A one-pot grain-scale synthetic route for the preparation of gamma-hydroxybutenolides via catalyst-free annulation of alpha-amino acids with alpha-keto acids in water is reported. The method shows many advantages such as readily available starting materials, mild reaction conditions, operational simplicity, acceptable yields, and requiring no extra catalysts or additions. Furthermore, the method is innocuous to the environment, also is valuable to industry. (C) 2017 Elsevier Ltd. All rights reserved.