SEARCH Articles Figures Tables Four Technical Syntheses of Ethyl (R)-2-Hydroxy-4-Phenylbutyrate Four-Membered Rings Photochemistry in Synthesis Four-membered ring compounds synthesis Four-membered rings synthesis Four-membered rings, heterocycle synthesis Furan four-component synthesis Natural product synthesis four-membered ring formation Photochemical four-membered ring synthesis Pyrrole four-component synthesis Synthesis of Four-membered Rings Synthesis of the Four-Carbon Saccharinic Acids