Acetals and Ketals of the Pentitols

Acetals and Ketals of the Pentitols 1. Derivatives of Arabitol (Lyxitol) 

An example of yet another type of benzylidene acetal in the arabitol series was provided by Sowden,58 who synthesized l-nitro-l-desoxy-3,5-benzylidene-D-arabitol (VIII) and its epimer by condensing nitromethane with the known 2,4-benzylidene-D-erythrose. 

A list of acetals and ketals of arabitol is given in Table IX. 

Tanasescu and Iliescu70 reported a crystalline di-(o-nitrobenzylidene)-ribitol, but they furnished no experimental evidence to substantiate their claim that the acetal groups occupied positions 1,2,4 and 5. The compound could not be benzoylated until one of the o-nitrobenzylidene residues had been transformed into an o-nitrosobenzoyl ester by a photochemical reaction (see page 149). 

The monomethylene-ribitol monohydrate has been obtained also from 2,4-methylene-D-talitol (XI) by periodate oxidation and hydrogenation of the resulting 2,4-methylene-D-ribose.48 

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