35874-96-5Relevant academic research and scientific papers
Diastereoselection during 1,2-Addition of the Allylindium Reagent to α-Thia and α-Amino Aldehydes in Aqueous and Organic Solvents
Paquette, Leo A.,Mitzel, Thomas M.,Isaac, Methvin B.,Crasto, Curtis F.,Schomer, William W.
, p. 4293 - 4301 (2007/10/03)
The stereochemistry of the indium-promoted reaction of allyl bromide with α-thia (PhS and MeS), disubstituted α-amino (Bn2N, Me2N, isoindolyl), and protected α-amino aldehydes (Ac and Boc) in water has been evaluated. The reactions involving the sulfur derivatives are minimally diastereoselective, indicating that the allylindium reagent is not thiophilic. Chelation is not observed and π-facial discrimination is achieved via Felkin - Ahn transition states under the steric control of the substituents. The Garner aldehyde is also anti-diastereoselective. Interestingly, N-acetylmannosamine is appreciably responsive to chelation control and is capable of generating 90% of the syn β-amino alcohol when reacted in a 0.5 M NH4Cl solution. While the α-dibenzylamino substituent is too bulky to enter into complexation, the α-dimethylamino group is not and can lead to high levels (99%) of syn diastereomer. The size of other neighboring substituents does have an impact on π-facial discrimination in these systems and can erode the stereoselectivity accordingly.
Synthesis of 4-oxo-2-azetidineacetic acids by means of radical cyclization of N-vinylic α-bromo amides
Ishibashi, Hiroyuki,Kodama, Kazuya,Kameoka, Chisato,Kawanami, Hirotaka,Ikeda, Masazumi
, p. 13867 - 13880 (2007/10/03)
Bu2SnH-mediated radical cyclization of α-bromo amide 8, bearing phenyl and phenylthio substituents at the terminus of the N-vinylic bond, proceeded in a 4-exo-trig manner to give β-lactam 9. Ruthenium tetroxide oxidation of the phenyl group incorporated into the product 9 provided a new synthesis of 4-oxo-2-azetidineacetic acid 13, a useful intermediate for (±)-PS-5. Chiral 4-oxo-2-azetidineacetic acids 23 and 36, key intermediates for the synthesis of (+)-PS-5 and (+)-thienamycin, respectively, were also obtained through the asymmetric radical cyclization of N-vinylic α-bromo amides having chiral auxillaries at the side-chain.
CAN- and DDQ-Promoted Oxidation of Alkenyl Sulfides
Capella, Laura,Montevecchi, Pier Carlo,Nanni, Daniele
, p. 7379 - 7382 (2007/10/02)
Vinyl sulfides 1 react with CAN in acetonitrile at room temperature to give radical cations 2A in equilibrium with the thiiranyl radical cations 2B.The reaction products arise from nucleophilic attack of the nitrate counterion at either the sulfur atom of 2A or the trivalent carbon of 2B.The last reaction can proceed through 1,2-shift or displacement of the sulfide moiety.When α-methylenic protons are present in 2B, deprotonation occurs, leading to allyl radicals and, ultimately, to isomeric allyl alcohols.Reactions of 1 with DDQ in acetonitrile afford charge-transfer complexes and then zwitterionic electron-transfer (ET) complexes which can evolve rapidly through intramolecular proton transfer when trans methylenic protons are present.The resulting sulfur-oxygen ?-complexes are responcible for the reaction products mainly through either γ-elimination of DDQH2 or nucleophilic attack at the δ-vinilic carbon followed by displacement of DDQH(1-).
Additive Pummerer reactions of vinylic sulfoxides. Synthesis of γ-hydroxy-α,β-unsaturated esters, α-hydroxyketones, and 2-phenylsulfenyl aldehydes and primary alcohols
Craig, Donald,Daniels, Kevin,MacKenzie, A. Roderick
, p. 11263 - 11304 (2007/10/02)
Treatment of β-monosubstituted vinylic sulfoxides 1 with trifluoroacetic anhydride in dichloromethane gave excellent yields of 1,2-bis(trifluoroacetoxy)thioethers 6. Mildly basic methanolysis of 2-alkyl-substituted 6 gave α-hydroxyaldehydes 11 as monomer-dimer mixtures; similar treatment of the 2-aryl analogues afforded aryl (hydroxymethyl) ketones 12. Compounds 11 underwent Wittig reactions with methoxycarbonylmethylenetriphenylphosphorane to give high yields of γ-hydroxy-α,β-unsaturated esters 13, predominantly as the E-isomers. β-Monosubstituted vinylic sulfoxides 1 possessing a β-aryl group, and β-disubstituted vinylic sulfoxides 3 reacted with trifluoromethanesulfonic anhydride-sodium acetate in acetic anhydride to give 2-(phenylsulfenyl) acylals 14. These gave 2-phenylsulfenyl aldehydes 15 upon basic methanolysis, and the corresponding primary alcohols 16 on reduction with sodium borohydride. Reaction of both geometric isomers of enantiomerically pure vinylic sulfoxide 1o with TFAA gave racemic 6o as a mixture of diastereomers. Reaction of optically pure (E)- and (Z)-1p with trifluoromethanesulfonic anhydride-sodium acetate in acetic anhydride gave acylal 19 in 10.5 and 23% e.e., respectively.
Additive Pummerer reactions of vinylic sulphoxides. Synthesis of 2-(phenylsulphenyl) aldehydes and primary alcohols
Craig,Daniels,MacKenzie
, p. 6973 - 6976 (2007/10/02)
Reaction in acetic anhydride solution of α,β-unsaturated sulphoxides 1 with sodium acetate and triflic anhydride gives 2-(phenylsulphenyl) acylals 4. Basic methanolysis of 4 gives 2-(phenylsulphenyl) aldehydes 8, whilst reduction gives directly 2-(phenylsulphenyl) primary alcohols 9.
Homologation of aldehydes using (phenylthiomethylene) triphenylarsorane: Selective preparation of α-thiophenoxyepoxides and phenylthioenol ethers
Boubia,Mioskowski,Manna,Falck
, p. 6023 - 6026 (2007/10/02)
The title arsonium ylide reacts with aldehydes to give exclusively α-thiophenoxyepoxides in THF and phenylthioenol ethers in THF/HMPA. The former adducts are readily transformed to α-thiophenoxy carbonyls and the latter to one-carbon homologated aldehydes.
Peculiar Aspects of the Anodic Oxidation of Vinylic Sulfides
Guillanton, Georges Le,Simonet, Jacques
, p. 437 - 444 (2007/10/02)
In the anodic oxidation of vinylic sulfides on platinum in acetonitrile, a non-classical sulfonium ion explains satisfactorily the transfer of the thioether group leading to an aldehyde in the presence of water, or its acetal in the presence of methanol.Some other reactions depend on the structure of the substrate, particularly the dimerization into anodically inactive forms likely to decompose during the work-up, to lead in some cases to masked ketenes having the structure of a gem-disulfide.
