Sulfinyl imines

Ruano has reported substrate-controlled asymmetric ylide aziridination by treatment of enantiopure sulfinyl imines 117 with dimethyloxosulfonium methylide 118 to form terminal aziridines [63], The chiral tert-butylsulfinyl group was shown... 

More recently, Davis and co-workers developed a new method for the asymmetric syntheses of aziridine-2-carboxylates through the use of an aza-Darzens-type reaction between sulfinimines (N-sulfinyl imines) and a-haloenolates [62-66]. The reaction is highly efficient, affording cis- N-sulfmylaziridine-2-carboxylic esters in high yield and diastereoselectivity. This method has been used to prepare a variety of aziridines with diverse ring and nitrogen substituents. As an example, treatment of sulfinimine (Ss)-55 (Scheme 3.18) with the lithium enolate of tert-butyl bromoacetate gave aziridine 56 in 82% isolated yield [66],... 

The Stockman group has also studied reactions between the same imines and allyl sulfonium ylides (first reported by Hou and Dai [45]) [46], N-Sulfinyl vinylazir-... 

NSC-135758 428 N-sulfmimines 85 N-sulfinyl imine 80 nucleophilic ring opening 156 nucleophilicity 156... 

More recently, the addition of cyanide ion, generated from TMS cyanide and cesium fluoride, to a-aziridino N-siflfinyl imines, being chiral either at the a position or at sulfur, has been examined [87] (Scheme 28). The configuration of the newly formed stereocenter was determined only by the chiral (S)-sulfinyl group. In fact, the R configuration (diastereomeric excess, de, 98%) was obtained from either the Q -(ii)-imine 186 or the a-(S)-imine 188, giving 187 and 189, respectively. Acyclic 2,3-diaminonitriles can be obtained... 

Scheme 1.50 Test reaction with P/N-sulfinyl-imine ligand.

Scheme 5.2 Cu-catalysed Diels-Alder reaction with siam ligand and sulfinyl imine...

A highly stereoselective synthesis of the (3-substituted P-amino sulfone 271 involves the addition of a sulfonyl anion, derived from A-PMB sultam 268 upon treatment with NaHMDS, to chiral A-sulfinyl imine (5)-269 <06OL789>. Removal of the A-sulfinyl followed by basic workup affords amine 271. The stereochemical outcome of the adduct 270 was established via proton NMR analysis of the Mosher s amide derived from 271. 

The sulfinyl imine catalyst 63, which has a stereogenic sulfur atom, hydrogenated substrate 36 in 94% ee however, high catalyst loadings were used [45]. The full results for substrates 36 40 are detailed in Tables 30.7 to 30.11. 

Unsymmetrical vicinal diamines are prepared by reductive cross-coupling between nitrones and jY-/-butylsulfmyl imines with Sml2. The coupling proceeds in a high diastereoselective manner. Thus, optically pure unsymmetrical vicinal diamines are produced by using enantiomerically pure sulfinyl imines (Equation (74)). ... 

Many other uses of a-sulfinyl carbanions are found in the literature, and in the recent past the trend has been to take advantage of the chirality of the sulfoxide group in asymmetric synthesis. Various ways of preparation of enantiopure sulfoxides have been devised (see Section 2.6.2) the carbanions derived from these compounds were added to carbonyl compounds, nitriles, imines or Michael acceptors to yield, ultimately, with high e.e. values, optically active alcohols, amines, ethers, epoxides, lactones, after elimination at an appropriate stage of the sulfoxide group. Such an elimination could be achieved by pyrolysis, Raney nickel or nickel boride desulfurization, reduction, or displacement of the C-S bond, as in the lactone synthesis reported by Casey [388]. 

Addition of organocuprates to /V-sullinyl a,fi-unsaturated imines has proceeded with good yields with good diastereoselectivities.148 a,p-Unsaturated sulfinyl ketimines and aldimines have both been shown to be suitable substrates for this reaction. 

Addition of organocuprates to IV-sulfinyl imines R2CH=CH-C(R1)=NS(0)-(f-Bu) proceeds in good yields and with good diastereoselectivities (<96 4).222... 

The conjugate addition of iV-sulfinyl metalloeneamines to enones gave 19, which is converted in a facile manner to the corresponding piperidine in good diastereoselectivity after sequential stereoselective reduction, N-deprotection, cyclization, and imine reduction (Equation 35) <2005JOC7342>. 

The reduction of the chiral /3-hydroxy sulfinyl imines with HBcat or LiBHEt3 provided syn- and anti- 1,3-amino alcohols, respectively, with very high diastereomeric ratios (Equations (255) and (256)).1072... 

---