Diastereoselective synthesis of 1,2,3,4,4a,14a-hexahydro-8aH-xanthenone9,8a-bindole and 3,4b,5,6,7,8,8a,15b-octahydro-4H-benzodnaphtho1,8-abcarbazol-4-one derivatives has been developed based on a domino sequence that involves electrophilic ortho-spirodearomatization via the Ritter reaction and intramolecular nucleophilic trapping of spiro-σ-intermediates.
Y.S. Rozhkova (Wed,) studied this question.