Abstract
(4+1)-Cyclizations are an underutilized disconnect for the formation of five-membered
heterocyclic and carbocyclic frameworks. Herein we analyze methods employing oxyphosphonium
enolates and RhII /PdII -metallocarbenes as C1 synthons in the presence of several four-atom components for
the synthesis of 2,3-dihydrobenzofurans, 2,3-dihydroindoles, oxazolones, cyclopentenones,
and pyrrolones.
1 Introduction
2 (4+1)-Cyclizations Employing Kukhtin–Ramirez-Like Reactivity
3 (4+1)-Cyclizations Employing a Cyclopropanation/Ring-Expansion Sequence
4 Pd-Catalyzed (4+1)-Cyclizations through Carbene Migratory Insertion/Reductive Elimination
Processes
5 Summary
Key words (4+1)-cyclization - carbenes - rhodium - palladium - phosphorus - organocatalysis
- carbocycles - heterocycles