نتایج جستجو برای: -unsaturated ester
تعداد نتایج: 53007 فیلتر نتایج به سال:
Study on Synthesis and Characterization of Unsaturated Poly (ester-amide) as Bone Fixation Materials
A new type of unsaturated poly ester-amide was prepared by melt polycondensation and characterized completely. Influence of heat treatment conditions and cross-linking content on mechanical and degradation properties of unsaturated polyester-amide were studied. Results suggested that the newly synthesized unsaturated poly(ester-amide) possessed good heat stabilization properties. Mechanical...
a new efficient method for the synthesis of carboacyclic nucleosides as biologically interesting compounds via aza-conjugate addition of pyrimidine nucleobases to a,β-unsaturated esters in the presence of catalytic amount of lioh.h2o (1.2-4.8 mol%) under microwave irradiation is described. this method affords the title compounds in good to excellent yields and in short reaction times.
The efficiency and stereoselectivity of the conjugate addition of lithium (Z)- or (E)-beta-amino ester enolates, generated by lithium amide conjugate addition to an alpha,beta-unsaturated ester or deprotonation of a beta-amino ester, respectively, to a range of alpha,beta-unsaturated acceptors has been investigated. Deprotonation of a beta-amino ester with LDA, followed by conjugate addition to...
A new general concept for α,β-unsaturated acyl ammonium catalysis is reported that uses p-nitrophenoxide release from an α,β-unsaturated p-nitrophenyl ester substrate to facilitate catalyst turnover. This method was used for the enantioselective isothiourea-catalyzed Michael addition of nitroalkanes to α,β-unsaturated p-nitrophenyl esters in generally good yield and with excellent enantioselect...
Increasing prevalence of allergic diseases with an inadequate variety of treatment drives forward search for new alternative drugs. Fatty acids, abundant in nature, are regarded as important bioactive compounds and powerful nutrients playing an important role in lipid homeostasis and inflammation. Phytochemical study on Typhonium blumei Nicolson and Sivadasan (Araceae), a folk anti-cancer and a...
A thorough investigation of the mode of action of Aspergillus niger (4M-147) pectin lyase A (PLA) on differently C(6)-substituted oligogalacturonides is described. PLA appeared to be very specific for fully methyl-esterified oligogalacturonides: removal of the methyl-ester or changing the type of ester (ethyl esterification) or transamidation resulted in (almost) complete loss of conversion. Th...
Brucine diol (BD) catalyzed asymmetric Morita–Baylis–Hillman (MBH) reaction is observed for the first time. N-oxide (BNO) was found to not have an effective chiral catalyst. Faster rate obtained using unsaturated ester or aromatic aldehydes in presence of BNO. 4-Nitrobenzaldehyde and α,β-unsaturated ketone/ester were converted MBH adduct moderate yields (up 74%) with 70% ee value by this cataly...
Isothiourea HBTM-2.1 catalyzes the asymmetric Michael addition/lactonization of aryl- and alkenylacetic acids using α-keto-β,γ-unsaturated phosphonates as α,β-unsaturated ester surrogates, giving access to a diverse range of stereodefined lactones or enantioenriched functionalized diesters upon ring-opening.
A facile synthesis of the C4-substituted isoquinolines 5a-c and 6a-c is described. Commercially available 4-bromoisoquinoline is converted to the alpha,beta-unsaturated esters 8 and 10 on treatment with the appropriate acrylate ester under Heck reaction conditions. The saturated amides 5a-c were obtained from the reaction of ester 9 with the requisite primary amine. Similarly the unsaturated an...
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