The present invention relates to novel lipopeptide compounds. The invention also relates to pharmaceutical compositions of these compounds and methods of using these compounds as antibacterial compounds. The invention also relates to methods of producing these novel lipopeptide compounds and intermediates used in producing these compounds.
Additive and Vinylogous Pummerer Reactions of Amido Sulfoxides and Their Use in the Preparation of Nitrogen Containing Heterocycles
作者:Albert Padwa、Jeffrey T. Kuethe
DOI:10.1021/jo972093h
日期:1998.6.1
The alpha-thiocarbocation generated from the Pummerer re action of N-methyl-N-phenyl-2-[2-(toluene-4-sulfinyl)phenyl]acetamide undergoes Friedel-Crafts reaction at the gamma-carbon with the tethered aromatic ring. Reductive removal of the phenylthio group from the resulting product using Raney nickel occurs in high yield, and the overall reaction represents a new method for the synthesis of a variety of 3-phenyl-substituted oxindoles. Treatment of the related N-benzyl-N-alkyl amido sulfoxide system with trifluoroacetic anhydride affords tetrahydroisoquinolone derivatives. The product distribution encountered coincides with the rotamer population of the starting amide. When the N-benzyl-N-methyl amide is used, only the normal Pummerer product is formed. In this case, the thionium ion is generated in the wrong conformation for pi-cyclization to occur. The corresponding N-tert-butyl amido system, however, exists in a geometric orientation which places the benzylic group in the crucial conformation necessary for pi-cyclization, and consequently, the reaction proceeds smoothly. Related cyclization reactions occur in good yield with the corresponding furanyl and cyclohexenyl N-tert-butyl amido sulfoxides. The additive Pummerer reaction of 3-phenylsulfinyl-N-benzyl-N-tert-butylacrylamide gave products derived from both 5- and 6-exo trig cyclizations. Intramolecular electrophilic aromatic substitution via six-membered ring closure ultimately afforded a dihydropyridone. The competitive process involving ipso attack of the aromatic ring on the thionium ion generates a spiro cyclohexadienyl cation that undergoes fragmentation of the adjacent a-bond. The resulting acyl iminium ion is converted to N-tert-butyl-2-phenyl-3-phenylsulfinylacrylamide upon aqueous workup. Only cyclizations leading to five-membered rings occur with the corresponding indolyl and alkenyl N-tert-butyl amido sulfoxides.