Regio- and diastereoselective reactions of chiral secondary alkylcopper reagents with propargylic phosphates: preparation of chiral allenes

Abstract

The diastereoselective SN2′-substitution of secondary alkylcopper reagents with propargylic phosphates enables the preparation of stereodefined alkylallenes.

Recent Advances in Halogen–Metal Exchange Reactions

“…DFT calculations were performed to rationalize the high stability of chiral dialkylzincs and the stereoretention in the catalytic cycle. 38 The enantioselective preparation of secondary alkylmagnesium reagents is meaningful since organomagnesium reagents have numerous applications in organic synthesis. 40 We have developed a new method for the preparation of chiral secondary alkylmagnesium reagents by modifying the preparative procedure for the above-mentioned chiral organometallic reagents.…”

Polycyclic Compounds from Allenes via Palladium-Mediated Intramolecular Carbopalladation/Nucleophilic Substitution Cascade Processes

“…[1][2][3][4] Bonding between the central sp and the terminal sp 2 carbons of the allene moiety positions the planes of the double bonds orthogonally to each other and creates axial chirality. [5][6][7][8][9] An additional explanation of their structure, and consequently their stereochemical properties, suggests that their frontier molecular orbitals are comprised of p-orbitals with left-handed and right-handed helical topology, similar to that of Möbius aromatic compounds. 10,11 A typical allene functionality is linear with a C=C=C bond angle of 180°, but this can be significantly influenced by substituents attached directly to the allene fragment.…”

Nickel-Catalyzed Enantioconvergent and Diastereoselective Allenylation of Alkyl Electrophiles: Simultaneous Control of Central and Axial Chirality

“…Herein, we describe the development of a method that achieves the coupling of an alkyl electrophile to generate a carbon−carbon bond with control of both central and axial chirality (Figure 1B), specifically, a nickel-catalyzed reaction of racemic alkyl halides with prochiral 1,3-enynes to afford enantioenriched allenes (Figure 1D). 13 ■ RESULTS AND DISCUSSION Chiral allenes are of substantial interest, as they are found in natural products and have utility in wide-ranging fields such as asymmetric catalysis, 14 medicinal chemistry, 15,16 and materials science; 17 consequently, considerable attention has been focused on the development of methods for their synthesis. 18−22 We envisioned a new approach to the synthesis of enantioenriched allenes, through a metal-catalyzed coupling of an alkyl halide with a 1,3-enyne in the presence of a hydride reagent (Figure 1C).…”

“…Herein, we describe the development of a method that achieves the coupling of an alkyl electrophile to generate a carbon–carbon bond with control of both central and axial chirality (Figure B), specifically, a nickel-catalyzed reaction of racemic alkyl halides with prochiral 1,3-enynes to afford enantioenriched allenes (Figure D) …”