[S:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6]#[C:7][CH2:8][CH2:9][CH2:10][OH:11].C(N(CC)CC)C.[CH3:19][S:20](Cl)(=[O:22])=[O:21]>ClCCl.O>[CH3:19][S:20]([O:11][CH2:10][CH2:9][CH2:8][C:7]#[C:6][C:2]1[S:1][CH:5]=[CH:4][CH:3]=1)(=[O:22])=[O:21]To a solution of 145 mg of 2a and 200 μl of triethyl amine in 2 ml of dichloromethane was added dropwise at 0° C. 80 μl of methanesulfonyl chloride in 1 ml of dichloromethane. The reaction mixture was stirred for ½ hr and then diluted with 10 ml of water and extracted with dichloromethane. The organic layer was washed with 1M K2CO3, dried and concentrated, to provide 210 mg of essentially pure 2b as an oil; Rf (heptane/ethyl acetate 1/1) 0.55. NMR (CDCl3): δ 2.03 (m, 2, CH2), 2.60 (t, 2, CH2), 4.40 (t, 2, CH2), 3.03 (s, 3, CH3SO2), 6.95, 7.13, 7.20 (3×m, 3, thiophene-H).
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