Electrocyclic Ring Opening of the 6b,7a-Dihydro-7H-cyclopropacenaphthylene Radical Anion

Article abstract of DOI:10.1021/jo00321a033

The Na-K alloy and electrochemical reduction of the naphthocyclopropane 6 were investigated.The radical anion of 6 was found to be very labile and could not be observed spectroscopically.In the Na-K reduction of 6, the phenalenyl radical (9) was detected as an intermediate in the reduction, and the phenalenyl anion (10) and perinaphthane (8) were found to be the products of the reduction.Evidence was obtained from polarographic and cyclic voltammetric studies that 8-10 are also formed in the electrochemical reduction of 6.A mechanism is proposed for this reduction which involves an initial electrocyclic ring opening of the cyclopropane ring in the radical anion of 6 which is followed by a 1,2-shift of hydrogen to yield the radical anion of phenalene (11).The radical anion of 11 is then further transformed into 8 and 10; the latter transformation has previously been reported.