Here is a one-step transformation that I think few, perhaps not even Corey,* would come up with upon a traditional retrosynthetic analysis.
A and B are everyday organic reagents. The solvent is DCM and the temperature is around 0 °C. No metals, complexes or weird oxidation level crap. So – go ahead and name A and B!
Remember I have this Stuxnet 3.5 beta spyware installed on all of your computers that smell out and report the use of SciFinder and Reaxys. Likewise through your webcam, Vogel, March, Paquette and Larock are detected, to name a few.
Kudos to FA, my fellow grad student, who back in the days included this example in his thesis (also recognized by my software).
* Retract that. Corey would have.
Had to think about it for a while: A is obviously the 1,2-Ethanedithiol. The Dithiolan should then migrate when the cyclohexane ring is aromatized with B in this case maybe with a strong Lewis Acid?
Half-way there! A is what you said.
Must be an oxidant along with the dithiol – I’ll go for NCS.
We have a winner! The original recipe called for 1,2-ethanedithiol and NBS, but I guess NCS would work just as fine.
Can you see the mechanism? First the dithioacetal as expected, then oxidation/halogenation of a sulfur, ring opening to a sulfenyl halide, a bit of flipping around, more halogenation and loss of HBr and … hmpf, perhaps James over at masterorganicchemistry.com can draw it step by step in color for us?
Something like this?
https://imgur.com/BYy2E
In order to get formation of the thioacetal, you’ll need acid. I think it’s probably essential here to use “aged” NBS, which will have some HBr present.
That’s the spirit! Thanks a lot, dude!
My second guess yesterday would have been bromine or iodine. Found some reference where the second step works this way but NBS is a much nicer solution 🙂