Polylithiumorganic compounds. Part 27: C,C-bond forming reactions of 3,4-dilithio-2,5-dimethyl-2,4-hexadiene

Article abstract of DOI:10.1016/S0040-4020(00)00229-5

The reaction of the title compound 3,4-dilithio-2,5-dimethyl-2,4- hexadiene (4) with various mono- and bifunctional carbon-centered electrophiles is investigated, with special emphasis on carbonyl and carbonic acid derivatives. Depending on the nature of the electrophile, mono- and disubstituted derivatives with either butadiene, allene, or alkyne skeleton are obtained. Ring forming reactions in the second derivatization step are only observed in a few cases. Electrophiles bearing halogens as leaving groups react by a different mechanism and are not suitable in C,C-bond forming reactions. The compounds obtained in this investigation are suitable and highly reactive building blocks for further modifications. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00229-5

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 3373±3383
Polylithiumorganic Compounds. Part 27:1 C,C-Bond Forming
Reactions of 3,4-Dilithio-2,5-dimethyl-2,4-hexadiene
a
b
Adalbert Maercker,a, Joachim van de Flierdt and Ulrich Girreser
*
a
È È
Institut fur Organische Chemie der Universitat Siegen, Adolf-Reichweinstr. 2, D-57068 Siegen, Germany
b
È
Pharmazeutisches Institut der Christian-Albrechts-Universitat, Gutenbergstr. 76, D-24118 Kiel, Germany
Dedicated to Professor Harald GuÈnther on the occasion of his 65th birthday
Received 18 February 2000; accepted 13 March 2000
AbstractÐThe reaction of the title compound 3,4-dilithio-2,5-dimethyl-2,4-hexadiene (4) with various mono- and bifunctional carbon-
centered electrophiles is investigated, with special emphasis on carbonyl and carbonic acid derivatives. Depending on the nature of the
electrophile, mono- and disubstituted derivatives with either butadiene, allene, or alkyne skeleton are obtained. Ring forming reactions in the
second derivatization step are only observed in a few cases. Electrophiles bearing halogens as leaving groups react by a different mechanism
and are not suitable in C,C-bond forming reactions. The compounds obtained in this investigation are suitable and highly reactive building
blocks for further modi®cations. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
Results and Discussion
The results obtained upon reaction of 4 with different
electrophiles and biselectrophiles will be divided into the
following chapters:
Among dilithiumorganic compounds with both negative
charges formally located at sp2-hybridized carbon atoms,
3,4-dilithio-2,5-dimethyl-2,4-hexadiene (4)2 has a high
potential for the synthesis of heterocycles, only comparable
to the well investigated 1,2-dilithiobenzene (3) or (Z)-b,o-
dilithiostyrene (5) and its derivatives.3 The structure of 4 is
known in solution4 as well as in the solid state,5 and its
stability, rearrangement and decomposition products have
been analyzed in different solvents.6 4 Allows access to
fascinating compound classes, that are hetero[6]radialenes
6, hetero[3]radialenes 7, and allene derivatives 8.7 4 is easily
accessible, stabilized with lithium salt, by lithium bromine
exchange starting from dibromide 1, or free of lithium salt
by addition of lithium metal to the highly reactive triene 2,
even on a molar scale.8 Thus, a systematic investigation of
the reactivity of 4 towards carbon-centered biselectrophiles
and simple electrophiles was forwarded, in order to evaluate
the potential of 4 in the synthesis of functionalized carbo-
cycles and reactive disubstituted derivatives. The structure
of these derivatives is mainly determined by the nature of
the electrophile, i.e. its hardness according to Pearson's
concept of hard and soft acids and bases, as we have already
shown for the derivatization of unsymmetrically substituted
2,3-dilithiobutadienes with a variety of electrophiles
(Scheme 1).9
1. Ring closure reactions and attempted ring closure of 4
with carbon disul®de, carbon dioxide, and follow-up
reactions;
2. An investigation into the reaction of 4 with diethyl
carbonate, esters, and amides;
3. Reaction of 4 with various aldehydes and ketones; and
4. Reaction of 4 with miscellaneous electrophiles.
Ring closure reactions and attempted ring closure of 4
with carbon disul®de, carbon dioxide, and follow-up
reactions
A solution of the dilithiobutadiene 4 in diethyl ether is
brought to reaction with one equivalent of carbon disul®de.
After work-up of the reaction mixture with a degassed,
oxygen-free aqueous ammonium chloride solution the thio-
phenthione 15 is obtained in 60% yield as main product.
Puri®cation is possible by several cleaning procedures,
while avoiding thermal stress that leads to decomposition.
A possible reaction mechanism is outlined in Scheme 2,
structure assignment is simpli®ed by comparison of the
spectroscopic data with those of thiophenthione 20.10
Interestingly, when a non-degassed aqueous ammonium
chloride solution is used, the hydroxylated thiophenthione
16 is the major product. When hydrolysis of the reaction is
completely omitted in order to access the hypothetical
Keywords: C,C-bond formation; cyclizations; polylithiumorganic
compounds; synthetic methods.
* Corresponding author. Tel.: 149-271-740-4377; fax: 149-271-740-
2512; e-mail: maercker@chemie.uni-siegen.de
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00229-5

3374
A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
Scheme 1. XˆSiR2, SnR2, Ti, BNR; Rˆaryl, alkyl.
thioketones 14 and 17, exclusive formation of an
orange±red tar is observed, giving no evidence for the
wanted three-membered rings. The formation of tarry
products upon reaction of metallorganic compounds
with carbon disul®de is well known.11 Similarly, when
quenching 4 with either two equivalents of carbon disul-
®de or diethyl trithiocarbonate, complex mixtures are
formed, consisting mainly of polymeric material.
There is no suf®cient spectroscopic evidence for the
formation of 17 or the formation of a 1,4-dithioketo[6]-
radialene as is shown by GC/MS analysis of the volatile
compounds.
However, when a non-aqueous workup of the reaction
mixture of 4 with 1 equiv. of carbon disul®de is performed
by addition of methyl iodide, the three-membered ring 18,
the bismethylthio derivative of 11 is isolated in over 50%
yield. Structure assignment of the allene is straightforward
when looking at the 13C NMR data with the sp-hybridized
carbon atom at about 186 ppm and the allenic stretching
vibration at 2000 cm21 in the IR spectrum and the corre-
sponding Raman resonance at 2000 cm21 for the asym-
metric stretching vibration.12 Furthermore a chemical
proof is given by the fact that 18 does not react readily
with PTAD (3,5-dihydro-4-phenyl-4H-1,2,4-triazole-3,5-
Scheme 2.

A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
3375
Scheme 3.
dione), one of the strongest dienophiles,13 in contrast to the
[3]- and [6]radialenes investigated so far.14 The allene 18
rearranges quantitatively to the 1,3-diene 19 upon heating to
1508C, this rearrangement requires as much as 3608C for the
corresponding hydrocarbon without sulfur atoms.15
Obviously, lithium sul®de elimination of either 11 or 13 is
not the favored reaction, instead polymerization or
rearrangement of their hydrolysis products to 12 is observed
(Scheme 2).
with carbon dioxide in the presence of TMS chloride. Trig-
gering the reactivity of 4 by addition of freshly prepared
magnesium bromide has no effect on the outcome of the
reaction with carbon dioxide either.
Despite the reasonably assumed formation of 11 or 13 in the
reaction of 4 with carbon disul®de, the formation of 24
cannot be concluded. Probably steric constraints and not
the reactivity of the intermediate monosubstituted vinyl-
lithium compound determine the ring closure.
The reaction of 4 with carbon dioxide leads to 2,3-diiso-
propylidene-succinic acid (22) in over 80% yield.2 The
diacid is the only product isolated, either upon addition of
4 to a suspension of carbon dioxide in diethyl ether at
21208C or by slowly blowing carbon dioxide gas into a
solution of 4 at room temperature. Even the optimized reac-
tion conditions employed by Bickelhaupt et al. to cyclize
1,3-di(bromomagnesio)propane with carbon dioxide to
cyclobutane by using a carbon dioxide/argon mixture16 do
not afford any cyclization product with 4. Attempts to trap
the hypothetical cyclic intermediate 24 are performed in the
presence of trimethylsilyl (TMS) chloride. This derivatiza-
tion reagent reacts rather slowly with 4 affording 21 in 40%
yield and a remarkable amount of 23 as well as 2,5-
dimethyl-2,4-hexadiene. Yields are better when using a
better leaving group like the tri¯ate anion (see Experimental)
(Scheme 3).
An investigation into the reaction of 4 with diethyl
carbonate, esters, and amides
The reaction of 4 with diethyl carbonate affords a complex
product mixture (see Table 1 for the identi®ed compounds),
the possible cyclization product 26 is not found. Instead,
two monosubstituted and three disubstituted ester deriva-
tives can be identi®ed, besides minor amounts of the buta-
diene 32, arising from double hydrolysis. The structure of
these compounds can be determined by NMR spectroscopy
after fractional distillation and further separation by
preparative gas chromatography, the structure assignment
of diester 29 is only tentative. Formation of the isomeric
monoesters can be explained by the high acidity of diethyl
carbonate, responsible for the partial hydrolysis of the
dilithiobutadiene 4. The 1,4-dienes 29 and 31 are generated
via an intermolecular metallation of monosubstituted 30 by
4, as the acidity of the methyl groups is increased through
the already present ester function. Quenching of the stable
allyl anion 33 then leadsÐkinetically controlledÐto 31 or
to the thermodynamically more stable 1,3-diene 30, respec-
tively. The same is true for the interconversion between 27
So TMS chloride is a suitable reagent for the trapping of 24.
However, 1,1-bis(trimethylsilyloxy)cyclopropane 25 cannot
be detected when performing the simultaneous addition of
carbon dioxide and TMS chloride to 4 at temperatures
between 2908C and room temperature or by quenching 4
Table 1. Products obtained upon reaction of 4 affording esters and diesters 27 to 32
Entry
Reaction conditions
Yield of compound (%)a
27
28
29
30
31
32
1
2
3
4
5
6
7
Addition of 1 equiv. of (EtO)2CO at 2408C to 4
Addition of 4 to 1 equiv. of (EtO)2CO at 2308C
Addition of 4 to 2 eq. of (EtO)2CO at 2308C
Addition of 4 to 4 eq. of (EtO)2CO at 2308C
Addition of 4 to 8 equiv. of (EtO)2CO at 2308C
Addition of C(OEt)4 and BF3 at 2808C to 4
15
6
6
0
3
2
0
6
0
3
11
3
2
0
44
42
64
58
50
40
13
15
23
0
0
0
1
ndb
ndb
ndb
ndb
12c
5
22
35
50
15
3
3
34:62
3
0
Addition of 1 equiv. of (EtO)2CO and then Et2SO4 to 4 at 2308C
a Remainder consisting of a complex mixture of various by-products, a single compound to a small extent only.
b Not determined.
c Besides 4% of 2 and 5% of (EtO)2CO.

3376
A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
Scheme 4.
and 28. The 1,4-diene 31 can easily be rearranged to 30 by
using a 5% aqueous solution of sodium hydroxide
(Scheme 4). There is further evidence for the complex reac-
tion mechanism: when quenching 4 stepwise with 1 equiv.
of diethyl carbonate and 1 equiv. of diethyl sulfate, the 1,4-
diene 34 is obtained in 62% yield (Scheme 5).
kinetically controlled quenching of the allyl anion 33
(Scheme 5).
Furthermore, quenching 4 with ethyl chloroformiate affords
a 1:1 mixture of 30 and 31, probably as the true product
distribution of kinetic controlled reaction, as the lithium
chloride formed during the reaction is of course not a strong
base.
So the formation of 27 and 30 is partly occurring during the
work-up. This type of intermolecular rearrangement has
been investigated and proved previously by us for dilithio-
butadienes.9 Here the metallation occurs with the mono-
substituted compound 33 and is favored by the polar
solvent system, consisting of the solvent, unchanged
diethyl carbonate, and the already formed lithium ethoxide.
When the reacting mixture of 4 and diethyl carbonate is
quenched with deuterium oxide, no noticeable deuterium
incorporation into the products of hydrolysis is observed.
Upon reacting 30 with 1 equiv. of 4 and subsequent
hydrolysis a 2:1 mixture of 30 and 31 is found, demonstrat-
ing the postulated acidity of the methyl groups and the
The outcome of the reaction of 4 with ethyl acetate is
predictable, as the protons of this ester are even more acidic
than those of diethyl carbonate, monosubstituted butadiene
35 is isolated in 53% yield. With methyl acrylate, besides
many other products, the diester 36 is formed as the main
component arising by a double Michael-type addition.
When attempting to cyclize 4 with 1 equiv. of the diester
27 under high dilution conditions polycondensation occurs,
a hydrolysis product of the ®rst polymerization step, namely
37, is isolated in about 5% yield, demonstrating the nature
of the polycondensate (Scheme 6).
Scheme 5.
Scheme 6.

A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
3377
spectrometry after puri®cation by preparative gas chromato-
graphy. The reaction is analyzed in detail in the temperature
range of 2100 to 358C in intervals of 208C in diethyl ether,
the results thereby obtained are summarized in Table 2
(Scheme 8).
Three different products of disubstitution can be formed in
principle, arising from the three different mesomeric forms
4a±4c, as shown below (Scheme 9). Structure 4c has the
Scheme 7.
Table 2. Product distribution in the reaction of 4 with acetone
Entry
Reaction conditions
Yield of compound (%)
41
42
43
32
1
2
3
4
Addition of acetone to 4 between 2100 and 2608C
Addition of acetone to 4 between 260 and 358C
Addition of acetone to a mixture of 4 and 2 equiv. HMPA at 2808C
Addition of 4 to a tenfold excess of acetone at 2408C
29
31
28
70
34
23
34
20
15
3
33
0
6
9
5
10
two anionic centers located at sp3 hybridized carbon atoms
with the higher polarizability, thus being the softer base
according to Pearsons's concept of hard and soft acids and
bases,17 when compared to 4a. Esters, amides, and carbon
dioxide can be considered as hard acids, so the formation of
derivatives with a 1,3-butadiene skeleton is preferred. As
was observed for unsymmetrically substituted dilithiobuta-
dienes before,9 the preferential formation of the 1,4-substi-
tuted 2-butynes is observed upon reaction with aldehydes
and ketones. Quite interestingly, the allenic structure 43 is
obtained as well, arising from structure 4b with intermediate
basicity. Upon addition of complexing additives like
hexamethyl phosphoric acid (HMPA) or DMPU or
TMEDA the amount of allene increases, here the charge
distribution is changed in the complex in favoring the
formation of 43. When adding 4 to an excess of acetone
partial hydrolysis is the main reaction observed. The
rearrangement of allene 43 to butyne 42 is not possible,
stirring of 43 with an excess of n-butyllithium at room
temperature for several days does not afford any 42 after
the usual work-up (Scheme 8).
Scheme 8.
With N,N-dimethylformamide a mixture of products of di-
and monosubstitution (38: 48%, 39: 27%) is obtained upon
reaction with 4; with N,N-dimethylbenzamide the exclusive
formation of the monosubstituted compound 40 (85%) is
observed (Scheme 7).
Reaction of 4 with various aldehydes and ketones
The reaction with acetone is quite remarkable and delivers
three different alcohols, 41, 42, and 43, the structure of these
products is unequivocally assigned by NMR and mass
Scheme 9.
Table 3. Alcohols obtained upon reaction of 4 with aldehydes and ketones
Entry
Reaction conditions
Compound, R1, R2
Yield (%)a
44
45
32
1
2
3
4
5
Introducing formaldehyde gas into a solution of 4 at 2508C
Addition of acetaldehyde at 2608C
Addition of benzaldehyde at 2308C
Addition of acetophenone at 2608C
Addition of benzophenone at 2308C
a: R1ˆR2ˆH
0
33
0
10
0
83 (68)
47
65 (52)
70
78 (65)
0
20
0
20
0
b: R1ˆH, R2ˆMe
c: R1ˆH, R2ˆPh
d: R1ˆMe, R2ˆPh
e: R1ˆR2ˆPh
a Isolated yield of crude product after distillation, number in brackets isolated compound after recrystallization, 45b±d as mixture of diastereomers.

3378
A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
employing proper electrophiles, however, ring closure reac-
tions are only observed in a few cases. The reason for this is
the high steric requirements of this ring closure reaction, the
carbon±carbon bond to be formed is short (154 pm)
compared to the carbon, heteroatom bonds which are
formed upon reaction of 4 with heteroatom electrophiles
(for example C±B 157 pm, C±P 184 pm, C±Si 189 pm,
C±Sn 216 pm). Furthermore the ring closure of 4 is success-
ful with dichloromethylsilane, but not with dichloro-
dimethylsilane, demonstrating the steric requirements of
the ring closure. Secondly, only those intermediates can
cyclize easily, which exhibit a 1,3-butadiene skeleton, the
ring closure is nearly impossible if the monosubstituted
derivative has preferentially an allenic or alkynic skeleton.
Thirdly, the heteroatoms mentioned above probably react
via ate complexes, which is not possible for carbon centered
electrophiles.
Scheme 10.
4 is brought to reaction with a number of aldehydes and
ketones, the results are summarized in Table 3. The forma-
tion of allenic derivatives cannot be strictly excluded,
however, under the reaction conditions the amount is too
small to allow structure assignment. The formation of 1,4-
disubstituted 2-butyne derivatives 45 is observed through-
out. The monosubstituted derivatives 44 are formed after
hydrolysis of one carbanionic center and have a 1,3-buta-
diene skeleton (Scheme 10).
Experimental
Reaction of 4 with miscellaneous electrophiles
General methods
Using a nitrogen analogue of carbon disul®de, for example
dicyclohexyl carbodiimide, affords the expected disubsti-
tuted butadiene 46. Electrophiles with one nitrogen and
one sulfur at the electrophilic carbon atom, that is ethyl
and phenyl thiocarbamate work well too, when the primarily
formed addition product is trapped with methyl iodide,
allowing the isolation of 47 and the hydrolysis product 48
(Scheme 11).
All reactions with air sensitive compounds were carried out
under an atmosphere of dried argon (99.996%). Ethereal
solvents were puri®ed by adsorptive ®ltration over basic
aluminium oxide (activity I) and freshly distilled under
argon from sodium±benzophenone ketyl. Mass spectra
were obtained on a Varian MAT 112 (OV 101 capillary);
m/z values are reported followed by the relative intensity in
parantheses. The ten strongest peaks and, if not enclosed,
the intensity of the molecular ion is given. The molecular
ion is given as M1, but of course radical cations are formed.
High resolution mass spectra were recorded on a Varian
MAT 311 A. Nuclear Magnetic Resonance (1H, and 13C)
spectra were recorded on the Bruker instruments WP 80
and WH 400. Chemical shifts are reported in parts per
million (d) down®eld from an internal TMS reference.
Coupling constants (J) are reported in Hertz (Hz), and
spin multiplicities are indicated by the following symbols
s(singlet), d(doublet), t(triplet), q(quartet), quint(quintet),
m(multiplet), br (broad signal). Separations of the reaction
mixtures were performed using a preparative gas chromato-
graph (Hupe und Busch, HP 1075c prep. GC). The follow-
ing stationary phases were employed: 10% DEGS on
Chromosorb W 47/60 mesh, 15% DEGS on Chromosorb
W 60/80 mesh, 20% CW 1000 42/60 mesh, 10% SE 30.
For analytical gas chromatography a Siemens L350 (FID)
with a Spectra Physics 4001 integrator with Silicon OV 101
(30 m, WAG Griesheim) and 5% Phenylmethylsilicon
(25 m, Hewlett Packard) capillary columns were employed.
Reaction of 4 with electrophiles bearing halogens as the
leaving groups does not afford any products of substitution.
Either quantitative lithium halogen exchange occurs, which
leads to the formation of triene 2, or the product mixtures
are of such a complexityÐusually together with a large
amount of polymeric materialÐthat no main compounds
can be isolated or identi®ed. Among the electrophiles,
which were tested are tetrachloromethane, dichloro-
methane, 2,2-dichloro-1,1-diphenylethene, phenylisonitrile
dichloride, phthalic acid dichloride, epichlorohydrin, t-butyl
chloride, or phosgene (employed as triphosgene). Among
the carbonyl compounds that were tested are diethyl phtha-
late, phthalic acid anhydride, and maleic acid anhydride, for
example. Carbonyl diimidazolide does not afford any
monomeric cyclopropanone derivative either, but instead
quantitative polymerization occurs.
Conclusions
4 is a suitable reagent for C,C-bond forming reactions when
Scheme 11.

A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
3379
IR spectra were recorded on either a Perkin Elmer PE 580 or
a Beckman Acculab 4. IR absorption bands are given in
cm21. Elemental analyses were performed by the Mikro-
an analytical sample was possible by preparative gas chro-
matography (DEGS). H NMR (80 MHz, CDCl3) 1.55 (s,
1
6H, 2£Me), 1.78 (s, 6H, 2£Me), 2.22 (s, 6H, 2£SMe). 13C
NMR (100 MHz, CDCl3) d 15.3, 21.5, 23.1, 36.7, 47.9,
94.6, 101.0, 187.7. MS (70 eV): m/z 214 (M1, 26),
199(100), 152(44), 151(53), 137(18), 111(48), 105(24),
91(40), 77(24), 41(21). IR (KBr pellet): 2000 cm21, s,
(CvCvC). Anal. calcd for C11H18S2: C, 61.63; H, 8.46;
S, 29.91; found: C, 61.62; H, 8.50; S, 29.09.
È
analytisches Labor Beller (Gottingen).
General procedure for the derivatization of 4 with
electrophiles
Salt free solutions of 4 were prepared in a concentration of
about 1 M as described elsewhere,8 the content of lithium-
organic compound was determined by titration of diphenyl-
acetic acid.18 The solutions were stored at 2408C to avoid
rearrangement.6 A solution of 4 in diethyl ether was cooled
to 2408C if not stated otherwise, and a solution of the
electrophile in diethyl ether was added dropwise at this
temperature. The reaction mixture was allowed to warm to
room temperature, then a saturated solution of ammonium
chloride was added. The organic layer was washed with a
solution of saturated sodium bicarbonate and dried over
magnesium sulfate. After evaporation of the solvent with
a rotary evaporator the crude product was usually puri®ed
by fractional distillation and analytical samples, when
necessary, were further puri®ed by preparative gas chroma-
tography.
1,1-Bis(methylthio)-2,3-diisopropylidenecyclopropane
(19). 0.5 ml of 18 were heated slowly to 1508C, when reach-
ing this temperature the rearrangement was completed
1
according to the spectroscopic data: H NMR (80 MHz,
CDCl3) d 1.98 (s, 6H, 2£Me), 2.00 (s, 6H, 2£Me), 2.30
(s, 6H, 2£SMe). 13C NMR (100 MHz, CDCl3) d 15.2,
23.2, 23.6, 35.1, 119.8, 122.7.
3,4-Bis(trimethylsilyl)-2,5-dimethyl-2,4-hexadiene (21)
and 2,5-dimethyl-3-trimethylsilyl-2,5-hexadiene (23).
To a solution of 55 mmol of 4 in 70 ml of diethyl ether
were added 20.0 ml (110 mmol) of trimethylsilyl tri¯uoro-
methanesulfonate in 60 ml of diethyl ether at 2208C. The
reaction mixture was then stirred for 24 h at room tempera-
ture. After the work-up the crude product (13.0 g) was
distilled to afford 5.0 g (20 mmol, 37%) of 21, bp 65±
3,3-Dimethyl-5-(1-hydroxy-1-methylethyl)-3H-thiophen-
2-thione (16). The reaction of 100 mmol of 4 in 100 ml of
diethyl ether with 6.0 ml (100 mmol) of carbon disul®de
afforded after distillation 14.0 g of crude product, consisting
of 16 and 15, bp 34±398C (0.01 Torr). Bulb-to-bulb distilla-
tion delivered 9.0 g (44 mmol, 44%) of 16 and 3.2 g
(17 mmol, 17%) of 15. Further puri®cation by preparative
gas chromatography (SE 30) was necessary. Characteriza-
tion of 16: 1H NMR (80 MHz, CDCl3) 1.31 (s, 6H, 2£Me),
1.52 (s, 6H, C(OH)Me2), 6.05 (s, 1H, vCH). 13C NMR
(100 MHz, CDCl3) d 28.5, 29.8, 68.5, 70.5, 132.0, 146.7,
250.6. MS (70 eV): m/z 202 (M1, 17), 186(17), 171(33),
145(33), 111(25), 110(75), 92(33), 77(33), 55(92), 43(100).
1
678C (0.01 Torr). H NMR (80 MHz, CDCl3) d 0.12 (s, 18
H, SiMe3), 1.56/1.86 (2£s, 2£6H, Me). MS (70 eV): m/z 254
(M1, 33), 180(17), 166(17), 155(17), 151(17), 124(15),
99(13), 84(23), 73(100), 45(17). Anal. calcd for C14H30Si2:
C, 66.06; H, 11.88; found: C, 66.16; H, 11.76. As by-
product, 23 was found: MS (70 eV): m/z 182 (M1, 9),
167(6), 113(15), 93(7), 74(13), 73(100), 59(15), 45(22),
43(9), 41(7).
Reaction with diethyl carbonate
To a solution of 50 mmol of 4 in 50 ml of diethyl ether were
added 12.0 ml (100 mmol) of diethyl carbonate. After work-
up the crude product (15.0 g) was puri®ed by distillation, the
main fractions with bp 63±658C (0.005 Torr). The mono-
substituted esters 30 and 31 could be further enriched by
preparative gas chromatography on DEGS, the diesters on a
SE 30 column. Yields are given in Table 1, the esters were
characterized as follows.
3,3-Dimethyl-5-isopropyl-3H-thiophen-2-thione (15). The
reaction was performed on the same scale as described
above, during the work-up degassed solutions of ammonium
chloride and sodium bicarbonate were used to afford 15 g of
a red oil as crude product, which was puri®ed by distillation,
bpˆ30±358C (0.01 Torr), yield 2.0 g (11 mmol, 11%). The
1
remaining compound formed a tar during distillation. H
1
Ethyl 2-isopropylidene-4-methyl-3-pentenoate (30). H
NMR (80 MHz, CDCl3) d 1.19 (d, Jˆ7.2 Hz, 6H,
CHMe2), 1.30 (s, 6H, 2£Me), 2.69 (septet of d, Jˆ7.2,
1.6 Hz, 1H, CH), 5.90 (d, Jˆ1.6 Hz, 1H, vCH). 13C
NMR (100 MHz, CDCl3) d 22.1, 29.1, 30.0, 68.2, 131.9,
145.3, 251.3. MS (70 eV): m/z 186 (M1, 83), 171(44),
153(30), 144(100), 127(35), 111(39), 95(43), 67(30),
59(22), 41(30).
NMR (80 MHz, CDCl3) d 1.29 (t, Jˆ7.3 Hz, 3H,
OCH2CH3), 1.55 (d, Jˆ2 Hz, 3H, Me), 1.75 (d, Jˆ1 Hz,
3H, Me), 1.81 (d, Jˆ1 Hz, 3H, Me), 2.00 (d, Jˆ2 Hz, 3H,
Me), 4.19 (q, Jˆ7.3 Hz, 2H, OCH2CH3), 5.78 (br. septet,
Jˆ2 Hz, 1H, vCH). 13C NMR {off-resonance decoupling}
(100 MHz, CDCl3) d 14.3(q), 19.3(q), 22.1(q), 22.5(q),
25.6(q), 60.2(t), 120.8(d), 126.7(s), 136.3(s), 142.8(s),
169.4(s). MS (70 eV): m/z 182 (M1, 100), 139(28),
137(39), 109(61), 93(61), 87(39), 67(50), 59(56), 43(44),
41(39). Anal. calcd for C11H18O2 (containing isomer 31):
C, 72.49; H, 9.95; found: C, 72.53; H, 10.00.
2,2-Bis(methylthio)-3,3-dimethyl-1-(2-methyl-1-propenyli-
dene)cyclopropane (18). The reaction was performed on the
same scale as above. After addition of the solution of carbon
disul®de the reaction mixture was kept at 2408C for 1 h,
then a solution of 12.5 g (200 mmol) of methyl iodide in
80 ml of diethyl ether was added dropwise. After the usual
work-up 23 g of crude product was obtained, which
afforded, after fractional distillation, 5.0 g (23 mmol,
23%) of 18, bp 558C (0.01 Torr). Further puri®cation of
Ethyl 2-(1-methylethenyl)-4-methyl-3-pentenoate (31).
1H NMR (80 MHz, CDCl3) d 1.27 (t, Jˆ7.3 Hz, 3H,
OCH2CH3), 1.58 (d, Jˆ2 Hz, 3H, Me), 1.66 (d, Jˆ1 Hz,
3H, Me), 1.77 (m, 3H, Me), 3.90 (d of m, Jˆ8 Hz, 1H,

3380
A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
CH), 4.14 (q, Jˆ7.3 Hz, 2H, OCH2CH3), 4.88 (m, 2H,
vCH2), 5.42 (d of m, Jˆ8 Hz, 1H, vCH). 13C NMR
{off-resonance decoupling} (100 MHz, CDCl3) d 14.2(q),
18.0(q), 20.9(q), 25.9(q), 52.3(d), 60.7(t), 112.7(t), 121.2(d),
135.3(s), 142.9(s), 172.9(s). MS (70 eV): m/z 182 (M1, 20),
111(12), 109(100), 108(8), 81(14), 79(8), 67(52), 55(14),
43(18), 41(14).
1.92 (d, Jˆ1.2 Hz, 3H, Me), 2.14 (s, 3H, COMe), 5.82 (m,
1H, vCH).
Dimethyl 3,4-diisopropylidene-1,6-hexanedicarboxylate
(36). From 100 ml of a 1 M solution of 4 in diethyl ether
(100 mmol) and 9.5 ml (100 mmol) of methyl acrylate.
After the usual work-up the material was further puri®ed
by bulb to bulb-distillation. Yield not determined. 1H NMR
(80 MHz, CDCl3) d 1.48/1.72 (2£s, 2£6H, vCMe2), 2.28
(m, 8H, CH2CH2), 3.64 (s, 6H, OMe). MS (70 eV): m/z 282
(M1, 55), 222(38), 218(50), 135(100), 133(50), 121(55),
119(50), 107(38), 105(38), 55(50).
Diethyl 2,3-diisopropylidene-succinate (27). 1H NMR
(80 MHz, CDCl3) d 1.23 (t, Jˆ7.2 Hz, 6H, OCH2CH3),
1.72/2.17 (2£s, 2£6H, Me), 4.14 (q, Jˆ7.2 Hz, 4H,
OCH2CH3). 13C NMR (100 MHz, CDCl3) d 14.2, 22.1,
23.6, 59.9, 125.8, 149.0, 167.3. MS (70 eV): m/z 254 (M1,
15), 209(30), 208(48), 167(11), 163(11), 162(100), 135(15),
134(37), 107(30), 43(15). Anal. calcd for C14H22O4: C,
66.12; H, 8.72; found: C, 66.34; H, 8.64.
Ethyl 4-keto-7-methyl-2,3,5-triisopropylidene-6-octeno-
ate (37). To a solution of 5.0 g (20 mmol) of 28 in 350 ml
of diethyl ether was added dropwise a solution of 4
(20 mmol) in 150 ml of diethyl ether over a period of
90 min. at 2708C. After the usual work-up a polyconden-
sate was isolated, furthermore 300 mg (1.0 mmol, 5%) of
Diethyl 2-(1-methylethenyl)-3-isopropylidene-succinate
(28). 1H NMR (80 MHz, CDCl3) d 1.22/1.25 (2£t,
Jˆ7 Hz, 2£3H, 2£OCH2CH3), 1.79/2.09 (2£s, 2£3H,
Me), 1.82 (m, 3H, C(vCH2)CH3), 4.12/4.15 (2£q,
Jˆ7 Hz, 2£2H, 2£OCH2CH3), 4.13 (m, 1H, CH), 4.85/
4.95 (2£m, 2£1H, C(vCH2)CH3). MS (70 eV): m/z 254
(M1, 20), 209(50), 208(70), 181(20), 162(75), 135(60),
134(40), 108(25), 107(100), 91(25). Tentatively assigned
29: MS (70 eV): m/z 254 (M1, 9), 209(42), 208(83),
162(67), 151(50), 135(42), 134(83), 107(100), 93(42),
43(50).
1
37, bp 115±1208C (0.01 Torr). H NMR (80 MHz, CDCl3)
d 1.17 (t, Jˆ7.1 Hz, 3H, OCH2CH3), 1.44/1.56 (2£d,
J,1 Hz, 2£3H, CHvC(CH3)2), 1.61/1.64/1.66/1.69/2.05/
2.07 (6£s, 6£3H, 6£Me), 4.02 (q, Jˆ7.1 Hz, 2H,
OCH2CH3), 5.48 (septet, J,1 Hz, 1H, vCH). MS
(70 eV): m/z 318 (M1, 50), 303(40), 257(41), 229(43),
109(100), 107(65), 55(42), 53(24), 43(70), 41(64).
2,3-Diisopropylidene-succinaldehyde (38) and 2-isopro-
pylidene-4-methyl-3-pentenal (39). To 100 ml (100 mmol)
of a 1 M solution of 4 in diethyl ether were added dropwise
at 2508C 19.0 ml (250 mmol) of N,N-dimethylformamide
in 150 ml of diethyl ether. After warming to room tempera-
ture the reaction mixture was poured into an ice-cold solu-
tion of 20 ml of hydrochloric acid in 150 ml of water. The
aqueous layer was extracted several times with diethyl
ether. After washing and drying of the combined organic
layers, the remainder (15.0 g) was distilled to afford 8.0 g
(48 mmol, 48%) of 38 and 3.8 g (27 mmol, 27%) of 39.
Characterization of 38: Bp 75±808C (0.05 Torr), the liquid
solidi®ed upon standing to a brownish solid. 1H NMR
(80 MHz, CDCl3) d 1.76/2.31 (2£s, 2£6H, Me), 10.09 (s,
2H, CHO). 13C NMR (100 MHz, CDCl3) d 19.2, 24.2,
133.2, 158.8, 188.9. MS (70 eV): m/z 166 (M1, 56),
151(50), 123(51), 95(59), 77(41), 67(73), 55(50), 43(100),
41(94), 39(56). HRMS calcd for C10H14O2: 166.09938;
found 166.09937. Anal. calcd for C10H14O2: C, 72.25; H,
8.49; found: C, 71.81; H, 8.55.
Ethyl 2-ethyl-2-(1-methylethenyl)-4-methyl-3-penteno-
ate (34). To 100 ml of a 1 M solution of 4 in diethyl ether
(100 mmol) was added slowly a solution of 12.0 ml
(100 mmol) of diethyl carbonate at 2308C and stirred for
another hour without cooling, the reaction mixture warmed
to 108C. This mixture was cooled to 2308C again, then a
solution of 13.0 ml (100 mmol) of diethyl sulfate in 30 ml of
ether was added dropwise and, as the reaction mixture
turned highly viscous, another aliquot of 100 ml of ether.
After the work-up the crude product (18.0 g) afforded after
distillation 13.0 g (62 mmol, 62%) of 34, bp 110±1128C
(12 Torr). An analytical sample was puri®ed by preparative
gas chromatography (SE 30). 1H NMR (80 MHz, CDCl3) d
0.82 (t, Jˆ8.0 Hz, 3H, CH2CH3), 1.25 (t, Jˆ7.2 Hz,
OCH2CH3), 1.58/1.77 (2£d, Jˆ1.5 Hz, 2£3H, 2£Me),
1.71 (t, Jˆ1.5 Hz, 3H, C(vCH2)CH3), 1.89/2.03 (AB part
of ABX3 system, 2£pseudoquartet, Jˆ8.0, 11.2 Hz,
CH2CH3), 4.16 (q, Jˆ7.2 Hz, 2H, OCH2CH3), 5.03 (m,
2H, vCH2), 5.62 (septet, Jˆ1.5 Hz, 1H, vCH). 13C
NMR {off-resonance decoupling} (100 MHz, CDCl3) d
9.4(q), 14.2(q), 20.8(q), 27.4(q), 28.9(t), 57.2(s), 60.7(t),
112.9(t), 124.3(d), 134.7(s), 145.2(s), 174.8(s), one signal
overlaid. MS (70 eV): m/z 210 (M1, 54), 195(15), 181(27),
138(15), 137(100), 109(19), 107(31), 95(81), 81(39),
41(19). Anal. calcd for C13H22O2: C, 74.24; H, 10.54;
found: C, 73.96; H, 10.80.
Characterization of 39. Bp 47±508C (0.05 Torr), the liquid
solidi®ed upon storing at 2308C to a red-brownish material.
1H NMR (80 MHz, CDCl3) d 1.44 (d, Jˆ1.1 Hz, 3H, Me),
1.82 (d, Jˆ1.4 Hz, 3H, Me), 1.85 (d, Jˆ0.5 Hz, 3H, Me),
2.21 (d, Jˆ1.5 Hz, 3H, Me), 5.60 (m, 1H, vCH), 10.10
(s, 1H, CHO). 13C NMR {off-resonance decoupling}
(100 MHz, CDCl3) d 19.0(q), 19.4(q), 24.2(q), 25.0(q),
118.4(d), 134.7(s), 137.5(s), 155.7(s), 190.1(d). MS
(70 eV): m/z 123 (M12Me, 51), 105(34), 95(59), 67(75),
55(56), 53(46), 51(41), 43(51), 41(100), 39(82). HRMS
calcd for C9H14O: 138.10447; found 138.10450.
3-Isopropylidene-5-methyl-4-hexen-2-one (35). To 100 ml
of a 1 M solution of 4 in diethyl ether was added at 2308C a
solution of 9.5 ml (100 mmol) of ethyl acetate in 100 ml of
ether. Fractional distillation of the crude product (10.3 g)
afforded 8.0 g (53 mmol, 53%) of 35, bp 808C (0.01 Torr).
1H NMR (80 MHz, CDCl3) d 1.53 (d, Jˆ1.6 Hz, 3H, Me),
1.70 (d, Jˆ1.4 Hz, 3H, Me), 1.82 (d, Jˆ0.9 Hz, 3H, Me),
3-Benzoyl-2,5-dimethyl-2,4-hexadiene (40). To 100 ml of
a 1 M solution of 4 in diethyl ether were added 13.4 g
(90 mmol) of N,N-dimethylbenzamide in 150 ml of diethyl

A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
3381
ether at 08C. Using an excess of this reagent led to problems
during isolation of the product. The work-up was performed
as described for 38 to afford 17.5 g of crude product, 16.4 g
(77 mmol, 85%) after distillation, bp 140±1458C
300 ml of diethyl ether at 2508C, until the red solution
turned slightly yellow. After warming to room temperature
and the usual work-up, the crude product (14.0 g) was puri-
®ed by fractional distillation, to afford 11.5 g (68 mmol,
68%) of 45a, bp 1208C (3 Torr), mp 90±928C (pentane/
1
(0.05 Torr) of a yellow oil, which solidi®es at 2258C. H
1
NMR (80 MHz, CDCl3) d 1.54 (d, Jˆ1.0 Hz, 3H, Me), 1.71
(s, 6H, 2£Me), 1.82 (s, 3H, Me), 5.87 (m, 1H, vCH), 7.40±
7.90 (m, 5H, phenyl-H). 13C NMR (100 MHz, CDCl3) d
19.1, 20.6, 21.3, 25.5, 120.7, 127.8, 128.7, 132.2, 133.7,
135.7, 136.2, 137.0, 198.5. MS (70 eV): m/z 214 (M1,
37), 213(23), 109(23), 105(100), 77(72), 67(44), 55(26),
43(29), 41(45). HRMS calcd for C15H18O: 214.13577;
found 214.13566. Anal. calcd for C15H18O: C, 84.06; H,
8.47; found: C, 83.61; H, 8.42.
methanol). H NMR (80 MHz, CDCl3) d 1.11 (s, 12H,
Me), 2.98 (s, 4H, CH2), 3.30 (s, 2H, OH). 13C NMR
(100 MHz, CDCl3) d 25.8, 34.0, 71.7, 86.7. MS (70 eV):
m/z 140 (M12CH2O, 10), 120(31), 110(54), 108(46),
90(38), 80(54), 68(62), 55(62), 43(100), 41(62). HRMS
calcd for C10H18O2±CH2O: 140.12012; found 140.12010.
Anal. calcd for C10H18O2: C, 70.55; H, 10.66; found: C,
70.39; H, 11.30.
5-Methyl-3-isopropylidene-4-hexen-2-ol (44b) and 3,3,6,
6-tetramethyl-4-octyn-2,7-diol (45b). To 100 ml of a 1 M
solution of 4 (100 mmol) was added at 2608C a solution of
11.3 ml (200 mmol) of acetaldeyde in 100 ml of diethyl
ether. After the usual work-up the two alcohols were
isolated by fractional distillation from the crude product
(18.0 g). For the yields see Table 3. 44b: Bp 908C
(0.01 Torr). 1H NMR (80 MHz, CDCl3) d 1.19 (d,
Jˆ6.5 Hz, 3H, CHCH3), 1.52 (d, J,1 Hz, 3H, Me), 1.57
(d, J,1 Hz, 3H, Me), 1.74 (d, J,1 Hz, 3H, Me), 1.74 (d,
J,1 Hz, 3H, Me), 4.50 (q, Jˆ6.5 Hz, 1H, CHCH3), 5.70 (m,
1H, vCH). 13C NMR (100 MHz, CDCl3) d 19.1, 19.5, 22.0,
23.3, 25.2, 67.0, 120.1, 128.1, 134.2, 137.2. MS (70 eV):
m/z 121 (M12H2O±Me, 100), 105(53), 93(40), 91(42),
79(22), 77(34), 67(26), 55(26), 41(50), 39(29). HRMS
calcd for C10H18O: 154.13576; found 154.13576; calcd for
C10H18O±H2O: 136.12520; found 136.12519. 45b: Bp
Reaction of 4 with acetone
To 100 ml of a 1 M solution of 4 were added 14.7 ml
(200 mmol) of acetone in 150 ml of diethyl ether with
varying reaction temperatures (see Table 2). The usual
work-up afforded the three alcohols 41±43 (for the yield
see Table 2). These products were characterized as
follows.
3-Isopropylidene-2,5-dimethyl-4-hexen-2-ol (41). Bp 75±
788C (0.4 Torr), mp 74±758C (pentane/methanol). 1H NMR
(80 MHz, CDCl3) d 1.35 (s, 6H, C(OH)(CH3)2), 1.49 (d,
Jˆ1.0 Hz, 3H, Me), 1.57 (d, Jˆ1.1 Hz, 3H, Me), 1.65 (s,
1H OH), 1.75 (d, Jˆ1.2 Hz, 3H, Me), 1.95 (d, Jˆ1.7 Hz,
3H, Me), 5.64 (m, 1H, vCH). 13C NMR (100 MHz, CDCl3)
d 19.0, 21.4, 24.0, 25.6, 29.4, 30.9, 73.9, 124.3, 129.3,
134.2, 136.9. The two signals at 29.4 and 30.9 ppm show
one broad signal at room temperature, at 2508C two signals
are observed for the methyl groups. MS (70 eV): m/z 150
(M12Me2CO±H2O, 36), 135(100), 119(32), 107(27),
93(29), 91(37), 81(22), 79(42), 77(26), 41(41). HRMS
calcd for C11H20O±H2O: 150.14085; found 150.14085.
Anal. calcd for C11H20O: C, 78.50; H, 11.99; found: C,
78.39; H, 11.82.
1
1608C (0.01 Torr). H NMR (80 MHz, CDCl3) d 1.15 (s,
6H, Me), 1.21 (d, Jˆ6.2 Hz, 6H, CHCH3), 1.22 (s, 6H,
Me), 1.87 (s, 2H, OH), 3.50 (q, Jˆ6.2 Hz, 2H, CHCH3).
13C NMR (100 MHz, CDCl3) d 18.0, 24.8, 25.9, 37.5,
74.2, 87.0. MS (70 eV): m/z 121 (M12MeCHO±H2O±
Me, 54), 111(100), 95(32), 93(31), 91(29), 67(73), 55(36),
45(43), 43(73), 41(42). HRMS calcd for C10H18O±H2O±
Me: 165.12795; found 165.12792.
2,2,5,5-Tetramethyl-1,6-diphenyl-3-hexyn-1,6-diol (45c).
From 100 ml of a 1 M solution of 4 (100 mmol) and 20.0 ml
(200 mmol) of benzaldehyde at 2308C. After the usual
work-up the crude product (21.0 g) was distilled to afford
16.5 g (52 mmol, 52%) of 45c, bp 1608C (0.01 Torr), mp
2,3,3,6,6,7-Hexamethyl-4-octyn-2,7-diol (42). Bp 98±1038C
(0.2 Torr), mp 80±828C (pentane/methanol). 1H NMR
(80 MHz, CDCl3) d 1.19 (s, 12H, Me), 1.24 (s, 12H, Me),
1.87 (s, 2H, OH). 13C NMR (100 MHz, CDCl3) d 24.8, 24.9,
40.6, 74.0, 87.9. MS (70 eV): m/z 150 (M12Me2CO±H2O,
18), 135(61), 125(32), 118(14), 110(25), 85(46), 67(18),
59(100), 43(46), 41(29). Anal. calcd for C14H26O2: C,
74.29; H, 11.58; found: C, 74.57; H, 11.58.
1
1088C (pentane/methanol). H NMR (80 MHz, CDCl3) d
1.06/1.26 (2£s, 2£6H, Me), 2.58 (d, Jˆ4.4 Hz, 2H, CH),
4.48 (d, Jˆ4.4 Hz, 2H, OH), 7.31 (m, 10H, phenyl). 13C
NMR (100 MHz, CDCl3) d 25.0, 26.5, 37.8, 80.6, 87.6,
127.5, 127.6, 127.7, 140.3. The signals between 20 and
90 ppm show a splitting due to the presence of two
diastereoisomers. MS (70 eV): m/z 216 (M12PhCHO,
23), 198(55), 184(100), 156(23), 142(36), 140(41), 81(55),
79(46), 77(41), 66(36). HRMS calcd for C22H26O2±H2O:
304.18272; found 304.18267. Anal. calcd for C22H26O2: C,
81.94; H, 8.13; found: C, 82.27; H, 8.30.
3-(2-Methyl-1-propenylidene)-2,4,4,5-tetramethylhexan-
2,5-diol (43). Bp 117±1208C (0.2 Torr), mp 136±1388C
1
(pentane/methanol). H NMR (80 MHz, CDCl3) d 1.16 (s,
6H, Me), 1.20 (s, 6H, Me), 1.37 (s, 6H, Me), 1.63 (s, 6H,
vCMe2), 3.78/4.24 (2£br. s, 2H, OH). 13C NMR (100 MHz,
CDCl3) d 20.1, 25.9, 27.0, 34.1, 46.1, 73.0, 76.0, 95.7,
115.9, 201.5. MS (70 eV): m/z 193 (M12Me±H2O, 81),
168(11), 150(38), 135(100), 125(27), 110(16), 95(27),
59(89), 43(35), 41(19). Anal. calcd for C14H26O2: C,
74.29; H, 11.58; found: C, 74.30; H, 11.59.
3,3,6,6-Tetramethyl-2,7-diphenyl-4-octyn-2,7-diol (45d).
From 100 ml of a 1 M solution of 4 and 23.0 ml (200 mmol)
of acetophenone in 100 ml of diethyl ether at 2608C. The
crude product proved extremely dif®cult to purify and was
2,2,5,5-Tetramethyl-3-hexyn-1,6-diol (45a). Gaseous
formaldehyde, obtained by depolymerization of paraformal-
dehyde, was introduced into a solution of 4 (100 mmol) in
1
characterized as such and by using GC±MS coupling. H
NMR (80 MHz, CDCl3) d 1.14/1.18/1.70 (3£s, 3£6H, Me),

3382
A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
2.30 (s, 2H, OH), 7.40 (m, 10H, phenyl-H). 13C NMR
(100 MHz, CDCl3) d 25.1, 25.6, 41.1, 44.3, 81.0, 88.1,
126.6, 127.0, 127.8, 143.6. MS (70 eV): m/z 223 (13),
197(11), 169(12), 121(34), 106(9), 105(100), 91(17),
77(50), 51(12), 43(46). HRMS calcd for C24H30O2±H2O:
332.21402; found 332.2140. Furthermore, there is spectro-
scopic evidence for 44d, as obtained by GC/MS coupling:
MS (70 eV): m/z 212 (M12H2O±Me, 72), 197(100),
156(54), 155(55), 143(39), 141(38), 121(35), 91(46),
77(42), 41(42).
Methyl N-phenyl-2-isopropylidene-4-methyl-3-pentenimi-
dothioate (48b) and dimethyl N,N0-diphenyl-2,3-diiso-
propylidene-succinimidothioate (47b). The reaction of
100 mmol of 4 in 100 ml of diethyl ether with 19.0 ml
(100 mmol) of phenyl isothiocyanate was performed as
described above. After the usual work-up by distillation a
fraction containing 15.0 g (58 mmol, 58%) of 48b was
obtained, bp 1458C (0.05 Torr). 1H NMR (80 MHz,
CDCl3) d 1.37/1.58/1.79/1.84 (4£s, 4£3H, Me), 2.50 (s,
3H, SMe), 5.58 (br s, 1H, vCH), 7.10 (m, 5H, phenyl-H).
13C NMR (100 MHz, CDCl3) d 13.5, 19.5, 20.2, 22.4, 25.7,
120.2, 121.1, 123.0, 128.3, 128.7, 134.1, 136.6, 150.7,
170.0. MS (70 eV): m/z 259 (M12Me, 41), 227(59),
226(49), 123(100), 93(23), 91(26), 81(90), 77(44), 67(26),
41(62). The disubstituted butadiene 47b decomposed upon
distillation and could not be obtained in pure form: MS
(70 eV): m/z 375 (M12SH, 100), 361(18), 360(71),
253(35), 252(16), 179(26), 171(18), 150(26), 91(26),
77(45).
2,2,5,5-Tetramethyl-1,1,6,6-tetraphenyl-3-hexyn-1,6-diol
(45e). To a solution of 50 mmol of 4 in 100 ml of diethyl
ether was added a solution of 18.2 g (100 mmol) of benzo-
phenone in 150 ml of diethyl ether. After work-up and
evaporation of the solvent the remainder (18.5 g) was
treated in an ultrasonic bath with pentane, thus a white
powder was isolated, which was recrystallized from pentane
and a small amount of methanol, mp 147±1498C, 15.4 g
1
(33 mmol, 65%). H NMR (80 MHz, CDCl3) d 1.32 (s,
12H, Me), 2.37 (s, 2H, OH), 7.00±7.80 (m, 20H, phenyl-
H). 13C NMR (100 MHz, CDCl3) d 26.5, 39.9, 81.1, 91.2,
126.7, 127.1, 128.5, 145.1. MS (70 eV): m/z 275
(M12Ph2CO±OH, 11), 274(5), 184(11), 183(73), 182(7),
110(6), 108(8), 106(8), 105(100), 77(40). HRMS calcd for
C34H34O2±Ph2CO: 292.18272; found 292.18272; calcd for
C34H34O2±Ph2CO±H2O: 274.17216, found 274.17224.
Anal. calcd for C34H34O2: C, 86.03; H, 7.22; found: C,
86.03; H, 7.10.
Acknowledgements
We would like to thank the Volkswagen-Stiftung and the
Fonds der Chemischen Industrie for the support given.
References
È
1. Maercker, A.; Bos, B.; Hajgholipour, M. T. (Part 26). J. Organo-
met. Chem. 1998, 566, 143±149.
N, N0, N00, N000-Tetracyclohexyl-2,3-diisopropylidene-
succinamidine (46). The reaction of 100 mmol of 4 in
100 ml of diethyl ether with 20.6 g (100 mmol) of N,N0-
dicyclohexylcarbodiimide in 100 ml of diethyl ether
afforded, after the usual work-up, 18.0 g of 46, which was
recrystallized twice from diethyl ether: 14.0 g (27 mmol,
54%), mp 119±1218C. 1H NMR (80 MHz, CDCl3) d
1.10±1.60 (br. m, 40H, cyclohexyl±CH2), 1.68/1.71 (2£s,
2£6H, Me), 2.05 (br. s, 4H, cyclohexyl±CH), 3.05/3.50
(2£br. s, 2H, NH). 13C NMR (100 MHz, CDCl3) d 21.5,
21.9, 22.2, 24.6, 25.8, 26.1, 32.8, 35.2, 48.9, 58.0, 131.0,
133.0, 154.5. Anal. calcd for C34H58N4: C, 78.10; H, 11.18;
found: C, 78.20; H, 11.10.
2. Maercker, A.; Dujardin, R. Angew. Chem. 1985, 97, 612±613;
Angew. Chem. Int. Ed. Engl. 1985, 24, 571±572.
3. Reviews: Maercker, A. In Methoden der Organischen Chemie
(Houben-Weyl); Hanack, M., Ed.; Thieme: Stuttgart, 1993; Vol.
E19d, 448±556; Maercker, A. In Lithium Chemistry; Sapse, A.-M.,
Schleyer, P. v. R., Eds.; Wiley Interscience: New York, 1995;
Chapter 11.
4. GuÈnther, H.; Moskau, D.; Dujardin, R.; Maercker, A.
Tetrahedron Lett. 1986, 27, 2251±2254; Moskau, D.; Brauers,
F.; GuÈnther, H.; Maercker, A. J. Am. Chem. Soc. 1987, 109,
5532±5534.
5. Maercker, A.; Dujardin, R.; Engelen, B.; Buchmeier, W.; Jung,
M. Unpublished results.
Methyl N-ethyl-2-isopropylidene-4-methyl-3-pentenimi-
dothioate (48a) and dimethyl N,N0-diethyl-2,3-diisopro-
pylidene-succinimidothioate (47a). To 100 ml of a 1 M
solution of 4 was added slowly a solution of 9.0 ml
(100 mmol) of ethyl isothiocyanate in 100 ml of diethyl
ether at 2608C. The reaction mixture was kept at this
temperature for half an hour, then at 2408C a solution of
12.0 ml (200 mmol) of methyl iodide in 50 ml of diethyl
ether was added dropwise. After the usual work-up the
crude product (23.0 g) was distilled to afford 3.8 g
(18 mmol, 18%) of 48a, bp 70±758C (0.01 Torr). 1H
NMR (80 MHz, CDCl3) d 1.15 (t, Jˆ7.1 Hz, 3H,
CH2CH3), 1.60/1.67/1.68/1.78 (4£d, J,1 Hz, 4£3H, Me),
2.28 (s, 3H, SMe), 3.30 (q, Jˆ7.1 Hz, 2H, CH2CH3), 5.60
(m, 1 H, vCH). Furthermore 12.5 g (40 mmol, 40%) of
6. Maercker, A.; Wunderlich, H.; Girreser, U. Eur. J. Org. Chem.
1998, 793±798.
7. Maercker, A.; Brieden, W.; Jung, M.; Lutz, H. D. Angew. Chem.
1988, 100, 413±414; Angew. Chem. Int. Ed. Engl. 1988, 27, 404±
405; Maercker, A.; Brieden, W.; Schmidt, T.; Lutz, H. D. Angew.
Chem. 1989, 101, 477±479; Angew. Chem. Int. Ed. Engl. 1989, 28,
477±478; Maercker, A.; Brauers, F.; Brieden, W.; Engelen, B.
J. Organomet. Chem. 1989, 377, C45±C51; Maercker, A.;
Brieden, W. Chem. Ber. 1991, 124, 933±938; Maercker, A.;
Brieden, W.; Kastner, F.; Mannschreck, A. Chem. Ber. 1991,
124, 2033±2036; Brieden, W.; Kellersohn, T. Chem. Ber. 1993,
126, 845±847; Maercker, A.; Groos, A. Angew. Chem. 1996, 108,
216±217; Angew. Chem. Int. Ed. Engl. 1996, 35, 205±206.
8. Maercker, A.; Dujardin, R.; Brauers, F. Organomet. Synth.
1988, 4, 362±365.
1
47a, bp 100±1108C (0.01 Torr) were obtained. H NMR
9. Maercker, A.; Wunderlich, H.; Girreser, U. Tetrahedron 1996,
52, 6149±6172.
(80 MHz, CDCl3) d 1.13 (t, Jˆ7.0 Hz, 6H, CH2CH3),
1.67/1.75 (2£s, 2£6H, Me), 2.26 (s, 6H, SMe), 3.38 (q,
Jˆ7.0 Hz, 4H, CH2CH3).
10. Meijer, J.; Ruitenberg, K.; Westmijze, H.; Vermeer, P.
Synthesis 1981, 551±554.

A. Maercker et al. / Tetrahedron 56 (2000) 3373±3383
3383
11. Brandsma, L.; Verkruijsse, H. Preparative Polar Organo-
metallic Chemistry; Springer: Heidelberg, 1986; Vol. 1, p 148.
12. Landor, S. R.; Whiter, P. F. J. Chem. Soc. 1965, 5625;
Bleichholder, R. F.; Shechter, H. J. Am. Chem. Soc. 1964, 86,
5032±5033; Schuster, H. F.; Coppola, G. M. Allenes in Organic
Synthesis; Wiley: New York, 1984, p 2; Smith, H.; Bates, J. B.
J. Raman Spectrosc. 1973, 1, 83; Weidlein, J.; MuÈller, U.;
Dehnicke, K. Schwingungsspektroskopie; Thieme: Stuttgart,
1982; p 100.
15. Paulson, D. R.; Crandall, J. K.; Bunnell, A. J. Org. Chem.
1970, 35, 3708±3714; Crandall, J. K.; Paulson, D. R. J. Am.
Chem. Soc. 1966, 88, 4302±4303.
16. Seetz, J. W. F. L.; Tol, R.; Ackerman, O. S.; Bickelhaupt, F.
Synthesis 1983, 721±722.
17. Parr, R. G.; Pearson, R. G. J. Am. Chem. Soc. 1983, 105,
7512±7522; Pearson, R. G.; Songstad, J. J. Am. Chem. Soc.
1967, 89, 1827±1836; Ho, T.-L. Chem. Rev. 1975, 75, 1±20;
Creary, X. J. Am. Chem. Soc. 1977, 99, 7632±7639.
18. Kofron, W. G.; Baclawski, L. M. J. Org. Chem. 1976, 41,
1879±1880.
13. Wurziger, H. Kontakte 1985, 2, 17.
14. Brieden, W. Ph.D thesis, University of Siegen, 1990.