[C:1]([OH:8])(=[O:7])[CH2:2][CH2:3][CH2:4][CH:5]=[CH2:6].[C:9](O)([CH3:12])([CH3:11])[CH3:10].C1CCC(N=C=NC2CCCCC2)CC1>CN(C1C=CN=CC=1)C.C(Cl)Cl>[C:1]([O:8][C:9]([CH3:12])([CH3:11])[CH3:10])(=[O:7])[CH2:2][CH2:3][CH2:4][CH:5]=[CH2:6]To a stirred solution of 5-hexenoic acid q-1 (6.00 g, 52.6 mmol), t-butyl alcohol (72.2 mL, 735.84 mmol) and DMAP (1.28 g, 10.51 mmol) in DCM (150 mL) at −10° C. was added DCC (16.26 g, 78.84 mmol). After stirring at room temperature overnight, solid was filtered off. The filtrate was evaporated under reduced pressure to give a crude oil, which was purified by chromatography (Biotage; 65i). Elution with a gradient of EtOAc/Hexane from 5/95 to 10/90 yielded 4.16 g (46.53%) of t-butyl ester q-2, which displayed a 1H NMR spectrum that matched literature (Johnson, P. Y.; Berchtold, G. A. J. Org. Chem. 1970, 35, 584-592) and was used without further purification).
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