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.

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 which are linked via the blue arrows to show the path required to work them all out. There are, of course, other possible thought pathways.

Diagram 1 just gives all the information from the question in black with no interpretation. You can use this to try to solve the problem based on that information.

Diagram 2 gives the basic information from the question in black and deductions directly from this information are indicated by red arrows and with blue text plus it identifies points that provide potential key information by green arrows and key initial structures

Diagram 3 gives the completed solution with the structures in blue. In this problem the are several routes to connect the structures. Key steps are :

• A MS gives MW = 84 g/mol and hence the MF = C6H12
• E must be a ketone (based on ozonolysis conditions and DNP test)
• E must be a pentan-3-one ketone due to the H-NMR
• D must be contain a =CH2 due to CO2 from ozonolysis
• deriving D from E
• A must be chiral
  
  

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