Geminal Bis(sulfoximine)s: Synthesis and Applications in Asymmetric Catalysis

Abstract

A number of C 2 -symmetrical geminal bis-(sulfoximine)s have been prepared for the first time and used as ligands in boron-mediated reductions of acetophenone and copper complex-catalyzed 1,4-additions of diethylzinc to 2-cyclohexenone. The copper complex of bis(sulfoximine) 46 was found to be highly active in this type of reaction, furnishing the addition product in nearly quantitative yield even at À 90 8C. From the reaction of bis(sulfoximine) 42 with Cu(OTf) 2 a copper complex was isolated and characterized by X-ray structural analysis. A mixture of SES-Cl and NaN 3 in acetonitrile was found to behave like SES-N 3 in FeCl 2 -mediated iminations of sulfoxides, affording the corresponding sulfoximines with complete retention of the sulfur configuration.

Sulfur(VI) Fluoride Exchange (SuFEx): Another Good Reaction for Click Chemistry

“…The same reasoning applies to the use of sulfonimidoyl fluorides over parent chlorides. [31] 4) Special nature of the fluoride-proton interaction. Both addition-elimination and direct substitution pathways are reasonable for nucleophilic substitution reactions of sulfonyl fluorides.…”

Synthesis of Bis(4-methylphenylsulfonimidoyl)methane - The First ‘Free' Geminal Bis(sulfoximine)

“…It crystallizes in the centrosymmetric space group P1 with two symmetry-related molecules (2/ent-2) present in the unit cell. In contrast to the crystal structure of OTBS-protected 11 (Scheme 4), 17 was converted in five steps into the known bis(sulfoximine) 11 in 79% yield (Scheme 4). 17 Mesylation followed by halogenation with NH 4 Br delivered the dibrominated compound 4 in 70% yield, albeit accompanied by 27% of the isomeric compound 15.…”

“…In contrast to the crystal structure of OTBS-protected 11 (Scheme 4), 17 was converted in five steps into the known bis(sulfoximine) 11 in 79% yield (Scheme 4). 17 Mesylation followed by halogenation with NH 4 Br delivered the dibrominated compound 4 in 70% yield, albeit accompanied by 27% of the isomeric compound 15. This observation is in accordance with the initial formation of aziridinium ions 13 or 14 which can be attacked either via path a) or path b).…”

“…15 Naturally, due to the achirality of the ligand, all products were formed as racemic mixtures. To render the process enantioselective we were interested in chiral analogues of the bis(iminophosphorane)s. Some years ago we 16,17 and others [18][19][20][21][22] demonstrated the applicability of sulfoximines in general and bis(sulfoximine)s 17 in particular as chiral ligands in metal-catalyzed reactions. Based on our work with the latter compounds we anticipated that bis(sulfoximine)-based ligands such as 2 may act as a chiral equivalent of the bis(iminophosphorane) 1.…”

“…For the sake of maximum structural flexibility we envisioned the synthesis of the double N-unsubstituted ('free') parent compound 2 which has proven to be highly reluctant to its synthesis. 17 Herein we describe two different routes for its preparation starting from bis(sulfoximine)s rac-3 (PMP = 4-methoxyphenyl) and 4, respectively (Scheme 1).…”