Dynamic kinetic resolution of γ,γ-disubstituted indole 2-carboxaldehydesviaNHC-Lewis acid cooperative catalysis for the synthesis of tetracyclic ε-lactones

Abstract

The ubiquity of ε-lactones in various biologically active compounds inspired the development of efficient and enantioselective routes to these target compounds. Described herein is the enantioselective synthesis of indole-fused ε-lactones...

NHC-Catalyzed Reaction of Aldehydes for C(sp2)–O Bond Formation

“…The NHC-Lewis acid cooperatively catalyzed formal [4 + 3] annulation was developed (Scheme 13) [117]. In the presence of the precursor (5aR,10bS)-A12ba, Bi(OTf) 3…”

Chiral Lewis Base‐Catalysed Asymmetric Syntheses of Benzo‐fused ϵ‐Lactones

“…Hereby we have been especially fascinated by the potential of preformed or in situ formed quinone methides (QMs) as building blocks for the synthesis of chiral oxygen‐containing heterocycles [8] . One class of QMs that serves well for cyclization reactions are o‐OH‐functionalized p‐QMs 1 (Scheme 1B), which can serve as versatile 4‐atom building blocks for formal (4+n)‐cyclization reactions when reacted with various dipolar species [5c–e,7c,9] . In contrast, the homologous o‐hydroxymethyl p‐QMs 2 have, to the best of our knowledge, so far not been systematically explored for analogous formal (5+n)‐cyclization reactions.…”

“…[8] One class of QMs that serves well for cyclization reactions are o‐OH‐functionalized p‐QMs 1 (Scheme 1 B), which can serve as versatile 4‐atom building blocks for formal (4+n)‐cyclization reactions when reacted with various dipolar species. [ 5c , 5d , 5e , 7c , 9 ] In contrast, the homologous o‐hydroxymethyl p‐QMs 2 have, to the best of our knowledge, so far not been systematically explored for analogous formal (5+n)‐cyclization reactions.…”