合成路线1

2) The condensation of the previously referenced azetidinone (III) with 1-(trimethylsilyloxy)cyclohexene (XVI) by means of trimethylsilyloxy trifluoromethanesulfonate in acetonitrile gives the corresponding addition product (XVII), which by reaction first with p-toluenesulfonyl hydrazide in acetic acid and then with lithium diisopropylamide in THF yields the cyclohexenyl derivative (XVIII). The regioselective epoxidation of (XVIII) with magnesium monoperoxyphthalate (MgMPP) in dichloromethane affords the epoxide (XIX), which is submitted to ring opening with methanol/p-toluenesulfonic acid and oxidation with sulfur trioxide and pyridine to give the methoxycyclohexylazetidinone (VIII) already described in Scheme 18359601a. 3) The condensation of the previously referenced azetidinone (III) with (2-cyclohexenyl)bis(trans-2-methylcyclohexyl)borane (XX) at room temperature in hexane/THF yields the cyclohexenyl-azetidinone derivative (XVIII) already described. 4) The enzymatic resolution of trans-2-methoxycyclohexanol (XX) with Pseudomonas fluorescens lipase or with Candida antarctica lipase in dry THF containing vinyl acetate and triethylamine gives the (S,S)-isomer (XXI), which is oxidized with oxalyl chloride in dichloromethane, or with CrO3/H2SO4, or with NaOCl or with N-bromoacetamide in acetone yielding 2(S)-methoxycyclohexanone (XXII). Finally, this compound is condensed with the previously referenced azetidinone (III) by means of SnCl4 in dichloromethane to afford the methoxycyclohexylazetidinone (VIII) already described. 5) The reaction of the previously described 2(S)-methoxycyclohexanone (XXII) with trimethylsilyl trifluoromethanesulfonate and triethylamine in THF gives the corresponding trimethylsilyl ether (XXIII), which is then condensed with the previously referenced azetidinone (III) by means of the SnCl4.S(Me)2 complex in dichloromethane yielding the previously described methoxycyclohexylazetidinone (VIII).