Opposite to Kiliani-Fischer, aldose aldehydes can be oxidized to carboxylic acids and then decarboxylated to shorten chains. This will utilize a reaction we learned before, except now it is applied to sugars. Let's try and refresh your memory.
Here are some practice problems to test what we just learned. Good luck!
Which aldohexoses produce the same Ruff Degradation product
Predict the product for the following reaction