In 2015 we described the one-pot transformation of diols 1 to
the thiolated tetracenes 2 via a cascade based on xanthate forma-
tion (Scheme 1).6The reactivity of this system was in accord with
the initial step in the cascade being triggered from the anionic in-
termediate A, as the isolable di-SMe analogue of A (the xanthate
attained by MeI dialkylation), was inert toward rearrangement to 2
at high temperatures (up to 250?C). Both the [3,3] sigmatropic
rearrangements resulting from A and the subsequent 6p electro-
cyclic rearrangements needed to access the cyclization precursor
B have stereospecific requirements; anti-1 leading to syn-B and