I'd noticed quite a few sites on StackExchange have adopted occasional challenges (in the style of the Programming Puzzles and Code Golf site on StackExchange) as a way of getting more people in the community engaged.
Chemistry.SE often has the same problems as the other sites who've had a go at this, namely that the bulk of questions are at an incredibly basic level and don't require multiple answers from different viewpoints or perspectives (which is possibly a topic of conversation in itself).
The idea of synthesis-golf is that it encourages people to get involved by providing an open-ended (but well defined) question that can be answered by users of different levels, hopefully encouraging both engagement and retention (and as @Ortho pointed out, anything that raises the bar scientifically is probably a good thing).
The first challenge:
The first challenge I put up was to devise some route towards the molecule below, sodium Fluvastatin.
Fluvastatin was chosen since it was complicated enough to need more than a cursory glance (i.e. it was challenging enough not to bore the actual chemists here), but hopefully not so complex as to be off-putting. The mixture of heterocyclic chemistry with asymmetric chemistry was also appealing (for rather selfish reasons).
In the space of 10 days, the post received 23 up-votes (+1 down vote), 12 favourites, and 439 views. This is far above average for a typical question posted here (excluding featured, general-interest questions).
More importantly, the question also got 5 (4 ignoring my own) good quality answers, submitted by users with a variety of 'experience' (take that as length of time on chem.se or otherwise).
Whilst I think this 'experiment' worked well, there should probably be some kind of discussion amongst the community here as to whether or not theres any benefit to continuing with this. One issue is with the frequency/format of any synthesis-golf type questions, as I'd be the first one to argue that if the homepage gets spammed with 5 of them a day then the whole thing becomes awfully counter-productive.