How to determine the order of elution in silica gel column chromatography? Benzofuranoids ustusoranes A (1), B (2), and E (3) were isolated from Aspergillus ustus 094102. If these compounds were separated by column chromatography on silica gel, what would be the elution order? (top — comes off the column first, bottom — comes off last).


As I get it, column chromatography is like TLC where in a silica gel the nonpolar compound comes out first.
Your conclusion is absolutely correct. Column chromatography can be thought of as three-dimensional version of TLC (and vice-versa). So the most polar compound which interacts with silica gel most elutes slowest and the least polar compound leaves the column first.

I also support your suggested order as an initial starting point. However, As Klaus mentioned in a comment, unless one has performed the same separation multiple times one should never rely on paper-chemical polarity analysis alone and always confirm structures independently — typically that means ‘measure an NMR of all fractions’.