Alicyclic six-membered rings

The general principle that the protons in the alicyclic six-membered rings of saturated six-five-, six-six-, and six-seven-membered fused ring systems give the smallest tJ values (ca. 8-11 Hz) for 4a- and 8a-H in the Z-in form, intermediate values (ca. 20 Hz) in the Z-out form for the ds-fused isomers, and clearly higher values (ca. 25-30 Hz) for the trans-fused isomers [71JCS(C)3222] is applied next to estimate the conformational equilibria in 4-oxo-(thioxo) and 2,4-dioxo(thioxo) derivatives. 

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