(±) Hirsuteine Vacuum Seven steps Me H Hirsute Formal syntheses of capnellene and corioli were reported sing a similar photoaddition/fragmentation reaction (±)- Pentalenene,(±)- Pentalenic Acid and (+)-Deoxypentalenic Acid from a Common Precursor CODE CooT hexane rt. 36 h Three steps The stereochemistry at the starred carbon determined, but the products were isolated as a mixture COoMe Stereochemical rationale(Crimmins R C-9 dr COOT CooT FPr>20:1 Consistent with predominant stereochemistry at C-9 nfluenced th stereoselectivity et al J. Am. Chem. Soc. 1986. 108. 800 36A-08 handout3/31/001:37PMMe (±)-Hirsutene O O O O C6H6 90% O O H H Me H O O hν, Pyrex, EtOAc, rt, 30 min 85% Flash Vacuum Pyrolysis 500 oC "Quantitative" Seven steps 8% Formal syntheses of capnellene and coriolin were reported using a similar photoaddition/fragmentation reaction. Me Me Hirsutene Mehta, G., et al. J. Am. Chem. Soc. 1986, 108, 3443. Me Me Me Me O O Me Me H H Me H Me Me Mehta, G., et al. J. Chem. Soc., Chem. Comm. 1981, 756. H (±)-Pentalenene, (±)-Pentalenic Acid and Crimmins, M.T., et al. J. Am. Chem. Soc. 1986, 108, 800. (±)-Deoxypentalenic Acid from a Common Precursor. COOEt O Me Me COOMe Me O Me Me Me COOMe COOEt H hν, uranium glass hexane, rt, 36 h 73% 9 Me O COOR Me Me COOEt H Me O C O O R Me Me COOEt H H Consistent with predominant stereochemistry at C-9 Stereochemical rationale (Crimmins) Crimmins, M.T., et al. J. Org. Chem. 1984, 49, 2076. R C-9 dr Me Et i-Pr 13:1 17:1 >20:1 O Me Me Me COOMe COOEt H 9 1 : 13 + COOMe COOMe Me Me Three steps 44% Varying the size of the indicated alkyl group influenced the stereoselectivity The stereochemistry at the starred carbon was not determined, but the products were isolated as a mixture. 36A-08-Handout 3/31/00 1:37 PM