Straightforward Synthesis of Isopropylidenediphenylsulfurane and Application to Industrially Viable Stereoselective Synthesis of Deltamethrin Insecticide

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)

Origin of Chiral Induction in Radical Reactions with the Diastereoisomers (5R)- and (5S)-5-l-Menthyloxyfuran-2[5H]-one

Acetalization of 5-hydroxyfuran-2[5H]-one with l-menthol yields (5R)- (1) and (5S)-5-l-menthyloxyfuran-2[5H]-one (2) in equal amounts. The diastereomer 1 crystallizes preferentially. For the first time, the isolation of pure diastereoisomer 2 is reported. Different diastereoselectivities were observed in the radical tandem reaction of 1 and 2 with N,N-dimethylaniline. The privileged conformations in solution of the substrates and the products of the radical reaction were then determined, and X-ray crystal structure analyses were carried out on the reaction products. The different stereoselectivities in both cases are explained by different orientations of the menthyloxy substituent.

4-Aryloxybutenolides as "chiral aldehyde" equivalents: an efficient enantioselective synthesis of (+)-brefeldin a

4-(2'-Naphthoxy)-2-butenolide, readily available with high enantiopurity by a dynamic kinetic asymmetric transformation (DYKAT) of racemic 4-acyloxybutenolides (available in two steps from furfural), serves as an excellent chiral building block where the naphthoxy group strongly directs the stereochemistry of cycloadditions to the double bond. Notably, the cycloadditions of trimethylenemethanepalladium intermediates which do not exhibit good diastereoselectivity in additions to acceptors that possess many common and important chiral auxiliaries undergo cycloadditions with excellent regio- and stereocontrol. The utility of this process set the stage for an efficient new synthesis of (+)-brefeldin A, a compound of growing pharmacological significance. This synthesis also highlights the Pd-catalyzed DYKAT of crotyl carbonate to create the remote stereocenter. A new two-step method to convert aldehydes to delta-hydroxy-E-alpha,beta-enoates is also outlined.