Editing Hexose (section)

==3-Ketohexoses==
In theory, the ketohexoses include also the 3-ketohexoses, which have the carbonyl in position 3; namely {{chem2|H\s(CHOH)2\sC(\dO)\s(CHOH)3\sH}}.  However, these compounds are not known to occur in nature, and are difficult to synthesize.<ref name=yuen1961/>

In 1897, an [[fermentation|unfermentable]] product obtained by treatment of fructose with [[base (chemistry)|bases]], in particular [[lead(II) hydroxide]], was given the name ''glutose'', a [[portmanteau]] of ''glucose'' and ''fructose'', and was claimed to be a 3-ketohexose.<ref name=bruyn1897>C. A. Lobry de Bruyn and W. Alberda van Ekenstein (1897): "Action des alcalis sur les sucres. VI: La glutose et la pseudo‐fructose". ''Recueil des Travaux Chimiques des Pays-Bas et de la Belgique'', volume 16, issue 9, pages 274-281. {{doi|10.1002/recl.18970160903}}</ref><ref name=clark1949/>  However, subsequent studies showed that the substance was a mixture of various other compounds.<ref name=clark1949>George L. Clark, Hung Kao, Louis Sattler, and F. W. Zerban (1949): "Chemical Nature of Glutose". ''Industrial & Engineering Chemistry'', volume 41, issue 3, pages 530-533. {{doi|10.1021/ie50471a020}}</ref><ref name=sera1962>Akira Sera (1962): "Studies on the Chemical Decomposition of Simple Sugars. XIII. Separation of the So-called Glutose (a 3-Ketohexose)". ''Bulletin of the Chemical Society of Japan'', volume 35, issue 12, pages 2031-2033. {{doi|10.1246/bcsj.35.2031}}</ref>

The unequivocal synthesis and isolation of a 3-ketohexose, [[xylo-3-hexulose|''xylo''-3-hexulose]], through a rather complex route, was first reported in 1961 by [[George U. Yuen]] and [[James M. Sugihara]].<ref name=yuen1961>George U. Yuen and James M. Sugihara (1961): "". ''Journal of Organic Chemistry'', volume 26, issue 5, pages 1598-1601. {{doi|10.1021/jo01064a070}}</ref>