Part 6: SYNTHESIS

Answers to the synthesis problems are given below.  These answers have been selected as they are short and efficient, but there are probably other reasonable solutions.  Note some targets have specific stereochemistry that needs to be considered.

When planning syntheses, one should try to work backwards by functional group analysis. The diagrams show the "retrosynthesis" - the design or plan and then below that the reaction scheme step-by-step (as required in the question). Red arrows try to show carbon-carbon bond forming reactions, blue arrows are functional group manipulations. The blue text rationalise the retrosynthetic analysis and information about important reactions are given in green.

Common errors: incorrect selectivity (regio or stereo) for common reactions (e.g. Markovnikov or anti-Markovnikov OR syn or anti). Miscounting C atoms. Using starting materials that were not hydrocarbons as the question specifically stated. Suggesting reactions of alkanes other than radical halogenation, for example, you can't make alcohols directly from alkanes.

A1 Several viable answers potentially emerge from the retrosynthetic analysis :

Common errors : Using a methoxide to react with the tertiary halide (E vs SN), making a carbocation then trying to react it with methoxide (acid / base !)

A2

Common errors : poor control of introduction of the -Br and of elimination to make the alkyne

B1

Common errors : poor control of the required stereochemistry

B2

Common errors : incorrect control of the regiochemistry by using methoxide instead of methanol to open the epoxide.

C1

Common errors : control of stereochemistry, attempting to use an acetylide in the presence of an alcohol (acid / base ! pKa !)

C2

Common errors : ozonolysis of an incorrect alkene or diene, trying to alkylate a carboxylic acid.