LETTER
Synthesis of Semicyclic Dienes by Modified Julia Olefination
2591
OBn
O
OBn
O
BnO
BnO
BnO
BnO
1) MeCHO
2) LiHMDS
SO2Btz
THF
–78 °C to r.t.
18 24%
7
Scheme 4 Modified Julia olefination with enolizable aldehyde
the 2-benzyloxy-substituted vinyl sulfone
6 with Electron-deficient aldehydes appear to give slightly better
LiHMDS at –78 °C to room temperature failed to provide results. When the Julia olefination was performed with
the corresponding diene 8, despite clean disappearance of benzene-1,3-dicarboxaldehyde (Table 1, entry 5), the re-
the starting material by TLC. This failure can be attributed action provided the mono adduct 14 in good yield (66%).
in part to the highly congested and electron-rich nature of We also evaluated the possibility of extending the reaction
the tetrasubstituted endocyclic alkene of 8. Treating the 2- to enolizable aldehydes. However, an attempt with vinyl
deoxy derivative 7 under the same conditions provided the sulfone 7 and acetaldehyde led to the desired diene in poor
diene 9 in relatively good yield (72%). The reaction led yield (24%) and a large amount of side products
selectively to the E-isomer.9
(Scheme 4). Presumably, enolization competes with the
formation of the g-lithiated sulfone under the Barbier con-
ditions.
To evaluate the scope and limitations of this reaction, we
performed the modified Julia olefination between vinyl
sulfone 7 and a range of aromatic and heteroaromatic al- To conclude, we have developed an efficient route to ano-
dehydes under standard reaction conditions (Table 1). meric semicyclic dienes derived from carbohydrates in
Semicyclic dienes were obtained in moderate to good good yield via a modified Julia olefination. To our knowl-
yields (50–85%) depending on the substituent on the edge, this is the first example of modified Julia olefination
benzene ring or the nature of the heterocyclic ring.
starting from a vinyl sulfone derivative which could be an
alternative to the well-established Julia modified reaction
starting from allylic sulfones, with both reactions pro-
ceeding via the same intermediate. Further studies are in
progress in order to extend this methodology to enolizable
aldehydes and other 2-deoxysugars.
Table 1 Synthesis of Diverse Semicyclic Dienes Derived from
Carbohydrates
8
OBn
6
O
BnO
BnO
1
7
3
Ar
5
4
2
Acknowledgment
Entry
1
Compound Aryl
Yield
64%
Financial support from the European Union (contract N° LSHB-
CT-2004-503467) is gratefully acknowledged.
10
OMe
References and Notes
2
3
11
12
70%
66%
(1) Giuliano, R. M. Cycloaddition Reactions in Carbohydrate
Chemistry; American Chemical Society: Washington / DC,
1992.
O
OMe
OMe
OMe
(2) (a) Sun, K. M.; Fraser-Reid, B.; Tam, T. F. J. Am. Chem.
Soc. 1982, 104, 367. (b) Sun, K. M.; Giuliano, R. M.;
Fraser-Reid, B. J. Org. Chem. 1985, 50, 4774. (c) Giuliano,
R. M.; Buzby, J. H. Carbohydr. Res. 1986, 158, C1.
(d) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc.,
Chem. Commun. 1988, 706. (e) Lipshutz, B. H.; Nguyen, S.
L.; Elworthy, T. R. Tetrahedron 1988, 44, 3355.
(f) Burnouf, C.; Lopez, J. C.; Calvo-Flores, F. G.; Laborde,
M. A.; Olesker, A.; Lukacs, G. J. Chem. Soc., Chem.
Commun. 1990, 823. (g) Giuliano, R. M.; Buzby, J. H.;
Macropulos, N.; Springer, J. P. J. Org. Chem. 1990, 55,
3555. (h) Lopez, J. C.; Lameignere, E.; Burnouf, C.;
Laborde, M. A.; Ghini, A. A.; Olesker, A.; Lukacs, G.
Tetrahedron 1993, 49, 7701.
4
5
6
13
14
15
85%
66%
54%
N
CHO
(3) (a) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc.,
Chem. Commun. 1988, 514. (b) Giuliano, R. M.; Jordan, A.
D. Jr.; Gauthier, A. D.; Hoogsteen, K. J. Org. Chem. 1993,
58, 4979. (c) Al-Abed, Y.; Al-Tel, T. H.; Schröder, C.;
Voelter, W. Angew. Chem., Int. Ed. Engl. 1994, 33, 1499.
(d) Hayashi, M.; Tsukada, K.; Kawabata, H.; Lamberth, C.
Tetrahedron 1999, 55, 12287.
7
8
16
17
50%
65%
N
Synlett 2007, No. 16, 2590–2592 © Thieme Stuttgart · New York