New syntheses of unsymmetrical thiepins and their selenium analogues

New routes toward fused thiepins and their selenium analogues are described, wherein initial cleavage of suitable diaryl disulfides or selenides bearing masked aldehyde functionalities with an N-protected and metalated indole-3-carbaldehyde acetal or a lithiated 2-bromobenzaldehyde acetal derivative gave a set of unsymmetrical diacetals. Subsequent deacetalization, followed by McMurry coupling, afforded the target unsymmetrical thiepins and selenepins.