Hemiacetal moiety reduction

The radical elongation process was involved in the another synthesis of KDO which started from D-lyxose bromide 159 and alkene 160 [108], (Scheme 34). The reaction proceeded in dry benzene under reflux to give a (3 1) diastereoisomeric mixture of 161 and 162. Conversion of the isomer 161 to the KDO salt required deprotection and reduction of the hemiacetal moiety, which led to 163. Ozonolysis process subsequent by treatment with NHjaq gave the desired KDO in high yield. 

The reduction of phthalidetetrahydroisoquinoline alkaloids was studied in an attempt to duplicate the hemiacetal moiety of rhoeagenine (154c) (706). The final product depends on the temperature and on the reducing... 

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