Part 7: STRUCTURE DETERMINATION

Note that these types of questions are often the most difficult on the examination. This is because they are holistic in that they require a good understanding of the reactions and the concepts and the ability to apply those concepts. They can't be memorised, they require understanding and ability to apply. Hence they help discriminate those who truly understand from those who have memorised and will soon forget. They are like a good Sudoku, no need to guess. Once you find the key, you can work it out logically.

A schematic of the solution is shown below. The information from the question is given in black. Deductions directly from this information are given in red. Points that provide potential key information are shown in green which leads to the structures.

The logical thought pathway would be based on identifying D from the ozonolysis results (nomenclature (the key)). D then leads to C to B to A. There maybe, of course, other possible thought pathways or factors that can help complete the solve.

Common mistakes:

• Incorrect structure for D deduced from the name heptane-2,6-dione
• Ignored the stereochemistry of B and C which contain chiral centers.
• Incorrect reactions especially C to D.
• "Guessed" structure for A to start rather than deduced A by working back from D.