合成路线1

The alkylation of indane-2-carboxylic acid methyl ester (I) with ethyl iodide by means of lithium isopropylcyclohexylamide (LiICA) in THF/DMSO gives the 2-ethyl substituted compound (II), which is hydrolyzed with tBu-OK in DMSO, yielding 2-ethylindane-2-carboxylic acid (III). The reaction of (III) with methanesulfonyl chloride and diazomethane affords the alpha-diazoketone (IV), which is treated with dimethyldioxirane (DMDO) in acetone to provide the ketoaldehyde (V). Finally, this compound is cyclized with 11C-formaldehyde and NH4OH by means of ZnO in THF/water to yield the target labeled imidazole derivative. The intermediate ketoaldehyde (V) has also been obtained in two other ways: a) The alkylation of 2-(diethoxyacetyl)indane (VI) with ethyl iodide by means of tBu-OK in THF gives the corresponding 2-ethyl-substituted compound (VII), which is finally hydrolyzed to the desired ketoaldehyde (V) with HCl in THF/water. b) The oxidation of 2-acetyl-2-ethylindane (VIII) with SeO2 in hot acetic acid/water gives also the desired ketoaldehyde (V).