169900-77-0Relevant articles and documents
Syntheses of α,β-unsaturated carbonyl compounds from the reactions of monosubstituted ozonides with stable phosphonium ylides
Hon, Yung-Son,Lu, Ling,Chang, Rong-Chi,Lin, Sheng-Wun,Sun, Pei-Pei,Lee, Chia-Fu
, p. 9269 - 9279 (2007/10/03)
Ozonides derived from terminal alkenes reacted with 1.3 mol equiv. of stable phosphonium ylides to give (E)-αβ-unsaturated carbonyl compounds in good to excellent yields. No reducing agent is needed in the reaction. However, alkoxyalkyl-substituted ozonides afforded a mixture of (Z)- and (E)-αβ-unsaturated carbonyl compounds under similar condition. The E/Z isomeric ratio is affected by the position of the heteroatom in the substituent of the ozonides. The possible mechanism of this reaction will be discussed. (C) 2000 Elsevier Science Ltd.
Application of oxazolidinone α-fluoro amide chiral building blocks in the asymmetric synthesis of fluorinated carbohydrates: 2-Deoxy-2-fluoropentoses
Davis, Franklin A.,Qi, Hongyan,Sundarababu, Gajendran
, p. 5303 - 5310 (2007/10/03)
Deconjugative electrophilic fluorination of the lithium dienolate of Z-α,β-unsaturated imide (+)-9 with N-fluorobenzene-sulfonimide (NFSi) afforded the E-β,γ-unsaturated α-fluoro imide (+)-10 as a single diastereoisomer. Dihydroxylation resulted in the formation of 2-fluoro-2-deoxy-γ-xylonic and -lyxonic lactones, 12a and 12b, respectively. Reduction and deprotection of the lactones afforded 2-deoxy-2-fluoro-xylo-D-pyranose (15) and 2-deoxy-2-fluoro-lyxo-L-pyranose (17). (C) 2000 Elsevier Science Ltd.
Asymmetric synthesis of 2-deoxy-2-fluoro-γ-aldonolactones and their conversion to 2-deoxy-2-fluoropentoses
Davis, Franklin A.,Qi, Hongyan
, p. 4345 - 4348 (2007/10/03)
2-Fluoro-2-deoxy-γ-xylonic and -lyxonic lactones, 7a and 7b, were prepared via the diastereoselective fluorination of the α,β-unsaturated chiral imide 5 followed by dihydroxylation. Lactones 7a and 7b were converted to 2-deoxy-2-fluoro-xylo-D-pyranose (1) and 2-deoxy-2-fluoro-lyxo-L-pyranose (2) by reduction and deprotection.
A simple route to α-substituted-β-amino ester precursors of carbapenem antibiotics
Perlmutter,Tabone
, p. 6515 - 6522 (2007/10/03)
A three-step process is presented for the preparation of α-substituted-β-amino esters which can serve as precursors to a key intermediate in carbapenem synthesis. The pivotal reaction in this sequence involves a highly diastereoselective conjugate addition reaction. Two series of alkenoates bearing a stereogenic substituent attached to C2 were prepared and their conjugate addition reactions with benzylamine studied under several different sets of conditions. Conjugate addition of benzylamine to alkenoates 7a and 7d, in methanol at room temperature, gave adducts 8a and 8d with virtually complete anti-diastereoselectivity. These two β-amino esters bear the correct relative stereochemistry and side chain to serve as precursors for carbapenem antibiotic synthetic intermediates. The role of the allylic substituents of the alkenoates 7a-e in determining the stereochemical outcome of these additions is discussed. These conjugate additions were explored further by the preparation and conjugate addition reactions of the α,β-disubstituted alkenoates 15a and 15b. It was found that the presence of a β-substituent led to a dramatic reduction in yield although the same anti-diastereoselectivity was maintained. The relative stereochemistry of the adducts was established by examination of the relevant coupling constants in the 1H NMR spectra of their tetrahydro-1,3-oxazine derivatives.
