One-Carbon Homologation of Aldoses The Thiazole-Based Method

2 One-Carbon Homologation of Aldoses The Thiazole-Based Method 

SCHEME 13.26 Dondoni s iterative aldose chain elongation [63]. 

SCHEME 13.27 Examples of syntheses of aldoses by Dondoni s one-carbon chain homologation. 

L-serine was converted into aminotetrose and pentose derivatives 51 and 52, respectively [66]. The anti diastereoselectivity observed for addition of 42 to the A, A -diprotected a-amino aldehyde 

2- lithiothiazole giving the syn adduct 54 with 92% diastereoselectivity. Interestingly, the same reaction applied to 53 precomplexed with Et2AlCl or TiCl4 gave the anti diastereomer 55 

---