C([C:5]1[CH:6]=[C:7](C2OC=C(CCO)N=2)[CH:8]=[C:9](C(C)(C)C)[C:10]=1[OH:11])(C)(C)C.C(NCC[C:31]1[CH:36]=[CH:35][C:34](O)=[CH:33][CH:32]=1)(=O)CC.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.CCOC(/N=N/C(OCC)=O)=O>O1CCCC1>[C:31]1([O:11][C:10]2[CH:5]=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH:36]=[CH:35][CH:34]=[CH:33][CH:32]=1
To a stirred solution of 2-(3,5-di-t-butyl-4-hydroxyphenyl)-4-(2-hydroxyethyl)oxazole (5.51 g, 17.38 mmole) in tetrahydrofuran (47 ml) was added N-ethyl, N-propionyl tyramine (3.5 g, 15.8 mmole) and triphenylphosphine (4.55 g, 17.38 mmole). After cooling to 0° C., a solution of diethylazodicarboxylate (2.73 ml, 17.38 mmole) in tetrahydrofuran (16 ml) was added dropwise over 10 minutes. The reaction was allowed to warm to room temperature and stir for 22 hours, evaporated, and triturated with methylene chloride (50 ml) and filtered. The filtrate was chromatographed on silica gel twice using methylene chloride-ethyl acetate and hexane-acetone gradients to give the intermediate phenyl ether (2.95 g, 36%):
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