N sulfinyl imines

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],... 

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

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

From semiamidals, the correspondmg tnfluoromethyl substituted N-acyl mines [25, 28], 1,3-diawbutadienes [27], N-sulfonyl immes [5, 29], N sulfinyl imines [30], and N-phosphotyl mines [31] can be obtained m high yields on reaction with powerful dehydrating reacts like POC -pyndine ortnfluoroacetic anhydnde-pyndme [2,5]... 

Davis, F. A., Liu, H., Zhou, P., Fang, T., Reddy, G. V., Zhang, Y. Aza-Darzens asymmetric synthesis of N-(p-toluenesulfinyl)aziridine 2-carboxylate esters from sulfinimines (N-sulfinyl imines). J. Org. Chem. 1999, 64, 7559-7567. 

Although N sulfinyl imines can be prepared by several other methods (oxidation of sulfenimines [12] and iminolysis of sulfinates [13]), they are most conveniently synthesized by condensing aldehydes with tert butanesulfinamide in the presence of copper(II) sulfate or magnesium sulfate/pyridinium p toluenesulfonate as a Lewis add catalyst and water scavenger (Scheme 1.4) [14]. When ketones, more sterically hindered aldehydes or even electronically deactivated aldehydes are used, titanium tetraethoxide is the preferred Lewis add and water scavenger. These methods are convenient to synthesize both alkyl and aryl substituted imines. 

Scheme 1.13 Addition of methylmagnesium chloride to N sulfinyl imines.

Scheme 1.14 Allylation, benzylation, and alkenylation of N sulfinyl imines.

All four diastereomers of indolizidine 223AB have been isolated from frog skin extracts. Three approaches to the (5Z,9Z)-isomer (re/-1566) that use late-stage C-3/N bond formation have been described since mid-1999. The first step in the synthesis by Shimizu and coworkers was the boron trifluoride-promoted addition of aUylmagnesium chloride to the (S)-N-sulfinyl imine (- -)-1765 to produce 1766, essentially as a single dia-stereomer (dr >99 1) (Scheme 222). Oxidation to the sulfonamide and hydrogenation of the double bond produced (-)-1767, the spectroscopic... 

Davis, F.A. and Deng, (. (2005) Asymmetric total synthesis of (—)-agelastatin A using sulfinimine (N-sulfinyl imine) derived methodologies. Org. Lett., 7, 621-623. 

After their introduction [73] as imine auxiliaries [74], the use of chiral p-toluenesulfinylimines 81 was pioneered by Davis (Scheme 11.12) [24, 26], The most facile and widely used synthesis of the parent sulfonamide involves the Andersen reagent 83 [75], both enantiomers of which are commercially available. Treatment of 83 with Li HMDS followed by aqueous workup gives optically active primary sulfmamide 84. This amide participates in condensation reactions with aldehydes or ketones under mild conditions to give a diverse array of N-sulfinyl imines 81 [24, 26, 76],... 

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