First Highly Stereoselective Synthesis of Fungicide Systhane

Abstract

[reaction: see text] Highly enantiopure (R)-2-p-chlorophenyl-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile 1 (myclobutanil or systhane) was obtained in six synthetic steps from commercially available 1-hexyne (35% yield, 92% ee). The sulfinyl group controls the two key steps of the synthetic sequence, the highly stereoselective hydrocyanation of vinyl sulfoxides with Et(2)AlCN and the further introduction of the proper functionality into the molecule.

Recent developments in chiral non-racemic sulfinyl group chemistry in asymmetric synthesis

“…This methodology has been applied to the asymmetric total synthesis of the fungicide Systhane (163) (Scheme 73). 136 The synthetic sequence involves six steps from commercially available 1-hexyne via the described hydrocyanation and affords (R)-systhane in 35% yield and 92% e.e. …”

Acetone Cyanohydrin as a Source of HCN in the Cu-Catalyzed Hydrocyanation of α-Aryl Diazoacetates

“…The obtained products in this study, α-aryl cyanoesters, are a key precursor of β-cyano alcohols which can be regarded as an important building motif in organic synthesis . α-Aryl cyanoesters could be readily reduced to the corresponding aryl-substituted hydroxylpropane nitrile in high yield upon treatment with magnesium borohydride under mild conditions (eq ) …”

Synthesis and Biological Activity of Some Novel Trifluoromethyl-Substituted 1,2,4-Triazole and Bis(1,2,4-Triazole) Mannich Bases Containing Piperazine Rings

“…In the early 1970s, the azole fungicides were synthesized and used for the protection of various crops. Since the discovery of these fungicides, a variety of other 1,2,4-triazole compounds have been discovered − . The introduction of these 1,2,4-triazole sterol biosynthesis inhibitors represented significant progress in the chemical control of fungal diseases.…”