A versatile method for the post-synthetic removal of primary amino groups from metal-organic frameworks (MOFs) has been developed. The method allowed the first successful synthesis of the missing parent compound of an important family of MOFs – the unsubstituted (Al)MIL-101. The material was shown to be a useful reference compound for the elucidation of the role of amino groups in the adsorption and deactivation of olefin metathesis catalysts. The chemoselectivity of the deamination is sufficient for the selective removal of NH2 substituents from mixed-linker MOFs bearing both NH2 and RCONH groups.