Of branched-chain sugars

The general chemistry of branched-chain sugars has not been the subject of systematic investigation, mainly because of the scarcity of these compounds. Nevertheless, the totality of reactions employed for elucidating the unique structures of these compounds constitutes a body of valuable information which is basic for future developments. Lucid articles on the chemistry of streptose, by Lemieux and Wolfrom,1 and of apiose, by Hudson, have appeared in earlier volumes of this Series the present article will therefore not include information on these two sugars, except as regards comparison with other sugars and in reference to new developments. 

The favored oxidative cleavage of a primary-secondary over a primary-tertiary vicinal diol grouping has been utilized in the synthesis of branched-chain sugar derivatives.482,483... 

As was described for phthalan 330, the intermediate 374 has also been nsed for the EPC synthesis of branched-chain sugars 378 and 379"° and the steroid 380 in 15-70% yield, employing ketones 133 and 270, as well as 280, respectively. 

With the spiro-epoxides of branched-chain sugars, the oxirane protons appear somewhat farther upfield, between r 6.8 and 7.5, the two protons showing a variable difference in chemical shift.224,227... 

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