Stereoselective Access to (E)-1,3-Enynes through Pd/Cu-Catalyzed Alkyne Hydrocarbation of Allenes

Abstract

PdII and CuI cooperate in catalyzing the alkynes hydrocarbation of allenes (AHA) giving (E)-1,3-enynes with high yields, atom economy, and high regio-/stereoselectivities. We devised new efficient conditions and expanded the substrate scope. Experimental and computational studies support a nonorthodox PdII/PdIV catalytic cycle involving an oxidative addition triggered by a stereodeterminant H+ transfer. This reaction is leveraged in a new strategy of stereoselective synthesis of 1,3-dienes.

Total Synthesis of Tiacumicin B: Implementing Hydrogen Bond Directed Acceptor Delivery for Highly Selective β‐Glycosylations

“…As to our contribution, we reported two related synthetic pathways leading to the aglycone . We designed an original strategy for the synthesis of the C12—C15 diene region of this aglycone and this resulted in the discovery that Pd‐nanoparticles catalyze the Kumada–Corriu reaction of vinylsulfides, and also led us to study Grigg's allene/alkyne cross‐coupling and to propose a mechanism based on DFT calculations …”

“…[17] We designed an original strategy for the synthesis of the C12-C15 diene region of this aglycone and this resulted in the discovery that Pd-nanoparticles catalyze the Kumada-Corriu reaction of vinylsulfides, [18] and also led us to study Griggs allene/alkyne cross-coupling and to propose a mechanism based on DFT calculations. [19] The new total synthesis of 1 we depict here is based on strategic and methodological innovations that allowed an original and selective assemblage of the three main regions of the molecule (Scheme 1). It naturally relies on our synthesis of the Tcn-B aglycone, the strategy of which was designed with an eye to the total synthesis.…”

Hydroarylation of N‐Allenyl Derivatives Catalyzed by Copper**

“…Hydrofunctionalization of allenes mainly allowed the selective formation of C–N, C–O, and C–C bond. [ 2,3,5–8 ] The latter being performed through the addition of pronucleophiles such as malonates, [ 9–12 ] nitriles, [ 13–16 ] alkynes, [ 17–19 ] alkenes, [ 20–22 ] and aryl derivatives. The reaction of aromatic compounds with allenes, known as hydroarylation reaction, consists of adding an aryl moiety to a C–C double bond and constitutes a powerful tool to form a Csp 3 –Csp 2 bond in a regio‐ and stereoselective manner.…”

Total Synthesis of Tiacumicin B: Study of the Challenging β‐Selective Glycosylations**

“…The development of our strategy led us to discover a Kumada‐Corriu reaction of vinyl sulfides catalyzed by Pd nanoparticles [15] . We also reexplored the Grigg's allene/alkyne cross‐coupling and proposed an unprecedented mechanism [16] . Until 2020, only the Gademann's team managed to complete the total synthesis of Tcn‐B, providing solutions to the challenging problem of the 1,2‐ cis ‐glycosylations but there was still room for innovation and improvement of selectivity [17] .…”