Chirality transfer in metal-catalysed intermolecular addition reactions involving allenes

Abstract

Allene chemistry in the presence of transition metal complexes is nowadays a very important topic that underpins many challenges and advances in organic synthesis. The amount of research articles covering new transformations of allenes is vast and the development of enantioselective reactions involving allenes has flourished in the last 10-15 years. In this review we cover three important topics in allene chemistry that we feel are timely appropriate for this special issue celebrating the work of Prof Trost: the metal-catalysed reactions involving chirality transfer from chiral allenes to products; the analysis of the possible racemization processes that have been observed in the interaction of some metals with allenes; and the chirality transfer using racemic allenes in reactions catalysed by metal complexes bearing chiral ligands to produce enantioriched products. We have focussed the review on intermolecular addition reactions as they are still much less explored than the intramolecular version.

Hydroarylation of N‐Allenyl Derivatives Catalyzed by Copper**

“…Allylic or vinylic molecules are highly valuable intermediates [ 1 ] which are easy‐to‐prepare through transition metal‐catalyzed hydrofunctionalization of monosubstituted allenes. [ 2–4 ] This atom economical strategy usually occurs without any prefunctionalization and with very high chemo‐, regio‐ and stereospecificity. Hydrofunctionalization of allenes mainly allowed the selective formation of C–N, C–O, and C–C bond.…”

“…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.…”

Gold(I)‐Catalysed Hydroarylation of 1,3‐Disubstituted Allenes with Efficient Axial‐to‐Point Chirality Transfer

“…The axial chirality that is present within some 1,3‐disubstituted allenes offers a useful opportunity for asymmetric synthesis; specifically, axial‐to‐point chirality transfer upon π Lewis acid catalysed nucleophilic addition . Within this context, the ability of gold(I) catalysts to activate allenes towards nucleophilic addition is well documented. For example, the intramolecular gold‐catalysed hydroarylation of allenes has been utilised extensively for the synthesis of cyclic systems, and the literature includes reports of reactions with enantioselectivity as well as excellent diastereoselectivity .…”

Catalytic Regio- and Enantioselective Proton Migration from Skipped Enynes to Allenes

“…1,2 Due to their diverse reactivity and axial chirality, allenes are also useful chiral building blocks in organic synthesis. [3][4][5][6][7][8][9][10][11][12][13][14] Historically, the synthesis of enantiomerically enriched allenes [15][16][17][18][19][20][21][22][23][24][25] mainly relied on chirality-transfer processes from enantiomerically enriched propargylic amine or alcohol derivatives, such as the Crabbé -type reaction, [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] stereospecific rearrangements, [41][42][43] and S N 2 0 reactions. [44][45][46][47][48][4...…”