(+)-Pentalenolactone G Methyl Ester Two steps Mixture of anomers Four steps LiBr. HMPA COOMe Nine steps Pirrung, M.C., et al.Tetrahedron Lett 1986, 27, 2703. Pirrung, M.C., et al. J. Org. Chem. 1988, 53, 227. Ten steps hv(350 nm), hexane 47% COOMe 10% Hatakeyama, S, Takano, s, et al. J Am. Chem. Soc. 1994, 116, 408 36A-05 Handout3/31/001:34PM
Me (-)-Paeoniflorin Hatakeyama, S., Takano, S., et al. J. Am. Chem. Soc. 1994, 116, 4081. Me H O O O O O COOMe Me Ten steps 47% O O Me MeOOC Me O O Me MeOOC Me hν (350 nm), hexane, 64% O Me MeOOC Me H O R* O O O O OH BzO O OH HOHO OH H 1) NaBH4 2)Acylation 3)Resolution (-)-Paeoniflorin Twelve steps 10% 47% (±)-Pentalenolactone G Methyl Ester Pirrung, M.C., et al. J. Org. Chem. 1988, 53, 227. O O COOMe Me Me O H O O O Me Me O O Me Me O O Me Me Two steps 46% H O O Me Me H MeO O hν, Pyrex, CH2Cl2, rt 70% Four steps 62% O O Me Me MeO O H O LiBr, HMPA C6H6 95% Nine steps 2% Pentalenolactone G Methyl Ester Pirrung, M.C., et al.Tetrahedron Lett. 1986, 27, 2703. Me Mixture of anomers. One anomer. Stereochemistry unknown. 36A-05-Handout 3/31/00 1:34 PM
(±)- Valeranone 0-15°c,10 1: 1 mixture of diastereomers Separated after photolysis DIBAL-H TsOH 4: 1 mixture Seperable mixture Epi-valeranone Takeshita, H. et al. Bull. Chem. Soc. Jpn. 1993, 66, 2699 Studies toward Cytochalasin C le Base Oxidation state crucia Me hv(254 nm), MeCN rt. 40 min 3.7:1.0 Fuchs, P- L, et al J. Org Chem. 1982, 47, 3121. 36A-06 handout3/31/001:35PM
H (±)-Valeranone Takeshita, H. et al. Bull. Chem. Soc. Jpn. 1993, 66, 2699. Me Me O Me Me O O O Me H Me O O Me Me O Me Me O O TsOH 61% hν, Pyrex, MeCN/acetone (9:1), 0-15 o C, 10h H O O Me Me OH Me Me Me Me O O 1) DIBAL-H 2) TsOH 98% 50% Seperable mixture α:β 3:2 Me Me O Four steps 74% 1:1 mixture of diastereomers. Separated after photolysis. 4:1 mixture Valeranone:7-Epi-valeranone 7 Studies toward Cytochalasin C Fuchs, P.L., et al. J. Org Chem. 1982, 47, 3121. O EtO Me O O Br Seventeen steps 17% O O Me S O Me Me Me O O O Me Me Me Me O SO2 H H O O O Me Me Me Me O SO2 H H O hν (254 nm), MeCN, rt, 40 min 94% Oxidation state crucial O O Me Me Me Me O SO2 H H O Base O O 3.7 : 1.0 Me Me OH H NH H Bn Me OH O Me O OAc Cytochalasin C 36A-06-Handout 3/31/00 1:35 PM