In 1970 he obtained his MSc degree (Organic Chemistry) followed by his DSc degree in 1972. In the same year he joined the organic chemistry division of the Council for Scientific and Industrial Researcher’s (CSIR) National Chemical Research Laboratory as senior specialist researcher. He focused on research involving the structure elucidation, biosynthesis and analysis of physiologically-active fungal metabolites, the so-called mycotoxins. In 1986, Prof Vleggaar was appointed as research leader of the bioorganic chemistry group in the division and in 1987 as acting divisional head. In 1975, he left South Africa to take up a postdoctoral fellowship at Cambridge University to study the stereospecificity of enzyme-mediated reactions.

Prof Vleggaar joined the newly-formed division of food science and technology at the CSIR in 1987 as Programme Manager: Food and Agricultural Chemicals. In 1990 he was appointed as professor of organic chemistry in the Department of Chemistry at UP – a position he retained till his untimely death. He was a member of the Royal Society of Chemistry, United Kingdom (UK), a member of the South African Chemical Institute and served as Chairperson of the Pretoria section from 1985 to 1986. He was also a member of the American Chemical Society. Prof Vleggaar has authored or co-authored more than 128 scientific articles. The impact of his work was reflected by an impressive ISI H-factor of 27. During the centenary celebrations in 2008 he was taken up in the list of honour of the hundred most prominent researchers in the University’s existence.

He leaves his wife, Connie, two children and three grandchildren behind.