A Large-Scale Synthesis of Potent Glucokinase Activator MK-0941 via Selective O-Arylation and O-Alkylation

An efficient, practical preparation of MK-0941, a potent glucokinase activator, is described. Keys to the success of the synthesis are a highly selective mono-O-arylation of methyl 3,5-dihydroxybenzoate with 2-ethanesulfonyl-5-chloropyridine and the choice of a proper protective group for the subsequent SN2 O-alkylation. With the thorough understanding of the origins and fate of in-process impurities, the second-generation robust synthesis with a minimum number of operations reproducibly prepares MK-0941 in 56% overall yield with >99% purity.