Enantioselective Propargylation and Allenylation Reactions of Ketones and Imines

Abstract

Enantioselective propargylation and allenylation reactions pose an interesting challenge because they require control of regioselectivity as well as enantioselectivity. This review presents recent advances in enantioselective propargylation and allenylation reactions of ketones and imines. In this context, a brief discussion of the possible mechanisms of these transformations and consequences for regioselectivity is provided.

Ruthenium-Catalyzed Transfer Hydrogenation for C–C Bond Formation: Hydrohydroxyalkylation and Hydroaminoalkylation via Reactant Redox Pairs

“…One may view these protocols as an alternative to the use of stoichiometric allenylmetal reagents in carbonyl propargylation. 64,65 …”

Unprecedented Spectroscopic and Computational Evidence for Allenyl and Propargyl Titanocene(IV) Complexes: Electrophilic Quenching of Their Metallotropic Equilibrium

“…[47] Although the Gibbs energy barriers for the tautomerization could be low enough to invoke the Curtin-Hammett principle (15.4 and 11.1 kcal mol À1 for R = Ha nd Pn, respectively), the reactionb etween allenyla nd propargyl Ti complexes with 3-fluorobenzaldehyde, E,h as also been computed.…”

C‐Propargylation Overrides O‐Propargylation in Reactions of Propargyl Chloride with Primary Alcohols: Rhodium‐Catalyzed Transfer Hydrogenation

“…[6] Accordingly, we turned our attention to the redox-triggered coupling of primary alcohols with propargyl chloride with the goal of developing methods for enantioselective carbonyl propargylation (Figure 2). [7-15] In earlier work from our laboratory, [16] an iridium-catalyzed transfer hydrogenative carbonyl propargylation was developed (eq. 1), [16c] but suffered from two severe limitations in scope: (a) trialkylsilyl substitution was required at the acetylenic terminus of the propargyl chloride, and (b) only benzylic alcohols would participate in C-C coupling.…”