Olympicene's "Top Secret" Final Step

Over in London, preparations for the 2012 Summer Olympic games continue apace. The torch winds its way through the countryside, the ticket printers hum along, and the British Army has mounted defensive missiles on local apartment roofs. But, for those who've been missing the synthetic chemistry connection, wait no longer: enter, Olympicene!

Olympicene
Source: IBM Zurich | BBC

Olympicene, a tight five-ringed structure, does indeed resemble the famous logo of the quadrennial international contest. IBM Zurich, who used specially-functionalized AFM tips to image pentacene in 2009, now brings us fantastic high-res images of this polycycle (see right). 

I won't go into the story behind the science, as that's been elegantly summarized in a number of places already. Instead, I want to highlight a perplexing 'teaser line' from yesterday's ChemConnector post: 

"You can see the Olympicene compound coming together step by step and yes, the final step is not yet reported!" 

OK. Let's see, we have the first few steps laid out for us, thanks to RSC's ChemSpider. Easiest way to make anything? Start with most of it intact! From commercial 1-pyrenecarboxaldehyde, a Wittig olefination, H2 reduction, basic ester hydrolysis, chlorination, Friedel-Crafts, and lithium aluminum hydride (LAH) reduction brings us to the 5-ringed alcohol (shown below). All the steps are greater than 89% yield, except the F/C (15%), which one imagines might make the "other" pentacene isomer preferentially.

I find the final "Top Secret" step amusing, because any organic chemist "familiar with the art" could think of at least five ways to do it! (Non-chemist readers: the molecule on the left needs a single C=C double bond, and standing in the way is just a molecule of water). That alcohol is fairly "activated" for elimination. My guess? A little strong acid, gentle heat, and some molecular sieves.

Pro Tip: Don't believe the hype declaring olympicene the "smallest 5-ringed structure," at just 1.2 nm across. Skeptics, cynics should check their bond lengths. Is olympicene smaller than cubane? (6 rings, ~0.6 nm). How about a ladderane? (5 rings, ~1 nm). Anyone know other molecules that might qualify?


Updates (04:18, 5/29/12) - ChemConnector mentions, via Twitter, that the step is less 'Top Secret,' and more not-yet-drawn-up for ChemSpider Synthetic Pages. Per Excimer's comment, fixed the position of the 'saturated' CH2 carbon. 
(21:10, 5/31/12) - Commenter (And U. Warwick Prof!) Peter Scott points out the new ChemSpider page, showing major isomer and detailing conditions.