Protecting-group-free synthesis of 3-tert-prenylated oxindoles: contiguous all-carbon quaternary centers via tertiary neopentyl substitution.
Ruthenium-catalyzed tert-prenylation of isatin 1 occurs efficiently in the absence of N-protecting groups under the conditions of C-C bond-forming transfer hydrogenation employing 1,1-dimethylallene as the prenyl donor. The prenylated adduct, 3-hydroxy-3-tert-prenyl-oxindole 2, is converted to the tertiary neopentyl chloride 3, which participates in nucleophilic substitution by way of an aza-o-xylylene intermediate to furnish adducts 4a-4i. Through tertiary neopentyl substitution, two contiguous all-carbon quaternary centers are established.
Grant
Christopher D
CD
Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Krische
Michael J
MJ
D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry*; D054876:Prenylation
D007211:Indoles; D002244:Carbon