Four isomeric 7-isopropyloctahydro-4H-inden-4-ones

Abstract

The four isomeric 7-isopropyl-4-hydrindanones (2)–(5) have been prepared and their configurations assigned, using arguments based on the results of equilibration of the two pairs of ketones and on the products formed on hydrogenation of enone precursors. Base-catalysed equilibration at ca. 22 °C indicates that for (3)⇄(2), –ΔG 4.5 kcal mol^–1 and for (5)⇄(4), –ΔG ca. 0.1 kcal mol^–1. Possible diagnostic features in the ¹H n.m.r. spectra of (2)–(5) are discussed briefly.