157635-97-7Relevant academic research and scientific papers
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.
Self-assembled organic-inorganic hybrid silica with ionic liquid framework: A novel support for the catalytic enantioselective Strecker reaction of imines using Yb(OTf)3-pybox catalyst
Karimi, Babak,Maleki, Aziz,Elhamifar, Dawood,Clark, James H.,Hunt, Andrew J.
supporting information; experimental part, p. 6947 - 6949 (2010/11/04)
Yb(OTf)3-pybox is immobilized in a novel self-assembled ionic liquid hybrid silica and has been successfully applied as a catalyst for the asymmetric Strecker hydrocyanation of aldimines. This catalytic system can be reused for at least 6 times without any significant loss of activity and enantioselectivity.
Catalytic asymmetric Strecker hydrocyanation of imines using Yb(OTf) 3-pybox catalysts
Karimi, Babak,Maleki, Aziz
supporting information; experimental part, p. 5180 - 5182 (2009/12/08)
We have explored the highly enantioselective Strecker hydrocyanation of a wide range of aromatic, α,β-unsaturated, heterocyclic, and aliphatic aldimines with good to excellent conversions and ees up to 98% in the presence of catalytic amounts of Yb(OTf)s
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.
The synthesis of 1-aminobenzylphosphonic acids from benzylidenediphenylmethylamines, for use as structural units in antithrombotic tripeptides
Green, Donovan,Patel, Geeta,Elgendy, Said,Baban, Jehan A.,Claeson, Goran,Kakkar, Vijay V.,Deadman, John
, p. 5099 - 5108 (2007/10/02)
Acid hydrolyses of O,O-dimethyl or O,O-diethyl 1-(diphenylmethylamino) benzylphosphonate intermediates 2, formed from the addition at elevated temperature of dimethyl or diethyl phosphite to benzylidenediphenylmethylamines 1, generates 1-aminobenzylphosphonic acids 3 in good yield.
