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Vinyl sulfoximines

Recently, enantiomerically pure vinylic sulfoximines have been shown to undergo effective and highly stereocontrolled conjugate addition of hydrocarbon groups using organocopper reagents108. [Pg.846]

Endocyclic allylic sulfoximines 5 were synthesized from cydoalkanones and lithi-ated enantiomerically pure (S)-S-methyl-S-phenylsulfoximine, by addition and subsequent elimination and isomerization of the intermediate vinylic sulfoximines. [Pg.264]

Scheme 1.3.3 Asymmetric synthesis of cicaprost by the vinyl sulfoximine route. Scheme 1.3.3 Asymmetric synthesis of cicaprost by the vinyl sulfoximine route.
When a high-yield synthesis of the enantio- and diastereomerically pure mono-cyclic 2,3-dihydrofurans 44 from the vinyl sulfoximines 39 had been developed, the synthesis ofbicyclic 2,3-dihydrofurans of type 50 (Scheme 1.3.19) was investigated. Since a number of tetrahydrofuranoid natural products contain a fused bicyclic ring skeleton, the attainment ofbicyclic 2,3-dihydrofurans of the 50 type would also be desirable. [Pg.97]

Synthesis of the polymer-bound allyl sulfoximine 60 was accomplished by the addition-elimination-isomerization route starting from the enantiomerically pure polymer-bound N-methyl-S-phenylsulfoximine 59, which was prepared as previously described from Merrifield resin and sulfoximine 12 with a loading of 84% (Scheme 1.3.23) [42]. The successive treatment of resin 59 with n-BuLi in THF and with isovaleraldehyde furnished the corresponding polymer-bound lithium alcoholate, which upon reaction with ClC02Me and DBU afforded the corresponding polymer-bound vinylic sulfoximine (not shown in Scheme 1.3.23), the isomerization of which with DBU in MeCN afforded sulfoximine 60. [Pg.101]

Scheme 1.3.28 Asymmetric synthesis of bicyclic amino acids via Pauson-Khand cycloaddition of vinyl sulfoximines. Scheme 1.3.28 Asymmetric synthesis of bicyclic amino acids via Pauson-Khand cycloaddition of vinyl sulfoximines.
The synthesis of the protected 5-hydroxy P-amino acids 91 required a stereoselective amination of the vinyl sulfoximine 4 (Scheme 1.3.29). Carbamoylation of alcohols 4 with trichloroacetyl isocyanate afforded carbamates 86 in high yields. [Pg.109]

TABLE 12. Nucleophilic epoxidation of vinyl sulfoximines with alkali alkyl peroxides [diastereomeric ratios are given in brackets the yields of the two diastereomers are shown]... [Pg.367]

Axially chiral vinyl sulfoximines have been prepared with high diastereoselec-tivity (> 99 1) by asymmetric elimination of LiOSiMe3 from 3-siloxy sulfoximines.72 For example, addition of lithiated (+)-(S)-2a to ketone 94 gave the (3-hydroxy sulfoximines 95 with a 99 1 diastereoselectivity. When the dianion of 95 was quenched at -78 °C with chlorotrimethylsilane, the vinyl sulfoximine 97 was... [Pg.314]

The geometry of the alkene is determined solely by the chirality at sulfur of the P-hydroxy sulfoximines 99 and 101 were converted to the (Z)- and ( )-vinyl sulfoximines 100 and 102, respectively, in high yield and with a high product diastereoselection (99 1). [Pg.315]

These vinyl sulfoximines undergo nickel-catalyzed cross-coupling reactions with organometallic reagents to give optically active alkenes (see Section V.D for details). [Pg.315]

The synthesis of vinyl sulfoximines via the elimination reactions of P-hydroxy sulfoximines11,12,33,72,78 has been discussed in Section TV. A. The method of Craig33 is particularly useful for the preparation of N-unsubstituted vinyl sulfoximines 210 which can be readily substituted at nitrogen by reactions with a number of reagents (see Section II.A) including trifluoromethane sulfonic anhydride (triflic anhydride).33... [Pg.338]

V-Tosyl vinyl sulfoximines 211 can be prepared in a one-pot reaction via an in situ Wadsworth-Emmons procedure from S-methyl-S-phenyl-N-tosylsulfoximine by sequential treatment at -78 °C with n-BuLi, potassium fert-butoxide, and diethyl chlorophosphate, followed by addition of an aldehyde and wanning to 0 °C.103 The resulting (V-tosyl vinyl sulfoximines 211 are formed almost exclusively as the ( )-isomer in good overall yields (60-91%). [Pg.338]

Both Gais and Jackson have reported the preparation of a-alkyl and a-trimethyl-silyl vinyl sulfoximines 219 by a-lithiation of vinyl sulfoximines 218 with butyl-lithium or methyllithium followed by treatment with alkyl halides, chloro-trimethylsilane,78 88,107,108 or diphenyl disulfide.109... [Pg.339]

Further experiments, in which the stereochemical outcomes could be rationalized as arising from analogous coordinated intermediates to 226 and 227, were performed on the enantiomerically pure vinyl sulfoximines 228 and 231.12 Vinyl sulfoximine 228 underwent conjugate addition of R2CuLi in the expected stereochemical sense, presumably via a coordinated intermediate analogous to 226 (Table... [Pg.341]

The stereochemical outcome of the reaction of the vinyl sulfoximine 231 with Me2CuLi (Table 16, entry 1) appears anomalous, whereas that from the reaction of... [Pg.342]

The reaction of racemic A-phthalimido-S-p-tolyl-S-vinylsulfoximine with a deficiency (0.5 molar equiv) of enantiomerically pure (-)-ephedrine resulted in a kinetic resolution of the vinyl sulfoximine.113 When the reaction was conducted at -30 °C the unreacted vinyl sulfoximine could be recovered with an enantiomeric purity of 46%. (-)-Amphetamine and (+)-l-phenylethylamine were not effective for kinetic resolution. The analogous (Z)-propenyl sulfoximine also underwent kinetic resolution with (-)-ephedrine, but the extent of kinetic resolution was not determined. [Pg.346]

Treatment of the terf-butyldimethylsilyloxy vinyl sulfoximine 139b with tetrabutylammonium fluoride in THF at 0 °C afforded the 2,3,4,5-tetrasubstituted dihydrofuran 253 in greater than 97% diastereoselectivity.86,87 This method works equally well with the other diastereoisomers of 139b. [Pg.349]

The reaction of N-tosyl vinyl sulfoximines 236 with lithium cyanide in DMF at room temperature for 1 h gave the vinyl nitriles 254 in good yields.117 Treatment of 236 with lithium dimethylphosphonate in THF at -78 °C to room temperature gave moderate yields of the vinyl phosphonates 255.117 These yields could be improved to 54-64% by isolation of the initial Michael adducts by quenching these reactions at -20 °C and then treatment of these products with sodium methoxide in methanol at reflux. These reactions proceed via the intermediates 256 and 257. [Pg.350]

The intramolecular Diels-Alder reactions of vinyl sulfoximines 270 (n = 1,2) have been studied by Craig.121,122 In all cases mixtures of four diastereomeric cycloadducts were formed. When n = 1 the major diastereoisomer was the transfused compound 271 (n = 1) while when n = 2 the major diastereoisomer was the cis-fused compound 273 (n = 2) The diastereoselectivity of these reactions when n = 1 were essentially independent of the nature of the N-substituent in 270, while when n = 2 thejV-2,4,6-triisopropylphenylsulfonyl (Tris) derivative gave the highest selectivity for 273. [Pg.353]

The reactions of the vinyl sulfoximines 281 with C./V-diphenylnitrone 282 are highly regioselective and give only 4-sulfonimidoyl-isoxazolidine cycloadducts 283 and 284.104 These reactions proceed with modest n-facial selectivity with respect to the dipolarophiles 281. The stereochemical outcomes of these reactions are consistent with attack on the ground-state conformation 238 of the sulfoximine through an endo -like transition state. [Pg.355]


See other pages where Vinyl sulfoximines is mentioned: [Pg.366]    [Pg.78]    [Pg.96]    [Pg.97]    [Pg.108]    [Pg.108]    [Pg.110]    [Pg.162]    [Pg.366]    [Pg.284]    [Pg.317]    [Pg.338]    [Pg.339]    [Pg.340]    [Pg.341]    [Pg.342]    [Pg.343]    [Pg.343]    [Pg.344]    [Pg.344]    [Pg.345]    [Pg.346]    [Pg.349]    [Pg.350]    [Pg.352]   
See also in sourсe #XX -- [ Pg.10 , Pg.679 ]

See also in sourсe #XX -- [ Pg.10 , Pg.679 ]




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Vinyl sulfoximines cross-coupling reactions

Vinyl sulfoximines cyclization

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