α-Metallated O-2-Alkenyl Carbamates: Synthetic Equivalents of Chiral Homoenolates and Materials for Asymmetric Homoaldol Reaction

Abstract

The review article provides a personal overview on the development and application in enantioselective synthesis of nonracemic chiral homoenolate reagents, based on allylic N,N-dialkylcarbamates and the ideas behind it. Further, the impact of these results, concerning stereoselective deprotonation, mainly under the influence of the chiral diamine (-)-sparteine, for the generation of a wide range of chiral building blocks is briefly presented.

Lithiation–Electrophilic Substitution of N‐Thiopivaloylazetidine

“…[15] Possible extension of this procedure to incorporate electrophiles onto the protected aziridine in an enantiocontrolled fashion was first examined by replacing TMEDA with the lupine alkaloid (À)-sparteine (6; Scheme 3); this chiral ligand has previously been shown to be effective in several asymmetric lithiation reactions. [9,16,17] When methyl iodide was used as the electrophile in diethyl ether, methylated azetidine (R)-5 h was obtained in an e.r. of 61:39 (99 % conversion by GC-MS; Table 2, entry 1).…”

Configurationally Labile Enantioenriched Lithiated 3-Arylprop-2-enyl Carbamates: Joint Experimental and Quantum Chemical Investigations on the Equilibrium of Epimers

“…The enantioselective lithiation of prochiral allyl carbamates followed by substitution represents a valuable tool for introduction of a stereogenic center into a molecule . In that context, an important challenge in the investigation of lithiated allyl carbamates is to determine the selectivity (enantioselectivity) at the stage of the deprotonation but also to solve the question of the configurational stability/lability of the lithiated species.…”

Synthesis of insect pheromones: Improved method for the preparation of queen substance and royal jelly of honeybeesApis mellifera

“…Since Nickon and Lambert introduced the concept of homoenolate anions in 1962 (Nickon & Lambert 1962), the homoenolates and their synthons have been used in many organic synthesis applications (for recent reviews see Nair et al 2008;Hoppe 2009). As a part of a program aimed at developing new homoenolate synthons, we have reported on the synthetic utility of lithium anions derived from allylphosphoramides as aldehyde (Coutrot et al 1993(Coutrot et al , 1994(Coutrot et al , 1999 and ketone (Grison et al , 2004 homoenolate equivalents.…”