H₂C. CI 2 C H₂ 9 Name using I.U.P.A.C nomenclature.

HBr HBr H₂SO4, H₂O HgSO4 H2SO4, H₂O HgSO4 1. BH3 2. H₂O₂, NaOH

1. You have the tools to accomplish one of the early synthesis of a major alkaloid. Porantherine (molecule M) is the main alkaloid of the low woody shrub Poranthera corymbosa distributed in the southwest. The following questions pertain to the attached synthetic scheme (J. Am. Chem. Soc. 1974, 96, 6516). The are key steps that utilize an aldol-like mechanism to close three rings (A) What kind of transformation is the D → E step; show NO mechanism, but what was added to D? Hint: molecule E clearly has a terminal alkene and ketone, but what is the third functional group (it's not another alkene)? You've done the mechanism for making this functional group in chapter 20. (B) The E F transformation is rather elegant and it is promoted by an acid (toluenesulfonic acid). It involves formation of an enol (tautomerization) followed by protonation on the C=C bond in the ring to form a resonance- stabilized carbocation. Show the mechanism of this cyclization starting from the enol (i.e. double…

1. Describe Joule's experiment and the conclusion he came up with as a result.