Chiral Dilithiomethane Derivatives: Structure Determination and Application in Stereoselective Reactions

Abstract

The synthesis and X‐ray analysis of chiral dilithiomethane analogues derived from sulfoximines are presented. The structures of the sulfoximine‐stabilised mono‐ and dilithio salts have been compared and allow a rationalization of the second lithiation. Organophosphorus‐based dilithiomethane derivatives are also structurally described. The gas‐phase structures of N,S,S‐trimethylsulfoximine 19 and of its mono‐ and dilithiated isomers 20–21 were calculated by ab initio methods employing different levels of theory. For an application in asymmetric synthesis, the dilithiation of (N‐methyl)‐S‐ethyl‐S‐phenylsulfoximine (11) afforded a chiral dinucleophile that undergoes highly regio‐ and stereoselective alkylation reactions with electrophiles. The transmetallation of a chiral dilithiomethane reagent such as 14 with ClTi(OiPr)3 followed by addition of an aldehyde, constitutes a simple one‐pot process for the formation of (E)‐alkenylsulfoximines with excellent diastereoselectivity.

Consecutive reactions with sulfoximines: a direct access to 2-sulfonimidoylylidene tetrahydrofurans and 6-sulfonimidoylmethyl-3,4-dihydro-2H-pyrans

“…30 Depending on the work-up, different products would then be produced. Addition of a 5% aqueous solution of sodium hydroxide (conditions A) could lead after transmetallation, to the corresponding a-Na-sulfoximine D. The latter would then undergo a rapid O-cyclization providing the observed sulfonimidoylylidene tetrahydrofurans 2.…”

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“…46 Multinuclear and multidimensional NMR studies on enantiomerically pure lithium (S)methyl(1-phenyl-2-pyrrolidinoethyl)[ 15 N]amide and both racemic and enantiomerically pure lithium (1-isopropyl-2-pyrrolidinoethyl)methyl[ 15 N]amide have shown that these compounds form trimers as well as symmetrically and unsymmetrically solvated dimers, depending on the solvent used. The magnitude of the 6 Li, 15 N coupling constant was found to be a sensitive tool for probing changes in the coordination number of lithium; T 1 relaxation rates were sensitive to aggregation state. 47 The activation parameters for the exchange of an ether ligand in a chiral lithium amide have been determined from full bandshape analysis of the dynamic NMR spectra and ligand dissociation was also modelled using semi-empirical and density functional calculations.…”

“…Reviews have appeared on thiolates, selenolates and tellurolates 1 and the molecular structure of the halides 2 of the s-block elements, the experimental evidence for alkalimetal cation-p interactions, 3 Group 1 complexes of P-and As-donor ligands, 4 Group 2 b-diketonates, 5 Group 2 element precursors for chemical vapour deposition of electronic materials, 6 organometallic m-terphenyl derivatives of lithium, sodium, beryllium and magnesium, 7 molecular clusters of lithium, sodium and magnesium dimetallated primary phosphanes and arsanes, 8 ab initio studies of the complexation of lithium, sodium and potassium cations with water and ammonia, 9 noncyclopentadienyl organometallic compounds of calcium, strontium and barium, 10 bicyclic and tricyclic bis(amido)cyclophosph(III)azane compounds of lithium and magnesium, 11 the aqueous solution chemistry of beryllium, 12 reactions of organolithium compounds with alkali metal alkoxides to give superbases, 13 new methodologies based on arene catalysed lithiation reactions, with their applications in organic synthesis, 14 the preparations and crystal structures of chiral dilithiomethanes derived from sulfoximes with examples of applications in asymmetric synthesis, 15 and lithiosilanes and their application to the syntheses of polysilane dendrimers. 16 A book on Grignard reagents has been published.…”