Yes you can. The leaves are high in Oxalic Acid and are therefore very toxic to humans but, in the compost pile, the 8 carbon long acid is either broken down into smaller molecules or simply diluted. So, it is not toxic in the soil.
I have been composting the leaves of rhubarb for years and they are actually great. I don't have any nutrient values off the top of my head but you may wish to peruse the NPK tables in the organic forum to see if there is anything there.
Cheers, and happy composting! Don't forget those browns