Sugars and Meso-Compounds as Building Blocks

Two syntheses and one formal synthesis of (+)-preussin have been reported using sugars as chiral pool building blocks. In these syntheses parts of the sugar backbone have been implemented into the preussin skeleton. All four pyrrolidine carbon atoms stem from the carbohydrate. As a consequence, the two carbon-nitrogen bonds (N/C-2 and N/C-5) of the pyrrolidine ring 

Up to now, the Pak synthesis is the highest yielding synthesis of (+)-preussin with a total yield of 42% over eleven steps, starting from 5,6-anhydro-3-deoxy-l,2-0-isopropylidene-a-D-allofuranose (116). The stereogenic centers at C-2, C-4, and C-5 of D-glucose were elaborated into the three stereogenic centers of (+)-preussin (cf. Fig. 3). 

The second total synthesis using a sugar derivative as chiral pool starting material was published by Yoda et al. [66] and is based on 2,3,5-tri-O-ben-zyl-/ -D-arabinofuranose (121) (Fig. 4). Via 13 steps they were able to synthesize (+)-preussin with an overall yield of 18%. 

Dong and Lin [68, 69] did not start with a sugar as chiral building block, but a product from an asymmetric Sharpless epoxidation commonly used 

They were able to synthesize the first homochiral intermediate 131 from both diastereomeric acids 129 and 130 formed in the desymmetrization step [73]. The stereogenic center, to which the silyl group is attached, was carried 

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