 (d, J=27 Hz), 196.3 (d, J=8 Hz), 155.9 (d, J=6 Hz),
37.9 (d, J=28 Hz), 131.3 (d, J=2 Hz), 129.9 (d, J=15 Hz), 128.4 (d, J=
0 Hz), 99.9 (d, J=3 Hz), 44.7 (d, J=7 Hz), 15.3 (d, J=5 Hz), ꢀ1.8 ppm
7
1
1
3
1
1
3
): d=151.2 (d,
JPP =28,
1
III
1
V
1
(
d, J=2 Hz); IR (pentane): n˜ =2076, 1989, 1956, 1943, 1942, 1914,
JPW =294 Hz; P ), 14.8 ppm (d, JPP =28 Hz, P ); H NMR (300 MHz,
CDCl ): d=8.02 (dd, JHH =7, JHH =2 Hz, 2H; Ph), 7.72–7.63 (m, 2H;
ꢀ
1
3
4
1
6
665 cm ; HRMS (solution in MeOH): m/z calcd for C18
H
21
O
7
PSiWNa:
3
+
15.02012 [M+H
2
O+Na] ; found: 615.01994.
Ph), 7.59–7.50 (m, 6H; Ph), 7.45–7.37 (m, 5H; Ph), 4.72 (dd, JHP =6,
Oxaphosphole 3b: Prepared from 1 (0.156 g, 0.27 mmol) and ketone 2b
3 Hz, 1H; HCPh), 3.63–3.48 (m, 2H; OCH
2
CH
CH ), 0.73 ppm (t,
); C NMR (75 MHz, CDCl ): d=198.3 (d, J=
3
), 3.44–3.24 (m, 2H;
3
3
(
(
(
(
7
4
0.05 g, 0.27 mmol). The final compound was obtained as a colorless oil
0.056 g, 35%) after column chromatography by using pentane/CH Cl
): d=132.0 ppm
): d=7.34–7.29 (m, 2H; Ph),
OCH
7 Hz, 3H; OCH
2
CH
3
), 0.90 (t,
CH
J
HH =7 Hz, 3H; OCH
2
3
HH
J =
1
3
2
2
2
3
3
3
1
95:5) as eluent (R
J
f
=0.26). P NMR (161 MHz, C
PW =277 Hz); H NMR (400 MHz, C
.10–7.05 (m, 2H; Ph), 6.96–6.92 (m, 1H; Ph), 4.34 (ddq, JHP =19, JHH
6
D
6
30 Hz), 194.7 (d, J=8 Hz), 166.7 (dd, J=28, 8 Hz), 141.6 (d, J=29 Hz),
137.4 (d, J=4 Hz), 131.6 (s), 130.9 (d, J=2 Hz), 130.1 (dd, J=3, 1 Hz),
129.8 (s), 129.6 (d J=3 Hz), 129.4 (d, J=6 Hz), 129.0 (d, J=9 Hz), 128.6
(d, J=3 Hz), 128.4 (s), 126.8 (d, J=12 Hz), 106.9 (d, J=200 Hz), 62.4
1
1
6 6
D
3
3
=
4
2
3
5
,
J
HH =2 Hz, 1H; HC=), 2.35 (ddq,
J
HP =7,
J
HH =4,
J
HH =2 Hz, 1H;
), 0.96 (t, JHH =8 Hz, 9H;
4
4
3
HCP), 1.60 (dd, JHP =4, JHH =2 Hz, 3H; CH
CH CH Si), 0.85–0.76 ppm (m, 6H; CH CH
3
(dd, J=11, 7 Hz), 62.0 (d, J=5 Hz), 16.1 (d, J=7 Hz), 15.8 ppm (d, J=
1
3
ꢀ1
3
2
3
2
Si); C NMR (100 MHz,
7 Hz); IR (CH
2
Cl
2
): n˜ =2078, 1950, 1596, 1025 cm ; HRMS (solution in
Chem. Eur. J. 2013, 19, 13692 – 13704 ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
13701

S. Ott et al.
MeOH/CHCl
3
with addition of AgCF
3
COO): m/z calcd for C30
H
27
O
6
PW:
CDCl
3
): d=7.82–7.75 (m, 2H; Ph), 7.39–7.33 (m, 3H; Ph), 3.21 (dd,
+
2
2
2
7
77.06396 [M+H] ; found: 777.06253.
J
HH =18,
J
HP =7 Hz; 1H; CH
2
), 3.03 (d,
J
HH =17 Hz, 1H; CH
2
), 2.75
HP =17 Hz,
), 1.09 (s, 21H; TIPS),
.97 ppm (s, 21H; TIPS); C NMR (100 MHz, CDCl ): d=199.0 (d, J=
CP =7 Hz), 135.6 (d, J=34 Hz), 130.0 (s),
2
2
2
3
(
dd,
J
HH =18,
J
2
HP =7 Hz, 1H; CH ), 2.43 (dd, JHH =17, J
Oxaphospholes 3e and 4e: Prepared from 1 (0.14 g, 0.24 mmol) and
ketone 2e (0.06 g, 0.24 mmol). Final compounds were obtained after
chromatography by using CH
1
0
2
1
5
2 3 3
H; CH ), 1.83 (s, 3H; CH ), 1.60 (s, 3H; CH
1
3
2
Cl (10%) in pentane as eluent to give
3
2
1
1
4 Hz), 196.4 (d,
JCW =126, J
pure 3e (R =0.37, 0.045 g, 28%) as a white solid followed by 1:1 diethyl
f
29.9 (d, J=7 Hz), 128.1 (d. J=9 Hz), 125.4 (d, J=7 Hz), 121.1 (d, J=
Hz), 105.4 (s), 104.7 (d, J=5 Hz), 86.9 (d, J=6 Hz), 85.6 (d, J=4 Hz),
ether in pentane as eluent to give 4e (R
yellow oil.
f
=0.26, 0.03 g, 15%) as a pale-
3
1
1
44.8 (s), 34.8 (d, J=22 Hz), 34.2 (d, J=24 Hz), 21.3 (d, J=8 Hz), 20.0 (d,
J=1 Hz), 18.5 (d, J=2 Hz), 18.4 (d, J=1 Hz), 11.2 (s), 11.1 ppm (s); IR
Compound 3e: P NMR (161 MHz, CDCl
3
): d=132.8 ppm ( JPW
=
1
3
2
7
79 Hz); H NMR (400 MHz, CDCl
.43–7.28 (m, 8H; Ph), 5.58 (dd,
3
): d=7.65 (d,
J
HH =7 Hz, 2H; Ph),
HH =4 Hz, 1H; HC=), 2.72
ꢀ
1
3
3
(pentane): n˜ =2072, 1947, 1941, 1708 cm ; HRMS (solution in MeOH/
CHCl with addition of AgCF3COO): m/z calculated for
J
HP =19,
J
2
3
3
3
(
dd,
J
HP =8,
J
HH =4 Hz, 1H; HCTES), 1.04 (t,
JHH =8 Hz, 9H;
+
1
3
40 57 5 2
C H O PSi Wag: 997.20392 [M+Ag] ; found: 995.20525.
SiCH
CDCl
2
CH
): d=198.5 (d, J=27 Hz), 196.0 (d,
d, J=6 Hz), 145.9 (d, J=26 Hz), 130.8 (d, J=5 Hz), 129.6 (d, J=2 Hz),
3 2 3
), 0.96–0.83 ppm (m, 6H; SiCH CH ); C NMR (100 MHz,
1
1
Reaction between 1 and ketone 11: A solution of LDA (0.44 mL of a 2m
solution in THF/heptanes) was added dropwise at ꢀ308C to a solution of
1 (0.5 g; 0.88 mmol) in THF (50 mL). The reaction mixture was stirred
for 30 min, then cooled to ꢀ788C. Ketone 11 (0.2 g; 0.88 mmol) was
added and the resulting dark red-brown solution was stirred for 2 h at
ꢀ208C. After this, water was added (50 mL) and the resulting suspension
was stirred for 5 h at RT. The solvents were removed in vacuo and the
residue was extracted with diethyl ether (3ꢃ50 mL). Combined organic
3
J
CW =126,
J
CP =8 Hz), 155.1
(
1
1
28.8 (s), 128.7 (s), 128.3 (d, J=9 Hz), 125.4 (d, J=12 Hz), 124.8 (s),
01.9 (d, J=4 Hz), 40.4 (d, J=6 Hz), 7.6 (s), 3.3 ppm (d, J=2 Hz);
HRMS (solution in MeOH/CHCl
3
): m/z calcd for
C
26
H
28
O
6
PSiW:
+
6
79.09021 [M+H] ; found: 679.09109.
3
1
1
Compound 4e: P NMR (161 MHz, CDCl
3
): d=161.5 (d,
JPP =36,
1
III
1
V
1
J
PW =281 Hz;
P
), 16.0 (d,
JPP =36 Hz; P ); H NMR (400 MHz,
4
fractions were dried over MgSO . Removal of the solvent resulted in a
crude red-brown product. Chromatographic purification on silica (2%
CDCl ): d=7.82–7.79 (m, 4H; Ph), 7.51–7.41 (m, 6H; Ph), 4.01–3.88 (m,
), 3.84–3.78 (m, 2H; OCH
H; HCTES), 1.09 (t,
3
2
1
H; OCH
2
CH
3
2
CH
3
), 3.64 (dd, JHP =5, 2 Hz,
3
3
acetone in CH Cl ; R =0.6) afforded 17 (0.34 g, 49%) as a red solid.
J
HH =7 Hz, 3H; OCH
2
CH
3
), 1.02 (t,
J
HH =7 Hz,
), 0.51 (dq, JHP =16,
HH =8 Hz, 3H;
3
): d=198.8 (d, J=28 Hz), 196.1
2
2
f
3
1
1
III
3
3
2 2
P NMR (161 MHz, CD Cl ): d=37.2 (d, JPP =32, P ), 13.4 ppm (d,
3
H; OCH
2
CH
3
), 0.84 (t, JHH =8 Hz, 9H; SiCH
2
CH
HP =16,
3
1
V
1
3
3
3
2 2
JPP =32 Hz, P ); H NMR (400 MHz, CD Cl ): d=11.5 (brs, 2H; OH),
J
HH =8 Hz, 3H; SiCH
2
CH
); C NMR (100 MHz, CDCl
d, JCW =126, JCP =8 Hz), 162.2 (d, J=27 Hz), 137.4 (d, J=32 Hz), 132.3
3
), 0.38 ppm (dq,
J
J
1
3
7.39–7.35 (m, 2H; Ph), 7.28–7.24 (m, 8H; Ph), 7.21–7.19 (m, 2H; thio-
phene), 6.91–6.87 (m, 4H; thiophene), 6.70–6.50 (brm, 2H; thiophene),
SiCH
2
CH
3
1
(
(
(
6
(
6
.25–5.80 (brm, 4H; thiophene) 4.29–4.21 (m, 4H; OCH
m, 2H; OCH CH ), 3.95–3.85 (m, 2H; OCH CH ), 1.41 (t,
HH =7 Hz, 6H; OCH CH
2 3
CH ), 4.09–4.00
d, J=3 Hz), 131.7 (d, J=15 Hz), 131.3 (dd, J=6, 2 Hz), 130.7 (s), 129.5
d, J=1 Hz), 128.3 (d, J=11 Hz), 128.0 (s), 103.5 (d, J=205 Hz), 62.3 (d,
J=7 Hz), 61.4 (d, J=6 Hz), 46.0 (dd, J=10, 2 Hz), 15.8 (d, J=4 Hz), 15.7
d, J=4 Hz), 7.6 (s), 3.6 ppm (d, J=2 Hz); HRMS (solution in MeOH/
3
2
3
2
3
J
HH =7 Hz,
3
13
H; OCH
2
CH
3
), 1.05 ppm (t,
Cl
J
2
3
); C NMR
(
100 MHz, CD
2
2
): d=198.1 (d, J=23 Hz), 196.4 (d, JCP =7 Hz, JCW
=
(
+
126 Hz), 161.4 (d, J=31 Hz), 155.4 (dd, J=23, 18 Hz), 133.6 (d, J=
CHCl
3 30 37 9 2
): m/z calcd for C H O P SiW: 815.11914 [M+H] ; found:
1
1
1
6
2
1 Hz), 133.5 (d, J=12 Hz), 131.0 (d, J=2 Hz), 130.0 (dd, J=5, 1 Hz),
28.4 (d, J=10 Hz), 128.3 (s), 128.3 (dd, J=166, 9 Hz), 126.6 (d, J=
Hz), 124.8 (s), 118.8 (brm), 118.6 (brm), 63.8 (d, J=6 Hz), 63.5 (d, J=
8
15.11893.
Reaction of 1 with ketone 2 f: Compound 1 (0.31 g, 0.54 mmol, 1 equiv)
was dissolved in THF (25 mL) and cooled to ꢀ208C. A solution of LDA
Hz), 15.9 (d, J=8 Hz), 15.7 ppm (d, J=7 Hz); IR (CH
306, 1940, 1712, 1600, 1193, 1049 cm ; HRMS (solution in ACN/
2
Cl
2
): n˜ =3618,
(
0.27 mL, 0.54 mmol, 1 equiv, 2m in THF/heptanes) was added dropwise
ꢀ
1
to the reaction mixture and stirred for another 20 min. After this time, it
+
CHCl
3 44 18 2 2 2
): m/z calcd for C56H O S P W Na: 1646.92756 [M+Na] ; found:
was cooled to ꢀ788C and a solution of ketone 2 f (0.12 g, 0.54 mmol,
1
646.92837.
1
equiv) in THF (1 mL) was added dropwise. The reaction mixture was
Reaction of 1 and ketones 18 and 19: Compound 1 (1 equiv) was dis-
solved in THF (5–15 mL) and cooled to ꢀ208C. A solution of LDA
stirred for 30 min at the same temperature and subsequently methanol
0.2 mL) was added in one portion and the mixture was allowed to reach
RT. Solvents were removed in vacuo and the residue was chromatograph-
ed on a silica gel column (R =0.3, pentane) to give 6 f (0.36 g, 66%) as a
mixture of two isomers in a 3:2 ratio. NMR data are given for the major
(
(
1 equiv, 2m in THF/heptanes) was added dropwise and the reaction mix-
ture was stirred for 20 min. After cooling to ꢀ788C, a solution of the
ketone (1 equiv) in THF was added dropwise. The reaction mixture was
stirred for 1.5 h at ꢀ508C. For compounds 20 and 22: the reaction mix-
ture was quenched with water (0.5 mL) at ꢀ508C and allowed to warm
to RT. Products were extracted with diethyl ether, washed with brine and
concentrated in vacuo. Crude products were chromatographed by using
f
3
1
31
isomer only (except P NMR). P NMR (161 MHz, C
6
D
6
): d=134.8
1
1
(
JPW =287 Hz; major isomer), 134.3 ppm ( JPW =284 Hz; minor isomer);
1
H NMR (400 MHz, C
Ph), 3.08 (m, 1H; HC), 3.00 (d, JHP =12 Hz, 3H; OCH
1
6
D
6
): d=7.67–7.63 (m, 2H; Ph), 7.11–7.06 (m, 3H;
3
3
3
), 1.27 (dd, JHP
=
3
13
5,
J
HH =7 Hz, 3H; HCCH
): d=198.4 (d, J=27 Hz), 196.6 (d,
Hz), 136.8 (d, J=36 Hz), 131.0 (d, J=2 Hz), 130.4 (d, J=12 Hz), 128.4
3
), 1.10 ppm (brs, 21H; TIPS); C NMR
CH
2
Cl
2
(20%) in pentane as eluent to give 20 (R
f
=0.68) as a white solid
1
1
(
100 MHz, C
6
D
6
J
CW =125,
J
CP
=
and 22 (R
f
=0.8) as a colorless oil. For compounds 21 and 23: the reaction
8
mixture was directly poured onto a silica plug and washed with THF.
After removal of the solvent in vacuo the residue was subjected to
column chromatography by using diethyl ether/pentane (1:1) as eluent
(
(
(
d, J=9 Hz), 105.5 (d, J=1 Hz), 87.7 (d, J=7 Hz), 54.2 (d, J=6 Hz), 34.4
d, J=26 Hz), 19.6 (s), 16.0 (d, J=2 Hz), 11.4 ppm (d, J=1 Hz); HRMS
solution in MeOH): m/z calcd for
C
25
H
33
O
6
PSiWaNa: 695.11910
(R
f
=0.5) to give final products 21 and 23 as white solids.
+
[
M+Na] ; found: 695.11898.
Compound 20: Reaction was performed by using 1 (0.18 g, 0.32 mmol)
3
1
Reaction between 1 and ketone 9: Compound 1 (0.39 g (0.69 mmol,
and 18 (0.1 g, 0.32 mmol) to give 20 (0.11 g, 37%). P NMR (121 MHz,
1
1
1
equiv) was dissolved in THF (25 mL) and cooled to ꢀ208C. A solution
CDCl
3 3
): d=150.0 ppm (ssatellite, JPW =292 Hz); H NMR (300, CDCl ): d=
of LDA (0.35 mL, 0.69 mmol, 1 equiv, 2m in THF/heptanes) was added
dropwise and the reaction mixture was stirred for 20 min at this tempera-
ture. After cooling to ꢀ788C, a solution of ketone 9 (0.27 g, 0.69 mmol,
7.62–7.51 (m, 4H; Ph), 7.47–7.38 (m, 4H; Ph), 7.32–7.28 (m, 2H; Ph),
3
3
2
3
5.72 (dd, JHP =17, JHH =4 Hz, 1H; HC=), 4.26 (dd, JHP =4, JHH =4 Hz,
1
3
3
1H; HCPh), 1.18 ppm (brs, 21H; TIPS); C NMR (75 MHz, CDCl ): d=
1
1
1
equiv) in THF (1 mL) was added dropwise. The reaction mixture was
198.3 (d, J=30 Hz), 194.5 (d, JWC =126, JCP =8 Hz), 142.4 (d, J=6 Hz),
142.0 (d, J=30 Hz), 137.0 (d, J=5 Hz), 130.4 (d, J=2 Hz), 129.4 (d, J=
3 Hz), 129.0 (d, J=5 Hz), 128.7 (d, J=9 Hz), 128.4 (d, J=4 Hz), 126.7 (d,
J=12 Hz), 114.4 (s), 98.2 (s), 96.2 (d, J=5 Hz), 59.9 (d, J=10 Hz), 18.6
(s), 11.2 ppm (s); IR (CH
HRMS (solution in CH CN/CHCl
calcd for C31 PSiWAg: 853.03549 [M+Ag] ; found: 853.03577.
stirred for 30 min at the same temperature and then 2,3-dimethylbuta-
,3-dyene (0.4 mL) was quickly added to the reaction mixture, which was
then allowed to reach RT. All volatile compounds were removed in
vacuo and the residue was chromatographed on a silica gel column (R
1
ꢀ1
Cl
2
): n˜ =2078, 1949, 1603, 1200, 1123 cm
;
f
=
2
3
1
0
.6, pentane) to give 13 (0.22 g, 35%) as a pale-yellow oil. P NMR
3
3
with addition of AgCF COO): m/z
3
1
1
+
(
161 MHz, CDCl
3
): d=9.7 ppm ( JPW =251 Hz); H NMR (400 MHz,
33 6
H O
13702
www.chemeurj.org ꢂ 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2013, 19, 13692 – 13704

Oxaphospholes and Bisphospholes
FULL PAPER
Compound 21: Reaction was carried out by using 1 (0.18 g, 0.32 mmol)
and 18 (0.1 g, 0.32 mmol) to give 21 (84 mg, 30%). P NMR (121 MHz,
11 Hz), 129.1 (d, J=5 Hz), 128.4 (s), 101.9 (s), 101.5 (s), 100.9 (s), 63.4 (d,
3
1
J=5 Hz), 63.3 (d, J=5 Hz), 7.4 (s), 4.4 ppm (s); IR (CH
2
Cl
2
): n˜ =2077,
1
1
III
1
ꢀ1
C
6
D
6
): d=156.0 (d,
J
PW =295,
7 Hz); H NMR (300 MHz, CDCl
.36 (m, 4H; Ph), 7.33–7.28 (m, 2H; Ph), 4.44 (dd, JHP =6, JHP =3 Hz,
H; HCPh), 3.73–3.63 (m, 2H; OCH CH ), 3.56–3.36 (m, 2H;
J
PP =27 Hz; P ), 12.4 ppm (d,
J
PP
=
1946, 1606, 1210, 1048 cm ; HRMS (solution in ACN/CHCl
3
): m/z calcd
1
+
2
7
1
3
): d=7.61–7.48 (m, 4H; Ph), 7.46–
for C43H
51
O
9
P
2
Si
2
W: 1013.20548 [M+H] ; found: 1013.20612.
2
3
3
OCH
2
CH
3
), 1.20 (brs, 21H; TIPS), 1.00 (t, JHH =7 Hz, 3H; OCH
HH =7 Hz, 3H; OCH
d=197.9 (d, J=30 Hz), 194.2 (d,
2
CH
3
),
):
3
13
0
.88 ppm (t,
J
2
CH
3
); C NMR (75 MHz, CDCl
3
1
1
J
CW =124,
J
CP =9 Hz), 148.9 (dd, J=
Acknowledgements
2
1
3
3
1
5, 7 Hz), 141.0 (d, J=29 Hz), 136.1 (d, J=4 Hz), 130.6 (d, J=2 Hz),
29.3 (d, J=3 Hz), 129.1 (d, J=5 Hz), 128.7 (d, J=9 Hz), 128.5 (d, J=
Hz), 126.7 (d, J=12 Hz), 116.1 (d, J=196 Hz), 105.2 (s), 95.1 (dd, J=5,
Hz), 61.9 (d, J=5 Hz), 61.8 (d, J=5 Hz), 61.7 (dd, J=9, 7 Hz), 18.5 (s),
The Swedish Research Council, the Gçran Gustafsson Foundation,
3
COST action CM0802 PhoSciNet, Uppsala University (U MEC molecu-
lar electronics priority initiative), and VU Amsterdam are greatly ac-
knowledged for financial support. A.O. thanks the Austrian Science
Funds (FWF) for an Erwin Schrçdinger fellowship (J3193-N17). Dr.
Marie-Pierre Santoni is acknowledged for solving the crystal structure of
compound 3e.
5.9 (d, J=7 Hz), 15.8 (d, J=7 Hz), 11.2 ppm (s); HRMS (solution in
+
MeOH/CHCl
3
): m/z calcd for C35
H
42
O
9
PSiWNa: 903.14749 [M+H] ;
found: 903.14884.
Compound 22: Reaction was performed by using 1 (0.11 g, 0.2 mmol)
and 19 (0.05 g, 0.2 mmol). Compound 21 (15 mg, ca. 10%) appears to be
unstable upon chromatography and cannot be isolated in pure form.
3
1
1
1
P NMR (121 MHz, CDCl
3
): d=150.1 ppm ( JWP =292 Hz); H NMR
[1] G. Wittig, G. Geissler, Lieb. Annal. Chem. 1953, 580, 44–57.
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(
5
1
300 MHz, CDCl ): d=7.63–7.41 (m, 8H; Ph), 7.31–7.28 (m, 2H; Ph),
3
3
3
2
3
.73 (dd, JHP =17, JHH =4 Hz, 1H; HC=), 4.28 (dd, JHP =4, JHH =4 Hz,
3
H; HCPh), 1.09 (t, JHH =8 Hz, 9H; SiCH
2
CH
3
), 0.91–0.63 ppm (m, 6H;
[3] a) P.-A. Bouit, A. Escande, R. Sz u˝ cs, D. Szieberth, C. Lescop, L.
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6527; b) J. Casado, R. Rꢅau, V. Hernꢄndez, J. T. L. Navarrete, Synth.
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1265; d) T. Sanji, K. Shiraishi, M. Tanaka, Org. Lett. 2007, 9, 3611–
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1
3
SiCH
2
CH
3
); C NMR (75 MHz, CDCl
3
): d=198.2 (d, J=30 Hz), 194.5
1
1
(
d, JCW =126, JCP =8 Hz), 142.5 (d, J=6 Hz), 141.9 (d, J=30 Hz), 137.0
(
d, J=5 Hz), 130.4 (d, J=2 Hz), 129.3 (d, J=3 Hz), 129.0 (d, J=5 Hz),
28.7 (d, J=7 Hz), 128.3 (d, J=4 Hz), 126.6 (d, J=12 Hz), 114.7 (s), 98.9
s), 95.3 (d, J=6 Hz), 59.8 (d, 10 Hz), 7.4 (s), 4.0 ppm (s); HRMS (solu-
tion in ACN/CHCl with addition of AgCF COO): m/z calcd for
PSiWAg: 810.98850 [M+Ag] ; found: 810.98942.
Compound 23: Reaction was performed by using 1 (0.1 g, 0.18 mmol)
1
(
3
3
+
28 27 6
C H O
6
711–6721.
3
1
[4] T. Baumgartner, R. Rꢅau, Chem. Rev. 2006, 106, 4681–4727.
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Wu, R. Rꢅau, J. Am. Chem. Soc. 2006, 128, 983–995.
and 19 (0.05 g, 0.18 mmol) to form 23 (39 mg, 27%). P NMR (121 MHz,
1
III
1
V
CD
2
Cl
2
): d=156.0 (d,
J
PP =27 Hz; P ), 11.7 ppm (d,
Cl
H; Ph), 7.44–7.39 (m, 3H; Ph), 7.33–7.29 (m, 2H; Ph), 4.66 (dd, JHP =6,
J
PP =27 Hz; P );
1
H NMR (300 MHz, CD
2
2
): d=7.64–7.54 (m, 4H; Ph), 7.51–7.48 (m,
[
6] a) A. I. Aranda Perez, T. Biet, S. Graule, T. Agou, C. Lescop, N. R.
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1
3
6
7
3
Hz, 1H; HCPh), 3.74–3.35 (m, 4H; OCH
2
CH
HH =7 Hz, 3H; SiCH
), 0.82–0.73 ppm (m, 6H; SiCH
): d=198.2 (d, J=30 Hz), 194.5 (d, J=8 Hz), 140.9 (d,
J=30 Hz), 136.5 (d, J=6 Hz), 130.9 (d, J=2 Hz), 129.5 (d, J=3 Hz),
3
), 1.10 (t,
J
HH =8 Hz,
3
3
H; OCH
Hz, 3H; SiCH
Cl
2
2
CH
3
), 1.03 (t,
J
2
CH
3
), 0.91 (t,
CH ); C NMR
2 3
J
HH
=
1
3
2
CH
3
[
[
(
75 MHz, CD
2
129.3 (d, J=6 Hz), 129.0 (d, J=9 Hz), 128.7 (d, J=3 Hz), 126.9 (d, J=
12 Hz), 116.9 (d, J=195 Hz), 105.9 (s), 94.5 (dd, J=5, 3 Hz), 61.8 (dd, J=
9, 7 Hz), 62.2 (d, J=5 Hz), 62.1 (d, J=5 Hz), 16.0 (d, J=7 Hz), 15.9 (d,
8] a) T. Baumgartner, T. Neumann, B. Wirges, Angew. Chem. 2004,
1
16, 6323–6328; Angew. Chem. Int. Ed. 2004, 43, 6197–6201; b) W.
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J=7 Hz), 7.34 (s), 4.1 ppm (s); IR (CH
2
Cl
2
): n˜ =2079, 1951, 1605, 1290,
): m/z calcd for
32 37 9 2
C H O P SiW: 839.11859 [M+H] ; found: 839.12016.
ꢀ
1
1
047 cm
;
HRMS (solution in MeOH/CHCl
3
+
[9] a) O. Fadhel, D. Szieberth, V. Deborde, C. Lescop, L. Nyulꢄszi, M.
Hissler, R. Rꢅau, Chem. Eur. J. 2009, 15, 4914–4924; b) S. Graule,
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One-pot reaction of 1 with 19 and 8: Compound 1 (0.1 g, 0.18 mmol) was
dissolved in THF (10 mL) and the solution was cooled to ꢀ788C. After
this, a solution of BuLi (0.1 mL, 1 equiv, 1.6m in hexane) was added
dropwise to the reaction mixture and stirred for 30 min. Subsequently, a
solution of ketone 19 (0.047 g, 0.18 mmol) in THF (1 mL) was added
dropwise and the reaction mixture was stirred for 1 h at ꢀ508C. After
this, a solution of ketone 8 (0.054 g, 0.18 mmol) in THF (1 mL) was
added. The reaction mixture was stirred for 30 min at ꢀ508C and then
warmed to RT within 30 min. The reaction mixture was directly applied
onto a silica gel plug and washed with THF. After removal of solvents in
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3
1
1
1
Cumulene 25: P NMR (161 MHz, CD
2
1
Cl
2
): d=150.5 (d, JPP =43, JPW
97 Hz, P ), 5.8 ppm (d, JPP =43 Hz); H NMR (400, CD Cl
.65 (m, 5H; Ph), 7.40–7.30 (m, 3H; Ph), 7.06–7.04 (m, 2H; Ph), 4.17–
=
III
1
2
7
2
2
): d=7.74–
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3
3
.97 (m, 4H; OCH
HH =7 Hz, 3H; OCH
HH =8 Hz, 9H; SiCH
C NMR (100 MHz, CD
26, JCP =8 Hz), 161.9 (dd, J=17, J=5 Hz), 157.9 (s), 142.9 (s), 142.6 (s),
35.5 (d, J=32 Hz), 133.3 (d, J=2 Hz), 131.5 (dd, J=13, 4 Hz), 130.8 (d,
2
CH
3
), 1.24 (t,
J
HH =7 Hz, 3H; OCH
HH =8 Hz, 9H; SiCH
), 0.72–0.64 ppm (m, 12H; SiCH
2
CH
3
), 1.21 (t,
), 1.03
CH );
3
3
J
2
CH
3
), 1.04 (t,
J
2
CH
3
3
(
t,
J
2
CH
3
2
3
1
3
1
2
Cl
2
): d=197.7 (d, J=30 Hz), 194.6 (d,
J
CW
=
1
1
1
J=16 Hz), 130.2 (d, J=2 Hz), 130.0 (dd, J=178, 6 Hz), 129.6 (d, J=
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