Environmentally friendly products and procedures are being developed both in industry and academia, mainly due to the depletion of fossil resources and the growing global awareness of the need to protect the environment. Thus, since polyurethanes represent a highly demanded class of polymers, straightforward, isocyanate and phosgene-free methods are required for the synthesis of their precursors (monomers) in order to achieve a sustainable production. To foster the discussion with the final goal to meet such a sustainable production, this review provides an overview of classic as well as modern and more sustainable routes towards polyurethanes and their precursors.