211735-37-4Relevant academic research and scientific papers
Microwave-assisted synthesis of α-aminophosphonates with sterically demanding α-aryl substituents
Hudson, Harry R.,Tajti, ádám,Bálint, Erika,Czugler, Mátyás,Karaghiosoff, Konstantin,Keglevich, Gy?rgy
, p. 1446 - 1455 (2020/03/16)
A series of N-benzhydryl protected α-aminophosphonates with α-phenyl, α-(1-naphtyl), α-(9-anthryl) or α-(1-pyrenyl) substituents was synthesized by the Kabachnik–Fields condensation of diphenylmethylamine (benzhydrylamine), the corresponding aryl aldehyde and a dialkyl phosphite under MW irradiation. X-ray studies performed at low temperatures for a few of these α-aminophosphonates confirmed the presence of unusually short intramolecular Cα–Hδ+ ··· δ+H–Cperi contacts.
Access to α-Arylglycines by Umpolung Carboxylation of Aromatic Imines with Carbon Dioxide
Guo, Chun-Xiao,Zhang, Wen-Zhen,Zhou, Hui,Zhang, Ning,Lu, Xiao-Bing
supporting information, p. 17156 - 17159 (2016/11/23)
A straightforward and transition-metal-free approach for the efficient synthesis of α-arylglycine derivatives from aromatic imines and carbon dioxide was enabled by an umpolung carboxylation reaction. Various substituted diphenylmethimines underwent the carboxylation smoothly with carbon dioxide in the presence of potassium tert-butoxide and 18-crown-6 to give the corresponding carboxylated products in good to high yields. Besides the enhancement of the solubility of potassium tert-butoxide in THF, 18-crown-6 also plays key roles in suppressing the reverse protonation or 1, 3-proton shift isomerization as well as by stabilizing the carboxylated intermediate.
Extremely short H?H distances and intermolecular hydrogen-bonding patterns of dialkyl α-aryl-α-(diphenylmethylamino)methanephosphonates
Hudson, Harry R.,Czugler, Mátyás,Lee, Rosalind J.,Woodroffe, Thomas M.
, p. 469 - 477 (2016/04/09)
Single crystal X-ray diffraction studies of four N-benzhydryl protected diethyl α-amino-α-arylmethanephosphonates (aryl = phenyl, 1-naphthyl, 1-anthryl, and 1-pyrenyl) reveal several distinct types of hydrogen bonding, leading to the formation of (a) dime
Catalytic asymmetric aziridination with borate catalysts derived from VANOL and VAPOL ligands: Scope and mechanistic studies
Zhang, Yu,Desai, Aman,Lu, Zhenjie,Hu, Gang,Ding, Zhensheng,Wulff, William D.
experimental part, p. 3785 - 3803 (2009/05/28)
An extended study of the scope and mechanism of the catalytic asymmetric aziridination of imines with ethyl diazoacetate mediated by catalysts prepared from the VANOL and VAPOL ligands and triphenylborate is described. Nonlinear studies with scalemic VANOL and VAPOL reveal an essentially linear relationship between the optical purity of the ligand and the product suggesting that the catalyst incorporates a single molecule of the ligand. Two species are present in the catalyst prepared from B(OPh)3 and either VANOL or VAPOL as revealed by 1H NMR studies. Mass spectral analysis of the catalyst mixture suggests that one of the species involves one ligand molecule and one boron atom (B1) and the other involves one ligand and two boron atoms (B2). The latter can be formulated as either a linear or cyclic pyroborate and the 11B NMR spectrum is most consistent with the linear pyroborate structure. Several new protocols for catalyst preparation are developed which allow for the generation of mixtures of the B1 and B2 catalysts in ratios that range from 10:1 to 1:20. Studies with catalysts enriched in the B1 and B2 species reveal that the B2 catalyst is the active catalyst in the VAPOL catalyzed asymmetric aziridination reaction giving significantly higher asymmetric inductions and rates than the B1 catalyst. The difference is not as pronounced in the VANOL series. A series of 12 different imines were surveyed with the optimal catalyst preparation procedure with the finding that the asymmetric inductions are in the low to mid 90s for aromatic imines and in the mid 80s to low 90s for aliphatic imines for both VANOL and VAPOL catalysts. Nonetheless, the crystallinity of the N-benzhydryl aziridines is such that nearly all of the 12 aziridine products screened can be brought to >99% ee with a single recrystallization.
1-Amino-1-aryl- and 1-amino-1-heteroaryl-methanephosphonic acids and their n-benzhydryl-protected diethyl esters: Preparation and characterization
Hudson, Harry R.,Lee, Rosalind J.,Matthews, Ray W.
, p. 1691 - 1709 (2007/10/03)
N-Benzhydryl-protected diethyl esters of 1-amino-1-aryl- (phenyl, cumyl, p-dimethylaminophenyl, piperonyl, 1′-naphthyl, 9′-anthryl, 1′-pyrenyl) and 1-amino-1-heteroaryl- (furyl, 2′-thienyl, 3′-thienyl, 2′-pyrrolyl)-methanephosphonic acids, prepared by the
