Mesylates reaction with LiCl

The latter reaction set up the possibility of making such exotic derivatives as 2,3-anhydro-4-chloro-talo-sucrose (Scheme 13) by a four-step sequence involving O-mesylation of 3,6,l, 3, 4, 6 -hexa-0-pivaloylsucrose, high-temperature LiCl displacement, O-depivaloylation with concomitant epoxide formation, and finally O-acetylation. 

An alternate procedure involves mesylate formation and Sx2 replacement by LiCl. This reaction should be monitored carefully (especially with active alcohols such as allylic and benzylic alcohols) as frequently the chloride by-product will displace the mesylate in situ. 

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