Aldolases as Catalyst for the Synthesis of Carbohydrates and Analogs

A particular field of interest for the application of aldolases is in multistep and cascade reactions for the preparation of carbohydrate-hke compounds and analogs 

Cascade Biocatalysis Integrating Stereoselective and Environmentally Friendly Reactions, First Edition. 

Edited by Sergio Riva and Wolf-Dieter Fessner. 

Here we recount the latest research on chemoenzymatic multistep and cascade strategies for the synthesis of iminocyclitols, carbohydrates, and deoxysugars from N-protected ami noaldehydes, hydroxyaldehydes, and simple alkylaldehydes, respectively. The key step in all of them is the stereoselective aldol addition reaction of dihydroxyacetone phosphate (DHAP) and its unphosphorylated analogs to the acceptor aldehydes using DH AP-dependent and dihydroxyacetone- (DH A)-utilizing aldolases, respectively, as biocatalysts. 

In these reactions, RhuA was the most versatile aldolase, accepting both linear and branched C-a-substituted N-Cbz-aminoaldehydes, while FucA tolerated only C-a hnear alkane substitutions. Aware of the importance of the reaction medium, the reactions were assayed in both highly concentrated gel emulsions [17] and 1 4 N,N -dimethylformamide (DMF)/water mixtures. In this case, the 1 4 DMF/water mixtures was the reaction medium of choice providing the best conversions especially for stericaUy more demanding branched alkyl substituents [16]. 

---

I )6 Aldolases as Catalyst for the Synthesis of Carbohydrates and Analogs Table 16.1 [Continued]... 

---