Cross‐Coupling/Cyclization Reactions of Two Different Allenic Moieties

Abstract

The allene moiety represents an excellent building block for allene cross-coupling cyclization reactions, affording heterocyclic skeletons in a single step. This strategy is of particular interest when two different allene derivatives are involved in a series of metal-catalyzed cross-coupling heterocyclization processes. This Concept article is focused on the Pd-catalyzed union of two different allenic moieties, with cyclization of at least one of them by intramolecular cyclometalation. These new, versatile, and highly effective transformations are complex multistep processes leading to potential privileged structures that could find wide applications in related medicinal chemistry.

Poly(1,4‐cyclohexylenedimethylene‐1, 4‐cyclohexanedicarboxylate): analysis of parameters affecting polymerization and cis–trans isomerization

“…im Jahr 1997276 wurde über Pd II ‐katalysierte cyclisierende Kupplungen von Allensäuren und ‐amiden, Allenolen, Allenonen, 1,2‐Allenylphosphonsäuren und Allenaminen in Gegenwart von Allylhalogeniden277 oder ω‐1‐Alkenylhalogeniden,278 Alkenen,279 Alkinen,280 Allenylalkoholen oder ‐acetaten,281 Allenen282 und Bisallenen283 berichtet. Diese Umsetzungen lieferten vielfältige cyclische Produkte, die häufig als Strukturmotive in Naturstoffen zu finden sind, unter hoch effizientem Chiralitätstransfer über eine anti ‐Nukleometallierung (Schema ) 284…”

Palladium-catalyzed approach to the synthesis of five-membered O-heterocycles

“…A mild, palladium(II)-catalyzed reaction of α-allenols and α-allenic esters in a heterocyclization/cross-coupling sequence that is applicable to a wide range of substitution patterns has been developed for the preparation of 2,3,4-trifunctionalized 2,5-dihydrofurans, including β-lactam derivatives. The heterocyclizative cross-coupling between 2-azetidinone-tethered allenols and α-allenic acetates resulted in the achievement of β-lactam-dihydrofuran hybrids in good yields (Scheme 82) [170][171][172]60].…”

Unravelling mechanistic insights in the platinum-catalysed dihydroalkoxylation of allenes

“…Transition metal catalysed reaction of allenes [26][27][28][29][30][31][32][33][34] with nucleophiles is one of the most representative examples where the choice of metal has profound implications in the outcome and selectivity, including enantioselectivity, of the reaction [35][36][37][38][39][40][41][42]. For example, the intermolecular reaction of allenes with palladium or gold catalysts in the presence of oxygen nucleophiles gives allyl ethers with the regioselectivity of the addition controlled by the substitution on the allene and the reaction conditions (Scheme 1a and b) [43][44][45][46][47][48][49][50][51][52].…”