A tribute to Professor Ghosez

Abstract

Prof. Léon Ghosez's life started in a French-speaking family in Aalst, a small city located in the Flemish part of Belgium. As Prof. Ghosez's father was a chemist, he probably passed on his genes coding for chemistry to his son, but he certainly had a definite influence on his career. Prof. Ghosez studied at the Catholic University of Leuven and, in 1955, he obtained his degree of "licencié en sciences chimiques" with "summa cum laude". After his degree, he joined Prof. Smets' group at the University of Leuven for a PhD on "kinetics of polymerization and co-polymerization of N-vinyl urethane", 1,2 which he was awarded in 1958 also with "summa cum laude". It seems that these two "summa cum laude" distinctions set up Dr L Ghosez's future career. As he was about to do his military service, he was integrated into a laboratory of the Royal Military School where he studied chemisorption on molecular layers of metals evaporated under high vacuum. However, after his training in polymers and in physical properties, he felt that he was more attracted to creating new molecules. Léon Ghosez needed to take a big step between the synthesis of polymers and the synthesis of small molecules, but he likes challenges. At that point in time, not many Belgium students were crossing the Atlantic to achieve a postdoctoral stay in the US but Léon Ghosez decided to complete his training by a postdoctoral internship in the US, and he joined Prof. Woodward's group in Harvard (who had not yet obtained the Nobel prize). His project in Woodward's group was to find a substitute "to the Edman's method to study the amino acid sequence in peptides which consisted in attaching hydrazino-acetic acid to a terminal NH2 group in order to cleave at least two N-terminal amino-acids".In 1961, back in Belgium at the University of Leuven, he decided to prepare his "thèse d'aggrégation" e.g. his habilitation. During, his habilitation, he decided to combine organic chemistry with mechanistic studies and to study carbenes. At that time, there was a big controversy about the spin states of carbenes and their reactivity. Léon Ghosez was able to show that a stereospecific cycloaddition of dichlorocarbene occurred on cisand trans-cyclooctenes and these results strongly supported the absence of any 1,4-dipole or diradical intermediates in the cycloaddition. He proved that the two  bonds were formed by a concerted mechanism 3,4 (Scheme 1).