[N+:1]([C:4]1[CH:9]=[CH:8][C:7]([CH:10]2[CH2:13][CH:12]([C:14]([O:16][CH3:17])=[O:15])[CH2:11]2)=[CH:6][CH:5]=1)([O-])=O.[H][H]>C(OCC)(=O)C.[Pd]>[NH2:1][C:4]1[CH:5]=[CH:6][C:7]([CH:10]2[CH2:11][CH:12]([C:14]([O:16][CH3:17])=[O:15])[CH2:13]2)=[CH:8][CH:9]=1A solution of this nitro compound (750mg.) in ethyl acetate (20ml.) was stirred for 16 hours with a 5% palladium on carbon catalyst (250mg.) in an atmosphere of hydrogen. The solution was filtered through a pad of "Hyflo" and evaporated to give methyl 3-(4-aminophenyl)cyclobutanecarboxylate. A solution of this amine (800mg.) in dry benzene (20ml.) was stirred under argon at room temperature during the dropwise addition of amyl nitrite (0.755ml.). The temperature of the reaction mixture was slowly (over 21/2 hours) raised to its boiling point and the mixture was then refluxed for 1 hour. The solvent was evaporated under reduced pressure and the residue was chromatographed on a dry column of silica gel `MFC` (supplied commercially by Hopkin and Williams) (25g.), eluting with toluene to give a mixture of cis and trans isomers of methyl 3-(4-biphenylyl)cyclobutanecarboxylate, RF = 0.70 (9:1 v/v toluene/ethyl acetate). The n.m.r. spectrum in deuteriochloroform showed the following characteristic features (δ values):
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