Cobalt-catalysed (4+3)-annulation of oxiranes with 4-vinyl indoles: stereospecific access to fused oxepinoindoles

A tandem C-C and C-O bond formation of oxiranes with 4-vinyl indoles has been accomplished under Co-catalysis following a base-promoted annulation to deliver fused oxepinoindole cores. The use of Co-catalysis, diastereoselectivity and chirality transfer (≥95% ee) are the important practical features.