Diastereoselective diallylation of various butane-2,3-diacetals by allylsilane

Article abstract of DOI:10.1016/S0040-4039(03)01224-3

Five butane-2,3-diacetals obtained from the reaction of 1,2-diols and methanol with biacetyl have been treated with allylsilane in the presence of titanium tetrachloride to afford bis-allyldioxanes as single diastereoisomers.

Full text of DOI:10.1016/S0040-4039(03)01224-3

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 44 (2003) 5315–5317
Diastereoselective diallylation of various butane-2,3-diacetals
by allylsilane
Natacha Mariet, Malika Ibrahim-Ouali* and Maurice Santelli*
Laboratoire de Synthe`se Organique, UMR No. 6009, Avenue Escadrille Normandie-Niemen, F-13397 Marseille Cedex 20, France
Received 30 April 2003; revised 6 May 2003; accepted 10 May 2003
Abstract—Five butane-2,3-diacetals obtained from the reaction of 1,2-diols and methanol with biacetyl have been treated with
allylsilane in the presence of titanium tetrachloride to afford bis-allyldioxanes as single diastereoisomers. © 2003 Elsevier Science
Ltd. All rights reserved.
1. Introduction
ethers.2 In 1995, we have shown that the cis-tetra-
oxadecaline 1 (resulting from the acetalisation of biacetyl
with glycol) treated with allyltrimethylsilane in the pres-
ence of titanium tetrachloride leads to the selective
formation of meso-2,3-diallyl-2,3-dimethyl-1,4-dioxane
2.3 Clearly, double addition oftheallyl moiety isoccurring
according a stepwise process.
Extensive efforts have been devoted to the carbonꢀcarbon
bond formation of acetals with silylated nucleophiles
promoted by various reagents.1 In particular, the reaction
between acetals or less often cetals and allylsilanes is a
mild and general method for the formation of homoallylic
* Corresponding authors. Fax: +33-4-9198-3865; e-mail: m.ibrahim@univ.u-3mrs.fr; m.santelli@univ.u-3mrs.fr
0040-4039/03/$ - see front matter © 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0040-4039(03)01224-3

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N. Mariet et al. / Tetrahedron Letters 44 (2003) 5315–5317
Recently, Ley and co-workers have described the
preparation from biacetyl of some 1,2-diacetals bearing
a dioxane ring and a trans-diaxial 1,2-dimethoxy moi-
ety.4 Moreover, compounds 4–6 could constitute
remarkable chiral building blocks.
The twice retention of configuration observed in the
case of 4, can result from a participation of one
methoxy group providing the departure of the other. As
described below, the first substitution occurs with reten-
tion. Then, the anomeric assisted ionisation8 of the last
methoxy group leads to an oxocarbenium ion which is
attacked by allylsilane on the axial position.
Then, we studied the TiCl4-mediated addition of allylsi-
lane and, for each case, we observed a very clean
reaction. So, from 3 and 6 and using 3 equivalents of
Similarly, the dioxane 11 has been obtained from 5 and
here too, no ring closure metathesis using the Grubbs
reagent was observed. NOESY data allowed us to
confirm the identity of the structure 11.
allylsilane in the presence of
4 equivalents of
nitromethane, we obtained only meso-4,5-dimethyl-4,5-
dimethoxyocta-1,7-diene 8 (43% yield from 3, 60% yield
from 6).5 The structure of 8 was established by its ring
closure metathesis using the Grubbs catalyst,6 into
meso-1,2-dimethyl-1,2-dimethoxycyclohex-4-ene 9 (90%
yield).
For the asymmetric dioxane 7, with one equivalent of
allylsilane, the first reaction is a substitution of the
methoxy group with overall retention followed by an
In the case of 4, the substitution of methoxy groups was
observed and the dioxadecaline 10 was obtained in 68%
yield as the sole product. The NMR spectra prove that
the C2-axis is maintained. Only two structures 10 and
10% having a C2-axis can be obtained. Nevertheless and
in spite of various procedures, all attempts of ring
closure metathesis applied on 10 failed, leading us to
propose the structure 10 resulting from a substitution
with retention of configuration.7
invertive (‘SN2-like’) substitution on the mixed ketal
moiety. Again, the stereochemistry of 13 has been
checked by a ring closure metathesis using the Grubbs
catalyst giving rise to a cis-ring junction dioxadecaline
14. Moreover, NOESY experiments are in agreement
with the proposed structure.9
For the substitution with retention, the most reasonable
interpretation is that, after coordination of titanium

N. Mariet et al. / Tetrahedron Letters 44 (2003) 5315–5317
5317
tetrachloride with the oxygen atom of the methoxy
group, an oxygen participation occurred to give an
oxonium ion which is attacked by allylsilane with an
overall retention. Then, the coordination of titanium
tetrachloride with the oxygen atom of the bridge pro-
vokes the substitution with inversion. In each case, the
more CꢀO reactive bond is in axial position.
Practical Approach; Oxford University Press: Oxford,
1999.
3. Pellissier, H.; Santelli, M. J. Chem. Soc., Chem. Commun.
1995, 607–608.
4. (a) Douglas, N. L.; Ley, S. V.; Osborn, H. M. I.; Owen, D.
R.; Priepke, H. W. M.; Warriner, S. L. Synlett 1996,
793–795; (b) Hense, A.; Ley, S. V.; Osborn, H. M. I.;
Owen, D. R.; Poisson, J.-F.; Warriner, S. L.; Wesson, K.
E. J. Chem. Soc., Perkin Trans. 1 1997, 2023–2031; (c)
Ley, S. V.; Michel, P. Synlett 2001, 1793–1795; (d) Ley, S.
V.; Baeschlin, D. K.; Dixon, D. J.; Foster, A. C.; Ince, S.
J.; Priepke, H. W. M.; Reynolds, D. J. Chem. Rev. 2001,
101, 53–80.
2. Conclusion
We have shown that allylsilane can react with 1,2-diac-
etals with an high stereoselectivity consistent with a
substitution mechanism controlled by the anomeric
effect.
5. Oil with about 4% of dl-isomers (chiral VPC). 9, 1H
(CDCl3, 300 MHz) l 5.53 (2H, br s), 3.23 (6H, s), 2.44
(2H, 0.5AB, d, J=16.3 Hz), 1.96 (2H, 0.5AB, d, J=16.3
Hz), 1.13 (6H, s); 13C (CDCl3, 75 MHz) l 124.8 (d), 78.0
(s), 49.8 (q), 33.8 (t), 17.8 (q).
Acknowledgements
6. Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413–
4450.
7. 10, oil; structure confirmed by NOESY experiments: we
observed that only the allyl methylene gives cross peaks
with axial hydrogen geminated with oxygen.
8. (a) Kirby, A. J. The Anomeric Effect and Relative
Stereoelectronic Effects at Oxygen, 1st ed.; Springer:
Heidelberg, 1983; (b) Deslongchamps, P. Stereoelectronic
Effects in Organic Chemistry, 1st ed.; Pergamon: Oxford,
1993; (c) Salzner, U. J. Org. Chem. 1995, 60, 986–995.
9. 12, 13 and 14 are oils. For 13 and 14, in the NOESY
experiments, we note cross peaks between the two methyl
groups and the hydroxymethyl group.
N.M. is grateful to the ‘Re´gion Provence-Alpes-Coˆte
d’Azur’ and the CNRS for a grant.
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