2757-10-0Relevant articles and documents
A new nitrogen-to-oxygen phosphoryl migration
Koziara,Zwierzak
, p. 15 - 21 (1999)
The reaction of diethyl N-acetyl-N-methylphosphoramidate 1 with aldehyde in the presence of LDA at -70°C results in the formation of the unstable oxyanion 6 which undergoes intramolecular rearrangement involving migration of a phosphoryl group from nitrogen to oxygen affording an amide anion 8. Subsequent proton transfer in 8 followed by elimination of phosphate anion provides the respective α,β-unsaturated N-methylcarboxamide 4. The formation of considerable amounts of diethyl N-methylphosphoramidate 5 is also always observed.
Organocatalytic Trans Semireduction of Primary and Secondary Propiolamides: Substrate Scope and Mechanistic Studies
Grams, R. Justin,Lawal, Monsurat M.,Szwetkowski, Connor,Foster, Daniel,Rosenblum, Carol Ann,Slebodnick, Carla,Welborn, Valerie Vaissier,Santos, Webster L.
supporting information, p. 172 - 178 (2021/10/14)
We report a chemoselective, phosphine-catalyzed semireduction of primary and secondary propiolamides. In the presence of stoichiometric pinacolborane and catalytic n-tributylphosphine, a variety of propiolamides were successfully converted to the corresponding acrylamides in excellent yield with (E)-stereoselectivity. The reaction condition is tolerant of various functional groups including alkene, alkyne, ketone, or ester. Deuterium labeling studies established that the hydride from activated pinacolborane is added to the α-carbon and the proton on the amide nitrogen is abstracted by the ?-carbon to furnish the (E)-acrylamides. DFT calculations revealed a clear energetic driving force for the (E)- over the (Z)-isomer. (Figure presented.).
Manganese Catalyzed Enantioselective Epoxidation of α,β-Unsaturated Amides with H2O2
Ottenbacher, Roman V.,Kurganskiy, Vladimir I.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
supporting information, p. 2778 - 2782 (2021/04/29)
Herewith, we report the enantioselective epoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially, the cis-enamides epoxidation enantioselectivity and yield are dramatically enhanced by the presence of NH-moiety, which effect can be explained by the hydrogen bonding interaction between the cis-enamide substrate and the manganese based oxygen transferring species. (Figure presented.).
Dealkoxylation ofN-alkoxyamides without an external reductant driven by Pd/Al cooperative catalysis
Suzuki, Hirotsugu,Shiomi, Takahiro,Yoneoka, Kenji,Matsuda, Takanori
supporting information, p. 7545 - 7548 (2020/10/15)
Lewis acid-assisted palladium-catalysed dealkoxylation ofN-alkoxyamides has been developed. This reaction proceeded smoothly with a range ofN-alkoxyamides in the absence of an external reductant, thereby establishing a convenient and reductant-free protocol. In addition, a gram-scale reaction could be achieved. Preliminary mechanistic investigations indicated that β-hydrogen elimination from a palladium alkoxide intermediate generated an intramolecular hydride source.
Catalytic, transition-metal-free semireduction of propiolamide derivatives: Scope and mechanistic investigation
Grams, R. Justin,Garcia, Christopher J.,Szwetkowski, Connor,Santos, Webster L.
supporting information, p. 7013 - 7018 (2020/09/12)
We report a transition-metal-free trans-selective semireduction of alkynes with pinacolborane and catalytic potassium tert-butoxide. A variety of 3-substituted primary and secondary propiolamides, including an analog of FK866, a potent nicotinamide mononucleotide adenyltransferase (NMNAT) inhibitor, are reduced to the corresponding (E)-3-substituted acrylamide derivatives in up to 99% yield with >99:1 E/Z selectivity. Mechanistic studies suggest that an activated Lewis acid-base complex transfers a hydride to the α-carbon followed by rapid protonation in a trans fashion.
Copper(I)-Catalyzed Asymmetric 1,4-Conjugate Hydrophosphination of α,β-Unsaturated Amides
Li, Yan-Bo,Tian, Hu,Yin, Liang
supporting information, p. 20098 - 20106 (2021/01/01)
A catalytic asymmetric conjugate hydrophosphination of α,β-unsaturated amides is accomplished by virtue of the strong nucleophilicity of copper(I)-PPh2 species, which provides an array of chiral phosphines bearing an amide moiety in high to excellent yields with excellent enantioselectivity. Furthermore, the dynamic kinetic resolution of unsymmetrical diarylphosphines (HPAr1Ar2) is successfully carried out through the copper(I)-catalyzed conjugate addition to α,β-unsaturated amides, which affords P-chiral phosphines with good-to-high diastereoselectivity and high enantioselectivity. 1H NMR studies show that the precoordination of HPPh2 to copper(I)-bisphosphine complex is critical for the efficient deprotonation by Barton's Base. Moreover, the relative stability of the copper(I)-(R,RP)-TANIAPHOS complex in the presence of excessive HPPh2, confirmed by 31P NMR studies, is pivotal for the high asymmetric induction, as the ligand exchange between bisphosphine and HPPh2 would significantly reduce the enantioselectivity. At last, a double catalytic asymmetric conjugate hydrophosphination furnishes the corresponding product in high yield with high diastereoselectivity and excellent enantioselectivity, which is transformed to a chiral pincer palladium complex in moderate yield. This chiral palladium complex is demonstrated as an excellent catalyst in the asymmetric conjugate hydrophosphination of chalcone.
Chemoselective Synthesis of Aryl Ketones from Amides and Grignard Reagents via C(O)-N Bond Cleavage under Catalyst-Free Conditions
Sureshbabu, Popuri,Azeez, Sadaf,Muniyappan, Nalluchamy,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
, p. 11823 - 11838 (2019/10/02)
Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.
Bioactivity and structure–activity relationship of cinnamic acid derivatives and its heteroaromatic ring analogues as potential high-efficient acaricides against Psoroptes cuniculi
Chen, Dong-Dong,Zhang, Bing-Yu,Liu, Xiu-Xiu,Li, Xing-Qiang,Yang, Xin-Juan,Zhou, Le
, p. 1149 - 1153 (2018/03/05)
A series of cinnamic acid derivatives and its heteroaromatic ring analogues were synthesized and evaluated for acaricidal activity in vitro against Psoroptes cuniculi, a mange mite. Among them, eight compounds showed the higher activity with median lethal concentrations (LC50) of 0.36–1.07 mM (60.4–192.1 μg/mL) and great potential for the development of novel acaricidal agent. Compound 40 showed both the lowest LC50 value of 0.36 mM (60.4 μg/mL) and the smallest median lethal time (LT50) of 2.6 h at 4.5 mM, comparable with ivermectin [LC50 = 0.28 mM (247.4 μg/mL), LT50 = 8.9 h], an acaricidal drug standard. SAR analysis showed that the carbonyl group is crucial for the activity. The type and chain length of the alkoxy in the ester moiety and the steric hindrance near the ester group significantly influence the activity. The esters were more active than the corresponding thiol esters, amides, ketones or acids. Replacement of the phenyl group of cinnamic esters with α-pyridyl or α-furanyl significantly increase the activity. Thus, a series of cinnamic esters and its heteroaromatic ring analogues with excellent acaricidal activity emerged.
Tandem superelectrophilic hydroarylation of CC bond and carbonyl reduction in cinnamides: Synthetic rout to 3,3-diarylpropylamines, valuable pharmaceuticals
Zakusilo, Dmitry N.,Ryabukhin, Dmitry S.,Boyarskaya, Irina A.,Yuzikhin, Oleg S.,Vasilyev, Aleksander V.
, p. 102 - 108 (2015/02/02)
Cinnamides ArCHCHCONRR′ in reactions with arenes Ar′H under the action of Bronsted (TfOH, FSO3H) or Lewis (AlBr3) superacids at rt for 1-2 h give CC bond hydroarylation products ArAr′CHCH2CONRR′ in yields of 63-98%. Reduction (LiAlH4/Et2O) of carbonyl group in the latter results in the formation of 3,3-diarylpropylamines ArAr′CHCH2CH2NRR′, valuable drugs. The reaction intermediates, superelectrophilic dications ArC+H-CH2C(OH+)NRR′, have been characterized by DFT calculations in terms of global electrophilicity index, natural charges, and atomic orbitals contributions.
Reductive N-O cleavage of Weinreb amides by sodium in alumina and silica gels: synthetic and mechanistic studies
Jackson, James E.,O'Brien, Brittany N.,Kedzior, Sonya K.,Fryz, Gage R.,Jalloh, Fatmata S.,Banisafar, Arash,Caldwell, Michael A.,Braun, Max B.,Dunyak, Bryan M.,Dye, James L.
supporting information, p. 6227 - 6230 (2015/10/20)
The use of sodium in alumina and silica gels for the reductive cleavage of the N-O bond of N-methoxy-N-methylamides, commonly referred to as Weinreb amides, has been investigated. This method reduces a diverse set of Weinreb amides with different function
