- trans-Selective hydrocyanation of ynoates, ynones and ynoic acids catalyzed by nucleophilic phosphines
-
trans-Selective hydrocyanation of ynoates and ynones in the presence of TMSCN and an alcohol additive are catalyzed by nucleophilic phosphines. The trisubstituted E-olefin products of anti-addition of hydrogen cyanide to the alkyne are produced with high regio- and stereoselectivity. The alcohol additive reacts with TMSCN to produce hydrogen cyanide in situ. Ynoic acids undergo the phosphine catalyzed hydrocyanation in the presence of TMSCN under aprotic conditions only. In these reactions, TMSCN reacts with the acid to generate hydrogen cyanide and the silyl ester which, unlike the acid, undergoes phosphine catalyzed hydrocyanation and gives the stereo-defined E-2-cyano-acrylic acids after work up.
- Meyer, Maximilian,Peri?, Milica,Sch?mberg, Fritz,Vilotijevi?, Ivan
-
supporting information
(2021/10/04)
-
- Synthesis of (E)-α,β-unsaturated carboxylic esters derivatives from cyanoacetic acid via promiscuous enzyme-promoted cascade esterification/Knoevenagel reaction
-
A new enzymatic protocol based on lipase-catalyzed cascade toward (E)-α,β-unsaturated carboxylic esters is presented. The proposed methodology consists of elementary organic processes starting from acetals and cyanoacetic acid leading to the formation of desired products in a cascade sequence. The combination of enzyme promiscuous abilities gives a new opportunity to synthesize complex molecules in the one-pot procedure. Results of studies on the influence of an enzyme type, solvent, and temperature on the cascade reaction course are reported. The presented methodology provides meaningful qualities such as significantly simplified process, excellent E-selectivity of obtained products and recycling of a biocatalyst.
- Wilk, Monika,Trzepizur, Damian,Koszelewski, Dominik,Brodzka, Anna,Ostaszewski, Ryszard
-
-
- Aza-Wittig Reaction with Nitriles: How Carbonyl Function Switches from Reacting to Activating
-
Transformations of α-EWG-substituted (electron-withdrawing group, EWG) γ-azidobutyronitriles proceeding via unusual aza-Wittig reactions between the phosphazene and nitrile functions and affording pyrrole-derived iminophosphazenes were developed. α-EWGs w
- Tukhtaev, Hamidulla B.,Ivanov, Konstantin L.,Bezzubov, Stanislav I.,Cheshkov, Dmitry A.,Melnikov, Mikhail Ya.,Budynina, Ekaterina M.
-
supporting information
p. 1087 - 1092
(2019/02/19)
-
- Sevelamer as an efficient and reusable heterogeneous catalyst for the Knoevenagel reaction in water
-
A catalyst system of Sevelamer, a phosphate-binding drug, has been prepared and used in the Knoevenagel reaction of aromatic aldehydes in water to produce substituted electrophilic alkenes. The products were obtained in excellent yields. Several novel, re
- Zhao, Xian-Liang,Yang, Ke-Fang,Zhang, Yan-Ping,Zhu, Ju,Xu, Li-Wen
-
supporting information
p. 1141 - 1144
(2014/08/18)
-
- Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors
-
Metal-free transfer hydrogenation of polarized olefins (RR′ CCEE′: R, R′ = H or organyl, E, E′ = CN or CO2Me) using amine borane adducts RR′NH-BH3 (R = R′ = H, AB; R = Me, R′ = H, MAB; R = tBu, R′ = H, tBAB; R = R′ = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the HN transfer is in agreement with a concerted transition state. The very reactive intermediate [NH2BH2] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy2BNH2. The final product borazine (BHNH)3 is assumed to be formed by dehydrocoupling of [NH2BH2] or its solvent stabilized derivative [NH2BH2]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH2NH 2)3 which is the trimerization product of [NH 2BH2].
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
-
experimental part
p. 852 - 860
(2012/02/05)
-
- Microwave synthesis of α-cyano chalcones
-
A novel methodology for facile production of α-cyano chalcones under microwave irradiation is described. Utilizing a Knoevenagel condensation between benzoylacetonitriles and aromatic aldehydes, substituted chalcones are generated via a 15-min, one-pot synthesis. Diversification of aromatic groups, including electron-withdrawing, electron-donating, and heterocyclic substitutions, has led to the isolation of over twenty colored, solid chalcone products. Furthermore the methodology can be extended to the synthesis of benzylidenemalononitriles as well as methyl and ethyl α-cyano cinnamates.
- Deshpande, Shyam J.,Leger, Paul R.,Sieck, Stephen R.
-
supporting information; experimental part
p. 1772 - 1775
(2012/05/04)
-
- Rhodium/chiral diene-catalyzed asymmetric 1,4-addition of arylboronic acids to arylmethylene cyanoacetates
-
Asymmetric 1,4-addition of arylboronic acids to (£)-methyl 2-cyano-3-arylpropenoates proceeded in the presence of a rhodium catalyst (3 mol %) coordinated with a chiral diene ligand, (R,R)-Ph-bod*, to give high yields of the corresponding methyl 3,3-diaryl-2-cyanopropanoates with high enantioselectivity (up to 99% ee). This catalytic asymmetric transformation was applied to the asymmetric synthesis of (R)-tolterodine. American Chemical Society.
- Soegel, Sebastian,Tokunaga, Norihito,Sasaki, Keigo,Okamoto, Kazuhiro,Hayashi, Tamio
-
p. 589 - 592
(2008/04/12)
-
- Novel, efficient, and green procedure for the Knoevenagel condensation catalyzed by diammonium hydrogen phosphate in water
-
Knoevenagel condensation of various aromatic and heteroaromatic aldehydes with active methylene compounds like methyl and ethyl cyanoacetate, malononitrile, and cyanoacetamide proceeds smoothly with stirring in water in the presence of 4 mol% of diammoniu
- Balalaie, Saeed,Bararjanian, Morteza,Hekmat, Shohreh,Salehi, Peyman
-
p. 2549 - 2557
(2007/10/03)
-
- Novel, efficient, and green procedure for the Knoevenagel condensation catalyzed by diammonium hydrogen phosphate in water
-
Knoevenagel condensation of various aromatic and heteroaromatic aldehydes with active methylene compounds such as methyl and ethyl cyanoacetate, malononitrile, and cyanoacetamide proceeds smoothly with stirring in water in the presence of 4 mol% of diammo
- Balalaie, Saeed,Bararjanian, Morteza,Hekmat, Shohreh,Salehi, Peyman
-
p. 3703 - 3711
(2007/10/03)
-
- NaNO2-ceric ammonium nitrate mediated conversion of acrylic esters and Baylis-Hillman derived acrylic esters into corresponding β-nitro acrylic esters
-
A variety of acrylic esters, including those derived from Baylis-Hillman reactions, react with NaNO2-ceric ammonium nitrate to form the corresponding β-nitro alcohols 2 and 5 whose dehydration, via their mesylates, leads to β-nitro acrylic esters, in good to excellent yields. Further, β-nitro acrylic esters containing a mesylate group 6, obtained from the Baylis-Hillman products, react with NaN3 to form 2-cyano-3-substituted acrylic esters 10 in excellent yields.
- Jayakanthan,Madhusudanan,Vankar, Yashwant D.
-
p. 397 - 403
(2007/10/03)
-
- Calcite and fluorite as catalyst for the Kn?venagel condensation of malononitrile and methyl cyanoacetate under solvent-free conditions
-
When milled together with calcite or fluorite, malononitrile and methyl cyanoacetate readily underwent Kn?venagel condensation with aromatic aldehydes, giving the corresponding arylidenemalononitriles and (E)-α-cyanocinnamic esters in good to excellent yi
- Wada, Shinobu,Suzuki, Hitomi
-
p. 399 - 401
(2007/10/03)
-
- CATALYSIS OF THE KNOEVENAGEL CONDENSATION.
-
Xonotlite alone or made more basic by doping of potassium t-butoxide catalyses the title reaction between aromatic aldehydes and malononitrile or alkyl cyanoacetates.At ambient temperatures, this procedure specifically gives high yields of E olefinic Knoe
- Chalais, Stephane,Laszlo, Pierre,Mathy, Arthur
-
p. 4453 - 4454
(2007/10/02)
-