Regio- and Chemoselective Synthesis of Fully Substituted Thiophenes
journal contributionposted on 15.01.2009 by Fabian M. Piller, Paul Knochel
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A full functionalization of all four positions of the thiophene ring was achieved. Starting from readily available 2,5-dichlorothiophene, successive magnesiations of the 3- and 4-positions using TMPMgCl·LiCl furnish, after trapping with various electrophiles, 3,4-difunctionalized dichlorothiophenes. Subsequent dechlorination and metalation or magnesium insertion into the C−Cl bond provides fully functionalized thiophenes in high yields. An application to the synthesis of a thiophene analogue of Atorvastatin (Lipitor) is reported.