Léon Ghosez

Léon Ghosez was born in Aalst, Belgium, on 7 June 1934. He completed classical secondary studies in 1951 at the Collège de Bonne-Espérance and the Collège Saint-Pierre in Uccle.

He studied chemistry at the Université catholique de Louvain, graduating with a licence in chemical sciences with the highest distinction in 1955 and a teaching qualification in 1957. In 1958 he received his doctorate in science, supervised by Professor Georges Smets, with a thesis on the polymerisation and copolymerisation of vinyl urethane.

From 1959 to 1961 he was a research fellow at Harvard University, working in the laboratory of Robert B. Woodward, who later won the 1965 Nobel Prize in Chemistry, with a fellowship from the C.R.B. Educational Foundation. In 1963, on a NATO grant, he spent several months in the Munich laboratory of Rolf Huisgen.

Ghosez returned to Louvain as a research fellow of the Belgian FNRS from 1961 to 1963, then became a chef de travaux and, from 1966, a lecturer. His habilitation thesis of 1966 dealt with the cycloaddition reactions of carbenes. He was appointed full professor in October 1969, and from 1971 also taught at the University of Liège. From 1993 he was a professor in the chemistry department of the École polytechnique at Palaiseau in France.

In 1965 he and Heinz-Günter Viehe founded the organic chemistry school at Louvain, which gained a strong international reputation. His own research focused on reactive intermediates, cycloadditions, keteniminium chemistry and new methods of synthesis. A chloroenamine reagent developed in his group is widely known as Ghosez's reagent, and the Ghosez cyclisation, used to make unsaturated delta lactones, carries his name. He also helped create a European postgraduate diploma in molecular chemistry. Over his career at Louvain he supervised some 125 doctoral students and 135 postdoctoral researchers, among them the chemist Véronique Gouverneur, later a professor at Oxford.

After becoming emeritus at Louvain in 1999 he moved much of his work to France. He was a founding member of the European Institute of Chemistry and Biology (IECB) at the University of Bordeaux in Pessac, where he established a research group in 1998, and co-directed the institute with Jean-Jacques Toulmé from 2000 until the end of 2009. His later projects included designing compact molecular scaffolds for drug discovery and developing metal free silicon based Lewis superacid catalysts.

A university tribute on his retirement credited him with more than 160 published papers at that point, over 400 invited lectures, 25 visiting professorships, more than 40 international conferences organised and editorial work for several scientific journals.

According to his family's death notice, Ghosez was widowed by his first wife, Monique Ducarme, and was later married to Huguette Vanlierde. He was survived by his wife, children, grandchildren and a great-grandson. Colleagues described him as a lover of classical music, which he also played, as well as good food and wine, and as a tireless traveller.

Léon Ghosez died at Mont-Saint-Guibert, in the Belgian province of Walloon Brabant, on 24 October 2026, aged 92. His family announced the death in a notice that described him as emeritus professor of UCLouvain, co-founder of the IECB in Pessac, emeritus member of the Royal Academy of Belgium and a knight of the Legion of Honour. The cause of death was not made public.

His funeral mass was scheduled for 3 November 2026 at the church of Saint-François-d'Assise in Louvain-la-Neuve. The family asked that any donations be made to the Fondation Saint-Luc. Former students and colleagues from several countries left tributes recalling his teaching and the warmth of his laboratory.

Ghosez helped build Louvain's organic chemistry school into one of the best known in Europe and trained a large generation of chemists who went on to careers in universities and industry. His name remains attached to a widely used reagent and to a ring forming reaction, and the Bordeaux institute he helped to found continues his commitment to work at the boundary of chemistry and biology. Former students remembered him as an exceptional teacher who could hold a lecture hall of 500 first year students and still recognise them in the street.