Structural and spectroscopic evidence for the occurrence of gauche- betaine intermediates in the thio Wittig reaction

Article abstract of DOI:10.1002/(SICI)1099-0690(199908)1999:8<1831::AID-EJOC1831>3.0.CO;2-R

Reaction of the ylide (cyclopropyl)₃P=CH₂ with Michler's thioketone S=C(C₆H₄NMe₂)₂ in [D₅]pyridine gave the thio Wittig intermediate [(cyclopropyl)₃P⁺-CH

Full text of DOI:10.1002/(SICI)1099-0690(199908)1999:8<1831::AID-EJOC1831>3.0.CO;2-R

FULL PAPER
Structural and Spectroscopic Evidence for the Occurrence of gauche-Betaine
Intermediates in the Thio Wittig Reaction
Carsten Puke,[a] Gerhard Erker,*[a] Birgit Wibbeling,[°] and Roland Fröhlich[°]
Keywords: Ylides / Wittig olefination / Reaction mechanism / Phosphorus-carbon coupling constants / Substituent
perturbation
Reaction of the ylide (cyclopropyl)3P=CH2 with Michler’s
thioketone S=C(C6H4NMe2)2 in [D5]pyridine gave the thio
Wittig intermediate [(cyclopropyl)3P+–CH2–CAr2–S–] (11; 31P
NMR: δ = +27.7). Compound 11 was characterized by X-ray
diffraction and shown to exhibit a gauche-betaine-type
structure with an S–C–C–P dihedral angle of 52.9(3)° and a
3Ј) or bis(p-methoxyphenyl) thioketone (to give 5),
respectively. The oxaphosphetane series 3Јa–3Јc shows a
strong response of the 1JPCipso(aryl) values (3a: 94 Hz; 3Јb: 74
Hz; 3Јc: 47 Hz) to this substituent perturbation, as it is
expected for a dynamic trigonal-bipyramidal situation at the
phosphorus atom, whereas the thio Wittig intermediate is
only very little affected [1JPCipso(aryl) of 5a: 92 Hz; 5b: 86 Hz;
5c: 82 Hz]. Thus, the thio Wittig intermediates 5 seem to
˚
P···S separation of 3.312(2) A. The characteristic averaged
1JPCipso(aryl) coupling constant was used to elucidate the
characteristic structural properties of Wittig and thio Wittig
intermediates derived by treatment of the series Ph3P=CH2
(2a), Ph2MeP=CH2 (2b), and PhMe2P=CH2 (2c) with bis(p-
methoxyphenyl) ketone to give 3 or benzophenone (to give
exhibit
a pronounced phosphonium character in polar
solvents and may be regarded as thiabetaine-type
intermediates in solution.
is characterized by a 31P-NMR resonance at a strongly
Introduction
1
negative δ value of Ϫ40 with coupling constants JCC
ϭ
1
The Wittig olefination reaction is among the most im- 37 Hz and JPC ϭ 93 Hz (the corresponding 31P-NMR res-
portant preparative methods for selectively forming new onance of the analogous oxaphosphetane Wittig intermedi-
carbonϪcarbon bonds in organic synthesis.[1] Its detailed ate 3Јa is at δ ϭ Ϫ68). At 253 K the intermediate 5Јa de-
mechanism had been a matter of controversy for some time, composed to give the thiirane 6Ј and triphenylphosphane.
but now it seems to be clear that oxaphosphetanes are the At 273 K these products again disappear from the solution
essential reaction intermediates,[2] and that their betaine to eventually yield the final thio Wittig products CH2ϭ
isomers are probably not involved at all in Wittig olefi- CPh2 (8Ј) and Ph3PS (7).[6] The observed spectroscopic fea-
nation reactions of nonstabilized ylides under the typical tures of the intermediate 5Ј are strongly solvent-depen-
salt-free conditions.[3]
dent.[7] Successive addition of several portions of [D2]di-
Thermodynamic features make the thio Wittig reaction chloromethane to the solution of 5Ј in [D8]toluene resulted
somewhat different. The phosphorusϪsulfur bond is in a continuous shifting of the 31P-NMR resonance from a
weaker than the phosphorusϪoxygen linkage, and this potential thiaphosphetane range (δ ϭ Ϫ40) to a limiting
should make a thiaphosphetane formation less favorable value in the phosphonium range (δ ϭ ϩ1 in pure CD2Cl2,
1
1
than the formation of the oxaphosphetane Wittig inter- with coupling constants JCC ϭ 38 Hz, JPC ϭ 82 Hz).
mediates. Thus, if betaines play any role in Wittig chemistry, The model reaction Me3PϭCH2 ϩ SϭCMe2 was recently
they should have a chance to be detected in the reactions studied by an ab initio calculation.[7] A gauche-betaine (9),
between phosphorus ylides and thiocarbonyl compounds. similar to the proposed species 5 in solution, was shown to
Wittig reactions of thioketones and thioaldehydes have be the essential intermediate of this reaction. Eventually we
been shown to take a kinetically different course than their succeeded in isolating a reasonably stable example of such
ordinary ketone or aldehyde analogues in that episulfide a gauche-betaine thio Wittig addition product. CϪC coup-
formation can often be observed.[4] We have recently stud- ling of the ylide (C2H5)3PϭCHCH3 with the stabilized
ied a representative example of a thio Wittig reaction in thioketone SϭC(C6H4OCH3)2 gave 10. Its X-ray crystal
some detail, namely the reaction of the ylide Ph3PϭCH2 structure analysis has for the first time to our knowledge
with thiobenzophenone.[5] At 233 K in [D8]toluene an inter- characterized a gauche-betaine structure of a Wittig olefin-
mediate (5Јa) (”primed” numbers are used throughout this ation intermediate.[7]
paper for the phenyl derivatives, ”unprimed” numbers for
The question has remained of whether the solid-state
the p-MeOC6H4- or p-Me2NC6H4 analogues) is formed that structure of the gauche-betaine 10 represents a rarely enco-
untered or even unique example of such a species or if this
[a]
type of dipolar structures is rather common in thio Wittig
chemistry. It also had to be resolved whether the solution
structure of the [R3PϪCH2ϪCAr2ϪS] intermediates in a
polar solvent resembled the observed solid-state structure.
Organisch-Chemisches Institut der Universität Münster,
Corrensstraße 40, D-48149 Münster, Germany
Fax: (internat.) ϩ 49(0)251/833-6503
E-mail: erker@uni-muenster.de
[°] X-ray crystal structure analysis.
Eur. J. Org. Chem. 1999, 1831Ϫ1841
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ193X/99/0808Ϫ1831 $ 17.50ϩ.50/0
1831

C. Puke, G. Erker, B. Wibbeling, R. Fröhlich
FULL PAPER
at the phosphorus atom [CH2(cis/trans) at δ ϭ 1.00/0.75;
CH at δ ϭ 1.92]. The corresponding 13C-NMR signals oc-
cur at δ ϭ 4.2 (2JPC ϭ 4.8 Hz) and δ ϭ 4.0 (1JPC ϭ 88 Hz),
and are characterized by their typical JPC coupling con-
stants.[11] The newly formed carbonϪcarbon single bond is
1
characterized by H/13C-NMR CH2 resonances at δ ϭ 3.89
(2JPH ϭ 10 Hz)/δ ϭ 46.4 (1JPC ϭ 72 Hz) and a quaternary
2
carbon signal at δ ϭ 50.8 with a JPC coupling constant of
1.8 Hz (CAr2). In [D5]pyridine the 31P-NMR resonance of
11 is in the typical phosphonium range at δ ϭ ϩ27.7.
The thus prepared solution of 11 in [D5]pyridine was
oversaturated. Keeping it for ca. 2 h at 300 K resulted in
the formation of single crystals of 11 that were suited for
X-ray diffraction. The crystals of 11 contained one mol-
ecule of pyridine in the unit cell. The X-ray crystal structure
analysis showed again that a gauche-betaine had resulted
from the addition of an ylide (here 2g) to a diaryl thioke-
tone (here 4d) (Figure 1). The newly formed carbonϪcar-
bon bond is in the expected range of a C(sp3)ϪC(sp3) single
Scheme 1. Reaction paths followed in Wittig and thio Wittig reac-
tions
In this article we present a second example of a thio Wittig
gauche-betaine structure that was characterized by X-ray
diffraction, and we will discuss a substituent-perturbation
NMR study that characterizes the coordination geometry
at the phosphorus atom and thus allows to better assess the
structural features of the essential betaine-type intermediate
of these thio Wittig reactions in solution in a polar solvent.
˚
bond at 1.557(4) A (C2ϪC3). The adjacent C3ϪP4
˚
˚
[1.806(3) A] and S1ϪC2 [1.841(3) A] bonds are also in the
respective single-bond ranges.[12] The central core of atoms
is clearly nonplanar. The S1ϪC2ϪC3ϪP4 dihedral angle
was found at θ ϭ 52.9(3)°, and the S1···P4 separation is very
˚
large at 3.312(2) A. Both these values are even increased
as compared to the previously described first example of a
gauche-betaine structure[7] (10; see above and Scheme 1).
They even exceed the reported respective values [S···P 3.247
Results and Discussion
X-ray Crystal-Structure Analysis of an
˚
A; θ(SCCP) ϭ 40.9°] of the stabilized betaine 13 that was
R3P؉؊CH2؊CAr2S؊ Example
previously obtained upon treatment of the ylide Ph3Pϭ
To our knowledge, I. V. Borisova et al.[8] have first pro- CMe2 with carbon disulfide.[13]
posed the formation of a betaine-type intermediate in the
In both structures, the bond angles at the central carbon
reaction of ”thio MichlerЈs ketone” [SϭC(p-Me2NϪC6H4)2 atoms C2 and C3 are far away from 90° {11: C2ϪC3ϪP4:
(4d)] with the ylide (C2H5)3PϭCHCH3 based upon the ob- 117.6(2)° [10: 113.0(4)°], S1ϪC2ϪC3: 107.6(2)° [10:
served 31P-NMR resonance at a positive δ value of ϩ25 (in 105.9(4)°]}. The phosphonium character of the
[D5]pyridine). The closely related gauche-betaine 10, that we C3ϪP(C5,C8,C11) unit (see Figure 1) also becomes evident
have prepared and characterized by X-ray diffraction (see upon inspection of the respective bond angles around the
above),[7] shows a 31P-NMR resonance at δ ϭ ϩ28 (1JPC ϭ phosphorus atom P4 of the adduct 11. Two of the bond
3
4Ar2
71 Hz, JPC ϭ 0 and 14 Hz) in [D5]pyridine.
angles involving the C3ϪP4 linkage are very close to tetra-
We have now treated the ylide (cyclopropyl)3PϭCH2, hedral [C3ϪP4ϪC5: 108.5(2)°, C3ϪP4ϪC11: 107.7(2)°]
prepared by the procedure described by Schmidbaur et whereas one is slightly larger [C3ϪP4ϪC8: 115.9(2)°]. The
al.,[9] with SϭC(p-Me2NC6H4)2.[10] In [D5]pyridine solution corresponding bond angles of the related complex 10
a 1:1 mixture of the two reagents rapidly reacted at 300 K amount to 104.1(4)°, 116.4(5)°, and 117.6(3)°. The remain-
to give a single intermediate (11) by ylide addition to the ing three CϪPϪC angles at P4 in 11 again deviate only
thiocarbonyl carbon atom. Although the addition product marginally from tetrahedral [C5ϪP4ϪC8: 108.3(2)°,
is stable at this temperature, warming above ambient tem- C5ϪP4ϪC11: 108.9(2)°, C8ϪP4ϪC11: 107.5(2)°; 10:
perature results in a slow decomposition of 11 with forma- 106.0(4)°, 98.7(6)°, 111.2(5)°].
tion of the olefination product.
These bonding features indicate a pronounced betaine-
At 300 K in [D5]pyridine solution the 1H-NMR spectrum type character of 11. Although the S1···P4 separation is still
of 11 shows three sets of signals of the cyclopropyl groups just within the sum of S and P van der Waals radii (3.6
1832
Eur. J. Org. Chem. 1999, 1831Ϫ1841

Evidence for the Occurrence of gauche-Betaine Intermediates in the Thio Wittig Reaction
FULL PAPER
1
pyramid the JPCipso(aryl) coupling constants of the ipso-
carbon atoms at the aryl substituents adjacent to the phos-
phorus atom are very characteristically dependent on their
position at the phosphorus coordination polyhedron. Ac-
cording to a study carried out by Vedejs and Marth[2][17]
1
on suitable model compounds the JPCipso(aryl) coupling
constant of the apical P-aryl linkage in the trigonal-bipyr-
amidal structure is rather small at values Յ 18 Hz, whereas
1
the corresponding JPCipso(aryl) values of the basal P-aryl
groups are much larger at ca. 130 Hz. In the oxaphosphe-
1
tane 3Јa (R ϭ Ph, see Schemes 2 and 3) a single JPCip-
so(aryl) coupling constant of 94 Hz is observed experimen-
tally. This represents an averaged value of the individual
1
basal and apical JPCipso coupling constants because of a
rapidly proceeding geometric equilibration, probably pro-
ceeding by means of a turnstile mechanism,[18] of the phenyl
positions at the phosphorus atom, that is not frozen out on
the NMR time scale at the conditions of the spectroscopic
Figure 1. View of the molecular structure of the thiabetaine 11
(with unsystematical atom-numbering scheme); selected bond
˚
lengths [A] and angles [°]: S1ϪC2 1.841(3), C2ϪC3 1.557(4),
C2ϪC21 1.535(5), C2ϪC31 1.540(4), C3ϪP4 1.806(3), P4ϪC5
1.773(5), P4ϪC8 1.768(4), P4ϪC11 1.772(4), S1···P4 3.312(1);
S1ϪC2ϪC3 107.6(2), S1ϪC2ϪC21 113.6(2), S1ϪC2ϪC31
109.5(2), C21ϪC2ϪC31 110.8(3), C3ϪC2ϪC21 108.4(2),
C3ϪC2ϪC31 106.6(2), C2ϪC3ϪP4 117.6(2), C3ϪP4ϪC5
108.5(2), C3ϪP4ϪC8 115.9(2), C3ϪP4ϪC11 107.7(2), C5ϪP4ϪC8
108.3(2), C5ϪP4ϪC11 108.9(2), C8ϪP4ϪC11 107.5(2),
S1ϪC2ϪC3ϪP4 52.9(3)
1
measurement. Statistical equilibration of individual JPCip-
so(aryl) values close to those proposed by Vedejs et al. (see
1
1
above), namely JPCipso(aryl apical) ϭ 18 Hz and JPCip-
so(aryl basal) ϭ 133 Hz, would be suited to adequately re-
produce the observed averaged value of 3Јa and the further
examples investigated in this series (3Јb,c, see below).
In CD2Cl2 solution the alleged thiabetaine-type com-
pound 5Јa (Ar ϭ Ph, see Scheme 2) gives rise to an ob-
1
served value of the JPCipso(aryl) coupling constant of
1
92 Hz. This very close similarity between the JPCipso(aryl)
values of the oxaphosphetane 3Јa and the thiabetaine 5Јa
led to the concern that this might indicate the presence of
a pentacoordinate coordination geometry in 5Јa, and thus
might suggest a strong PϪS interaction in solution even
when polar solvents were used.
[14]
˚
A),
the observed coordination geometry at the phos-
phorus atom reveals that there is probably only a very small
(potentially electrostatic) interaction between the negative
sulfur end of the ϪSϪCϪCϪPϩ dipole and the strongly
phosphonium-structured C3ϪP(cyclopropyl)3 unit of 11.
Thus, it appears that compound 11 is to be regarded as a
typical example of a gauche-betaine-type thio Wittig inter-
mediate. Such weakly internally stabilized gauche-betaine
”resting stages” may possibly be more common in this area
of Wittig olefination chemistry than previously thought.
NMR Evidence for the Occurrence of Betaine-Type
Thio Wittig Intermediates in Solution
We were concerned whether analogous gauche-betaine-
type structures of the thio Wittig intermediates occurred in
solution in polar solvents. Could evidence be obtained to
indicate that the coordination geometry of these intermedi-
ates at the phosphorus atom was substantially different
from the trigonal-bipyramidal situation typically encoun-
Scheme 2. Structures of compounds used in the substituent pertur-
bation study
However, it must be pointed out that due to the rapid
tered with the well-established oxaphosphetanes? Monitor- pseudo-rotational equilibration that leads to averaging of
1
1
ing the JPC coupling constants is a powerful tool for the extremely different JPCipso(aryl basal/apical) coupling
characterizing the structural features of the Wittig inter- constants, a differentation between pentacoordinate trig-
mediates at the phosphorus atom. From a combination of onal-bipyramidal and tetracoordinate tetrahedral geo-
X-ray crystallography[15] and NMR-spectroscopic stu- metries at the phosphorus atom by means of the observed
dies[16] it is well known that the oxaphosphetane intermedi- coupling constants is not possible in the Ph3P-derived cases:
ates contain a trigonal-bipyramidal phosphorus atom with Both situations would provide very similar averaged
the oxygen atom in the apical position. In the trigonal bi- 1JPCipso(aryl) values, as is actually found for the 3Јa/5Јa pair
Eur. J. Org. Chem. 1999, 1831Ϫ1841
1833

C. Puke, G. Erker, B. Wibbeling, R. Fröhlich
1
FULL PAPER
of compounds. It is evident from this analysis that a clear the turnstile-averaged JPCipso(aryl) coupling constant: It is
differentiation should occur if one or two of the aryl sub- reduced from 94 Hz in 3Јa consecutively to 74 Hz (in 3Јb)
stituents at the phosphorus atom were replaced by alkyl and 47 Hz (in 3Јc). An analogous trend is observed in the
groups. Such a substituent perturbation should lead to p-methoxyphenyl series 3(b,c) (see Experimental Section).
1
1
clearly different expected averaged JPCipso(aryl) coupling Thus, a continuous reduction of the averaged JPCipso(aryl)
constants for the two extreme geometric coordinative situ- coupling constant is a direct consequence of the structural
ations at the phosphorus center, the trigonal-bipyramidal and dynamic features of the trigonal-bipyramidal geometry
or the tetrahedral one. We, therefore, have prepared several of the pentacoordinate phosphorus atom in the oxaphos-
series of ”alkyl-perturbed” analogues[19] of 3a and 5a and phetanes, and this alkyl-perturbation effect may therefore
compared the response of the respective 1JPCipso(aryl) values be used as an analytical indicator of the structural situation
on the number of alkyl groups introduced. This has led to specifically encountered here.
a rather clear structural distinction between the compounds
The response of the thio Wittig intermediate 5 to the sub-
3 and 5 in solution.
stituent perturbation at the phosphorus atom is quite differ-
Treatment of Ph2PCl with methyllithium followed by ent. Introducing one or two methyl groups has only a very
1
electrophilic methylation and treatment with base furnished small effect on the observed JPCipso(aryl) coupling con-
the ylide Ph2MePϭCH2 (2b). Its reaction with bis(p-meth- stant. For 5a we observe a value of 92 Hz, for 5b and 5c
oxyphenyl) ketone or benzophenone gave the oxaphosphe- this value is only slightly smaller at 86 Hz and 82 Hz,
tanes 3b and 3Јb, respectively; treatment of 2b with bis(p- respectively. A comparison with the respective 1JPCipso(aryl)
methoxyphenyl) thioketone generated 5b. The ylide values of the corresponding phosphonium salts (1) or phos-
PhMe2PϭCH2 (2c) was prepared analogously starting from phorus ylides (2, see Table 1; for a comparison of additional
PhPCl2. Subsequent treatment with OϭCAr2 or SϭCAr2 selected NMR-spectroscopic features of these series of com-
gave 3c, 3Јc, or 5c, respectively.
pounds, see Tables 2 and 3) indicates that the phosphorus
1
The observed JPCipso(aryl) coupling constants of the center in compounds 5 seems to exhibit a behavior as it is
oxaphosphetane 3Јb is 74 Hz. This is the expected basal/ grossly expected for a close to tetracoordinated tetrahedral
apical averaged value using the VedejsЈ values of 1JPCipso(ba- geometry. Two additional series of related ”alkyl-per-
1
sal) ഠ 133 Hz and JPCipso(apical) ഠ 18 Hz (see above).[17] turbed” oxaphosphetanes and thiabetaines were prepared
Apparently, a dynamic structural situation is found for 3Јb introducing cyclopropyl (3Ј/5e؊g) or ethyl substituents (3/
where one of the phenyl groups is predominately oriented 5h؊k) at the phosphorus atom. In the 3/5h systems the
in the apical position trans to the oxaphosphetane oxygen NMR resonances of a pair of diastereotopic aryl substitu-
1
atom. The observed JPCipso(aryl) coupling constant of the ents are observed at the phosphorus atom even under the
oxaphosphetane 3Јc is much smaller at 47 Hz. Assuming here encountered nonstatic conditions due to the chirality
the same individual 1JPCipso(aryl) coupling constants for ba- center at the adjacent carbon atom C3.
1
sal and apical phenyl substituents at the phosphorus atom
Their JPCipso(aryl) response is analogous as it was ob-
as above, namely 133 Hz and 18 Hz, this would indicate a served in the (3)3Ј/5a؊c series described above. Thus, it
dynamic equilibration of the two major pseudorotamers seems that the structures of the thio Wittig intermediates 5
3Јc-A and 3Јc-B (see Scheme 2) in a 3:1 equilibrium ratio. in solution are markedly different from those of the oxa-
Thus, perturbing the substituent pattern at the phosphorus phosphetane intermediates 3 of the parent Wittig olefin-
atom in the oxaphosphetanes 3Ј by formally exchanging ation reaction, here starting from an ordinary diaryl ketone.
phenyl for methyl groups has a very pronounced effect on The response of the relevant structural indicator
1
Table 1. Comparison of 31P-NMR chemical shifts and J(PCipso)(aryl) coupling constants of 3, 5, 1 and 2
Oxaphosphetane 3 (3Ј)[a]
δ31P[c] 1JPCipso(aryl)[i] δ31P[e]
Thiabetaine 5
1JPCipso(aryl)[i]
Phosphonium salt 1
δ31P[f] 1JPCipso(aryl)[i] δ31P[g]
Ylide 2
1JPCipso(aryl)[i]
R3P
Compd.
Ph3P
a
b
c
d
e
(Ϫ68)
(Ϫ76)
(Ϫ85)
(Ϫ88)
(Ϫ67)
(94)
(76)
(47)
Ϫ
5[d]/Ϫ40[b,l] 92[b,k]
22
20
21
23
30
88
89
88
Ϫ
21
11
4
85
78
66
Ϫ
MePh2P
Me2PhP
Me3P
2
86
82
Ϫ
9
11
14
Ϫ3
26
(cyclopro-
pyl)Ph2P
(cyclopro-
pyl)2PhP
(cyclopropyl)3P
EtPh2P
Et2PhP
Et3P
(71)
86
89
88
f
(Ϫ70)
(33)
17
101
36
89
31
90
g
h
i
k
l
Ϫ69
Ϫ63
Ϫ65
Ϫ66
(Ϫ61)
Ϫ
33
14
25
Ϫ
43
33
37
Ϫ
36
16
18
Ϫ
47/89
68/88
82
74
24
77
80
65
Ϫ
27
Ϫ
41
Ϫ
18
Ϫ
[h]
[h]
[h]
[h]
[h]
[h]
Ph3P
(94)
[a]
[b]
[c]
3: Derived from (p-CH3OC6H4)2CO; 3Ј derived from Ph2CO (in parentheses). Ϫ
Values for 5Јa, derived from Ph2CS. Ϫ
In
[d]
[e]
[f]
[g]
[h]
[i] 1
[D8]THF. Ϫ In CD2Cl2. Ϫ In [D5]pyridine. Ϫ In CDCl3. Ϫ In [D6]benzene. Ϫ Not determined. Ϫ
structures see Scheme 3. Ϫ Broad signal. Ϫ In [D8]toluene.
J
PCipso
(aryl) in Hz, for
[k]
[l]
1834
Eur. J. Org. Chem. 1999, 1831Ϫ1841

Evidence for the Occurrence of gauche-Betaine Intermediates in the Thio Wittig Reaction
1JPCipso(aryl) points to a pronounced phosphonium charac-
FULL PAPER
Experimental Section
ter of the thio Wittig intermediates 5 under the applied con-
ditions. In view of the structural results obtained for two
representative examples in the solid state by X-ray diffrac-
tion, these NMR observations make it likely that gauche-
General Remarks: All reactions involving air-sensitive compounds
were carried out under argon in a glove box or using Schlenk-type
glassware. Solvents (including deuterated solvents) were dried and
distilled under argon prior to use (THF: sodium/potassium alloy;
thiabetaines may also be the favored structural types of the [D5]pyridine, [D2]dichloromethane: calciumhydride). Trimeth-
ylphosphane, the chlorophosphanes, cyclopropyl bromide, 1.6 
methyllithium solution in diethyl ether and 4,4Ј-dimethoxybenzo-
phenone were purchased from commercial sources. Cyclopro-
thio Wittig intermediates in solution in sufficiently polar
solvents.
pyllithium,[20]
the
phosphanes,[21Ϫ25]
the
phosphonium
salts,[22,26Ϫ29] the ylides[29Ϫ35] and the thioketone[36] were prepared
according to literature procedures. NMR experiments were per-
formed with a Bruker AC 200 P FT-NMR spectrometer (1H:
200.1 MHz; 31P: 81.0 MHz; 13C: 50.3 MHz), a Bruker AM 360
spectrometer (1H: 360.1 MHz; 13C: 90.6 MHz) and with a Varian
Unity Plus 600 spectrometer (1H: 599.9 MHz; 31P: 242.9 MHz; 13C:
1
150.8 MHz). The assignments in the H- and 13C-NMR spectra of
selected examples were confirmed through GCOSY, GHSQC, and
GHMBC spectra[37] (atom-numbering scheme used as depicted in
Scheme 3). IR spectra were acquired with a Nicolet 5 DXC Fourier
transform IR spectrometer. Melting points were obtained by
differential scanning calorimetry (DSC 2010, TA Instruments); el-
emental analyses were determined with a Foss-Heraeus CHN-rapid
elemental analyzer.
Scheme 3. Structures of the compounds listed in Tables 1Ϫ3
Table 2. Selected 13C-NMR data of 3 and 5
Oxaphosphetane 3/3Ј[a]
Thiabetaine 5[f]
[c]
[c]
R3P
Compd.[b] δ(Cipso
)
δC-3 1J(PC-3)[d] δ(C4Ar2)[e] 3J(PC4Ar2)[d,e] Compd. δ(Cipso
)
δC-3 1J(PC-3)[d] δ(C4Ar2)[e] 3J(PC4Ar2)[d,e]
Ph3P
3Јa
143
66
87
151
6.9
5Јa
5a
5b
5c
133[g]
127[h]
130
65
52
52
51
49
52
93
82
79
74
75
78
152
144
147
147
147
147
8.6
7.4
8.3
8.9
8.3
8.4
MePh2P
Me2PhP
Me3P
3Јb
3Јc
3Јd
148
152
Ϫ
68
67
65
65
87
90
89
90
152
152
153
151
6.9
6.9
8.2
6.9
129
5d
5e
Ϫ
127
(cyclopro- 3Јe
pyl)Ph2P
148
(cyclopro- 3Јf
pyl)2PhP
154
67
59
97
94
151
144
6.9
6.9
5f
129[h]
49
46
81
72
147
148
8.2
9.1
(cyclopro- 3g
pyl)3P
Ϫ
5g
Ϫ
EtPh2P
Et2PhP
Et3P
3h
3i
3k
3Јl
149/144
149
Ϫ
143
68
69
64
70
93
95
90
89
145/140 9.0/4.9
145/140 6.9/5.6
146/141 6.9/6.4
151/146 12.5/2.8
5h
5i
10
124/122[h] 58
126
Ϫ
72
67
68
147/143 1.0/14.0
148/144 0/13.7
148/144 0/12.9
53
49
Ph3P
[a]
[b]
[c]
[d]
In [D8]THF. Ϫ
3ЈaϪf and l derived from Ph2CO, 3gϪk from (p-CH3OC6H4)2CO. Ϫ P(Ar)-ipso-C. Ϫ
Coupling constants in
[h]
[e]
3
[f]
[g]
Hz. Ϫ ipso-C of the aryl groups at C-4, chemical shift and J(PC) coupling constant. Ϫ In [D5]pyridine. Ϫ In [D8]toluene. Ϫ
In CD2Cl2.
Table 3. Selected 13C-NMR data of 1 and 2 for comparison
Phosphonium salt 1[a]
Ylide 2[d]
1JPCalkyl
δ(Cipso
)
δCϭP
1J(PϭC)
[b]
[c]
[b]
[c]
R3P
Compd.
δ(Cipso
)
δCalkyl
Ph3P
a
b
c
118
119
120
Ϫ
11
10
11
8
57
58
56
56
135
137
140
Ϫ
Ϫ4
Ϫ5
100
97
MePh2P
Me2PhP
Me3P
Ϫ6
96
[e]
[e]
d
(cyclopropyl)Ph2P
(cyclopropyl)2PhP
(cyclopropyl)3P
e
f
g
119
119
Ϫ
10
7
3
58
59
61
136
135
Ϫ
Ϫ15
Ϫ23
Ϫ14
109
112
114
EtPh2P
Et2PhP
Et3P
h
i
k
117
116
Ϫ
15
13
12
50
50
49
135
135
Ϫ
Ϫ2
117
Ϫ7
117
[e]
[e]
[a]
[b]
[c]
[d]
[e]
In CDCl3. Ϫ P(Ar)-ipso-C. Ϫ Coupling constants in Hz. Ϫ In [D6]benzene. Ϫ Not determined.
Eur. J. Org. Chem. 1999, 1831Ϫ1841
1835

C. Puke, G. Erker, B. Wibbeling, R. Fröhlich
FULL PAPER
1
Dicyclopropyl(phenyl)phosphane: Treatment of 70 mL (64.4 mmol)
of a 0.92  solution of cyclopropyllithium in diethyl ether with
4.0 g (3.0 mL, 22.1 mmol) of dichloro(phenyl)phosphane in 20 mL
of diethyl ether yielded 3.2 g (76%) of dicyclopropyl(phenyl)phos-
phane. Ϫ 1H NMR (200.1 MHz, 300 K, [D6]benzene): δ ϭ 7.72 (m,
yellow liquid. Ϫ H NMR (200.1 MHz, 300 K, [D6]benzene): δ ϭ
7.91 (m, 2 H, o-H, Ph), 7.16 (m, 3 H, p-, m-H, Ph), 0.78 (m, 4 H,
CH2), 0.62 (m, 2 H, PCH), 0.43 (m, 4 H, CH2), Ϫ0.59 (d, 2 H, Pϭ
CH2, JPH ϭ 9.1 Hz). Ϫ 13C NMR (50.3 MHz, 300 K, [D6]ben-
zene): δ ϭ 135.3 (d, i-C, JPC ϭ 90.1 Hz), 131.4 (d, p-C, JPC
2
1
4
ϭ
2
3
2 H, m-H, Ph), 7.23 (m, 3 H, p-, o-H, Ph), 0.83 (m, 2 H, PCH), 2.4 Hz), 130.7 (d, o-C, JPC ϭ 7.9 Hz), 128.3 (d, m-C, JPC
ϭ
0.64 (m, 8 H, CH2). Ϫ 13C NMR (50.3 MHz, 300 K, [D6]benzene):
11.0 Hz), 7.4 (d, CH, 1JPC ϭ 83.6 Hz), 1.8 (d, CH2, 2JPC ϭ 3.1 Hz),
δ ϭ 142.2 (d, i-C, 1JPC ϭ 10.7 Hz), 131.5 (d, o-C, JPC ϭ 15.3 Hz), 1.3 (d, CH2, JPC ϭ 3.1 Hz), Ϫ21.8 (d, PϭCH2, JPC ϭ 112.9 Hz).
2
2
1
3
4
128.4 (d, m-C, JPC ϭ 5.4 Hz), 128.0 (s, p-C, JPC ϭ 0 Hz), 7.9 (d,
Ϫ
31P NMR (81.0 MHz, 300 K, [D6]benzene): δ ϭ 31.4. Ϫ IR
1
2
PCH, JPC ϭ 4.1 Hz), 4.1 (d, CH2, JPC ϭ 11.6 Hz), 3.9 (d, CH2,
2JPC ϭ 12.4 Hz). Ϫ 31P NMR (81.0 MHz, 300 K, [D6]benzene):
δ ϭ 10.3.
(KBr): ν˜ ϭ 3091, 3004, 1499, 1438, 1302, 1177, 1037, 949, 899, 749,
696 cmϪ1. Ϫ M.p. 8°C.
(Ethyl)(ethylidene)diphenylphosphorane (2h): 4.7 mL (7.52 mmol) of
a 1.6  BuLi solution in hexane was slowly added to a suspension
of 2.50 g (7.73 mmol) of diethyldiphenylphosphonium bromide in
10 mL of THF at 0°C. After 30 min, the reaction was complete.
The solvent was removed in vacuo and the ylide was purified by
vacuum transfer to give 1.65 g (90%) of a red, highly viscous liquid.
(Cyclopropyl)(methyl)diphenylphosphonium Iodide (1e): Treatment
of 3.4 g (15.2 mmol) of (cyclopropyl)diphenylphosphane with 2.2 g
(1.1 mL, 15.5 mmol) of methyl iodide in 20 mL of diethyl ether for
2 d at room temperature yielded 5.3 g (95%) of the phosphonium
1
salt. Ϫ H NMR (360.1 MHz, 303 K, CDCl3): δ ϭ 7.83 (m, 4 H,
1
Ϫ H NMR (200.1 MHz, 300 K, [D6]benzene): δ ϭ 7.64 (m, 4 H,
o-H, Ph), 7.73 (m, 2 H, p-H, Ph), 7.63 (m, 4 H, m-H, Ph), 2.70 (d,
2
o-H, Ph2P), 7.08 (m, 6 H, m-, p-H, Ph2P), 2.05 (dd, 3 H, PCHCH3,
3 H, PCH3, JPH ϭ 13.3 Hz), 2.40 (m, 1 H, PCH), 1.48, 0.81 (m,
3
2
3JPH ϭ 18.8 Hz, JHH ϭ 6.7 Hz), 1.92 (dq, 2 H, CH2CH3, JPH
ϭ
each 2 H, CH2). Ϫ 13C NMR (50.3 MHz, 300 K, CDCl3): δ ϭ
3
3
2
134.7 (d, p-C, 4JPC ϭ 3.3 Hz), 132.7 (d, o-C, JPC ϭ 9.9 Hz), 130.0
11.9 Hz, JHH ϭ 7.5 Hz), 1.00 (dt, 3 H, CH2CH3, JPH ϭ 17.0 Hz,
3JHH ϭ 7.5 Hz), 0.67 (dq, 2 H, PϭCHCH3, JPH ϭ 13.6 Hz,
2
3
1
(d, m-C, JPC ϭ 13.2 Hz), 118.6 (d, i-C, JPC ϭ 89.1 Hz), 9.5 (d,
3JHH ϭ 6.7 Hz). Ϫ 13C NMR (50.3 MHz, 300 K, [D6]benzene): δ ϭ
134.6 (d, i-C, Ph2P, 1JPC ϭ 74.2 Hz), 132.3 (d, o-C, 2JPC ϭ 9.9 Hz),
1
2
CH3, JPC ϭ 57.7 Hz), 4.9 (d, CH2, JPC ϭ 5.0 Hz), 1.8 (d, PCH,
1JPC ϭ 85.8 Hz). Ϫ 31P NMR (81.0 MHz, 300 K, CDCl3): δ ϭ
29.5. Ϫ IR (KBr): ν˜ ϭ 3012, 2975, 2934, 2881, 1586, 1484, 1436,
1328, 1196, 1170, 1117, 894, 755, 755, 663 cmϪ1. Ϫ C13H18PI
(368.20): calcd. C 52.19, H 4.93; found C 52.09, H 4.92. Ϫ M.p.
154°C.
4
3
130.3 (d, p-C, JPC ϭ 3.3 Hz), 128.6 (d, m-C, JPC ϭ 9.9 Hz), 19.9
(d, PCH2, JPC ϭ 64.3 Hz), 10.7 (d, PCHCH3, 2JPC ϭ 5.0 Hz), 7.0
1
(d, PCH2CH3, 2JPC ϭ 3.3 Hz), Ϫ1.8 (d, PϭCH, 1JPC ϭ 117.1 Hz).
Ϫ
31P NMR (81.0 MHz, 300 K, [D6]benzene): δ ϭ 16.2. Ϫ IR
(KBr): ν˜ ϭ 3067, 2980, 2926, 2894, 2829, 1451, 1440, 1180, 1105,
830, 753, 696 cmϪ1
Dicyclopropyl(methyl)(phenyl)phosphonium Iodide (1f): Treatment
of 3.3 g of (17.2 mmol) dicyclopropyl(phenyl)phosphane with 2.9 g
(1.3 mL, 20.6 mmol) of methyl iodide in 20 mL of diethyl ether for
2 d at room temperature yielded 5.3 g (93%) of the phosphonium
.
Diethyl(ethylidene)(phenyl)phosphorane (2i): 4.2 mL (6.72 mmol) of
a 1.6  BuLi solution in hexane was slowly added to a suspension
of 2.00 g (7.27 mmol) of triethyl(phenyl)phosphonium bromide in
10 mL of THF at 0°C. After 30 min, the reaction was complete.
The solvent was removed in vacuo and the phosphorane was puri-
fied by vacuum transfer to give 1.29 g (97%) of a light red viscous
liquid. Ϫ 1H NMR (360.1 MHz, 303 K, [D6]benzene): δ ϭ 7.67 (m,
1
salt. Ϫ H NMR (200.1 MHz, 300 K, CDCl3): δ ϭ 7.94 (m, 2 H,
2
o-H, Ph), 7.62 (m, 3 H, p-, m-H, Ph), 2.27 (d, 3 H, PCH3, JPH
ϭ
13.2 Hz), 1.82 (m, 2 H, PCH), 1.32 (m, 4 H, CH2), 1.02 (m, 4 H,
CH2). Ϫ 13C NMR (50.3 MHz, 300 K, CDCl3): δ ϭ 134.6 (d, p-C,
2
4JPC ϭ 3.3 Hz), 132.2 (d, o-C, JPC ϭ 9.1 Hz), 130.0 (d, m-C,
2 H, o-H, PhP), 7.19 (m, 3 H, m, p-H, PhP), 2.09 (br. s, 3 H,
3JPC ϭ 12.4 Hz), 118.6 (d, i-C, 1JPC ϭ 89.1 Hz), 7.4 (d, CH3, 1JPC ϭ
59.4 Hz), 4.8 (d, CH2, 2JPC ϭ 5.0 Hz), 4.4 (d, CH2, 2JPC ϭ 5.0 Hz),
3
PCHCH3, JPH
,
3JHH not resolved), 1.55 (br. s, 4 H, PCH2CH3,
2JPH
,
3JHH not resolved), 0.93 (br. s, 6 H, PCH2CH3, JPH
,
3JHH
3
1
1.1 (d, PCH, JPC ϭ 87.4 Hz). Ϫ 31P NMR (81.0 MHz, 300 K,
2
not resolved), 0.36 (br. s, 1 H, PϭCHCH3, JPH
,
3JHH not re-
CDCl3): δ ϭ 35.7. Ϫ IR (KBr): ν˜ ϭ 3070, 2969, 2939, 2882, 1440,
1315, 1192, 1117, 1047, 913, 821, 757, 696 cmϪ1. Ϫ C13H18PI
(332.16): calcd. C 47.01, H 5.46; found C 47.03, H 5.45. Ϫ M.p.
119°C.
solved). Ϫ 13C NMR (90.6 MHz, 303 K, [D6]benzene): δ ϭ 135.4
1
2
(d, i-C, JPC ϭ 65.2 Hz), 132.0 (d, o-C, JPC ϭ 8.4 Hz), 130.3 (d,
p-C, 4JPC ϭ 3.2 Hz), 128.5 (d, m-C, 3JPC ϭ 10.5 Hz), 19.6 (d, PCH2,
1JPC ϭ 58.9 Hz), 10.7 (br. s, PCHCH3, JPC not resolved), 7.0 (br.
2
2
1
(Cyclopropyl)(methylene)diphenylphosphorane (2e): Treatment of
2.24 g (6.08 mmol) of (cyclopropyl)(methyl)diphenylphosphonium
iodide with 0.36 g of KH (8.98 mmol) in 10 mL of THF for 2 h at
room temperature yielded 1.30 g (89%) of the ylide as wax-like
s, PCH2CH3, JPC not resolved), Ϫ6.8 (d, PϭCH, JPC ϭ 116.8).
31P NMR (81.0 MHz, 300 K, [D6]benzene): δ ϭ 17.7. Ϫ IR
(KBr): ν˜ ϭ 2973, 2926, 2908, 2880, 2831, 1458, 1443, 1410, 1388,
1284, 1173, 1101, 1051, 832, 777, 690 cmϪ1
Ϫ
.
1
solid. Ϫ H NMR (200 MHz, 300 K, [D6]benzene): δ ϭ 7.87 (m, 4
Generation of the Wittig and Thio Wittig Intermediates. ؊ General
Description of the NMR Experiments: In a typical NMR experi-
ment the phosphorus ylide was given into a 5-mm NMR tube and
dissolved in ca. 0.2 mL of solvent, fitted with a rubber septum and
kept at Ϫ78°C (Ϫ35°C for pyridine samples) for at least 10 min.
Into this NMR tube the solution of the benzophenone derivative
in ca. 0.4 mL of solvent was injected by syringe. Under these con-
ditions the two phases mixed slowly. The system was allowed to
thermally equilibrate for a period of 10 min before it was quickly
shaken three times outside the cooling bath. Then the in situ
formed Wittig and thio Wittig intermediates were characterized by
H, o-H, Ph), 7.08 (m, 6 H, p-, m-H, Ph), 1.05 (m, 2 H, PCH), 0.92
(m, 4 H, CH2), 0.46 (m, 4 H, CH2), Ϫ0.02 (d, 2 H, PϭCH2, 2JPH ϭ
8.7 Hz). Ϫ 13C NMR (50.3 MHz, 300 K, [D6]benzene): δ ϭ 135.8
2
(d, i-C, 1JPC ϭ 87.5 Hz), 131.9 (d, o-C, JPC ϭ 8.4 Hz), 130.6 (s, p-
4
3
C, JPC ϭ 0 Hz), 128.4 (d, m-C, JPC ϭ 11.7 Hz), 6.6 (d, CH,
1JPC ϭ 78.2 Hz), 1.5 (d, CH2, JPC ϭ 3.0 Hz), Ϫ14.8 (d, PϭCH2,
2
1JPC ϭ 108.9 Hz). Ϫ 31P NMR (81.0 MHz, 300 K, [D6]benzene):
δ ϭ 25.9. Ϫ IR (KBr): ν˜ ϭ 3060, 3007, 1484, 1436, 1294, 1196,
1112, 933, 893, 741, 711 cmϪ1. Ϫ M.p. 45°C.
Dicyclopropyl(methylene)(phenyl)phosphorane (2f): Treatment of
2.55 g (7.68 mmol) of dicyclopropyl(methyl)(phenyl)phosphonium NMR spectroscopy. For the description of the obtained NMR
iodide with 0.46 g (11.47 mmol) of KH in 10 mL of THF for 2 h spectra the atom-numbering schemes as shown in Scheme 3 were
at room temperature yielded 1.45 g (93%) of the ylide as a pale used.
1836
Eur. J. Org. Chem. 1999, 1831Ϫ1841

Evidence for the Occurrence of gauche-Betaine Intermediates in the Thio Wittig Reaction
FULL PAPER
3
P,P,P,4,4-Pentaphenyl-1,2-oxaphosphetane (3Јa): 22 mg (80 µmol)
(d, 4 H, o-H, Ph, JHH ϭ 8.7 Hz), 7.21 (m, 3 H, p-, m-H, PhP),
of (methylene)triphenylphosphorane was treated with 15 mg (82 6.74 (d, 4 H, m-H, Ph, 3JHH ϭ 8.7 Hz), 4.35 (d, 2 H, PCH2, 2JPH ϭ
µmol) of benzophenone in ca. 0.6 mL of [D8]THF at Ϫ78°C. Ϫ 1H
NMR (360.1 MHz, 243 K, [D8]THF): δ ϭ 7.45 (m, 4 H, o-H, Ph),
7.42 (m, 3 H, p-H, Ph3P), 7.37 (m, 6 H, m-H, Ph3P), 7.17 (m, 6 H,
17.4 Hz), 3.68 (s, 6 H, OCH3), 1.76 (d, 6 H, PCH3, 2JPH ϭ 13.1 Hz).
13C NMR (90.6 MHz, 243 K, [D8]THF): δ ϭ 158.4 (p-C, Ph),
Ϫ
1
3
151.8 (d, i-C, PhP, JPC ϭ 47.2 Hz), 144.4 (d, i-C, Ph, JPC
ϭ
2
o-H, Ph3P), 7.11 (m, 4 H, m-H, Ph), 7.01 (m, 2 H, p-H, Ph), 5.23 6.9 Hz), 129.5 (d, o-C, PhP, JPC ϭ 6.9 Hz), 128.4 (d, m-C, PhP,
(d, 2 H, PCH2, JPH ϭ 16.5 Hz). Ϫ 13C NMR (90.6 MHz, 243 K, 3JPC ϭ 8.3 Hz), 128.1 (s, p-C, PhP, JPC ϭ 0 Hz), 127.4 (o-C, Ph),
2
4
[D8]THF): δ ϭ 151.0 (d, i-C, Ph, JPC ϭ 6.9 Hz), 143.4 (d, i-C, 113.3 (m-C, Ph), 69.6 (d, C-4, 2JPC ϭ 13.9 Hz), 67.1 (d, C-3, 1JPC ϭ
3
1
2
1
Ph3P, JPC ϭ 94.3 Hz), 133.2 (d, o-C, Ph3P, JPC ϭ 9.7 Hz), 129.1
88.8 Hz), 55.1 (OCH3), 22.6 (d, PCH3, JPC ϭ 84.6 Hz). Ϫ 31P
4
(s, p-C, Ph3P, JPC ϭ 0 Hz), 128.3 (m-C, Ph), 128.1 (d, m-C, Ph3P, NMR (81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ84.8.
3JPC ϭ 12.5 Hz), 126.5 (o-C, Ph), 126.2 (p-C, Ph), 71.1 (d, C-4,
P,P,P-Trimethyl-4,4-diphenyl-1,2-oxaphosphetane (3Јd): 8 mg (89
µmol) of trimethyl(methylene)phosphorane was treated with 16 mg
(88 µmol) of benzophenone in ca. 0.6 mL of [D8]THF at Ϫ78°C.
1
2JPC ϭ 13.9 Hz), 66.0 (d, C-3, JPC ϭ 87.4 Hz). Ϫ 31P NMR
(81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ68.3.
1
P-Methyl-P,P,4,4-tetraphenyl-1,2-oxaphosphetane (3Јb): 50 mg (233 Ϫ H NMR (599.9 MHz, 203 K, [D8]THF): δ ϭ 7.56 (m, 4 H, o-
µmol) of (methyl)(methylene)diphenylphosphorane was treated
H, Ph), 7.20 (m, 4 H, m-H, Ph), 7.04 (m, 2 H, p-H, Ph), 4.31 (d, 2
2
2
with 43 mg (236 µmol) of benzophenone in 740 mg of [D8]THF at H, PCH2, JPH ϭ 16.5 Hz), 1.26 (d, 9 H, PCH3, JPH ϭ 11.7 Hz).
1
Ϫ78°C. Ϫ H NMR (360.1 MHz, 243 K, [D8]THF): δ ϭ 7.58 (m,
4 H, o-H, Ph), 7.30 (d, 4 H, o-H, Ph2P), 7.23 (m, 4 H, m-H, Ph),
Ϫ
13C NMR (150.8 MHz, 203 K, [D8]THF): δ ϭ 152.8 (d, i-C, Ph,
3JPC ϭ 8.2 Hz), 128.2 (m-C, Ph), 126.4 (o-C, Ph), 125.9 (p-C, Ph),
2
1
7.19 (m, 6 H, m-, p-H, Ph2P), 7.10 (d, 2 H, p-H, Ph), 4.66 (d, 2 H, 79.7 (d, C-4, JPC ϭ 13.9 Hz), 65.3 (d, C-3, JPC ϭ 88.5 Hz), 24.1
2
2
1
PCH2, JPH ϭ 17.2 Hz), 2.23 (d, 3 H, PCH3, JPH ϭ 14.2 Hz). Ϫ (d, PCH3, JPC ϭ 68.3 Hz). Ϫ 31P NMR (242.9 MHz, 203 K,
13C NMR (90.6 MHz, 243 K, [D8]THF): δ ϭ 151.6 (d, i-C, Ph,
[D8]THF): δ ϭ Ϫ88.2.
3JPC ϭ 6.9 Hz), 148.0 (d, i-C, Ph2P, JPC ϭ 73.5 Hz), 131.6 (d, o-
1
P-Cyclopropyl-P,P,4,4-tetraphenyl-1,2-oxaphosphetane (3Јe): 26 mg
(108 µmol) of (cyclopropyl)(methylene)diphenylphosphorane was
treated with 20 mg (110 µmol) of benzophenone in 700 mg of
[D8]THF at Ϫ78°C. Ϫ 1H NMR (360.1 MHz, 243 K, [D8]THF):
δ ϭ 7.39 (m, 4 H, o-H, Ph), 7.25 (m, 4 H, o-H, Ph2P), 7.15 (m, 6
H, m-, p-H, Ph2P), 7.13 (m, 4 H, m-H, Ph), 7.03 (m, 2 H, p-H, Ph),
2
4
C, Ph, JPC ϭ 9.7 Hz), 128.7 (br. s, p-C, Ph2P, JPC < 1 Hz), 128.6
(m-C, Ph), 128.1 (m-C, Ph2P, 3JPC ϭ 9.7 Hz), 126.5 (o-C, Ph), 126.4
2
1
(p-C, Ph), 70.5 (d, C-4, JPC ϭ 13.9 Hz), 67.5 (d, C-3, JPC
ϭ
87.4 Hz), 21.8 (d, PCH3, 1JPC ϭ 97.1 Hz). Ϫ 31P NMR (81.0 MHz,
243 K, [D8]THF): δ ϭ Ϫ75.5.
2
4,4-Bis(4Ј-methoxyphenyl)-P-methyl-P,P-diphenyl-1,2-oxaphos-
phetane (3b): 21 mg (98 µmol) of (methyl)(methylene)diphenylphos-
4.80 (d, 2 H, PCH2, JPH ϭ 16.8 Hz), 1.23 (br. m, 2 H, CH2), 0.89
(m, 1 H, PCH), 0.82 (m, 2 H, CH2). Ϫ 13C NMR (90.6 MHz,
3
phorane was treated with 27 mg (111 µmol) of bis(p-methoxyphe- 243 K, [D8]THF): δ ϭ 151.1 (d, i-C, Ph, JPC ϭ 6.9 Hz), 147.8 (d,
nyl) ketone in ca. 0.6 mL of [D8]THF at Ϫ78°C. Ϫ 1H NMR i-C, Ph2P, JPC ϭ 70.8 Hz), 130.7 (d, o-C, Ph2P, JPC ϭ 8.3 Hz),
1
2
4
(360.1 MHz, 243 K, [D8]THF): δ ϭ 7.50 (m, 4 H, o-H, Ph2P), 7.43 128.4 (m-C, Ph), 128.3 (s, p-C, Ph2P, JPC ϭ 0 Hz), 128.1 (d, m-C,
3
3
(d, 4 H, o-H, Ph, JHH ϭ 8.7 Hz), 7.31 (m, 2 H, p-H, Ph2P), 7.26 Ph2P, JPC ϭ 11.1 Hz), 126.3 (p-C and o-C, Ph), 70.4 (d, C-4,
3
1
(m, 4 H, m-H, Ph2P), 6.78 (d, 4 H, m-H, Ph, JHH ϭ 8.7 Hz), 4.55 2JPC ϭ 13.9 Hz), 64.6 (d, C-3, JPC ϭ 90.2 Hz), 13.4 (d, PCH,
2
2
(d, 2 H, PCH2, JPH ϭ 17.4 Hz), 3.70 (s, 6 H, OCH3), 2.23 (d, 3 1JPC ϭ 142.9 Hz), 5.7 (d, CH2, JPC ϭ 4.2 Hz). Ϫ 31P NMR
2
H, PCH3, JPH ϭ 14.5 Hz). Ϫ 13C NMR (90.6 MHz, 243 K,
(81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ66.7.
1
[D8]THF): δ ϭ 158.5 (p-C, Ph), 148.5 (d, i-C, Ph2P, JPC
ϭ
P,P-Dicyclopropyl-P,4,4-triphenyl-1,2-oxaphosphetane (3Јf): 31 mg
(151 µmol) of dicyclopropyl(methylene)(phenyl)phosphorane was
treated with 28 mg (154 µmol) of benzophenone in 700 mg of
[D8]THF at Ϫ78°C. Ϫ 1H NMR (360.1 MHz, 243 K, [D8]THF):
δ ϭ 7.63 (m, 2 H, m-H, PhP), 7.38 (m, 4 H, o-H, Ph), 7.23 (m, 2
H, o-H, PhP), 7.16 (m, 5 H, m-H, Ph and p-H, PhP), 7.04 (m, 2
3
76.3 Hz), 143.9 (d, i-C, Ph, JPC ϭ 7.0 Hz), 131.7 (d, o-C, Ph2P,
2JPC ϭ 8.2 Hz), 128.6 (s, p-C, Ph2P, JPC ϭ 0 Hz), 128.1 (d, m-C,
4
3
Ph2P, JPC ϭ 10.6 Hz), 127.4 (o-C, Ph), 113.5 (m-C), 69.8 (d, C-4,
2JPC ϭ 15.3 Hz), 67.7 (d, C-3, JPC ϭ 88.6 Hz), 55.1 (OCH3), 21.6
1
(d, PCH3, JPC ϭ 96.3 Hz). Ϫ 31P NMR (81.0 MHz, 243 K,
1
[D8]THF): δ ϭ Ϫ76.3.
2
H, p-H, Ph), 4.19 (d, 2 H, PCH2, JPH ϭ 16.9 Hz), 1.30 (m, 2 H,
P,P-Dimethyl-P,4,4-triphenyl-1,2-oxaphosphetane (3Јc): 39 mg (256
µmol) of dimethyl(methylene)(phenyl)phosphorane was treated
PCH), 1.00, 0.73 (m, each 2 H, CH2), 0.62 (m, 4 H, CH2). Ϫ 13C
NMR (90.6 MHz, 243 K, [D8]THF): δ ϭ 154.0 (d, i-C, PhP, 1JPC ϭ
3
with 46 mg (253 µmol) of benzophenone in 690 mg of [D8]THF at 32.3 Hz), 151.3 (d, i-C, Ph, JPC ϭ 6.9 Hz), 129.8 (d, o-C, PhP,
1
3
Ϫ78°C. Ϫ H NMR (360.1 MHz, 243 K, [D8]THF): δ ϭ 7.57 (m,
2JPC ϭ 5.6 Hz), 128.5 (m-C, Ph), 128.2 (d, m-C, PhP, JPC
ϭ
4
4 H, o-H, Ph), 7.48 (d, 2 H, o-H, PhP), 7.22 (m, 7 H, m-H, Ph, m-
5.6 Hz), 127.5 (s, p-C, PhP, JPC ϭ 0 Hz), 126.3 (p-C, Ph), 126.1
and p-H, PhP), 7.08 (m, 2 H, p-H, Ph), 4.43 (d, 2 H, PCH2, 2JPH ϭ
(o-C, Ph), 70.2 (d, C-4, JPC ϭ 12.5 Hz), 66.6 (d, C-3, JPC
ϭ
2
1
2
1
2
17.1 Hz), 1.81 (d, 3 H, PCH3, JPH ϭ 13.1 Hz). Ϫ 13C NMR 97.1 Hz), 12.9 (d, PCH, JPC ϭ 129.0 Hz), 5.0 (d, CH2, JPC
ϭ
3
2
(90.6 MHz, 243 K, [D8]THF): δ ϭ 152.2 (d, i-C, Ph, JPC
ϭ
5.6 Hz), 4.1 (d, CH2, JPC ϭ 2.8 Hz). Ϫ 31P NMR (81.0 MHz,
1
6.9 Hz), 151.6 (d, i-C, PhP, JPC ϭ 47.2 Hz), 129.5 (d, o-C, Ph, 243 K, [D8]THF): δ ϭ Ϫ70.1.
2JPC ϭ 8.3 Hz), 128.43 (obscured, m-C, PhP, 3JPC not determined),
P,P,P-Tricyclopropyl-4,4-bis(4Ј-methoxyphenyl)-1,2-oxaphos-
4
128.4 (m-C, Ph), 128.2 (br. s, p-C, PhP, JPC not resolved), 126.5
phetane (3g): 14 mg (83 µmol) of tricyclopropyl(methylene)phos-
phorane was treated with 19 mg (78 µmol) of 4,4Ј-dimethoxybenzo-
2
(o-C, Ph), 126.2 (p-C, Ph), 70.3 (d, C-4, JPC ϭ 13.9 Hz), 67.0 (d,
C-3, 1JPC ϭ 90.2 Hz), 22.4 (d, PCH3, 1JPC ϭ 84.6 Hz). Ϫ 31P NMR
(81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ83.9.
phenone in ca. 0.6 mL of [D8]THF at Ϫ78°C. Ϫ 1H NMR
3
(360.1 MHz, 243 K, [D8]THF): δ ϭ 7.26 (d, 4 H, o-H, Ph, JHH
ϭ
4,4-Bis(4Ј-methoxyphenyl)-P,P-dimethyl-P-phenyl-1,2-oxaphos-
phetane (3c): 15 mg (99 µmol) of dimethyl(methylene)(phenyl)phos-
8.7 Hz), 6.70 (d, 4 H, m-H, Ph, 3JHH ϭ 8.7 Hz), 4.18 (d, 2 H, PCH2,
2JPH ϭ 16.5 Hz), 3.67 (s, 6 H, OCH3), 0.71 (m, 6 H, CH2), 0.58
phorane was treated with 24 mg (99 µmol) of 4,4Ј-dimethoxybenzo- (m, 3 H, PCH), 0.46 (m, 6 H, CH2). Ϫ 13C NMR (90.6 MHz,
phenone in ca. 0.6 mL of [D8]THF at Ϫ78°C. Ϫ 1H NMR 243 K, [D8]THF): δ ϭ 158.2 (p-C, Ph), 144.3 (d, i-C, Ph, JPC
ϭ
3
2
(360.1 MHz, 243 K, [D8]THF): δ ϭ 7.49 (m, 2 H, o-H, PhP), 7.38
Eur. J. Org. Chem. 1999, 1831Ϫ1841
6.9 Hz), 127.0 (o-C, Ph), 113.4 (m-C, Ph), 69.5 (d, C-4, JPC
ϭ
1837

C. Puke, G. Erker, B. Wibbeling, R. Fröhlich
FULL PAPER
1
12.5 Hz), 59.3 (d, C-3, JPC ϭ 94.3 Hz), 55.0 (OCH3), 13.2 (d,
6.4 Hz), 128.6 (o-C, Ph), 127.8 (o-CЈ, Ph), 113.1 (m-C, Ph), 112.9
PCH, JPC ϭ 97.1 Hz), 4.1 (d, CH2, JPC ϭ 2.8 Hz). Ϫ 31P NMR (m-CЈ, Ph), 72.7 (d, C-4, JPC ϭ 11.6 Hz), 63.9 (d, C-3, JPC
(81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ68.5.
ϭ
1
2
2
1
1
90.4 Hz), 55.0 (OCH3, OCH3Ј), 26.1 (d, PCH2, JPC ϭ 63.1 Hz),
2
2
14.0 (d, PCHCH3, JPC ϭ 6.6 Hz), 9.3 (d, PCH2CH3, JPC
ϭ
(±)-P-Ethyl-4,4-bis(4Ј-methoxyphenyl)-3-methyl-P,P-diphenyl-1,2-
oxaphosphetane (3h): 33 mg (136 µmol) of (ethyl)(ethylidene)di-
phenylphosphorane was treated with 35 mg (135 µmol) of 4,4Ј-di-
methoxybenzophenone in 870 mg of [D8]THF at Ϫ78°C. Ϫ 1H
NMR (200.1 MHz, 243 K, [D8]THF): δ ϭ 7.51Ϫ7.17 (m, 10 H, o-
, m-, p-H, PPh2), 7.45 (d, 2 H, o-H, Ph, 3JHH ϭ 8.7 Hz), 7.10 (d, 2
H, o-HЈ, Ph, JHH ϭ 8.7 Hz), 6.85 (d, 2 H, m-H, Ph, JHH
8.7 Hz), 6.58 (d, 2 H, m-HЈ, Ph, JHH ϭ 8.7 Hz), 5.21 (dq, 1 H,
PCHCH3, JPH ϭ 18.6 Hz, JHH ϭ 8.3 Hz), 3.75, 3.63 (s, each 3
H, OCH3, OCH3Ј), 2.58, 2.18 (m, each 1 H, PCHHЈ), 1.17Ϫ0.94
(m, 6 H, PCHCH3 and PCH2CH3 signals superimposed). Ϫ 13C
NMR (50.3 MHz, 243 K, [D8]THF): δ ϭ 158.7 (p-C, Ph), 158.4 (p-
4.6 Hz). Ϫ 31P NMR (81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ65.5.
Generation of the Thiabetaine 5a: 18 mg (65 µmol) of (methylene)-
triphenylphosphorane was treated with 16 mg (62 µmol) of 4,4Ј-
dimethoxythiobenzophenone in 1.1 g of [D2]dichloromethane at
Ϫ78°C. Ϫ 1H NMR (360.1 MHz, 243 K, [D2]dichloromethane):
δ ϭ 7.66 (m, 6 H, o-H, Ph3P), 7.46 (m, 6 H, p-H, Ph3P), 7.40 (d,
3
3
ϭ
3
3
4 H, o-H, Ph, JHH ϭ 8.5 Hz), 7.33 (m, 6 H, m-H, Ph3P), 6.53 (d,
4 H, m-H, Ph, 3JHH ϭ 8.5 Hz), 5.18 (d, 2 H, PCH2, 2JPH ϭ 9.8 Hz),
3.68 (s, 6 H, OCH3). Ϫ 13C NMR (90.6 MHz, 243 K, [D2]dichloro-
2
3
3
methane): δ ϭ 156.2 (p-C, Ph), 144.0 (d, i-C, Ph, JPC ϭ 7.4 Hz),
2
4
133.5 (d, o-C, Ph3P, JPC ϭ 8.4 Hz), 131.4 (d, p-C, Ph3P, JPC
ϭ
3
1
3.2 Hz), 128.08 (o-C, Ph), 128.10 (d, m-C, Ph3P, JPC ϭ 11.6 Hz),
CЈ, Ph), 148.5 (d, i-C, Ph2P, JPC ϭ 47.3 Hz), 144.6 (d, i-C, Ph,
126.6 (d, i-C, Ph3P, 1JPC ϭ 91.6 Hz), 111.9 (m-C, Ph), 55.0 (OCH3),
3JPC ϭ 9.5 Hz), 143.5 (d, i-CЈ, Ph2P, JPC ϭ 88.5 Hz), 139.5 (d, i-
1
51.8 (d, C-3, JPC ϭ 82.1 Hz), 49.7 (d, C-4, JPC ϭ 2.1 Hz). Ϫ 31P
1
2
3
2
CЈ, Ph, JPC ϭ 5.2 Hz), 133.5 (d, o-C, Ph2P, JPC ϭ 7.0 Hz), 132.8
(d, o-CЈ, Ph2P, JPC ϭ 7.3 Hz), 129.33 (d, p-C, Ph2P, JPC
1.8 Hz), 129.25 (d, p-CЈ, Ph2P, JPC ϭ 1.8 Hz), 128.8 (o-C, Ph),
128.2 (d, m-C, Ph2P, JPC ϭ 10.7 Hz), 128.1 (o-CЈ, Ph), 127.9 (d,
m-CЈ, Ph2P, JPC ϭ 8.5 Hz), 113.4 (m-C, Ph), 112.9 (m-CЈ, Ph),
74.3 (d, C-4, JPC ϭ 12.2 Hz), 68.4 (d, C-3, JPC ϭ 91.3 Hz), 55.1
(OCH3), 55.0 (OCH3Ј), 29.5 (d, PCH2CH3, JPC ϭ 95.5 Hz), 14.3
2
4
NMR (81.0 MHz, 223 K, [D2]dichloromethane):
δ ϭ ϩ3.6;
ϭ
4
(243 K): δ ϭ ϩ0.4.
3
Thiabetaine 5b: 31 mg (145 µmol) of (methyl)(methylene)diphenyl-
phosphorane was treated with 37 mg (143 µmol) of 4,4Ј-dimeth-
oxythiobenzophenone in 720 mg of [D5]pyridine at Ϫ35°C. Ϫ 1H
NMR (200.1 MHz, 263 K, [D5]pyridine): δ ϭ 8.28 (d, 4 H, o-H,
3
2
1
1
2
2
(d, PCHCH3, JPC ϭ 7.6 Hz), 8.4 (d, PCH2CH3, JPC ϭ 5.8 Hz).
3
Ph, JHH ϭ 8.7 Hz), 7.82 (m, 4 H, o-H, Ph2P), 7.39 (m, 6 H, m, p-
Ϫ
31P NMR (81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ62.8.
3
H, Ph2P), 6.91 (d, 4 H, m-H, Ph, JHH ϭ 8.7 Hz), 5.01 (d, 2 H,
2
PCH2, JPH ϭ 10.0 Hz), 3.59 (s, 6 H, OCH3), 2.83 (d, 3 H, PCH3,
(±)-P,P-Diethyl-4,4-bis(4Ј-methoxyphenyl)-3-methyl-P-phenyl-1,2-
oxaphosphetane (3i): 16 mg (82 µmol) of diethyl(ethylidene)(phen-
yl)-phosphorane was treated with 20 mg (83 µmol) of 4,4Ј-dimeth-
2JPH ϭ 14.3 Hz). Ϫ 13C NMR (50.3 MHz, 263 K, [D5]pyridine):
3
δ ϭ 157.4 (p-C, Ph), 146.8 (d, i-C, Ph, JPC ϭ 8.3 Hz), 132.3 (d, o-
C, Ph2P, 2JPC ϭ 9.1 Hz), 131.9 (d, p-C, Ph2P, 4JPC ϭ 2.5 Hz), 129.8
(d, i-C, Ph2P, 1JPC ϭ 85.8 Hz), 129.7 (o-C, Ph), 129.2 (d, m-C, Ph2P,
3JPC ϭ 12.0 Hz), 112.9 (m-C, Ph), 55.1 (OCH3), 51.9 (d, C-4,
oxybenzophenone in ca. 0.6 mL of [D8]THF at Ϫ78°C. Ϫ 1H NMR
3
(360.1 MHz, 263 K, [D8]THF): δ ϭ 7.41 (d, 2 H, o-H, Ph, JHH
8.7 Hz), 7.37 (m, 2 H, o-H, PhP), 7.30 (d, 2 H, o-HЈ, Ph, JHH
ϭ
3
ϭ
1
2JPC ϭ 2.5 Hz), 51.6 (d, C-3, JPC ϭ 78.8 Hz), 14.2 (d, PCH3,
8.7 Hz), 7.24 (m, 2 H, m-H, PhP), 7.20 (m, 1 H, p-H, PhP), 6.79
1JPC ϭ 64.3 Hz). Ϫ 31P NMR (81.0 MHz, 243 K, [D5]pyridine):
δ ϭ ϩ4.4; (263 K): δ ϭ ϩ1.9.
(d, 2 H, m-H, Ph, 3JHH ϭ 8.7 Hz), 6.68 (d, 2 H, m-HЈ, Ph, 3JHH
ϭ
8.7 Hz), 4.73 (m, 1 H, PCHCH3, 2JPH ϭ 17.0 Hz, JHH ϭ 7.8 Hz),
3
3.73, 3.66 (s, each 3 H, OCH3, OCH3Ј), 2.38, 2.27, 2.09, 1.99 (m,
Thiabetaine 5c: 13 mg (85 µmol) of dimethyl(methylene)(phen-
yl)phosphorane was treated with 23 mg (89 µmol) of 4,4Ј-dimeth-
oxythiobenzophenone in 880 mg of [D5]pyridine at Ϫ35°C. Ϫ 1H
NMR (599.9 MHz, 293 K, [D5]pyridine): δ ϭ 8.23 (d, 4 H, o-H,
3
each 1 H, PCHHЈ), 1.33 (dt, 3 H, PCHCH3, JPH ϭ 19.4 Hz,
3JHH ϭ 7.8 Hz), 0.90 (dt, 3 H, PCH2CH3, 3JPH ϭ 18.9 Hz, 3JHH ϭ
7.8 Hz), 0.90 (dd, 3 H, PCHCH3, 3JPH ϭ 26.6 Hz, 3JHH ϭ 7.8 Hz).
13C NMR (90.6 MHz, 263 K, [D8]THF): δ ϭ 158.5 (p-C, Ph),
3
Ϫ
Ph, JHH ϭ 8.8 Hz), 7.86 (m, 2 H, o-H, PhP), 7.52 (m, 1 H, p-H,
1
3
158.4 (p-CЈ, Ph), 149.2 (d, i-C, PhP, JPC ϭ 23.6 Hz), 145.4 (d,
i-C, Ph, JPC ϭ 6.9 Hz), 140.2 (d, i-CЈ, Ph, JPC ϭ 5.6 Hz), 131.1
PhP), 7.47 (m, 2 H, m-H, PhP), 6.89 (d, 4 H, m-H, Ph, JHH
ϭ
3
3
8.8 Hz), 4.37 (d, 2 H, PCH2, 2JPH ϭ 10.6 Hz), 3.57 (s, 6 H, OCH3),
4
2.40 (d, 6 H, PCH3, JPH ϭ 14.1 Hz). Ϫ 13C NMR (150.8 MHz,
2
(d, p-C, PhP, JPC ϭ 4.2 Hz), 128.6 (o-C, Ph), 128.4 (d, o-C, PhP,
2JPC ϭ 6.9 Hz), 128.35 (o-CЈ, Ph), 127.8 (d, m-C, PhP, JPC
ϭ
3
293 K, [D5]pyridine): δ ϭ 157.4 (p-C, Ph), 147.2 (d, i-C, Ph, 3JPC ϭ
2
4
6.9 Hz), 113.3 (m-C, Ph), 113.0 (m-CЈ, Ph), 73.5 (d, C-4, JPC
12.5 Hz), 68.7 (d, C-3, JPC ϭ 94.3 Hz), 55.1 (OCH3), 55.0
(OCH3Ј), 27.6 (d, PCH2, JPC ϭ 83.2 Hz), 23.7 (d, PCH2, JPC
ϭ
8.9 Hz), 132.3 (d, p-C, PhP, JPC ϭ 2.7 Hz), 131.2 (d, o-C, PhP,
1
3
2JPC ϭ 8.9 Hz), 129.7 (o-C, Ph), 129.5 (d, m-C, PhP, JPC
ϭ
1
1
11.6 Hz), 129.2 (d, i-C, PhP, 1JPC ϭ 82.1 Hz), 112.8 (m-C, Ph), 55.1
ϭ
2
2
1
87.4 Hz), 13.9 (d, PCHCH3, JPC ϭ 6.9 Hz), 9.3 (d, PCH2CH3,
(OCH3), 52.2 (d, C-4, JPC ϭ 2.7 Hz), 50.9 (d, C-3, JPC
ϭ
2JPC ϭ 4.9 Hz), 9.2 (d, PCH2CЈH3, JPC ϭ 5.6 Hz). Ϫ 31P NMR
2
1
73.9 Hz), 14.1 (d, PCH3, JPC
ϭ 60.6 Hz). Ϫ
31P NMR
(81.0 MHz, 243 K, [D8]THF): δ ϭ Ϫ64.8.
(242.9 MHz, 253 K, [D5]pyridine): δ ϭ ϩ14.5; (273 K): δ ϭ ϩ12.0;
(293 K): δ ϭ ϩ9.2.
(±)-P,P,P-Triethyl-4,4-bis(4Ј-methoxyphenyl)-3-methyl-1,2-oxaphos-
phetane (3k): 19 mg (130 µmol) of triethyl(ethylidene)phosphorane
was treated with 33 mg (136 µmol) of 4,4Ј-dimethoxybenzophenone
Thiabetaine 5d: 25 µL of methanol (abs.) in 5 mL of THF was
added to 98 mg (0.60 mmol) of Me3PϭCHTMS in 10 mL of THF
in ca. 0.8 mL of [D8]THF at Ϫ78°C. Ϫ 1H NMR (360.1 MHz, at room temperature. Then the mixture was stirred at 0°C for
3
243 K, [D8]THF): δ ϭ 7.37 (d, 2 ϫ 2 H, o-H, o-HЈ, Ph, JHH
ϭ
20 min. To this mixture a solution of 156 mg (0.60 mmol) of bis(p-
methoxyphenyl) thioketone (i.e. 4,4Ј-dimethoxythiobenzophenone)
3
8.4 Hz), 6.75 (d, 2 H, m-H, Ph, JHH ϭ 8.4 Hz), 6.71 (d, 2 H, m-
3
2
HЈ, Ph, JHH ϭ 8.4 Hz), 4.62 (m, 1 H, PCHCH3, JPH ϭ 15.8 Hz, in 2 mL of THF was added until the color of the slurry remained
3JHH ϭ 7.9 Hz), 3.71, 3.68 (s, each 3 H, OCH3, OCH3Ј), 1.58 (m, pale blue. The precipitate was collected and dried in vacuo to give
3
3
6 H, PCH2), 1.24 (dd, 3 H, PCHCH3, JPH ϭ 24.5 Hz, JHH
ϭ
153 mg (73%) of the betaine. Ϫ 1H NMR (200.1 MHz, 300 K,
7.9 Hz), 1.12 (dt, 9 H, PCH2CH3, 3JPH ϭ 16.3 Hz, 3JHH ϭ 8.7 Hz). [D5]pyridine): δ ϭ 8.25 (d, 4 H, o-H, Ph, JHH ϭ 8.9 Hz), 6.91 (d,
3
3
2
Ϫ
13C NMR (90.6 MHz, 243 K, [D8]THF): δ ϭ 158.3 (p-C and p-
4 H, m-H, Ph, JHH ϭ 8.9 Hz), 4.05 (d, 2 H, PCH2, JPH
ϭ
CЈ, Ph), 145.9 (d, i-C, Ph, 3JPC ϭ 6.9 Hz), 140.8 (d, i-CЈ, Ph, 3JPC ϭ 10.5 Hz), 3.63 (s, 6 H, OCH3), 1.98 (d, 9 H, PCH3, JPH
ϭ
2
1838
Eur. J. Org. Chem. 1999, 1831Ϫ1841

Evidence for the Occurrence of gauche-Betaine Intermediates in the Thio Wittig Reaction
FULL PAPER
13.8 Hz). Ϫ 13C NMR (50.3 MHz, 300 K, [D5]pyridine): δ ϭ 157.4 PCH), 1.01 (m, 6 H, CH2), 0.77 (m, 6 H, CH2). Ϫ 13C NMR
3
(p-C, Ph), 147.5 (d, i-C, Ph, JPC ϭ 8.3 Hz), 129.7 (o-C, Ph), 112.8 (150.8 MHz, 300 K, [D5]pyridine): δ ϭ 157.3 (p-C, Ph), 147.6 (d, i-
2
3
(m-C, Ph), 55.1 (OCH3), 51.9 (d, C-4, JPC ϭ 3.3 Hz), 49.1 (d, C-
C, Ph, JPC ϭ 9.1 Hz), 129.9 (o-C, Ph), 112.7 (m-C, Ph), 55.2
3, JPC ϭ 75.1 Hz), 14.3 (d, PCH3, JPC ϭ 59.4 Hz). Ϫ 31P NMR (OCH3), 51.1 (d, C-4, JPC ϭ 1.9 Hz), 46.0 (d, C-3, JPC
(81.0 MHz, 300 K, [D5]pyridine): δ ϭ ϩ11.5. Ϫ C19H25PSO2
(348.45): calcd. C 65.49, H 7.23; found C 65.22, H 7.09. Ϫ M.p.
ϭ
1
1
2
1
71.7 Hz), 4.3 (d, CH2, 2JPC ϭ 4.6 Hz), 3.6 (d, CH, 1JPC ϭ 87.9 Hz).
Ϫ
31P NMR (242.9 MHz, 243 K, [D5]pyridine): δ ϭ ϩ33.5;
79°C (dec.). Ϫ IR: ν˜ ϭ 3052, 2960, 2894, 2835, 1604, 1506, 1467, (263 K): δ ϭ ϩ32.2; (300 K): δ ϭ ϩ29.9.
1290. 1249, 1183, 1111, 1045, 959, 907, 827 cmϪ1
.
Thiabetaine 11: 12 mg (71 µmol) of tricyclopropyl(methylene)phos-
phorane was treated with 20 mg (70 µmol) of 4,4Ј-bis(dimethylami-
Thiabetaine 5e: 31 mg (129 µmol) of (cyclopropyl)(methylene)di-
phenylphosphorane was treated with 33 mg (128 µmol) of 4,4Ј-di- no)thiobenzophenone in 890 mg of [D5]pyridine at Ϫ35°C. After
methoxythiobenzophenone in 720 mg of [D5]pyridine at Ϫ35°C. Ϫ
the measurement, crystal growth set in. Single crystals suited for
the X-ray crystal-structure analysis were obtained after keeping the
sample at ϩ4°C overnight. Ϫ 1H NMR (599.9 MHz, 300 K,
[D5]pyridine): δ ϭ 8.22 (d, 4 H, o-H, 3JHH ϭ 9.0 Hz), 6.74 (d, 4 H,
1H NMR (360.1 MHz, 263 K, [D5]pyridine): δ ϭ 8.32 (d, 4 H, o-
3
H, Ph, JHH ϭ 8.9 Hz), 7.64 (m, 4 H, o-H, Ph2P), 7.47 (m, 2 H, p-
H, Ph2P), 7.37 (m, 4 H, m-H, Ph2P), 6.88 (d, 4 H, m-H, Ph, 3JHH ϭ
8.9 Hz), 5.16 (d, 2 H, PCH2, 2JPH ϭ 10.0 Hz), 3.57 (s, 6 H, OCH3), m-H, JHH ϭ 9.0 Hz), 3.89 (d, 2 H, PCH2, JPH ϭ 10.2 Hz), 2.75
3
2
3.47 (m, 1 H, PCH), 0.59 (m, 2 H, CH2), 0.11 (m, 2 H, CH2). Ϫ
[s, 12 H, N(CH3)2], 1.92 (m, 3 H, PCH), 1.00 (m, 6 H, CH2), 0.75
13C NMR (90.6 MHz, 263 K, [D5]pyridine): δ ϭ 157.2 (p-C, Ph),
(m, 6 H, CH2). Ϫ 13C NMR (150.8 MHz, 300 K, [D5]pyridine):
3
2
3
147.0 (d, i-C, Ph, JPC ϭ 8.4 Hz), 133.4 (d, o-C, Ph2P, JPC
ϭ
δ ϭ 148.4 (p-C, Ph), 144.1 (d, i-C, Ph, JPC ϭ 8.6 Hz), 129.5 (o-C,
8.4 Hz), 132.0 (d, p-C, Ph2P, 4JPC ϭ 2.1 Hz), 129.7 (o-C, Ph), 129.0
(d, m-C, Ph2P, JPC ϭ 11.6 Hz), 127.3 (d, i-C, Ph2P, JPC
86.3 Hz), 112.7 (m-C, Ph), 55.1 (OCH3), 52.1 (d, C-3, JPC
Ph), 112.2 (m-C, Ph), 50.8 (d, C-4, JPC ϭ 1.8 Hz), 46.4 (d, C-3,
2
3
1
2
ϭ
ϭ
ϭ
1JPC ϭ 72.2 Hz), 40.9 [N(CH3)2], 4.2 (d, CH2, JPC ϭ 4.8 Hz), 4.0
1
(d, CH, 1JPC ϭ 87.8 Hz). Ϫ 31P NMR (242.9 MHz, 263 K, [D5]pyr-
idine): δ ϭ ϩ30.4; (283 K): δ ϭ ϩ29.0; (300 K): δ ϭ ϩ27.7.
2
1
77.9 Hz), 51.9 (d, C-4, JPC ϭ 2.1 Hz), 6.0 (d, PCH, JPC
94.7 Hz), 4.2 (d, CH2, JPC ϭ 4.2 Hz). Ϫ 31P NMR (81.0 MHz,
243 K, [D5]pyridine): δ ϭ ϩ16.9; (263 K): δ ϭ ϩ13.9; (283 K):
δ ϭ ϩ10.5.
2
X-ray Crystal-Structure Analysis of 11: Empirical formula
C27H37N2PS
·
C5H5N,
M
ϭ
531.72, yellow crystal,
0.40 ϫ 0.20 ϫ 0.10 mm, a ϭ 9.814(1), b ϭ 24.299(3), c ϭ 12.633(1)
3
A, β ϭ 97.56(1)°, V ϭ 2986.4(5) A , ρcalcd. ϭ 1.183 g cmϪ3
,
˚
˚
Thiabetaine 5f: 21 mg (103 µmol) of dicyclopropyl(methylene)-
(phenyl)phosphorane was treated with 23 mg (89 µmol) of 4,4Ј- F(000) ϭ 1144 e, µ ϭ 16.44 cmϪ1, empirical absorption correction
dimethoxythiobenzophenone in ca. 0.6 mL of [D5]pyridine at
with φ scan data (0.914 Յ C Յ 0.999), Z ϭ 4, monoclinic, space
Ϫ35°C. Ϫ 1H NMR (360.1 MHz, 283 K, [D5]pyridine): δ ϭ 8.28 group P21/n (no. 14), λ ϭ 1.54178 A, T ϭ 223 K, ω/2θ scans, 6359
˚
3
(d, 4 H, o-H, Ph, JHH ϭ 8.8 Hz), 8.02 (m, 2 H, o-H, PhP), 7.41
reflections collected (±h, ϩk, ϩl), (sinθ)/λ ϭ 0.62 AϪ1, 6085 inde-
˚
3
(m, 3 H, m-, p-H, PhP), 6.91 (d, 4 H, m-H, Ph, JHH ϭ 8.8 Hz), pendent and 4063 observed reflections [I Ն 2 σ(I)], 326 refined
2
4.59 (d, 2 H, PCH2, JPH ϭ 9.9 Hz), 3.62 (s, 6 H, OCH3), 1.97 (m,
parameters, R ϭ 0.078, wR2 ϭ 0.232, max. residual electron density
2 H, PCH), 0.90, 0.83, 0.66, 0.55 (m, each 2 H, CH2). Ϫ 13C NMR 10.2 (Ϫ0.74) eAϪ3, disordered pyridine molecule (refined with re-
˚
(90.6 MHz, 283 K, [D5]pyridine): δ ϭ 157.3 (p-C, Ph), 147.3 (d, i-
straints as rigid six-membered ring, highest positive and negative
Fourier peaks in the solvent molecule area), hydrogen atoms calcu-
3
2
C, Ph, JPC ϭ 8.2 Hz), 131.5 (d, o-C, PhP, JPC ϭ 8.2 Hz), 131.2
4
(d, p-C, PhP, JPC ϭ 2.7 Hz), 129.8 (o-C, Ph), 128.7 (d, m-C, PhP, lated and refined as riding atoms. Data set was collected with an
3JPC ϭ 13.6 Hz), 128.5 (d, i-C, PhP, 1JPC ϭ 101.4 Hz), 112.7 (m-C,
Enraf Nonius CAD4 diffractometer. Programs used: data reduction
Ph), 55.1 (OCH3), 51.9 (d, C-4, 2JPC ϭ 2.2 Hz), 48.8 (d, C-3, 1JPC ϭ MolEN, structure solution SHELXS-86, structure refinement
81.2 Hz), 4.5 (d, CH2, 2JPC ϭ 4.9 Hz), 4.0 (d, CH2, 2JPC ϭ 4.9 Hz), SHELXL-97, graphics SCHAKAL-92. Crystallographic data (ex-
1
3.7 (d, PCH, JPC ϭ 85.0 Hz). Ϫ 31P NMR (81.0 MHz, 243 K,
cluding structure factors) for the structure reported in this paper
[D5]pyridine): δ ϭ ϩ 20.0; (263 K): δ ϭ ϩ 18.6; (283 K): δ ϭ ϩ has been deposited with the Cambridge Crystallographic Data
16.8. Ϫ GHSQC NMR (150.8/599.9 MHz, 283 K, [D5]pyridine): Centre as supplementary publication no. CCDC-115321. Copies of
δ ϭ 131.5/8.02 (o-C, PhP/o-H, PhP), 131.2/7.41 (p-C, PhP/p-H, the data can be obtained free of charge on application to CCDC,
PhP), 129.8/8.28 (o-C, Ph/o-H, Ph), 128.7/7.41 (m-C, PhP/m-H,
12 Union Road, CambridgeCB2 1EZ, UK [Fax: int. code ϩ 44-
PPh), 112.7/6.91 (m-C, Ph/m-H, PPh), 55.1/3.62 (OCH3), 48.8/4.59 1223/336-033, E-mail: deposit@ccdc.cam.ac.uk].
(C-3/PCH2), 4.5/0.90 (CH2/CH2), 4.5/0.55 (CH2/CH2), 4.0/0.83
(±)-Thiabetaine 5h: 15 mg (62 µmol) of (ethyl)(ethylidene)diphenyl-
phosphorane was treated with 15 mg (58 µmol) of 4,4Ј-dimeth-
oxythiobenzophenone in 850 mg of [D5]pyridine at Ϫ35°C. Ϫ 1H
NMR (360.1 MHz, 263 K, [D5]pyridine): δ ϭ 8.65 (d, 2 H, o-H,
Ph, JHH ϭ 8.8 Hz), 8.33 (d, 2 H, o-HЈ, Ph, JHH ϭ 8.8 Hz), 8.26
(m, 2 H, o-H, PPh2), 7.82 (m, 2 H, o-HЈ, PPh2), 7.55Ϫ7.28 (m, 2
H, p-H, p-HЈ, PPh2), 7.35 (m, 4 H, m-H, m-HЈ, PPh2), 6.95 (d, 2
(CH2/CH2), 4.0/0.66 (CH2/CH2), 3.7/1.97 (PCH/PCH).
Ϫ
GHMBC NMR (150.8/599.9 MHz, 283 K, [D5]pyridine): δ ϭ
157.3/8.28 (p-C, Ph/o-H, Ph), 157.3/6.91 (p-C, Ph/m-H, Ph), 157.3/
3.62 (p-C, Ph/OCH3), 147.3/8.28 (i-C, Ph/o-H, Ph), 147.3/6.91 (i-C,
Ph/m-H, Ph), 147.3/4.59 (i-C, Ph/PCH2), 131.5/7.41 (o-C, PhP/p-H,
PPh), 131.2/8.02 (p-C, PhP/o-H, PhP), 129.8/6.91 (o-C, Ph/m-H,
Ph), 128.5/7.41 (i-C, PhP/m-H, Ph), 128.5/4.59 (i-C, PhP/CH2),
112.7/8.28 (m-C, Ph/o-H, Ph), 51.9/8.28 (C-4/o-H, Ph), 51.9/4.59
(C-4/PCH2), 4.0/1.97 (CH2/PCH), 3.7/0.90, 0.83, 0.66, 0.55 (PCH/
CH2).
3
3
3
3
H, m-H, Ph, JHH ϭ 8.8 Hz), 6.85 (d, 2 H, m-HЈ, Ph, JHH
ϭ
8.8 Hz), 5.50 (q, 1 H, PCHCH3, 2JPH ϭ 0 Hz, 3JHH ϭ 6.6 Hz), 4.06
(m, 1 H, PCHHЈ), 3.56, 3.49 (s, each 3 H, OCH3, OCH3Ј), 2.86
2
(m, 1 H, PCHHЈ), 1.68 (dd, 3 H, PCHCH3, JPH ϭ 20.4 Hz,
2
3
Thiabetaine (5g): 19 mg (113 µmol) of tricyclopropyl(methylene)-
3JHH ϭ 6.6 Hz), 0.57 (dt, 3 H, PCH2CH3 JPH ϭ 20.9 Hz, JHH
ϭ
phosphorane was treated with 29 mg (112 µmol) of 4,4Ј-dimeth- 7.2 Hz). Ϫ 13C NMR (90.6 MHz, 263 K, [D5]pyridine): δ ϭ 157.5
oxythiobenzophenone in ca. 0.6 mL of [D5]pyridine at Ϫ35°C. Ϫ
(p-C, Ph), 157.4 (p-CЈ, Ph), 147.2 (d, i-C, Ph, 3JPC ϭ 1.4 Hz), 143.2
1H NMR (599.9 MHz, 300 K, [D5]pyridine): δ ϭ 8.26 (d, 4 H, o- (d, i-CЈ, Ph, JPC ϭ 13.9 Hz), 136.4 (d, o-C, Ph2P, JPC ϭ 8.3 Hz),
3
2
3
3
2
4
H, JHH ϭ 8.9 Hz), 6.91 (d, 4 H, m-H, JHH ϭ 8.9 Hz), 3.89 (d, 2 134.0 (d, o-CЈ, Ph2P, JPC ϭ 6.9 Hz), 132.2 (d, p-C, Ph2P, JPC
ϭ
H, PCH2, JPH ϭ 10.6 Hz), 3.65 (s, 6 H, OCH3), 1.91 (m, 3 H, 2.1 Hz), 131.8 (d, p-CЈ, Ph2P, 4JPC ϭ 2.1 Hz), 130.1 (o-C, Ph), 129.4
2
Eur. J. Org. Chem. 1999, 1831Ϫ1841 1839

C. Puke, G. Erker, B. Wibbeling, R. Fröhlich
FULL PAPER
3
2
3
(d, m-C, Ph2P, JPC ϭ 9.7 Hz), 129.0 (o-CЈ, Ph), 128.3 (d, m-CЈ, 3JHH ϭ 9.0 Hz), 4.65 (dq, 1 H, PCHCH3, JPH ϭ 2.4 Hz, JHH
ϭ
3
1
Ph2P, JPC ϭ 12.5 Hz), 126.3 (d, i-C, Ph2P, JPC ϭ 92.3 Hz), ca.
123 (i-CЈ, Ph2P, obscured), 113.0 (m-C, Ph), 112.5 (m-CЈ, Ph), 58.3 3 H, CHHЈ, CHHЈ), 1.57 (dd, 3 H, PCHCH3, JPH ϭ 19.0 Hz,
6.8 Hz), 3.62, 3.58 (s, each 3 H, OCH3, OCH3Ј), 2.60, 2.17 (m, each
3
2
1
(s, C-4, JPC ϭ 0 Hz), 57.4 (d, C-3, JPC ϭ 70.1 Hz), 54.9 (OCH3),
3JHH ϭ 6.8 Hz), 1.03 (dt, 9 H, PCH2CH3, 3JPH ϭ 17.0 Hz, 3JHH ϭ
54.8 (OCH3Ј), 23.7 (d, PCH2CH3, JPC ϭ 56.2 Hz), 16.1 (d, 7.6 Hz). Ϫ 13C NMR (150.8 MHz, 298 K, [D5]pyridine): δ ϭ 157.6
1
2
2
3
PCHCH3, JPC ϭ 3.5 Hz), 8.8 (d, PCH2CH3, JPC ϭ 6.2 Hz). Ϫ (p-C, Ph), 157.4 (p-CЈ, Ph), 147.7 (s, i-C, Ph, JPC ϭ 0 Hz), 144.1
31P NMR (81.0 MHz, 253 K, [D5]pyridine): δ ϭ 16.8; (263 K): δ ϭ
14.4; (273 K): δ ϭ 12.4. Ϫ 17 mg (70 µmol) of (ethyl)(ethylidene)di-
(d, i-CЈ, Ph, JPC ϭ 12.9 Hz), 131.1 (o-C, Ph), 130.1 (o-CЈ, Ph),
112.8 (m-C, Ph), 112.5 (m-CЈ, Ph), 55.07 (OCH3), 55.03 (OCH3Ј),
3
2
1
phenylphosphorane was treated with 17 mg (66 µmol) of 4,4Ј-di- 57.6 (d, C-4, JPC ϭ 0 Hz), 48.5 (d, C-3, JPC ϭ 67.7 Hz), 16.8 (d,
methoxythiobenzophenone in ca. 0.6 mL of [D2]dichloromethane
1
2
PCH2, JPC ϭ 51.8 Hz), 14.6 (d, PCHCH3, JPC ϭ 4.0 Hz), 7.7
1
2
at Ϫ78°C. Ϫ H NMR (360.1 MHz, 243 K, [D2]dichloromethane):
(d, PCH2CH3, JPC ϭ 5.5 Hz). Ϫ 31P NMR (242.9 MHz, 243 K,
δ ϭ 8.10 (d, 2 H, o-H, Ph, 3JHH ϭ 8.8 Hz), 7.87 (d, 2 H, o-HЈ, Ph,
[D5]pyridine): δ ϭ ϩ31.0; (263 K): δ ϭ ϩ29.8; (283 K): δ ϭ 28.5;
3JHH ϭ 8.8 Hz), 7.68Ϫ7.53 (m, 6 H, o-H, o-HЈ, p-H, p-HЈ, PPh2), (298 K): δ ϭ ϩ27.5.
3
7.46 (m, 4 H, m-H, m-HЈ, PPh2), 6.72 (d, 2 H, m-H, Ph, JHH
ϭ
3
8.8 Hz), 6.60 (d, 2 H, m-HЈ, Ph, JHH ϭ 8.8 Hz), 4.78 (dq, 1 H,
PCHCH3, 2JPH ϭ 3.3 Hz, 3JHH ϭ 6.6 Hz), 4.06 (m, 1 H, PCHHЈ),
3.74, 3.65 (s, each 3 H, OCH3, OCH3Ј), 2.30 (m, 1 H, PCHHЈ),
1.30 (dd, 3 H, PCHCH3, 2JPH ϭ 20.4 Hz, 3JHH ϭ 6.6 Hz), 0.67 (dt,
Acknowledgments
Financial support from the Fonds der Chemischen Industrie, the
Deutsche Forschungsgemeinschaft, and the Ministerium für
Schule, Weiterbildung, Wissenschaft und Forschung des Landes
Nordrhein-Westfalen is gratefully acknowledged.
3 H, PCH2CH3, JPH ϭ 20.4 Hz, JHH ϭ 7.7 Hz). Ϫ 13C NMR
2
3
(90.6 MHz, 243 K, [D2]dichloromethane): δ ϭ 156.6 (p-C, Ph),
3
156.4 (p-CЈ, Ph), 145.7 (d, i-C, Ph, JPC ϭ 1.6 Hz), 141.8 (d, i-CЈ,
Ph, 3JPC ϭ 13.7 Hz), 135.9 (d, o-C, Ph2P, 2JPC ϭ 8.4 Hz), 133.0 (d,
2
4
o-CЈ, Ph2P, JPC ϭ 6.8 Hz), 132.6 (d, p-C, Ph2P, JPC ϭ 3.2 Hz),
132.1 (d, p-CЈ, Ph2P, JPC ϭ 2.6 Hz), 129.8 (o-C, Ph), 129.2 (d, m-
[1]
4
G. Wittig, Pure Appl. Chem. 1964, 9, 245; Acc. Chem. Res. 1974,
7, 6. A. W. Johnson, Ylide Chemistry, Academic Press, New
York, 1966. H. Pommer, Angew. Chem. 1977, 89, 437; Angew.
Chem. Int. Ed. Engl. 1977, 16, 423. A. W. Johnson, Ylides and
Imines of Phosphorus, Wiley, New York, 1993, and references
cited therein.
3
C, Ph2P, JPC ϭ 10.5 Hz), 129.17 (o-CЈ, Ph), 128.1 (d, m-CЈ, Ph2P,
3JPC ϭ 12.1 Hz), 124.4 (d, i-C, Ph2P, JPC ϭ 68.4 Hz), 121.5 (d, i-
1
1
CЈ, Ph2P, JPC ϭ 88.4 Hz), 112.2 (m-C, Ph), 111.6 (m-CЈ, Ph), 57.9
2
(s, C-4, JPC ϭ 0 Hz), 55.0 (OCH3), 54.9 (OCH3Ј), 52.6 (d, C-3,
[2]
M. Schlosser, Top. Stereochem. 1970, 5, 1; B. E. Maryanoff, A.
1JPC ϭ 62.6 Hz), 20.9 (d, PCH2CH3, JPC ϭ 52.1 Hz), 15.8 (d,
1
E. Reitz, Chem. Rev. 1989, 89, 863; E. Vedejs, M. J. Peterson,
Top. Stereochem. 1994, 21, 1; E. Vedejs, M. J. Peterson, Ad-
vances in Carbanion Chemistry, (Ed.: V. Snieckus), JAI Press,
Greenwich, CT, 1996, vol. 2, p. 1Ϫ85, and references therein.
2
2
PCHCH3, JPC ϭ 3.2 Hz), 8.3 (d, PCH2CH3, JPC ϭ 6.3 Hz). Ϫ
31P NMR (81.0 MHz, 233 K, [D2]dichloromethane): δ ϭ 27.9;
(243 K): δ ϭ 26.5; (253 K): δ ϭ 25.3.
[3]
E. Vedejs, C. F. Marth, J. Am. Chem. Soc. 1990, 112, 3905.
U. Schöllkopf, Angew. Chem. 1959, 71, 260; K. Okuma, Y. Yam-
[4]
(±)-Thiabetaine 5i: 11 mg (57 µmol) of diethyl(ethylidene)(phenyl)-
phosphorane was treated with 16 mg (62 µmol) of 4,4Ј-dimeth-
oxythiobenzophenone in ca. 0.6 mL of [D5]pyridine at Ϫ35°C. Ϫ
1H NMR (360.1 MHz, 268 K, [D5]pyridine): δ ϭ 8.76 (d, 2 H, o-
H, Ph, JHH ϭ 8.8 Hz), 8.38 (d, 2 H, o-HЈ, Ph, JHH ϭ 8.8 Hz),
8.13 (m, 2 H, o-H, PhP), 7.47 (m, 3 H, m-, p-H, PhP), 7.03 (d, 2
asaki, T. Komiya, Y. Kodera, H. Ohta, Chem. Lett. 1987, 357;
K. Okuma, Y. Tachibana, J. Sakata, T. Komiya, I. Kaneko, Y.
Komiya, A. P. Yamasaki, S. Yamamoto, H. Ohta, Bull. Chem.
Soc. Jpn. 1988, 61, 4323; A. P. Krapacho, M. P. Silvon, S. D.
Flanders, Tetrahedron Lett. 1974, 3817; E. Vedejs, D. A. Perry,
R. G. Wilde, J. Am. Chem. Soc. 1986, 108, 2985; review: E.
Schaumann, “The Thiocarbonyl Group”, In The Chemistry of
Double-bonded Functional Groups (Ed.: S. Patai), J. Wiley, New
York, 1989, p. 1269; for a related reaction, see: H. Fischer, K.
Treier, U. Gerbing, J. Organomet. Chem. 1992, 433, 127.
3
3
3
3
H, m-H, Ph, JHH ϭ 8.8 Hz), 6.86 (d, 2 H, m-HЈ, Ph, JHH
ϭ
8.8 Hz), 4.83 (q, 1 H, PCHCH3, 2JPH ϭ 0 Hz, 3JHH ϭ 6.7 Hz), 3.59
(s, 3 H, OCH3), 3.55 (m, 1 H, CHHЈ or CHHЈ), 3.49 (s, 3 H,
OCH3Ј), 3.08, 2.66, 2.12 (m, each 1 H, CHHЈ or CHHЈ), 1.56 (dd,
[5]
S. Wilker, C. Laurent, C. Sarter, C. Puke, G. Erker, J. Am.
Chem. Soc. 1995, 117, 7293.
3
3
3 H, PCHCH3, JPH ϭ 20.4 Hz, JHH ϭ 6.7 Hz), 0.96 (m, 6 H,
[6]
M. J. Boskin, D. B. Denney, Chem. Ind. (London) 1959, 330;
PCH2CH3, JPH,3JHH not determined). Ϫ 13C NMR (90.6 MHz,
3
N. P. Neureiter, F. G. Bordwell, J. Am. Chem. Soc. 1959, 81, 578;
D. B. Denney, M. J. Boskin, J. Am. Chem. Soc. 1960, 82, 4736.
268 K, [D5]pyridine): δ ϭ 157.3 (p-C, Ph), 157.2 (p-CЈ, Ph), 147.5
[7]
(s, i-C, Ph, 3JPC ϭ 0 Hz), 143.6 (d, i-CЈ, Ph, 3JPC ϭ 13.7 Hz), 134.3
C. Puke, G. Erker, N. C. Aust, E.-U. Würthwein, R. Fröhlich,
J. Am. Chem. Soc. 1998, 120, 4863.
2
4
(d, o-C, PhP, JPC ϭ 6.3 Hz), 132.0 (d, p-C, PhP, JPC ϭ 2.1 Hz),
130.2 (o-C, Ph), 128.8 (o-CЈ, Ph), 128.81 (d, m-C, PhP, JPC
[8]
I. V. Borisova, N. N. Zemlyanskii, A. K. Shestakova, Y. A. Us-
3
ϭ
tynyuk, Mendeleev Commun. 1996, 90.
1
[9]
10.5 Hz), 125.6 (d, i-C, PhP, JPC ϭ 76.8 Hz), 112.9 (m-C, Ph),
H. Schmidbaur, A. Schier, Chem. Ber. 1981, 114, 3385.
J. W. Scheeren, P. H. J. Ooms, R. J. F. Nivard, Synthesis 1973,
[10]
112.5 (m-CЈ, Ph), 58.2 (d, C-4, 2JPC ϭ 0 Hz), 55.0, 54.9 (OCH3 and
149.
1
1
OCH3Ј), 53.8 (d, C-3, JPC ϭ 67.4 Hz), 17.8 (d, PCH2, JPC
ϭ
[11]
Phosphorus-31 NMR Spectral Properties in Compound Charac-
1
55.8 Hz), 16.7 (d, PCH2, JPC ϭ 45.3 Hz), 14.7 (d, PCHCH3,
terization and Structural Analysis (Eds.: L. D. Quin, J. G. Verk-
ade), VCH, New York, 1994.
2JPC ϭ 5.3 Hz), 7.76, 7.68 (d, PCH2CH3, JPC ϭ 5.3 Hz). Ϫ 31P
2
[12]
F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G.
NMR (242.9 MHz, 243 K, [D5]pyridine): δ ϭ ϩ27.6; (263 K): δ ϭ
ϩ25.6; (268 K): δ ϭ ϩ25.3.
Orpen, R. Taylor, J. Chem. Soc., Perkin Trans. 2 1987, S1.
[13]
U. Kunze, R. Merkel, W. Winter, Chem. Ber. 1982, 115, 3653.
E. Schaumann, F.-F. Grabley, Liebigs Ann. Chem. 1979, 1702;
H. J. Bestmann, R. Engler, H. Hartung, K. Roth, Chem. Ber.
1979, 112, 28.
(±)-Thiabetaine 10: 87 mg (0.34 mmol) of 4,4Ј-dimethoxythioben-
zophenone in 2 mL of THF was added to 50 mg (0.34 mmol) of
triethyl(ethylidene)phosphorane in 5 mL of pentane at 0°C. The
supernatant solution was removed and the precipitate washed 5
times with 5 mL of pentane. The collected solid was dried in vacuo.
Ϫ H NMR (599.9 MHz, 298 K, [D5]pyridine): δ ϭ 8.62 (d, 2 H,
o-H, Ph, JHH ϭ 9.0 Hz), 8.39 (d, 2 H, o-HЈ, Ph, JHH ϭ 9.0 Hz),
6.97 (d, 2 H, m-H, Ph, JHH ϭ 9.0 Hz), 6.89 (d, 2 H, m-HЈ, Ph,
[14]
A. Bondi, J. Phys. Chem. 1964, 68, 441.
[15]
T. Kawashima, K. Kato, R. Okazaki, J. Am. Chem. Soc. 1992,
114, 4008; Angew. Chem. 1993, 105, 941; Angew. Chem. Int. Ed.
Engl. 1993, 32, 869, and references therein; review: T. Kawash-
ima, R. Okazaki, Synlett 1996, 600; M. Ul-Haque, C. N.
Caughlan, F. Ramirez, J. F. Pilot, C. P. Smith, J. Am. Chem.
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Evidence for the Occurrence of gauche-Betaine Intermediates in the Thio Wittig Reaction
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Received March 1, 1999
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