[NH:1]([C:9]([O:11][CH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)=[O:10])[C@H:2]([C:6]([OH:8])=[O:7])[C@@H:3]([CH3:5])[OH:4].S(=O)(=O)(O)O.[CH2:24]=[C:25]([CH3:27])[CH3:26].N#N>ClCCl.C(Cl)(Cl)Cl.CCCCCC>[NH:1]([C:9]([O:11][CH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)=[O:10])[C@H:2]([C:6]([O:8][C:13]([CH3:18])([CH3:14])[CH3:12])=[O:7])[C@@H:3]([CH3:5])[O:4][C:25]([CH3:27])([CH3:26])[CH3:24]
Z-Thr-OH (25.3 g, 0. 1 mol, Peptide Research Laboratories, Japan) was suspended in dichloromethane (250 ml), to which was added conc. sulfuric acid (1 ml). The mixture was cooled on a dry ice-acetone bath, to which was blown isobutene (the volume increased by 200 ml). The vessel was closed tightly, and the mixture was stirred for 2 days at 20° C. The vessel was opened, into which was blown N2 at 20° C. to purge isobutene, followed by addition of water. The mixture was neutralized with a 10% (W/V) aqueous solution of sodium hydrogencarbonate, which was subjected to extraction twice with dichloromethane. The dichloromethane layer was dried over anhydrous sodium sulfate, then the solvent was distilled off. The residue was purified by means of a silica gel column chromatography (n-hexane:chloroform =1:2) to give an oily product. The yield was 26.6 g (72.7%). Rf: 0.21 (n-hexane:chloroform =1:2) FAB-MS (M+H+)=366 (Theoretical value =366)
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