A general convenient synthesis of conjugated dieneynes

Article abstract of DOI:10.1016/S0022-328X(01)01275-X

A convenient synthesis of dieneynes 1 is described. Our strategy involves reaction of readily available thiophosphates with sodium acetylides, in which new single and double carbon-carbon bonds are formed.

Full text of DOI:10.1016/S0022-328X(01)01275-X

Journal of Organometallic Chemistry 643–644 (2002) 501–503
www.elsevier.com/locate/jorganchem
Note
A general convenient synthesis of conjugated dieneynes
Iwona Macia˛giewicz, Piotr Dybowski, Aleksandra Skowron´ska *
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland
Received 28 June 2001; accepted 18 September 2001
Abstract
A convenient synthesis of dieneynes 1 is described. Our strategy involves reaction of readily available thiophosphates with
sodium acetylides, in which new single and double carbon–carbon bonds are formed. © 2002 Elsevier Science B.V. All rights
reserved.
Keywords: Conjugated dieneynes; Thiophosphates; Sodium acetylides
provide, in one operation via single and double car-
bon–carbon bond formation, highly substituted conju-
gated dieneynes 1. ‘One-pot’ transformation of 2 into 1
is illustrated in Scheme 2.
As part of our studies on the development of a novel
approach to unsaturated systems [1] based on thiophos-
phates, we report on the preparation of non-linear
dieneynes 1.
Addition of sodium acetylides to thiophosphates 2
affords two diastereoisomeric anions 6. The intermedi-
ate anions rearrange with the migration of a phospho-
ryl group from sulphur to oxygen affording thiolate
anions 7. Subsequent cyclization via nucleophilic attack
with the elimination of phosphate anion gives episul-
phides 8, which lose sulphur spontaneously to provide
conjugated dieneynes 1. The reaction described gener-
ally proceeds in good yield, except in the few cases
indicated in Table 1 (entries 7–10).
The structure of all compounds described in Table 1
was confirmed by 1H-, 13C-NMR, IR and CI-MS
spectroscopy.
The reaction of 2 to form 1 is of low stereoselectivity
except when the R1 substituent is quite large (i-C3H7)
(see Table 1, entry 7, R1=i-C3H7). In this case the
Previously, using this methodology, we elaborated
the synthesis of a number of versatile and synthetically
valuable unsaturated compounds [2,3] including eney-
nes [4]. It was envisaged that this synthetic concept
might also be applicable to the preparation of conju-
gated dieneynes 1. Such highly unsaturated compounds
are useful intermediates in organic synthesis [5,6], in
particular as attractive precursors of conjugated trienes
[7]. Synthesis of only a few simple examples of dieney-
nes 1, have been published so far [8–10], generally with
low yield. A general method for the synthesis of 1 is
needed.
As shown in Scheme 1 a wide range of new thiophos-
phates 2 containing an a,b-unsaturated carbonyl moiety
is readily made from the corresponding carbonyl com-
pounds 3 in high yield [11]. Formation of 2 proceeds
via initial conversion of 3 into O-silylated dienolates 4
[12], followed by the addition of readily available
(EtO)2P(O)SCl (5) [13].
We have found that thiophosphates 2 are good can-
didates to be precursors of dieneynes 1. Reactions of 2
with sodium acetylides (generated from acetylenic
derivatives with NaNH2 in THF at room temperature)
* Corresponding author. Tel.: +48-42-6843120; fax: +48-42-
6847126.
E-mail address: askow@bilbo.cbmm.lodz.pl (A. Skowron´ska).
Scheme 1.
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01275-X

502
I. Macia˛giewicz et al. / Journal of Organometallic Chemistry 643–644 (2002) 501–503
Scheme 2.
ratio of isomers is 75:25. The observed stereochemistry
can be explained by kinetically controlled addition of
an acetylenic anion to the carbonyl function in 2. It
obeys the simple Cram asymmetric induction model
with the assumption that the (EtO)2P(O)S group is the
largest one.
Table 1
Dieneynes 1 from 2 and various sodium acetylides
In summary, application of methodology based on
intermediate thiophosphates provides a general and
convenient route to a wide range of conjugated dieney-
nes, via a reaction in which single and double carbon–
carbon bonds are formed. Application of these
compounds to the synthesis of cyclic systems is cur-
rently under investigation in our laboratory.
1. Experimental
A solution of SO2Cl2 (2.70 g, 0.02 mol) in CH2Cl2 (10
ml) was added dropwise to O,O,O-triethyl phospho-
rothioate (3.96 g, 0.02 mol) in CH2Cl2 (5 ml) at
−5 °C. Stirring was continued for 20 min at room
temperature (r.t.). After removal in vacuo of about 80%
of solvent, crude (EtO)2P(O)SCl was added dropwise to
a stirred solution of freshly prepared O-silylated dieno-
late (0.021 mol) in CH2Cl2 (10 ml) at −78 °C. Stirring
was continued at r.t. for an additional 1–2 h. The
solvent and trimethylsilyl chloride were removed under
reduced pressure to give thiophosphate 2, which was
purified by column chromatography on silica gel, using
benzene and then benzene–EtOAc 2:1 as eluent. Then
pure 2 (0.018 mol) in THF (10 ml) was added dropwise
to a stirred solution of sodium acetylide (commercial
from Fluka) (0.02 mol) or acetylide derivative gener-
ated from appropriate acetylene compound in THF (15
ml) with NaNH2 at r.t. (anion is obtained quantita-
tively after stirring for 1–3 h). Stirring was continued
for 10 min. Then a saturated solution of NH4Cl (15 ml)
was added and the reaction mixture extracted with
3×30 ml of Et2O. The organic layer was washed with
a
No attempts were made to optimize the yields. Yields refer to
analytically pure compounds.

I. Macia˛giewicz et al. / Journal of Organometallic Chemistry 643–644 (2002) 501–503
503
water, dried over MgSO4 and dieneynes 1 were purified
by flash chromatography on silica gel using benzene as
eluent.
132.5 [ꢀC(CH3)2]. IR (neat, cm−1): 2961.3, 2930.6,
2905.4, 2870.7, 2226.2 (CꢁC), 1620.8, 1595.1 (CꢀC),
1489.4, 956.3, 810.6.
1.1. Selected data for compound 1a
Acknowledgements
Yield 75%, yellowish oil; 1H-NMR (CDCl3, 200
MHz): l 2.05, 2.19 [2s, 6H, ꢀC(CH3)2]; 3.34 (br s, 1H,
ꢁH); 7.03, 7.11 (2d, 2H, Jtrans=15.7 Hz, PhCHꢀCH);
7.22–7.51 (m, 5Harom). 13C-NMR (CDCl3, AC-200): l
19.9, 24.5 [ꢀC(CH3)2]; 80.6 (CꢁCH); 82.0 (CꢁCH);
116.7 (ꢀCꢂCꢁ); 123.9, 130.3 (CHꢀCH); [126.4, 127.2,
128.4, 144.9 (C-4°)ꢂCarom]; 137.5 [ꢀC(CH3)2]. IR (neat,
cm−1): 3268.4, 2962.3, 2918.3, 2849.6, 2094.7 (CꢀC),
1618.0 (PhCꢀC), 1589.8 (CꢀC), 1568.9 (Ph), 1447.3,
959.6, 797.6. CI-MS (isobutane): 183.2 [M+1].
We gratefully acknowledge financial support from
the Polish State Committee for Scientific Research
(KBN) grant no 3 T09A 029 15.
References
[1] P. Dybowski, A. Skowron´ska, Tetrahedron Lett. 32 (1991) 4380.
[2] I. Macia˛giewicz, P. Dybowski, A. Skowron´ska, Tetrahedron
Lett. 40 (1999) 3791 (and references therein).
[3] E. Krawczyk, A. Skowron´ska, Heteroat. Chem. 11 (2000) 353
(and references therein).
[4] I. Macia˛giewicz, A. Skowron´ska, Synlett (2000) 1781.
[5] J. ApSimon (Ed.), The Total Synthesis of Natural Products,
Wiley, New York, 1981.
[6] F. Bolman, T. Burkhardt, C. Zolero, Naturally Occuring
Acetylenes, Academic Press, New York, 1973.
[7] R.F. Heck, Palladium Reagents in Organic Synthesis, Academic
Press, New York, 1985.
[8] M. Hoshi, A. Arase, J. Chem. Soc. Perkin Trans. 1 (1993) 2693.
[9] K. Karabelas, A. Halberg, J. Org. Chem. 53 (1988) 4409.
[10] M. Bujard, F. Ferri, M. Alami, Tetrahedron Lett. 38 (1998)
4243.
[11] P. Dybowski, M. Koprowski, I. Macia˛giewicz, A. Skowron´ska,
Synthesis (1999) 844.
[12] P. Cazeau, F. Duboudin, F. Moulines, O. Babot, T. Dunogues,
Tetrahedron 43 (1987) 2089.
[13] A. Skowron´ska, R. Dembin´ski, J. Gwara, J. Michalski, Phos-
phorus, Sulfur, Silicon (1988) 119 (and references therein).
1.2. Selected data for compound 1d
Yield 53%, brownish oil; 1H-NMR (CDCl3, 200
MHz): l 1.09 (t, 3H, J=7.3 Hz, ꢁCCH2CH2CH3); 1.67
(sext, 2H, J=7.2 Hz, ꢁCCH2CH2CH3); 1.99, 2.11 [2s,
6H, ꢀC(CH3)2]; 2.46 (t, 2H, J=7.0 Hz, ꢁCCH2CH2-
CH3); 6.90 (d, 1H, Jtrans=15.6 Hz, ArCH=CH); 7.05
(d, 1H, Jtrans=15.6 Hz, ArCHꢀCH); 7.28 (d, 2H, J=
8.7 Hz, Harom: ꢀCHCꢀCH); 7.36 (d, 2H, J=8.6 Hz,
H
arom: ClCꢀCH). 13C-NMR (CDCl3, 50.32 MHz): l
13.6 (ꢁCCH2CH2CH3); 19.9, 24.6 [ꢀC(CH3)2]; 21.5
(ꢁCCH2CH2CH3); 22.5 (ꢁCCH2CH2CH3); 77.3
(ꢁCCH2CH2CH3); 95.1 (ꢀCꢂCꢁ); 117.8 (ꢀCꢂCꢁ); 125.4,
128.6 (CHꢀCH); [127.6 (ꢀCHCCH), 128.6 (ClCCH),
136.4 (C-4°: ClCCH), 142.7 (C-4°: ꢀCHCCH)ꢂCarom];