A new synthesis of 4-[(prop-2-en-1-yloxy)methyl]-1,3-dioxolan-2-one (AGC) was performed by Williamson ether synthesis from 4-(hydroxymethyl)-1,3-dioxolan-2-one. Dicyclocarbonates were synthesized by UV thiol–ene coupling of allyl-cyclocarbonate with a 2,2′-oxydiethanethiol. This photochemical thiol–ene reaction was carried out under air, with neither solvent nor photoinitiator. The products, obtained with high yield, were characterized by 1H NMR and FTIR analysis. The synthesized dicyclocarbonates were used without purification to synthesize polyhydroxyurethanes without isocyanate by step growth polyaddition with 1,10-diaminodecane. The synthesized polyhydroxyurethanes were characterized by 1H NMR, FTIR, ATG and DSC analysis. These polyhydroxyurethanes exhibited glass transition temperatures from −31 °C to −14 °C, molecular weight from 7,000 g mol−1 to 9000 g mol−1 and degradation temperature for 5% of weight loss (Td 5%) between 227 °C and 250 °C.