A Pd-H/Isothiourea Cooperative Catalysis Approach to anti-Aldol Motifs: Enantioselective α-Alkylation of Esters with Oxyallenes

Angew Chem Int Ed Engl. 2022 Jun 20;61(25):e202201753. doi: 10.1002/anie.202201753. Epub 2022 Apr 20.

Abstract

The biological and therapeutic significance of natural products is a powerful impetus for the development of efficient methods to facilitate their construction. Accordingly, and reflecting the prevalence of β-oxy-carbonyl motifs, a sophisticated arsenal of aldol-based strategies has evolved that is contingent on the generation of single enolate isomers. Since this has the potential to compromise efficiency in reagent-based paradigms, direct catalysis-based solutions would be enabling. To complement the array of substrate-based strategies, and regulate enolate geometry at the catalyst level, a direct catalytic alkylation of esters with oxyallenes has been developed. Synergizing metal hydride reactivity with Lewis base catalysis has resulted in a broad reaction scope with useful levels of stereocontrol (up to >99 % ee). Facile derivatization of these ambiphilic linchpins is demonstrated, providing access to high-value vicinal stereocenter-containing motifs, including 1,2-amino alcohols.

Keywords: Allenes; C1-Ammonium Enolates; Enantioselectivity; Isothioureas; Palladium Catalysis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes
  • Alkylation
  • Catalysis
  • Esters*
  • Stereoisomerism
  • Thiourea*

Substances

  • Aldehydes
  • Esters
  • 3-hydroxybutanal
  • Thiourea