2482-39-5Relevant articles and documents
Water is an efficient medium for Wittig reactions employing stabilized ylides and aldehydes
Dambacher, Jesse,Zhao, Wen,El-Batta, Amer,Anness, Robert,Jiang, Changchun,Bergdahl, Mikael
, p. 4473 - 4477 (2007/10/03)
Water is demonstrated to be an excellent medium for the Wittig reaction employing stabilized ylides and aldehydes. Although the solubility in water appears to be an unimportant characteristic in achieving good chemical yields and E/Z-ratios, the rate of W
Excess sodium ions improve Z selectivity in Horner-Wadsworth-Emmons olefinations with the Ando phosphonate
Pihko, Petri M.,Salo, Taina M.
, p. 4361 - 4364 (2007/10/03)
New, improved conditions for Z selective Horner-Wadsworth-Emmons olefinations with Ando's bis(o-methylphenyl)phosphonates are reported. A combination of NaH and NaI affords Z olefins in up to >99:1 selectivity and good yields.
A study on the Z-selective Horner-Wadsworth-Emmons (HWE) reaction of methyl diarylphosphonoacetates
Kokin, Keisuke,Iitake, Ken-Ichro,Takaguchi, Yutaka,Aoyama, Hiromu,Hayashi, Sadao,Motoyoshiya, Jiro
, p. 21 - 40 (2007/10/03)
Experimental and theoretical studies were conducted to explore the Z-selectivities in the Horner-Wadsworth-Emmons (HWE) reaction employing several methyl diarylphosphonoacetates (3, 4, 5 and 6) and aldehydes. The Z-selectivity depended upon the reaction conditions such as the bases, reaction temperature, and the aromatic substituents on the phosphorus atoms but the almost phosphonoacetates used in the present study showed Z-selectivity in the reactions with both aromatic and aliphatic aldehydes. While the phosphonoacetate (3) with bis(2,4-difluorophenyl)phosphono group showed the highest Z-selectivity in all reaction conditions employed, decrease of the selectivity was observed in the case of some phosphonoacetates with diarylphosphono groups. These experimental results and the theoretical studies calculated by AM1 or 3-21G* ab initio methods suggested that the steric effect in the transition states of the addition steps was important rather than the electronic effect. A different aspect of the reaction courses between the Wittig and HWE reactions in the present computational chemistry was also described.
Synthesis of a 3-ether analogue of lipid A
Shiozaki, Masao,Kobayashi, Yoshiyuki,Arai, Masami,Ishida, Noboru,Hiraoka, Tetsuo,et al.
, p. 69 - 82 (2007/10/02)
Lipid A 3-ether analogues were synthesized from allyl 2-deoxy-4,6-O-isopropylidene-2-trifluoroacetamido-α-D-glucopyranoside and 3,4,6-tri-O-acetyl-2-trifluoroacetamido-α-D-glucopyranosyl bromide.The compound lost completely the endotoxic activity.