Enantioselective Alkylation of <i>N</i>
-Arylhydrazones Derived from α-Keto Esters and Isatin Derivatives through Asymmetric Phase-Transfer Catalysis
作者:Qi-Kai Kang、Sermadurai Selvakumar、Natarajan Arumugam、Abdulrahman I. Almansour、Raju Suresh Kumar、Keiji Maruoka
DOI:10.1002/asia.201800652
日期:2018.7.16
phase‐transfer‐catalyzed asymmetric alkylation reactions of N‐arylhydrazones derived from α‐keto‐esters and isatin derivatives afford enantioenriched azo compounds that bear a tetra‐substituted carbon stereocenter in good yields with high chemo‐ and enantioselectivity. The alkylation products can be readily converted into chiral amino esters, hydrazine derivatives, and aza‐β‐lactams without loss of
Oxidation of hydrazones by hypervalent organoiodine reagents: Regeneration of the carbonyl group and facile syntheses of α-acetoxy and α-alkoxy azo compounds
derivatives of α-keto esters were prepared. The carbonyl group was readily regenerated in high yield from phenylhydrazones through oxidative hydrolysis using hypervalent organoiodine(III) reagents—either bis(trifluoroacetoxy)-iodobenzene (BTIB) in aqueous acetonitrile or hydroxy(tosyloxy)iodobenzene (HTIB) in chloroform. α-Acetoxy phenyl- or methylazo compounds were readily synthesized by oxidation of the
α-Ketoacids and ketones can easily be regenerated in high yield from their phenylhydrazones via hydroxy azo compounds upon oxidation with hupervalent iodine reagents.