Thiocarbonates Thio sugars

The 1-thio-D-glucose derivative (15) has been synthesised from the corresponding free sugar (12) by treatment with 5,5 -bis( 1-phenyl-l f-tetrazoI-5-yl)dithiocarbonate, As indicated in Scheme 3, a thiocarbonate derivative (14) was formed initially with concomitant liberation of thiol (13). Direct attack by this thiol at C-1 (path a) gave the main product (15) in 63% yield, whereas benzyloxy participation in the displacement at C-1 with attack by the nucleophile at C-6 (path b) gave its regio-isomer (16) which was isolated in 33% yield. The use of compound (15) in silver triflate promoted glycosylations is referred to in Chapter 3. 

New methods have been reported for the deoxygenation of carbohydrate derivatives. One such procedure reported by Barton s group has been noted in Chapter 6 (see Scheme 25). This group has also shown that ring-opening reactions of diol thiocarbonates can be usefully applied to the synthesis of 6-deoxy-sugars (Scheme 75) 374 Thus, the diol thiocarbonate (201) was transformed into the iodo-thio-... 

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