Novel and Efficient Syntheses of Four Useful Shikimate- derived Epoxy Chiral Building Blocks via Cyclic Sulfite Intermediates

All of the four stereoisomers of methyl 4,5-epoxy-3-hydroxy-cyclohex-l-ene-carboxylate （la--ld） are useful chiral building blocks. Novel and efficient syntheses of these four epoxy chiral building blocks from naturally abun- dant （--）-shikimic acid （2） via cyclic sulfite intermediates are described in this article. The targeted compound （3R,4R,5S）-la was synthesized via four steps from （--）-shikimic acid in 79% overall yield. The other three targeted compounds （3S,4R,5S）-lb, （3S,4S,5R）-1c and （3R,4S,5R）-ld were synthesized via seven steps from （--）-shikimic acid in 56%, 64% and 65% overall yields, respectively.

Asymmetric synthesis of L-carnitine from (R)-3-chloro-1,2-propanediol

A practical chemical synthesis of L-camitine （1） has been accomplished from （R）-3-chloro-1,2-propanediol （（R）-4）, which is a main by-product originated from （R,R）-Salen Co（III） catalyzed hydrolytic kinetic resolution （HKR） of （±）-epichlorohydrin. （R）-4 was utilized as a chiral starting material to prepare the key intermediate cyclic sulfite （（R）-S）. The new synthetic approach demonstrated an efficient utilization of organic by-product for the asymmetric synthesis of bioactive compounds.