[CH3:1][CH:2]([CH3:12])[CH2:3][C:4](=[O:11])/[CH:5]=[CH:6]/[C:7]([O:9][CH3:10])=[O:8].C1(C)C=CC(S([CH2:22][N+:23]#[C-:24])(=O)=O)=CC=1.[H-].[Na+].[Cl-].[NH4+]>C(OCC)C.CS(C)=O>[CH3:1][CH:2]([CH3:12])[CH2:3][C:4]([C:5]1[C:6]([C:7]([O:9][CH3:10])=[O:8])=[CH:22][NH:23][CH:24]=1)=[O:11]A solution of (E)-methyl 6-methyl-4-oxo-2-heptenoate (10 g) prepared as described in a) above and (para-toluenesulfonyl)methyl isocyanide (11.5 g) in a mixture of dry dimethyl sulfoxide (30 ml) and diethyl ether (30 ml) was added over one hour to sodium hydride (2.75 g of a 60% oil dispersion, 0.068 mol) stirred in dry diethyl ether (90 ml) under nitrogen. After a further hour saturated ammonium chloride solution was added and the mixture was extracted with ethyl acetate, which was washed well with water, dried, and evaporated to a gum. The gum was chromatographed with ethyl acetate-isohexane (2:3) to afford a solid (3.3 g) which was crystallised from ethyl acetate-cyclohexane to give the sub-title ester.
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