From tartaric acid to the most biologically active insecticides

Professor Alain Krief: Advancing Chemistry; From Innovative Synthesis to Promoting Sustainable Development

Over more than five decades, Alain Krief’s career has encompassed many contributions to chemistry, notably in his innovative work in the areas of organic synthesis and the use of inorganic and organic reagents, as well as his work on bioorganic chemistry and applications of information technology in chemistry. His research on the synthesis of cyclopropanes, including chrysanthemic acid and other pyrethroids, and the uses of selenium compounds in organic synthesis, have been of particular importance and have found widespread applications. In addition, his roles in international collaborations in research and his leadership of the International Organization for Chemical Sciences in Development from 2009 to 2020 have marked his strong commitment to the importance of chemistry as a science for the benefit of society and a contributor to the goal of sustainable development.

1 Introduction

2 A Spectrum of Research

3 Leadership of the International Organization for Chemical Sciences in Development (IOCD)

Synthesis and insecticidal activity of new pyrethroids

BACKGROUND

Pyrethroids are among the most potent pesticides known, with great potential for structural variation with retention or enhancement of potency. The simple methyl ester is easier to prepare (at least one step shorter) than the more complex pyrethroids modified on the alcohol moiety. The objective was to synthesise methyl esters of pyrethroid acids containing an aromatic ring on the acid moiety and evaluate their biological activity against Ascia monuste orseis Latr., Tuta absoluta Meyrick, Periplaneta americana (L.), Musca domestica L. and Sitophilus zeamais (Motsch.).

RESULTS

The synthetic sequence required seven steps: protection of the hydroxyl groups of D-mannitol, diol oxidative cleavage with sodium metaperiodate, alkene formation by Wittig reaction with methoxycarbonylmethylidene(triphenyl)phosphorane, cyclopropanation, acetal hydrolysis with perchloric acid and oxidative cleavage with sodium metaperiodate gave methyl (1S, 3S)-3-formyl-2,2-dimethylcyclopropane-1-carboxylate. The final step comprised reaction of the aldehyde with five different aromatic phosphorus ylides to give the pyrethroids.

CONCLUSION

An efficient and versatile synthesis of ten new pyrethroid methyl esters has been accomplished from the readily available D-mannitol in seven steps. All compounds showed insecticidal activity, and methyl (1S, 3S)-3-[(Z)-2-(4-chlorophenyl)vinyl]-2,2-dimethylcyclopropane-1-carboxylate was the most active, killing 90% of A. monuste orseis and 100% of T. absoluta and P. americana.