Dihydroazocines and hydrooxocins, which are sought as the conjugate acids of novel 10X-heterocinyl-anions, are made available via cis-aza/oxa-bis-o-homobenzenes from 7-cyanotropilidene. The (Y2+o2+a2)-cycloreversion of cis-aza/oxa-bis-o-homobenzenes A is established as an efficient access to 1,4-diheterocines BIB. For a study of the monohetero-analogous, potentially 10X-diatropic anions EZ', the synthesis of the corresponding conjugate acids D via the monohetero-cis-bis-a-homobenzenes C was investigated. Ia b c d X I NR NR 0 S Y NR 0 0 S In this paper the realization of this route for cyanosubstituted aza/oxasystems (Ib-d -> 5b-d) is detailed. The cyanosubstituent was introduced for its ability to (inductively 3)) stabilize the supposedly very reactive heterocinylanions whilst not largely perturbing the electronic situation to be studied') and to increase the kinetic stability and the S-H-acidity of the intermediate cis-bis-a-homobenzenes 4 (C). Starting from trans-Se=0 -cyano-oxa-bis-a-homobenzene 2. readily available from 7-cyanotropilidene 1 and 'Oz'), the primary preparative goal required the transformation of the epoxide ring of 2 into the cis-(N-donor/acceptor-substituted) aziridine/epoxide/episulfide ring of 4. As to the regioselectivity of the attack upon 2 by the appropriate standard N-, 0-and S-nucleophiles, the allylic CI-position was considered highly preferred,especially at low reaction temperatures. In the ZnSOI-catalyzed I) reactions with NaN3 (20°C, 24h), 'butylamine (200C,24h) and chloramine T (60°C,10h) in isopropanol selective addition was observed at C4 to give 3a (oil. J~,3=4Hz)~), 36 (m.p. 102OC, J2,2=5.2Hz) 2513