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1.
Addition of (S)-dimethylsulfonium-(p-tolylsulfinyl)methylide to N-tosyl imines afforded the corresponding sulfinyl aziridines with full enantio- and diastereoselectivity. The chiral sulfinyl substituent was removed without ring opening leading to enantiopure 2-substituted aziridines.  相似文献   

2.
The enantioselective addition of thioacetic acid to nitroalkenes was achieved using N-sulfinyl urea catalysis. In this report, the scope of the reaction was extended to the enantio- and diastereoselective thioacetic acid addition to cyclic α,β-disubstituted nitroalkenes. Additionally, the role of the sulfinyl group was investigated by replacing it with a variety of aryl and sulfonyl groups. Of 15 urea catalysts synthesized and tested, none displayed comparable selectivity to the sulfinyl catalysts, highlighting the importance of the sulfinyl group in attaining high enantioselectivity in the thioacetic acid addition.  相似文献   

3.
The diastereoselective synthesis of N-sulfinyl α-aminophosphine sulfides and phosphines is reported. These molecules are synthesized by formation of sulfinyl imine followed by diastereoselective addition of a diphenylphosphine sulfide. The product N-sulfinyl α-aminophosphine sulfides can be converted to phosphines through removal of the sulfur by reaction with Raney nickel. Hydrolysis of the sulfinyl group provides an amine that can then be attached to other ligands or structural scaffolds.  相似文献   

4.
A mild acid-catalysed method is reported for the formation of sulfinyl imines from tert-butanesulfinamide and aromatic or aliphatic aldehydes using tetrafluoroboric acid diethyletherate (10?mol%) in dichloromethane. Reactions were performed at room temperature and gave the corresponding sulfinyl imines in excellent yield after 2?h. A DFT study was performed and a mechanism for the reaction is postulated.  相似文献   

5.
New chiral ligands, N-diphenylphosphano nitrogen-containing five-membered aromatic compounds bearing chiral sulfinyl groups as the sole chiral source has been developed. The structure of a palladium intermediate derived from the new chiral sulfoxide ligand was determined as a palladium complex with a five-membered chelate ring formed by coordination of the phosphano group and the sulfinyl sulfur atom involved. The stereoelectronic effects of substituents on the aromatic rings are discussed.  相似文献   

6.
Highly enantiomerically enriched N-protected α-amino acids can be easily prepared from optically pure N-(tert-butanesulfinyl)imines by a four-step sequence involving: diastereoselective addition of a triorganozincate to the imine, removal of the sulfinyl group, benzoylation of the nitrogen atom of the obtained primary amine and oxidation of one of the substituents on the carbon atom α to the nitrogen. Using the same configuration in the sulfinyl chiral auxiliary, amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α-Disubstituted α-amino esters with high optical purity can also be prepared by the diastereoselective addition of trialkylzincates to α-imino esters.  相似文献   

7.
《Tetrahedron: Asymmetry》1999,10(16):3177-3187
The reaction of sulfinyl chlorides with (l)-N-methylephedrine alone or in the presence of tertiary amines was found to produce diastereomeric sulfinates with diastereomeric purities up to 90%. The diastereomeric ratio is strongly influenced by the nature of substituents on the sulfinyl chlorides and to some extent by the reaction conditions. In a few cases, the pure diastereomers were isolated by chromatography and used for the preparation of optically active sulfoxides. The silica gel catalyzed rearrangement of sulfinates to the corresponding sulfones is also discussed.  相似文献   

8.
《Tetrahedron: Asymmetry》1998,9(21):3797-3817
Palladium-catalyzed asymmetric allylic alkylations were studied by using chiral sulfoxide ligands bearing nitrogen atoms as coordinating elements, such as chiral α-sulfinylacetamides, β or γ-amino sulfoxides, and β-sulfinyl sulfonamides. The effects of the chiral sulfinyl functions on the asymmetric induction were demonstrated. Use of (S)-2-pyrrolidinophenyl p-tolyl sulfoxide or (S)-2-(N-butyl-N-methylaminomethyl)phenyl p-tolyl sulfoxide as chiral ligands in the palladium-catalyzed asymmetric allylic alkylations provided the highest enantioselectivity (50 or 58% e.e., respectively) among chiral sulfoxide ligands examined by us. The participation of the sulfinyl groups in these catalytic asymmetric reactions is rationalized, and the mechanism for the asymmetric induction is proposed on the basis of the stereochemical outcome obtained.  相似文献   

9.
A stereoselective synthesis of (−)-allosedamine is disclosed. β-Aminosulfoxide 4 was generated stereoselectively by condensation of the sulfinyl anion 2 with N-Ts imine 3. The bromohydrin 5 was obtained by intramolecular sulfinyl group participation and the piperidine ring of allosedamine was elaborated using the ring-closing metathesis (RCM) reaction.  相似文献   

10.
A novel and stereospecific synthesis of (+)-exo-brevicomin is disclosed. The key step of the reaction sequence employs the sulfinyl moiety as an intramolecular nucleophile to functionalize an alkene π-complexed to a bromonium ion.  相似文献   

11.
A highly efficient and stereoselective synthesis of (2R,3R,4R)-HMP is disclosed employing the sulfinyl group as an internal nucleophile to functionalize an olefin in the key step of the reaction sequence. The proline ring is elaborated by a (4C+N) cyclization.  相似文献   

12.
Reactions of (2-p-tolylsulfinyl)benzyl alkyl (and aryl) ketones (δ-ketosulfoxides) with Et2AlCN in the presence of Yb(OTf)3 take place in a completely stereoselective manner, demonstrating the efficiency of the sulfinyl group in the control of the stereoselectivity of 1,5-asymmetric hydrocyanation processes as well as the ability of Yb(OTf)3 to form chelated species with ketosulfoxides. The behavior of their methyl derivatives at the benzylic position is dependent on the configuration at the chiral carbon. The resulting sulfinyl cyanohydrins were readily transformed into α-hydroxyamides by hydrolysis of the CN group and hydrogenolysis of the C-S bond.  相似文献   

13.
The reaction of chiral (2S)-enolates of dioxolan-4-ones, derived from lactic and mandelic acids, with (SR)-tert-butyl sulfinyl ketimines, derived from butan-2-one, pentan-2-one, and decan-2-one, afforded conformationally restrained β2,2,3,3-isoserines bearing two adjacent quaternary stereogenic centers in the form of N-sulfinyl protected 1′-amino-dioxolan-4-ones. The selective acid-induced removal of the sulfinyl protecting group provided the corresponding 1′-aminodioxolanones, whose base-induced cyclization afforded the corresponding chiral tetra-substituted 3-hydroxy-β-lactams. The synthesis of a dipeptide by reaction coupling between the 1′-aminodioxolanone (2S,5R,1′R)-19 and N,N-dimethylglycine was successfully achieved.  相似文献   

14.
A new entry to optically pure trans-2,3-disubstituted N-sulfinyl aziridines starting from 1,2-aminosulfides, involving formation of a sulfonium salt intermediate followed by intramolecular nucleophilic attack by the sulfinamide nitrogen atom, is reported. The regio- and stereoselective opening of the aziridine ring can be achieved by anchimeric assistance of the sulfinyl group.  相似文献   

15.
Ellman’s chiral auxiliary is converted into tert-butylsulfinyl chloride on sulfinamide deprotection with HCl and can be recovered in high yield upon treatment with ammonia. The enantiopure auxiliary can be obtained by trapping the sulfinyl chloride with a chiral alcohol followed by treatment of the resulting sulfinate ester with LiNH2.  相似文献   

16.
《Tetrahedron: Asymmetry》2005,16(22):3676-3681
A new series of chiral ferrocenyl bis-phosphine ligands have been synthesized. Elements of planar and central chirality have been incorporated into a ferrocene backbone through sulfinyl, sulfonyl and sulfenyl groups at the ortho-position to the phosphines. The effectiveness of these ligands has been demonstrated in Rh-catalyzed hydrogenations and Pd-catalyzed allylic alkylations.  相似文献   

17.
《Tetrahedron: Asymmetry》2003,14(1):101-105
A short, efficient and highly stereoselective synthesis of (−)-(R,R)-muricatacin is reported. The key steps include a highly diastereoselective reduction of a β-ketosulfoxide to a β-hydroxy sulfoxide, regio- and stereoselective bromohydration of an olefin employing the sulfinyl group as an internal nucleophile and chemoselective reduction of a double bond in the presence of a halogen atom.  相似文献   

18.
The anodic oxidation of some chiral non-racemic N-arylsulfinyl piperidines was investigated and for the first time α methoxylated sulfinyl piperidines were obtained. The so-formed compounds are equivalent of chiral N-sulfinyliminiums and used as new intermediates for the preparation of chiral α-substituted piperidine derivatives in good yield and diastereoselectivity.  相似文献   

19.
《Tetrahedron letters》1998,39(26):4687-4690
Fluorination of phenylsulfinyl bicycloamide using molecular fluorine proceeded preferentially with inversion of the carbon atom having the sulfinyl group to afford α-fluorinated sulfonyl bicycloamide in fair yield. The fluorinated sulfonyl bicycloamide was converted to 2′-fluoro substituted carbovir via reductive desulfonylchlorination.  相似文献   

20.
Qing Xu 《Tetrahedron letters》2004,45(29):5657-5660
cis-Carbocuperation reaction of monoorganocopper reagent with acetylenic sulfoxides, followed by electrophilic reaction with a variety of electrophiles, provided a regio- and stereoselective method to prepare the versatile polysubstituted vinyl sulfoxides. Sonogashira cross-coupling reaction of the obtained α-iodovinyl sulfoxides with terminal acetylenes was also investigated to afford the versatile conjugate sulfinyl enynes.  相似文献   

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