Diastereoselective synthesis of trans-2-(1-triphenylmethyl-1H-imidazol-4-yl)cyclopropanecarboxylic acids: key intermediates for the preparation of potent and chiral histamine H3 receptor agents

Abstract Procedures for the preparation of both enantiomers of trans -2-(1-triphenylmethyl-1 H -imidazol-4-yl)-cyclopropanecarboxylic acid are described. The key step in the synthesis is a 3:1 diastereoselective cyclopropanation of (5 R )- trans -4-aza-10,10-dimethyl-3-thia-4-(3-(1-triphenylmethyl-1 H -imidazol-4-yl)prop-2-enoyl)tricyclo[5.2.1.0 ]decane-3,3-dione using trimethylsulfoxonium ylide. These cyclopropanes are useful for the preparation of H 3 receptor agents.