28 Jugloneを出発物質とする抗菌性物質の合成

抄録

Eleutherins (2a,2b), caryopteron (3) and dideoxycryptosporin (22) have been synthesized by regiospecific manner. I) Synthesis of eleutherins (2a,2b). The starting material (5) derived from a Diels-Alder adduct was treated with CH_3MgI to give the hemiacetal 6, which was converted to the diol 8 by the Wittig reaction. Oxidation of 8 with manganese dioxide, and oxymercuration yielded 10. DDQ oxidation of 10 and methylation afforded eleutherin (2a) and isoeleutherin (2b). II) Synthesis of caryopteron (3). The Diels-Alder adduct 13 derived from 1 and dihydroanisol was alkylated with prenyl bromide to give 14a.The retro-Diels-Alder reaction, and epoxidation with NaBO_3 afforded 16a, which was converted to dihydrocaryopteron 17c with BF_3-DDQ. By acetylation, bromination and dehydrobromination, 17c was converted to 3. III) Synthesis of cryptosporin (4). The Diels-Alder adduct 19 was alkylated with crotyl bromide to give 20a, which was transformed to 21 by the retro-diene reaction and epoxidation with NaBO_3. Acid treatment of 21 yielded dideoxycryptosporin 22. Conversion of 22 to 4 is in progress.