... Keywords. enaminoesters; photocyclization; regioselective alkylation; indoline; tricyclic spiroindoline. References. 1; M. Dufour, J.-C. Gramain, H.-P. Husson, M.-E. Sinibaldi, Y. Troin; J. Org. ... C. Gramain, H.-P. Husson, Y. Troin; J. Heterocyclic Chem., 25 (1988), p. 201. 3; (a) M. Rubiralta, A. Diez, C. Vila; The synthesis of related tetracyclic spiroindolines lacking the acetate chain at the C-2 position has been recently reported: Tetrahedron Lett., 31 (1990), p. 3779. ...