合成路线1

The methylation of N-(tert-butoxycarbonyl)-L-tyrosine methyl ester (I) with methyl iodide and KOH gives the protected 4-O-methyl-L-tyrosine methyl ester (II), which is deprotected with TFA yielding (III). The Grundke oxidation of (III) affords the N-hydroxy derivative (IV), which is cyclocondensed with cyclohexane-1,4-dione monoethylene ketal (V) and ethyl acrylate (VI) in refluxing toluene to afford the spiroisoxazolidinone (VII). The reductive rearrangement of (VII) with H2 over Pd/C in acetic acid provides the spiropyrrolidinone (VIII), which is treated successively with tosyl chloride and with sodium azide to obtain the azido derivative (IX). The reduction of (IX) with H2 over Pd/C, protection of the resulting amine with Boc2O, and methylation of the resulting carbamate with NaH and methyl iodide affords the N-methylcarbamate (X). The reduction of the methoxycarbonyl group of (X) with LiBH4 in THF gives the carbinol (XI), which is oxidized with Dess-Martin periodinane to the aldehyde (XII). The rearrangement of (XII) by means of potassium tert-butoxide, followed by deprotection of the carbamate group yields the 7,10a-methanopyrrolo[1,2-a]azocin-8-one derivative (XIII), which is reduced at the carbonyl group with LiAlH4 in THF affords the 8(R)-hydroxy derivative (XIV). The protection of the amino group of (XIV) with benzyloxycarbonyl chloride and triethylamine yields the carbamate (XV).