Stereospecific synthesis of 1,2-difunctionalized buta-1,3-dienes via tandem [3,3]-[3,3] sigmatropic rearrangements

Article abstract of DOI:10.1016/S0040-4020(00)00459-2

Thermolysis of bis-thiocarbamates derived from but-3-yne-1,2-diols resulted in the formation of buta-1,3-dienes with carbamoylthio groups in positions 1 and 2 with good to excellent yields. The stereochemistry of the products is controlled by substituents

Full text of DOI:10.1016/S0040-4020(00)00459-2

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 5413±5419
Stereospeci®c Synthesis of 1,2-Difunctionalized Buta-1,3-Dienes
via Tandem [3,3]±[3,3] Sigmatropic Rearrangements
1
*
Klaus Banert and Jana Schlott
Institute of Chemistry, Chemnitz University of Technology, Strasse der Nationen 62, D-09111 Chemnitz, Germany
Dedicated to Professor Wolfgang Kirmse on the occasion of his 70th birthday
Received 24 May 2000; accepted 1 June 2000
AbstractÐThermolysis of bis-thiocarbamates derived from but-3-yne-1,2-diols resulted in the formation of buta-1,3-dienes with
carbamoylthio groups in positions 1 and 2 with good to excellent yields. The stereochemistry of the products is controlled by substituents
at C-1 of the starting material and can be explained by chair-like reacting conformations. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
acetamides (XYZˆNHCOCCl ), thioesters (XYZˆS-
3
COPh), thiocarbamates (XYZˆSCONMe ), thiocarbonates
2
Tandem [3,3]±[3,3] sigmatropic rearrangements like the
well-known reaction 1 ! 2 ! 3; for instance with
(XYZˆSCO Ar), or dithiocarbonates (XYZˆSC(O)SMe),
2
which resulted from [3,3] sigmatropic rearrangements, were
formed as mixtures of separable E/Z isomers. We describe
here that the tandem reaction 4 ! 5 ! 6 proved to be
completely stereospeci®c if a substituent is introduced at
C-1 of 4. This substituent controls both the stereochemistry
at the C-1/C-2 double bond and that at the C-3/C-4 double
bond of 6.
2
XYZˆC±CvC (Cope rearrangement), C±CO R (ortho-
2
3
ester Claisen rearrangement), NCO, NCS, NCSe, N ,
4
5
6
7
3
8
9
SCONMe , SCN, can be utilized to convert the but-2-
2
yne-1,4-diyl starting materials 1 into the 2,3-difunctional-
ized buta-1,3-dienes 3 (Scheme 1). The synthesis of similar
products proceeds analogously via two consecutive [2,3]
sigmatropic isomerizations, for example in the reaction of
1
0
phosphinites to phosphane oxides, phosphites to phos-
12
1
1
phonates, 2,1s3ul®nates to sulfones,
sulfoxides.
or sulfenates to
Results and Discussion
1
Starting with a 1:2 mixture of meso-10a and rac-10a, we
prepared a mixture of meso-11a and rac-11a (1:2, 89%
yield), since separation of these thiocarbamates by simple
crystallization from diethyl ether was much more con-
Recently, we described the ®rst tandem sigmatropic
rearrangements that provide a convenient approach to 1,2-
1
4
difunctionalized buta-1,3-dienes. Thus, a sequence of
3,3] migrations such as 4 ! 5 ! 6 as well as [2,3] shifts
1
5
[
venient than isolation of the diastereomeric diols
1
6
7
into vinylic positions (Scheme 2). The [2,3] isomerizations
! 8 ! 9 could be used to direct both functional groups
(Scheme 3). Pure meso-10a analogously yielded only
meso-11a as shown in a control experiment. A mixture of
syn-10b and anti-10b (1.9:1) was synthesized by
afforded the parent compounds of type 9 like sulfones
(
1
7
XYˆTs), sulfoxides (XYˆS(O)Ar), or phosphane oxides
dihydroxylation of pent-2-en-4-yne (cis/transˆ1.9:1),
1
4
18
however, we did not use the known procedure with
(
other hand, parent compounds of type 6 such as trichloro-
XYˆP(O)Ph ) with exclusive E con®guration. On the
2
H O /HCO H due to low yields. Instead, epoxidation of
2
2
2
Scheme 1.
Keywords: alkynes; thiocarbamates; dienes; rearrangements; diastereoselection.
*
Corresponding author. Fax: 149-371-531-1839; e-mail: klaus.banert@chemie.tu-chemnitz.de
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00459-2

5
414
K. Banert, J. Schlott / Tetrahedron 56 (2000) 5413±5419
Scheme 2.
2
Scheme 3. Reagents and conditions: (i) NaH, THF, 208C, 20±24 h (and 35±408C, 9 h in the case of 10a) and then Me NC(S)Cl, 208C, 16±24 h, 77±89%.
the enyne with 3-chloroperbenzoic acid (48% yield)
followed by hydrolysis (H O, 1008C, 2 days, 87%) gave
also completely stereospeci®c, however, in this case each
of the two rearrangement reactions afforded only one
product: (1E,3E)-12b from anti-11b and (1Z,3E)-12b from
syn-11b. The con®guration of the C-3/C-4 double bond of
12 was easily established by the vicinal coupling constants
2
10b, which was transformed into 11b (77% yield,
syn/antiˆ1.9:1). These diastereomeric compounds could
be separated by HPLC. Alternatively, anti-11b was synthe-
sized and puri®ed by crystallization from diethyl ether start-
ing with 10b (syn/antiˆ1:7), which was prepared from the
1
of the H NMR spectra, whereas the stereochemistry at the
C-1/C-2 double bond was determined with the help of NOE
difference spectra. Thus, saturating the proton H-1 led to an
enhancement of the signal of H-3, which was in the range of
11±15% in the case of (1Z,3Z)-12a, (1Z,3E)-12a, and
(1Z,3E)-12b, while no effect was observed in the case of
(1E,3E)-12a, (1E,3Z)-12a, and (1E,3E)-12b.
1
9
reaction of 2-bromopropanal and ethynylmagnesium
bromide (29%, syn/antiˆ1:7) followed by ring closure of
the bromohydrins by treatment with potassium hydroxide
(
87%, cis/transˆ1:7) and hydrolysis of the resulting
oxiranes (87%). Furthermore, the starting material syn-
0b could selectively be generated in analogy to the method
1
2
0
21
of R. W. Friesen. Thus, syn-4-iodopent-4-ene-2,3-diol
The stereochemical outcome of the transformation 11!12
could be explained by chair-like transition states such as A
and B as well as boat-like reacting conformations such as C
and D derived from the intermediate 13 (Scheme 4). For
example, starting with meso-11 or anti-11, (1E,3E)-12 and
(1Z,3Z)-12 prove to be the only 1,3-dienes, which could
result from tandem [3,3]±[3,3] sigmatropic rearrangements
via chair-like or boat-like transition states. Upon similar
consideration, rac-11 or syn-11 should be converted solely
into (1E,3Z)-12 and (1Z,3E)-12. However, the fact that
2
2
was available from penta-3,4-dien-2-ol and was then
transformed to syn-10b, however, the yields and their
reproducibility were very low.
The tandem rearrangement of 11 was performed by
thermolysis in toluene (Table 1). While meso-11a furnished
mainly (1E,3E)-12a and the minor product (1Z,3Z)-12a,
rac-11a gave the major product (1Z,3E)-12a and a small
amount of (1E,3Z)-12a. The isomerization of 11b was
Table 1. Thermolysis of 11 in toluene
Starting material
Temperature (8C)
Time (h)
Yield (%)
(
1E,3E)-12
(1E,3Z)-12
(1Z,3E)-12
(1Z,3Z)-12
meso-11a
rac-11a
anti-11b
syn-11b
110
110
100
100
1.5
2
8
66
±
100
±
±
9
±
±
±
68
±
9
2
±
8
100
±

K. Banert, J. Schlott / Tetrahedron 56 (2000) 5413±5419
5415
Scheme 4.
(1E,3E)-12 is the main product and (1Z,3Z)-12 the by-
product and that (1Z,3E)-12 is favored as compared to
interaction of R and NMe . The analogous unfavorable
2
steric effect is to be expected for boat C in comparison to
boat D. Nevertheless, (1E,3E)-12, which may result from
advantageous chair A or unfavorable boat C, is found to be
the preferred product. When the small ethynyl group of 11a
(
1E,3Z)-12, could only be rationalized by chair-like instead
of boat-like reacting conformations. For instance, the sub-
stituent R lies axial in chair B. Thus, this conformation
should be disfavored compared with chair A due to the
2
3
is replaced by the more bulky methyl group of 11b, chair
Scheme 5. Reagents and conditions: (i): TCNE, THF, 408C, 12 days, 50%; (ii) TCNE, THF, 208C, 8 h, 41%.

5
416
K. Banert, J. Schlott / Tetrahedron 56 (2000) 5413±5419
B is completely disfavored as compared to chair A. There-
fore, thermolysis of anti-11b produced solely (1E,3E)-12b,
and the exclusive formation of (1Z,3E)-12b from syn-11b
could be explained similarly (Scheme 5).
which was treated with a small amount of dry Et O. The
2
resulting precipitate was collected by suction ®ltration to
afford meso-11a (380 mg). The ®ltrate was passed through
a short column of silica gel using Et O as eluting agent.
2
Removal of the solvent in vacuo yielded rac-11a
1
Double functionalized dienes of type 6 and 9 may ®nd use as
(800 mg). Compound meso-11a: mpˆ1348C (Et O). H
2
1
4
synthetic building blocks. For example, [412] cyclo-
adducts 14 were prepared from 12b and TCNE (tetra-
cyanoethylene). The Diels±Alder reaction of (1Z,3E)-12b
was distinctly more rapid than that of (1E,3E)-12b.
Obviously, a cisoid conformation of the buta-1,3-diene
unit, which is necessary for [412] cycloaddition, is more
dif®cult to attain for (1E,3E)-12b due to steric factors.
During the sequence 11b ! 12b ! 14; the stereochemical
information of the relative con®gurations at two stereogenic
centers is ®rst transferred to that of different con®gurations
at CvC bonds and then retransformed into that of two
stereogenic centers again.
NMR (CDCl ): d 2.60 (dd, Jˆ1.4, 0.8 Hz, 2H, CuCH),
3
3.18 (s, 3H, NMe), 3.38 (s, 3H, NMe), 6.43 (dd, Jˆ1.4,
1
0.8 Hz, 2H, CH±CH). C NMR (CDCl ): d 38.13 (q,
3
3
NMe), 43.20 (q, NMe), 70.79 (d), 75.85 (d), 77.07 (s),
185.90 (s, CvS). IR (CDCl ): 3306 (CuCH), 2939, 1539,
1399, 1287, 1186, 1151, 1037 cm . Elemental analysis:
C H N O S ; calcd: C, 50.68; H, 5.67; N, 9.85; S, 22.55;
found: C, 50.58; H, 5.70; N, 9.47; S, 21.94. Compound rac-
3
2
1
1
2
16
2
2 2
1
11a: mpˆ89±908C (Et O/hexane). H NMR (CDCl ): d
2
3
2.61 (dd, Jˆ1.4, 0.8 Hz, 2H, CuCH), 3.18 (s, 3H, NMe)
3.38 (s, 3H, NMe), 6.48 (dd, Jˆ1.4, 0.8 Hz, 2H, CH±CH).
1
3
C NMR (CDCl ): d 38.15 (q, NMe), 43.18 (q, NMe),
3
6
9.87 (d), 75.86 (d), 77.39 (s), 185.75 (s, CvS). IR
(
1148, 1039 cm . Elemental analysis: C12
CDCl ): 3306 (CuCH), 2942, 1538, 1399, 1287, 1178,
3
2
1
Conclusion
H N O S ;
16 2 2 2
calcd: C, 50.68; H, 5.67; N, 9.85; S, 22.55; found: C,
1
6
In summary, we have demonstrated that the stereochemistry
of the formation of 1,2-difunctionalized buta-1,3-dienes
such as 12 is controlled by substituents at C-1 of the starting
materials of type 11. A plausible explanation including
chair-like reacting conformations is presented. Work is in
progress in our laboratory in order to develop further
examples of stereospeci®c tandem rearrangements in
analogy to 4 ! 5 ! 6 or 7 ! 8 ! 9 using other [3,3] or
50.67; H, 5.79; N, 9.77; S, 22.62. Pure meso-10a was
analogously treated with NaH in THF and N,N-
dimethylthiocarbamoyl chloride to give meso-11a without
the diastereomeric isomer.
Pent-4-yne-2,3-diol bis[(N,N-dimethyl)thiocarbamate]
(11b) from pent-2-en-4-yne. To a solution of pent-2-en-
Cl at 08C,
a solution of 3-chloroperbenzoic acid (40%, 24 g, 56 mmol)
in CH Cl (180 ml) was added in portions. The mixture was
1
7
4-yne (2.2 g, 33 mmol, cis/transˆ1.9:1) in CH
2 2
[
2,3] sigmatropic reactions.
2
2
stirred for 15 min at 08C and then for 16 h at room tempera-
ture. Thereafter, it was washed repeatedly with cold aqueous
Na SO solution, with aqueous NaHCO solution, and with
Experimental
2
3
3
General
water. The organic layer was dried with MgSO and concen-
4
trated by distillation. Recondensation of the residue at
0.001 Torr and distillation led to the epoxides (1.3 g, 48%,
Melting points (uncorrected): Electrothermal IA 9100.
Elemental analyses: Vario EL Elementar Analysensysteme
GmbH (Hanau). IR: Bruker IFS 28. H NMR: Varian
1
cis/transˆ1.9:1) as a colorless liquid, bp 68±708C. The H
1
NMR spectra of the products were similar to those of the
oxiranes synthesized by another method. NMR data of cis-
2
4
Gemini 300 (300 MHz), internal standard TMS (dˆ0) or
1
3
1
solvent signals, recalculated relative to TMS. C NMR:
Varian Gemini 300 (75 MHz); internal standard TMS
1-ethynyl-2-methyloxirane: H NMR (CDCl ): d 1.44 (d,
3
3
4
Jˆ5.3 Hz, 3H, Me), 2.36 (d, Jˆ1.8 Hz, 1H, CuCH),
3
3
(
dˆ0) or solvent signals, recalculated relative to TMS.
3.17 (qd, Jˆ5.3, 4.0 Hz, 1H, H-2), 3.41 (dd, Jˆ4.0 Hz,
4
13
The multiplicities were determined by the aid of gated
spectra and/or DEPT 135 experiments. HPLC: Knauer
HPLC Pump 64, Knauer UV detector (lˆ254 nm), column
LiChrospher Si 60 (5 mm), 2 cm B£20 cm. Flash column
chromatography was performed with silica gel, 32±63 mm.
Jˆ1.8 Hz, 1H, H-1). C NMR (CDCl
3
): d 14.21 (q, Me),
45.00 (d), 53.75 (d), 73.55 (d), 78.83 (s). NMR data of trans-
1
1-ethynyl-2-methyloxirane: H NMR (CDCl ): d 1.34 (d,
3
3
4
Jˆ5.3 Hz, 3H, Me), 2.31 (d, Jˆ1.6 Hz, 1H, CuCH),
3
3.06 (t, J<2.0 Hz, 1H, H-1), 3.17 (qd, Jˆ5.3, 2.2 Hz, 1H,
1
H-2). C NMR (CDCl ): d 17.28 (q, Me), 45.71 (d), 56.39
3
3
Hexa-1,5-diyne-3,4-diol bis[(N,N-dimethyl)thiocarbamate]
(
(d), 71.73 (d), 80.35 (s). The assignments of the con®gura-
tions of the epoxides are based on vicinal coupling constants
observed in the H NMR spectra and g effects detected in
11a). To a suspension of crystalline NaH (340 mg,
4.2 mmol) in dry THF (10 ml) under argon at room
1
1
1
5
13
temperature, a solution of 10a (580 mg, 5.27 mmol,
meso/racˆ1:2) in dry THF (15 ml) was added dropwise.
The mixture was stirred for 20 h at room temperature and
then for 9 h at 35±408C. Thereafter, a solution of N,N-
dimethylthiocarbamoyl chloride (1.37 g, 11.1 mmol) in
dry THF (5 ml) was added dropwise. The resulting mixture
was stirred for 24 h at room temperature, diluted with THF/
the C NMR spectra.
The mixture of oxiranes and an eightfold molar excess of
water were heated for 2 days at 1008C in a sealed glass
ampoule. After removal of the excess water in vacuo, the
residue was recondensed at 508C/0.001 Torr to give 10b
1
(87%, syn/antiˆ1.9:1) as a colorless oil. The H NMR spec-
Et O (1:2, 50 ml), washed three times with water (3£10 ml),
tra of the products were nearly identical to those of 10b
synthesized by another method. NMR data of syn-10b:
2
2
5
and dried with MgSO . Removal of the solvent in vacuo
4
1
3
gave a mixture of meso- and rac-11a (1:2, 1.33 g, 89%),
H NMR (CDCl
3
): d 1.29 (d, Jˆ6.5 Hz, 3H, Me), 2.47

K. Banert, J. Schlott / Tetrahedron 56 (2000) 5413±5419
5417
4
1
(
br. s, 2H, OH), 2.52 (d, Jˆ2.2 Hz, 1H, H-5), 3.85 (br.
yn-3-ol: mp 448C (Et O). H NMR (CDCl ): d 1.75 (d,
2 3
3 4
3
3
quint, J<6.5 Hz, 1H, H-2), 4.11 (dd, Jˆ6.8 Hz,
Jˆ6.8 Hz, 3H, Me), 2.56 (d, Jˆ2.2 Hz, 1H, H-1), 2.60
4
13
3
Jˆ2.2 Hz, 1H, H-3). C NMR (CDCl ): d 18.21 (q, Me),
(br. s, 1H, OH), 4.27 (qd, Jˆ6.8, 3.6 Hz, 1H, H-4), 4.43
3
3
4
13
6
6.15 (d), 69.18 (d), 75.19 (d), 84.38 (s, C-4). NMR data of
(dd, Jˆ3.6 Hz, Jˆ2.2 Hz, 1H, H-3). C NMR (CDCl ): d
3
1
3
anti-10b: H NMR (CDCl ): d 1.29 (d, Jˆ6.5 Hz, 3H, Me),
20.92 (q, Me), 54.14 (d), 66.62 (d), 74.81 (d), 80.58 (s, C-1).
IR (CDCl ): 3359 (OH), 3306 (CuCH), 1238, 1196, 1118,
3
4
2
.47 (br. s, 2H, OH), 2.52 (d, Jˆ2.2 Hz, 1H, H-5), 3.92 (qd,
3
21
3
3
4
Jˆ6.4, 3.5 Hz, 1H, H-2), 4.31 (dd, Jˆ3.5, Jˆ2.2 Hz, 1H,
1050 cm . Elemental analysis: C H BrO; calcd: C, 36.84;
H, 4.33; found: C, 36.45; H, 4.40. NMR data of syn-4-
bromopent-1-yn-3-ol: H NMR (CDCl ): d 1.70 (d,
5
7
1
H-3). C NMR (CDCl ): d 18.49 (q, Me), 65.87 (d), 69.35
3
3
1
(
d), 74.87 (d), 84.79 (s, C-4).
3
3
4
Jˆ6.8 Hz, 3H, Me), 2.56 (d, Jˆ2.2 Hz, 1H, H-1), 2.60
3
The mixture of diols 10b was treated with NaH in THF
208C, 24 h) and N,N-dimethylcarbamoyl chloride (208C,
6 h) as described in the case of 10a. The crude product
(br. s, 1H, OH), 4.19 (qd, Jˆ6.8, 5.4 Hz, 1H, H-4), 4.40
3
4
13
(
1
(dd, Jˆ5.4 Hz, Jˆ2.2 Hz, 1H, H-3). C NMR (CDCl ): d
3
21.52 (q, Me), 53.31 (d), 66.87 (d), 74.65 (d), 80.90 (s, C-1).
was ®ltered through silica gel eluting with ethyl acetate/
hexane, 1:3 to give 11b (77%, syn/antiˆ1.9:1). These dia-
stereomeric compounds could be separated by HPLC using
LiChrospher Si 60, 5 mm, 2 cm B£20 cm, ethyl acetate/
hexane, 1:3, order of elution: syn-11b (41 min), anti-11b
To a suspension of powdered potassium hydroxide (3.43 g,
61.1 mmol) in Et O (50 ml), a solution of the bromohydrins
2
(8.17 g, 50.1 mmol, syn/antiˆ1:7) in Et O was added drop-
2
wise. The reaction mixture was stirred at room temperature
for 16 h. After separation of the precipitate, distillation of
the resulting solution led to the epoxides (3.57 g, 87%, cis/
transˆ1:7) as a colorless liquid, bp 658C. The NMR data of
the products were identical to those of 1-ethynyl-2-methyl-
oxiranes obtained from pent-2-en-4-yne.
(
7
2
49 min). Compound anti-11b: Colorless solid, mpˆ69.5±
1
3
18C. H NMR (CDCl ): d 1.47 (d, Jˆ6.6 Hz, 3H, Me),
3
4
.55 (d, Jˆ2.3 Hz, 1H, CuCH), 3.11 (s, 3H, NMe), 3.14 (s,
3
H, NMe), 3.35 (s, 3H, NMe), 3.37 (s, 3H, NMe), 5.87 (qd,
3
3
4
Jˆ6.6, 3.2 Hz, 1H, CHMe), 6.27 (dd, Jˆ3.2, Jˆ2.2 Hz,
1
H, CH±CuC). C NMR (CDCl ): d 15.50 (q, Me), 37.68
3
1
3
(
q, NMe), 37.98 (q, NMe), 42.54 (q, NMe), 42.96 (q, NMe),
A mixture of 1-ethynyl-2-methyloxiranes (cis/transˆ1:7)
was hydrolyzed as described above (water, 1008C, 2 days,
87% yield), and the resulting 10b (syn/antiˆ1:7) was
treated with NaH in THF and then with N,N-dimethylcarba-
moyl chloride as depicted before. In this case, the obtained
mixture of syn-11b and anti-11b led to the pure anti
7
1
1
2.20 (d), 75.44 (d), 76.88 (d), 77.79 (s), 186.00 (s, CvS),
86.61 (s, CvS). IR (CDCl ): 3306 (CuCH), 2941, 1536,
3
2
400, 1289, 1199, 1050 cm . Elemental analysis:
1
C H N O S ; calcd: C, 48.15; H, 6.61; N, 10.21; S,
1
23.37; found: C, 48.16; H, 6.51; N, 10.18; S, 23.75.
Compound syn-11b: Colorless oil: H NMR (CDCl ): d
1
18
2
2 2
1
compound by multiple crystallization from Et O.
2
3
3
4
1
.47 (d, Jˆ6.6 Hz, 3H, Me), 2.53 (d, Jˆ2.2 Hz, 1H,
CuCH), 3.11 (s, 3H, NMe), 3.14 (s, 3H, NMe), 3.35 (s,
3
CHMe), 6.28 (dd, Jˆ6.5, Jˆ2.2 Hz, 1H, CH±CuC). C
NMR (CDCl ): d 15.77 (q, Me), 37.85 (q, NMe), 37.06 (q,
Conversion of 11a,b into 12a,b. Solutions of 11a,b in dry
toluene (0.05±0.07 M) were thermolyzed as described in
Table 1. Thereafter, the solvent was removed in vacuo. In
the case of meso-11a and rac-11a, the residue was treated
3
H, NMe), 3.37 (s, 3H, NMe), 5.86 (quint, Jˆ6.5 Hz, 1H,
3
4
13
3
NMe), 42.74 (q, NMe), 43.15 (q, NMe), 72.46 (d), 75.50 (d),
77.10 (d), 78.02 (s), 186.22 (s, CvS), 186.85 (s, CvS).
Elemental analysis: C H N O S ; calcd: C, 48.15; H,
with THF/hexane (2:1) or dry Et O, respectively, and
2
®ltrated. Then the ®ltrate was concentrated in vacuo to
yield the products, which were analyzed by H NMR spec-
1
1
1
18
2
2 2
6
1
.61; N, 10.21; S, 23.37; found: C, 48.08; H, 6.59; N,
0.10; S, 23.38.
troscopy. In the case of (1E,3E)-12b and (1Z,3E)-12b,
which were formed nearly quantitatively, puri®cation was
performed by ¯ash chromatography (Et O) or by crystal-
2
Pent-4-yne-2,3-diol bis[(N,N-dimethyl)thiocarbamate]
11b) from 2-bromopropanal. To a saturated solution of
lization from CH Cl /hexane, respectively. Compound
2
2
1
(1E,3E)-12a: H NMR (CDCl ): d 3.00 (br. s, 12H,
(
3
4
acetylene in dry THF at 08C, a solution of ethylmagnesium
bromide in THF prepared from EtBr (33.0 g, 303 mmol) and
magnesium (6.10 g, 251 mmol) was added dropwise while
further acetylene was introduced into the reaction mixture.
To this solution of ethynylmagnesium bromide cooled to
4£NMe), 3.14 (d, Jˆ2.45 Hz, 1H, H-6), 6.03 (dd,
3
3
4
J
ˆ15.4,
Jˆ2.45 Hz,
1H,
H-4),
7.01
(d,
trans
13
Jtransˆ15.4 Hz, 1H, H-3), 7.46 (s, 1H, H-1). C NMR
(CDCl ): d 36.98 (br. q, 4£NMe), 81.76 (d, C-6), 82.58
3
(s, C-5), 111.27 (d, C-4), 122.32 (s, C-2), 135.86 (d, C-1),
138.97 (d, C-3), 162.18 (s, CvO), 165.32 (s, CvO).
1
9
2
158C, a solution of 2-bromopropanal (24 g, 175 mmol)
in THF was added dropwise. The mixture was stirred at
room temperature for 16 h. Thereafter, saturated aqueous
NH Cl solution was added with cooling. The organic layer
Assignments were based on heteronuclear shift correlation.
Compound (1E,3Z)-12a: H NMR (CDCl ): d 3.00 (br. s,
1
3
3
4
13H, 4£NMe and H-6), 5.61 (ddd, J ˆ11.7, Jˆ2.7 Hz,
4
cis
3
was separated, and the aqueous layer was extracted
repeatedly with Et O. The combined organic extracts were
Jˆ0.9 Hz, 1H, H-4), 6.58 (dd, J ˆ11.7, Jˆ0.9 Hz, 1H,
cis
1
3
H-3), 7.41 (t, Jˆ0.9 Hz, 1H, H-1). C NMR (CDCl ): d
2
3
washed repeatedly with water and dried with MgSO . After
4
36.51 (br., 4£NMe), 80.68 (C-6), 82.53 (C-5), 109.53
removal of the solvent in vacuo, the residue was distilled to
give the bromohydrins as a light-yellow liquid (8.17 g, 29%,
syn/antiˆ1:7), bp 34±358C/0.01 Torr. After 2 days at
(C-4), 121.89 (C-2), 135.72 (C-1), 137.67 (C-3), 162.62
(CvO), 166.57 (CvO). Compound (1Z,3E)-12a:
1
H
NMR (CDCl ): d 3.00 (br. s, 12H, 4£NMe), 3.03 (d,
3
4
3
4
2
208C, the anti isomer crystallized as a colorless solid,
Jˆ2.5 Hz, 1H, H-6), 5.81 (dd, J ˆ15.4, Jˆ2.5 Hz,
trans
3
which could be separated by suction ®ltration and puri®ed
by washing with cold pentane. However, it was not possible
to isolate the pure syn isomer. Data of anti-4-bromopent-1-
1H, H-4), 6.89 (d, J ˆ15.4 Hz, 1H, H-3), 7.74 (s, 1H,
trans
1
3
H-1). C NMR (CDCl ): d 36.78 (br. q, 2£NMe), 37.01 (br.
3
q, 2£NMe), 80.49 (d, C-6), 82.47 (s, C-5), 107.55 (d, C-4),

5
418
K. Banert, J. Schlott / Tetrahedron 56 (2000) 5413±5419
1
23.84 (s, C-2), 140.62 (d), 142.46 (d), 162.42 (s, CvO),
62.58 (s, CvO). IR (CDCl ): 3306 (CuCH), 1673
CHMe), 42.25 (s), 45.18 (s), 49.08 (d, CHS), 108.15 (s,
CN), 109.35 (s, CN), 109.75 (s, CN), 111.03 (s, CN),
126.71 (s, SCvC), 139.43 (d, CHvC), 163.06 (s, CvO),
1
3
2
CvO), 1367, 1260, 1102 cm . Elemental analysis:
1
(
C H N O S ; calcd: C, 50.68; H, 5.67; N, 9.85; S, 22.55;
found: C, 50.13; H, 5.63; N, 9.47; S, 22.59. Compound
164.34 (s, CvO). IR (CDCl ): 2978, 2878, 1677 (CvO),
3
1
2
16
2
2
2
2
1
1444, 1409, 1368, 1259, 1111, 833 cm . Elemental analy-
sis: C H N O S ; calcd: C, 50.73; H, 4.51; N, 20.88; S,
15.93; found: C, 51.08; H, 4.90; N, 19.12; S, 15.13.
1
(
1Z,3Z)-12a: H NMR (CDCl ): d 3.00 (br. s, 12H,
3
4
17 18
6
2 2
4
£NMe), 3.37 (d, Jˆ2.7 Hz, 1H, H-6), 5.50 (dd,
3
4
3
J ˆ11.8, Jˆ2.7 Hz, 1H, H-4), 6.36 (d, J ˆ11.8 Hz,
cis
cis
1
H, H-3), 8.40 (s, 1H, H-1). C NMR (CDCl ): d 36.87
3
1
3
(br. q, 4£NMe), 80.92 (d, C-6), 85.11 (s, C-5), 105.25 (d,
C-4), 121.91 (s, C-2), 139.78 (d), 140.41 (d), 162.85 (s,
Acknowledgements
CvO), 163.84 (s, CvO). Compound (1E,3E)-12b:
We thank Miss J. Buschmann, Mrs K. K uÈ nzel and Dr M.
Hagedorn for assistance with some of the syntheses. Our
work was supported by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie.
1
mpˆ70.5±71.58C. H NMR (CDCl ): d 1.78 (ddd,
3
3
Jˆ6.7, Jˆ1.6, 0.7 Hz, 3H, Me), 2.98 (br. s, 12H,
3
3
4
£NMe), 6.08 (dqd, J ˆ14.8, Jˆ6.7, Jˆ0.7 Hz, 1H,
trans
3
H-4), 6.29 (dqd, J ˆ14.8, Jˆ1.6, 0.7 Hz, 1H, H-3),
trans
1
3
.12 (s, 1H, H-1). C NMR (CDCl ): d 18.00 (q, Me),
7
3
1
1
1
3
6.66 (q, 2£NMe), 36.83 (q, 2£NMe), 123.42 (s, C-2),
References
27.61 (d), 129.65 (d), 130.78 (d), 162.90 (s, CvO),
66.05 (s, CvO). IR (CDCl ): 2935, 1666 (CvO), 1441,
3
1. Part 10 of the series `Rearrangement reactions'.
2. Hopf, H.; Kirsch, R. Tetrahedron Lett. 1985, 26, 3327±3330.
3. Ishino, Y.; Nishiguchi, I.; Kim, M.; Hirashima, T. Synthesis
1982, 740±742; Srikrishna, A.; Nagaraju, S. J. Chem. Soc., Perkin
Trans. 1 1992, 311±312.
2
1
408, 1365, 1260, 1194, 1111, 1050, 954, 813 cm .
Elemental analysis: C H N O S ; calcd: C, 48.15; H,
1
1
18
2
2 2
6
1
.61; N, 10.21; S, 23.37; found: C, 48.12; H, 6.62; N,
0.22; S, 23.70. Compound (1Z,3E)-12b: Colorless solid,
1
mpˆ117.5±118.58C (CH Cl /hexane). H NMR (CDCl ):
4. Banert, K.; Groth, S. Angew. Chem. 1992, 104, 865±867;
Angew. Chem., Int. Ed. Engl. 1992, 31, 866±868.
5. Banert, K.; H uÈ ckst aÈ dt, H.; Vrobel, K. Angew. Chem. 1992, 104,
72±74; Angew. Chem., Int. Ed. Engl. 1992, 31, 90±92; Banert, K.;
Groth, S.; H uÈ ckst aÈ dt, H.; Vrobel, K. Phosphorus, Sulfur, Silicon
Relat. Elem. 1994, 95/96, 323±324.
2
2
3
3
d 1.74 (ddd, Jˆ6.7, Jˆ1.6, 0.7 Hz, 3H, Me), 2.96 (br. s,
3
3
1
1
7
2H, 4£NMe), 5.89 (dqd, J ˆ14.8, Jˆ6.7, Jˆ0.7 Hz,
trans
3
H, H-4), 6.27 (dqd, J ˆ14.8, Jˆ1.6, 0.7 Hz, 1H, H-3),
trans
1
.42 (s, 1H, H-1). C NMR (CDCl ): d 17.61 (q, Me), 36.23
3
3
(
1
q, 2£NMe), 36.65 (q, 2£NMe), 125.10 (s, C-2), 126.70 (d),
30.90 (d), 134.12 (d), 163.47 (s, CvO), 163.65 (s, CvO).
IR (CDCl ): 2935, 1666 (CvO), 1440, 1408, 1367, 1261,
6. Banert, K.; Toth, C. Angew. Chem. 1995, 107, 1776±1778;
Angew. Chem., Int. Ed. Engl. 1995, 34, 1627±1629.
7. Priebe, H. Angew. Chem. 1984, 96, 728±729; Angew. Chem.,
Int. Ed. Engl. 1984, 23, 736±737; Banert, K. Tetrahedron Lett.
1985, 26, 5261±5264; Chem. Ber. 1987, 120, 1891±1896; Banert,
K.; Hagedorn, M. Angew. Chem. 1989, 101, 1710±1711; Angew.
Chem., Int. Ed. Engl. 1989, 28, 1675±1676.
3
2
1
1
100, 956, 841 cm . Elemental analysis: C H N O S ;
11 18 2 2 2
calcd: C, 48.15; H, 6.61; N, 10.21; S, 23.37; found: C,
7.70; H, 6.53; N, 10.04; S, 23.39.
4
Diels±Alder reaction of 12b with TCNE. A solution of
1E,3E)-12b or (1Z,3E)-12b (150 mg, 0.55 mmol) and tetra-
cyanoethylene (TCNE, 100 mg, 0.78 mmol) in dry THF
5 ml) was stirred for 12 days at 408C or for 8 h at 208C,
(
8. M uÈ ller, B. Diplomarbeit, Technische Universit aÈ t Chemnitz,
1997.
(
9. M uÈ ller, A., Dissertation, Technische Universit aÈ t Chemnitz,
1999.
respectively (see Scheme 5). Thereafter, the mixture was
concentrated in vacuo, and the residue was puri®ed by
10. Pollok, T.; Schmidbaur, H. Tetrahedron Lett. 1987, 28, 1085±
1088; Chen, R. Y.; Cai, B. Z.; Feng, K. S. Chin. Chem. Lett. 1992,
3, 157±158.
11. Huch e , M.; Cresson, P. Bull. Soc. Chim. Fr. 1975, 3/4, 800±
804; Tetrahedron Lett. 1973, 4291±4292.
¯
ash chromatography (Et O) to give trans-14 (110 mg,
2
5
0%) or cis-14 (90 mg, 41%). Compound trans-14: Color-
1
less solid, mpˆ137.5±138.58C (Et O). H NMR (CDCl ): d
2
3
3
1
6
1
.63 (d, Jˆ7.1 Hz, 3H, Me), 2.98 (s, 6H, 2£NMe), 3.09 (s,
H, 2£NMe), 3.48 (m, 1H, CHMe), 5.48 (dd, Jˆ2.4, 1.0 Hz,
12. Smith, G.; Stirling, C. J. M. J. Chem. Soc. C 1971, 1530±1535.
13. Jeganathan, S.; Okamura, W. H. Tetrahedron Lett. 1982, 23,
4763±4764.
1
3
H, CHS), 6.19 (`t', Jˆ2.2 Hz, 1H, CvCH). C NMR
(
CDCl ): d 16.69 (q, Me), 36.48 (q, NMe), 36.87 (q,
3
NMe), 37.17 (q, NMe), 37.77 (q, NMe), 38.31 (d, CHMe),
5.56 (s), 47.41 (s), 50.80 (d, CHS), 107.95 (s, CN), 109.50
s, CN), 109.96 (s, CN), 110.53 (s, CN), 126.96 (s, SCvC),
40.34 (d, CHvC), 162.10 (s, CvO), 164.14 (s, CvO).
14. Banert, K.; Fendel, W.; Schlott, J. Angew. Chem. 1998, 110,
3488±3491; Angew. Chem., Int. Ed. Engl. 1998, 37, 3289±3292.
15. Holand, S.; Epsztein, R.; Marszak, I. Bull. Soc. Chim. Fr.
1969, 3213±3218.
4
(
1
Assignments were based on heteronuclear shift correlation.
Elemental analysis: C H N O S ; calcd: C, 50.73; H, 4.51;
N, 20.88; S, 15.93; found: C, 50.58; H, 4.49; N, 20.92; S,
16. Figeys, H. P.; Gelbcke, M. Tetrahedron Lett. 1970, 5139±
5142.
1
7
18
6
2 2
17. Eglinton, G.; Whiting, M. C. J. Chem. Soc. 1950, 3650±3656;
Allan, J. L. H.; Whiting, M. C. J. Chem. Soc. 1953, 3314±3316.
18. Epsztein, R.; Le Gallic, N.; Marszak, I.; C, R. Acad. Sci. Ser. C
1968, 266, 396±399.
1
1
3
6.05. Compound cis-14: Colorless solid, mpˆ140.5±
1
3
41.58C (Et O). H NMR (CDCl ): d 1.61 (d, Jˆ7.1 Hz,
2 3
H, Me), 2.97 (s, 3H, NMe), 3.00 (s, 3H, NMe), 3.04 (s, 3H,
NMe), 3.10 (s, 3H, NMe), 3.48 (m, 1H, CHMe), 5.60 (dd,
Jˆ2.4, 1.0 Hz, 1H, CHS), 6.18 (`t', Jˆ2.2 Hz, 1H, CvCH).
19. Yanovskaya, L. A.; Terent'ev, A. P. Zh. Obshch. Khim. 1952,
22, 1598±1602 [Chem. Abstr. 1953, 47, 9258e].
20. Friesen, R. W.; Vanderwal, C. J. Org. Chem. 1996, 61,
9103±9110; Friesen, R. W.; Giroux, A. Can. J. Chem. 1994, 72,
1
3
C NMR (CDCl ): d 16.74 (q, Me), 36.57 (q, NMe), 36.77
3
(
q, NMe), 37.05 (q, NMe), 37.75 (q, NMe), 38.29 (d,

K. Banert, J. Schlott / Tetrahedron 56 (2000) 5413±5419
5419
1
1
2
1
2
857±1865; Friesen, R. W.; Kolaczewska, A. E. J. Org. Chem.
991, 56, 4888±4895.
23. Carey, F. A.; Sundberg, R. J. Organische Chemie, VCH:
Weinheim, 1995 (p 132 and references cited therein).
24. Beny, J.-P.; Pommelet, J.-C.; Chuche, J. Bull. Soc. Chim. Fr. II
1981, 377±386.
1. For an alternative synthesis see: Adam, W.; Klug, P. Synthesis
994, 567±572.
2. This compound was prepared in analogy to the method of
25. Guanti, G.; Ban®, L.; Narisano, E. Gazz. Chim. Ital. 1987, 117,
681±687.
Landor, see: Cowie, J. S.; Landor, P. D.; Landor, S. R. J. Chem.
Soc., Perkin Trans. 1 1973, 720±724.