Organic:Model answers

• 2.1 Chair: 2.86 kJ, twist-boat 55.5. No pure boat form is normally locatable, although many a text book on organic chemistry implies that it is a true minimum, albeit somewhat higher in energy than the twist-boat. As noted in the references, it is of course a racemisation transition state connecting the two enantiomeric twist-boat forms.
• 2.2
• 2.3.1 cis-decalin. chair/chair: 17.2. boat/chair: 77.7, boat/boat 131.9
• 2.3.4 Trans: 14.1, cis 12.9. It appears cis is actually the more stable? Woodward states in his paper that in fact he only isolates 40% of the trans isomer, and comments that the energy difference between cis and trans is likely to be small. So the present result pretty much bears this out!
• 2.3.5 all-app 29.9, syn 29.7
• 2.4.1 Axial energies: Me, 12.96, t-Butyl, 77.73, OH, 2.95. Equatorial energies: Me, 2.64, t-Butyl, 32.4, OH, 3.55. The OH appears anomalous in preferring an axial orientation. One presumes the alkoxide will however be heavily solvated, and hence far larger and more akin to t-Butyl.
• 2.4.4 Thiomethyl, Chair, axial -7.51, equatorial -6.91. Oxamethyl, chair, axial, -2.90, equatorial 1.20
• 2.5 Caryophyllene ketone. Trans: 323.9, Cis 334.9
• 2.6 Germacrene. Divinyl trans: 29.44, cis 39.2,
• 2.7. Xestoquinone: Formed isomer, c + (a/b), 139.4 (global minimum?)

• 2.8 Ha+Oa, 323.6, Hb+Ob, 45.4. The third possibility is the formation of a cyclopropene.
• 2.9 7.19(unobs), 0.89 (obs)
• 2.10 lhs conformation: 32.98 H23 43 (approx 6Hz), H34 160.3 (approx 11.5 Hz) rhs conformation 30.2 H23 43.4 (6 Hz), H34 92 (1Hz)
• 2.11.1 38.5 (obs), 62.8 (unobs)