The stereochemical outcome of the two diastereoisomeric rigid benzocondensed epoxides 2a and 2b in the acid-induced nucleophilic attack by MeOH in the gas-phase was studied and compared with the corresponding results obtained with the mobile epoxides of type 1. The stereochemistry of the ring opening process in these systems (1, 2a, b) appears to be dependent on the extent of the positive charge developed a the benzylic carbon. A rationalization which implies different benzylic carbocationic species is proposed, while the hypothesis of the intermediacy of fully developed benzylic carbenium ions does not appear to be supported by the present results.
GAS-PHASE ACID-INDUCED RING-OPENING IN DIASTEREOISOMERIC 9,10-OXIDES DERIVED FROM TRANS-1,2,3,4,4A,10A-HEXAHYDROPHENANTHRENE
CROTTI, PAOLO;
1991-01-01
Abstract
The stereochemical outcome of the two diastereoisomeric rigid benzocondensed epoxides 2a and 2b in the acid-induced nucleophilic attack by MeOH in the gas-phase was studied and compared with the corresponding results obtained with the mobile epoxides of type 1. The stereochemistry of the ring opening process in these systems (1, 2a, b) appears to be dependent on the extent of the positive charge developed a the benzylic carbon. A rationalization which implies different benzylic carbocationic species is proposed, while the hypothesis of the intermediacy of fully developed benzylic carbenium ions does not appear to be supported by the present results.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
