Two enantioselective syntheses of a precursor of the biologically most active isomer of CGA 80000 (clozylacon)

✍ Scribed by H.P. Buser; B. Pugin; F. Spindler; M. Sutter

• Publisher: Elsevier Science
• Year: 1991
• Tongue: French
• Weight: 593 KB
• Volume: 47
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)86523-6

✦ Synopsis

The unchlonnated precursor 4 of CGA 80000 (lJ was synthestzed enanhoselecttvely by two conceptionally dtffetent routes a) by a "choral pool" approach stamng from L-mahc acid and b) by enanttoselecttve hydrogenahon of an enamlde mtemediate. catalyzed by chual Rh-or Ru-phosphme-complexes CGA SO000 Q) 1s the mtemal Cuba-Geigy code number for a new phenylamtde fungicide with the proposed common name clozylacon and the systematic name N-(3chloro-2,6-dlmethyl-phenyl)-2-methoxy-N-(tetrahydro-2-oxo-3-furanyI)-acetamide 111 It 1s especially suited for sol1 apphcatlon agamst oomycetes [2] Ftgure 1 1 cGAaocao (mcdum cd 4 stemoaomers) 2 X-cl Y-H 2 X-Ii Y-cl 5 X-Y-H Because of the stereogemc centre (marked with an *), and the atroptsomensm due to hindered rotatton around the carbon nitrogen bond (marked with an arrow). 1 (CGA 80000) consists of four stereolsomers, wluch can be separated by chromatography I31 Blologrcal tests have shown that the desued funglcldal achvlty arises mamly from 2 (CGA 204726). the Isomer with the absolute configuration aS,3R '&seOti m pra m a Poster at the Seventh htm~atmod Congress of Pestkxde the Hamburg.