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Chapter 2
Synthesis of substituted pyrimidines via Wittig
2.4 Applications of Wittig reaction
The Wittig reaction occupies a central role in organic synthesis as it generates
double bond with high level of stereocontrol: non stabilized ylides give high Z-
selectivity, where as stabilized ylides furnish high E-selectivity. 41 Here we discuss
various synthetic approaches for synthesize new chemical entities via Wittig reaction.
R. Antonioletti et al. 42 have developed a mild and practical procedure for the
Wittig olefination, promoted by lithium hydroxide and triphenylbenzyl phosphonium
bromide, has been set up for the synthesis of stilbenes and styrenes (Figure-21).
Ph
Ph
P
Br R CHO
Ph
LiOH·H2O
Solvent, refulx
E/Z isomer
Figure-21
Jesse Dambacher et al. 43 has reported that water is demonstrated to be an
excellent medium for the Wittig reaction employing stabilized ylides and aldehydes.
Although the solubility in water appears to be an unimportant characteristic in
achieving good chemical yields and E/Z-ratios, the rate of reactions in water is
unexpectedly accelerated (Figure-22).
R
Figure-22
Elsie Ramirez et al. 44 have been developed a highly efficient and rapid
protocol for the preparation of the unsaturated 7,3-lactone-a-D-xylofuranose
derivatives (Versatile chiral synthon for naturally important compounds) via selective
Wittig olefination in aqueous media (Figure-23).
Figure-23
James McNulty et al. 45 has reported direct synthesis of 1,3-dienes and 1,3,5-
trienes from the reaction of semi-stabilized ylides via Wittig reaction under aqueous
media employing sodium hydroxide as base (Figure-24).
Department of Chemistry, Saurashtra university, Rajkot-360005 52