An efficient and practical route for the synthesis of (-)-tasimelteon from 2,3-bis(2-hydroxyethyl)phenol has been developed. The product was prepared in seven steps in overall 16.4% yield using highly stereoselective cyclopropanation reaction of the intermediate as the key step.

A mild and efficient procedure is described for the synthesis of amine-substituted diazoacetoacetates by the addition of ethyl 3-(tertbutyldimethylsilanoxy)-2-diazobut-3-enoate to aldimines catalysed by MgI 2 etherate (MgI 2 •(OEt 2 ) n ) in MeCN. The reaction produces good to excellent yield at room temperature.

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