Synthesis of anti-[2.2](2.6)benzothiazolophane via 10π-10π coupling protocol

The known 6-methoxymethyl-2-methylbenzothiazole 6 has been converted into quaternary ammonium hydroxide 4 via demethoxy-bromination followed by quaternization with (CH3)(3)N and treatment with silver oxide. Pyrrolysis of 4, expected to generate both anti-1 and syn-[2.2](2.6) benzothiazolophane 2 via 10 pi-10 pi couplings of the quinodimethane intermediate 5, gives in practice only anti-benzothiazolophane 1. The structure has been established by comparison with an authentic sample of 1 recently synthesized by an unambigous route.