Carbohydrate-based chiron approach

Alternatively, the carbohydrate-based chiron approach has been extensively applied and reviewed by the Hanessian group. " ... 

A review of syntheses of the Prelog-Djerassi lactonic acid includes carbohydrate-based routes,27 and there have been two further reports of syntheses of the P-hydroxy-5-lactone unit (38) of mevinic acid and its congeners.28, 29 jn a synthesis of the mosquito oviposition pheromone (39), the chiral centres were derived from those of 2,3-0-ethylidene-D-erythrose, with this chiron being extended by Wittig reactions, in a similar manner to the use of 2-deoxy-D-ribose in an earlier approach to the same target (S.-K. Kang and I.-H. Cho, Tetrahedron Lett., 1989, 30, 743). 

In another synthesis, Gallagher described a fruitful approach based on the use of a carbohydrate enolate, which takes advantage of the presence of the C7 keto group in the target compound [265-267]. In this approach, an enolate had to be formed at the anomeric position of the gluco chiron, stable toward (3-elimination. Moreover, the use of a strained system, as in 357, should force enolization to occur on the correct side. 

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