Au(I)-catalyzed hydrative rearrangement of 1,1-diethynylcarbinol acetates to functionalized cyclopentenones and allenones.
Atom-economical syntheses of isomeric 5-acetoxy-2-alkyl-2-cyclopentenones (2) and acetoxymethyl alpha-alkylallenones (3) have been described via Au-catalyzed hydrative rearrangement of 1,1-diethynylcarbinol acetates (1). In anhydrous condition, Au(I)-catalyzed [3,3]-rearrangement of 1 afforded the 3-alkynylallenyl acetate 4 in low yield. Treatment of 1 with Au(I) catalyst in wet CH(2)Cl(2) produced either 2 or 3 as a major product depending on the temperature, reaction time, and catalyst loading. D has been proposed as an intermediate, which might be formed via Au(I)-induced internal oxacyclization of the intermediate 4 followed by chemoselective nucleophilic attack by the water molecule. Formation of 2 or 3 might be explained via sequential 1,3-dioxole ring opening and gold-promoted 5-endo-dig carbocyclization or simple protonation of the intermediate D, respectively.
Oh
Chang Ho
CH
Department of Chemistry, Hanyang University, Sungdong-Gu, Seoul 133-791, South Korea. changho@hanyang.ac.kr
Karmakar
Swastik
S
D000085:Acetates / Q000737:chemistry*; D002384:Catalysis; D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D000432:Methanol / Q000031:analogs & derivatives* / Q000737:chemistry*; D015394:Molecular Structure; D050607:Organogold Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D000085:Acetates; D003517:Cyclopentanes; D007659:Ketones; D050607:Organogold Compounds; D006046:Gold; C013905:cyclopentenone; D000432:Methanol