Trimethylene dithioacetal, preparation

The isopropylidenation of aldose trimethylene dithioacetals is covered in Chapter 6 and the acetolysis of aldose diethyl dithioacetals in Chapter 7. The C-C-l(C-2 bond cleavage of the a-oxoketene dithioacetal 7 on exposure to mineral acid is referred to in Chapters 13 and 14. The phenylthio precursor 8 of 2-keto-3-deoxy-D-flraZ //io-heptonic acid has been prepared by chain-extension of 2,3 4,5-di-O-cyclohexylidene-D-arabinose with PhSCH2C02Me, followed by de-protection. ... 

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