b) Product A is formed as a mixture of stereoisomers. Draw all possible forming stereoisomers as clear 3D conformational drawings of the lowest energy conformers. (3 p) Br HO t-Bu -Bu A

1E.) Which of the following two conformers is lower in energy? Both conformers are of equal enery O A Conformer A is lower in energy. B Conformer B is lower in energy. It cannot be determined

In each case below, identify the higest and lowest energy conformations. In cases where two or three conformations are degenerate, choose only one as your anwser. Use Me, H, and Et when drawing the structures.

Sighting along the appropriate C-C bond of neopentane C(CH3)4: a) Draw its Newman projections. b) How much energy does the most unstable conformation possess? c) Make the energy diagram for the different conformers.

Draw the most stable conformation

(c) Draw the most likely conformations of the following compounds H and J and explain your reasoning. Ph OMe H Br OH CO₂Me J

5) For the following: a) Draw the "flat" line structure of the following (be sure to indicate stereochemistry) Br OH b) Draw both chair conformations of the following compound. Indicate which form is the most stable H3C°

The diaxial conformation of cis- 1,3-dimethylcyclohexane is approximately 23kl/mol (5.4 kcal/mol) less stable than the diequatorial conformation. Draw thetwo possible chair conformations, and suggest a reason for the large energydifference.

(a) Convert each chair cyclohexane to a hexagon with wedges and dashed wedges. (b) Draw a stereoisomer of each compound in its more stable chair conformation.

Department Final EXd Q1: Coibacin B is a natural product that exhibits potent anti-inflammatory activity and potential activity in the treatment of leishmaniasis, a disease caused by certain parasites. HAH H (a) Assign the configuration (R or S) of each chiral center in coibacin B. (b) Identify the number of possible stereoisomers for this compound, assuming that the geometry of the alkenes is fixed.