Substituent effects on carbon-13 chemical shifts in 1-substituted camphenilones and some derived N-nitro-imines

Abstract

In a series of 1-substituted camphenilones (1)–(11) the carbonyl C(2) is markedly shielded by electron-withdrawing substituents. With respect to these camphenilones the corresponding C(2) in a limited series of derived N-nitro-imines (12)–(14) is shielded by ca. 30 p.p.m. The ¹³C behaviour of fenchone N-nitro-imine is consistent with the existence of configurational isomerism about the C(2)N bond.