Sulfoximines salts

The reaction of ketones with excess of the sulfoximine salt Na-2b gives oxetanes formed by ring opening of the initially formed oxirane and subsequent ring closure. These reactions are highly diastereoselective and generally the thermodynamically more stable oxetane, in which the C-O bond is axial, is formed from cyclic ketones since the intermediate oxirane is formed under thermodynamically controlled conditions.61... 

Associated to copper(II) pre-catalysts, bis(oxazolines) also allowed the asymmetric Diels-Alder and hetero Diels-Alder transformations to be achieved in nearly quantitative yield and high diastereo- and enantioselectivities. Optically active sulfoximines, with their nitrogen-coordinating site located at close proximity to the stereogenic sulfur atom, have also proven their efficiency as copper ligands for these asymmetric cycloadditions. Other precursors for this Lewis acid-catalyzed transformation have been described (e.g., zinc salts, ruthenium derivatives, or rare earth complexes) which, when associated to bis(oxazolines), pyridine-oxazolines or pyridine-bis(oxazolines), led to efficient catalysts. 

Certain chalcogen structures display the phenomenon of chirality (Chapter 10.2). As with carbon,2 chirality at sulfur can influence physiological events there are many stereoselectivities in the interactions of chiral sulfur compounds with enzymes and receptor molecules. Sulfur chirality in secondary metabolites is most commonly observed with sulfonium salts, sulfoxides and sulfoximines.3... 

The methylation of sulfoximines 45 with Me30BF4 proceeded readily and gave the corresponding cyclic aminosulfoxonium salts 46 in quantitative yields. Upon treatment with LiN(H)t-Bu first at-78 °C and then at room temperature, salts 46 delivered the enantio- and diastereomerically pure bicyclic 2,3-dihydrofurans 50 cleanly in high overall yields. It is proposed that the reactions of the aminosulfoxonium salts 40 and 46 with the lithium amide at low temperatures afford the vinyl aminosulfoxonium ylides 41 and 47, respectively. These alkylidene carbenoids eliminate sulfinamide 35 at higher temperatures with formation of the alkylidene carbenes 42 and 48, respectively. Subsequently, the alkylidene... 

The acyclic sulfonimidoyl-substituted amino acids 24 were selected as starting material for the synthesis of the unsaturated prolines of type 63. Because of the facile synthesis of the unsaturated bicyclic tetrahydrofurans 53 from the vinyl aminosulfoxonium salts 46 (cf. Scheme 1.3.20), it was speculated that upon treatment with a base the vinyl aminosulfoxonium salts 67 would experience a similar isomerization with formation of the allyl aminosulfoxonium salts 69, which in turn could suffer an intramolecular substitution of the allylic aminosulfoxonium group (Scheme 1.3.24). The methylation of sulfoximines 24 with Me30Bp4 gave... 

Whereas the T1 linker involves immobilization of a diazonium salt on an amine resin, the T2 linker is the reversal of this concept. An immobilized diazonium salt 73 was prepared from Merrifield resin 70 in two steps subsequent addition of primary and secondary amines generated triazenes 74. Attachment of hydroxylamine, hydrazines, sulfoximines, and phenols (to give azo coupling products) proceeds equally well (Scheme 6.1.16). 

The reaction of the sodium salt of (R)-Ar-(p-tolylsulfonyl)-5-methyl-5-phenyl-sulfoximine 2a (84% ee) with acetophenone at room temperature gave (-)-(S)-2-methyl-2-phenyloxirane.18The (S)-oxirane product must arise from the collapse of... 

P-Hydroxy sulfoximines are thermally labile and revert to their starting carbonyl compound and sulfoximine on mild thermolysis. This property has been exploited effectively as a method for the resolution of racemic chiral cyclic ketones.65 For example, the addition of the lithium salt of (+)-(S)-2b (99% ee) under kinetically controlled conditions (-78 °C) to racemic menthone gave three of the four possible diastereomeric adducts. The major two adducts resulted from attack on the menthone from the equatorial direction. These diastereomeric adducts could be readily separated by column chromatography. Thermolysis of the individual two major diastereomeric carbinols at 140 °C gave d- and /-menthone, respectively, in high enantiomeric purities (90-93% ee). This methodology has been successfully applied to the resolution of other 2-substituted cyclohexanones as well as other chiral ketones that have served as advanced synthetic intermediates for the synthesis of natural products.66-69... 

In the case of the reaction of the racemic allylic sulfoximine rac-121 with the lithium salt of BDMG (Table 10, entry 5, Nu = CH(N=Ph2)C02Bu )), a 90 10 mixture of regioisomeric adducts 183 and 184 resulted. The major regioisomeric product 183 (Nu = CH(N=Ph2)C02Bu ) was a 74 26 mixture of diastereoisomers. 

Methylation of the lithium salt of (5)-(+)-Ar-ethoxycarbonylmethyl-5-aryl-5-p-tolyl sulfoximines (286, 287) is 100% diastereoselective when the 5-aryl group is capable of coordination to the lithium cation.46... 

Preparative Methods methyl phenyl sulfoxide is treated with Hydrazoic Acid (generated by addition of sulfuric acid to a slurry of sodium azide) in chloroform maintained at 45 °C to produce -methyl- -phenylsulfoximine. The latter can be readily resolved using 10-Camphorsulfonic Acid, from the (+)-acid the salt of (+)-(5)-5 -methyl-5 -phenylsulfoximine is obtained pure by recrystallization. The Clarke-Eschweiler procedure using Formaldehyde and Formic Acid provides an effective method for conversion of the N-H sulfoximine to the title compound. ... 

Ylides derived from the salts obtained by A. A -dialkylation of sulfoximines and anions derived from A -tosylsulfoximines are useful reagents for the synthesis of epoxides or cyclopropanes from aldehydes and ketones or enones. ... 

Attyl and propargyl group transfer. Sulfinic acids or their sodium salts assist Pd(0)-catalyzed deallylation by accepting the allyl group. In addition to allylic esters, allylic sulfoximines can also deliver the allyl group to nucleophiles such as amines. Acrolein acetals react with 1,3-dicarbonyl compounds but the regiochemistry is strongly dependent on reaction temperatures. ... 

Application of a polymer-supported enantiopure sulfoximine in stereoselective conversion into hydroxysulfones has been reported (Scheme 12.30) [13, 41]. The chiral sulfoximine resin was prepared by coupling the sulfoximine potassium salt 78, in the presence of tetrabutylammonium bromide (TBAB), to Merrifield resin. Hydroxyalkylation of the polymer-bound sulfoximine 79 at the a-position with benzaldehyde and propanal furnished the hydroxysulfoximine resin 80. Oxidative cleavage gave hydroxysulfones 81 in 81 and 84% yield and enantiomeric excesses of 24 and 26% ee. 

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