An Expedient Route to the Tetrazole Analogues of α-Amino Acids
摘要:
[GRAPHIC]Convenient conditions are described for the transformation of alpha-aminonitriles to the tetrazole analogues of alpha-amino acids. Refluxing the starting material in water/2-propanol at 80 degreesC with sodium azide and catalytic zinc bromide affords the tetrazole product in yields generally exceeding 90%.
Enantioselective C--C bond formation to 2-pyridinesulfonylimines afforded products with good enantioselectivity. Dynamic induction of chirality on the sulfur by coordination of a chiral Lewis acid to the pyridine nitrogen and one of the prochiral sulfonyl oxygens induces enantioselectivity. Since the 2-pyridinesulfonyl group can easily be removed after the reaction, it acts not only as an activating
A catalyticenantioselectiveStreckerreaction catalyzed by novel chiral lanthanum(III)−binaphthyl disulfonate complexes was developed. The key to promoting the reactions was a semistoichiometric amount of AcOH or i-PrCO2H, which takes advantage of HCN generation in situ. The corresponding cyanation products were obtained in high yields and with high enantioselectivities.
Trimethylsilyl cyanide addition to aldimines and its application in the synthesis of (S)-phenylglycine methyl ester
作者:B.A. Bhanu Prasad、Alakesh Bisai、Vinod K. Singh
DOI:10.1016/j.tetlet.2004.11.015
日期:2004.12
reaction) in the presence of LiClO4 or BF3·Et2O in acetonitrile has been studied. The reaction provided the addition products in very high yields. The method has been successfully utilized for the synthesis of (S)-phenylglycine methyl ester.
The directamination of cyanohydrins with amines via a catalytic cyano-borrowing reaction was developed. The transformation features broad substrate scope, excellent functional group compatibility, and very mild and simple operations. Moreover, a titanium catalyst supported by quinine and (S)-BINOL ligands enabled an asymmetric cyano-borrowing reaction with moderate to high enantioselectivity.
Octahedron-based redox molecular sieves M -PKU-1 ( M = Cr, Fe): A novel dual-centered solid acid catalyst for heterogeneously catalyzed Strecker reaction
作者:Weilu Wang、Siyu Zhang、Shixiang Hu、Duo Wang、Wenliang Gao、Rihong Cong、Tao Yang
DOI:10.1016/j.apcata.2017.05.030
日期:2017.7
Cr-PKU-1, an octahedron-based redox molecular sieve, was found to be an efficient, environmentally benign and easily recoverable catalyst for the heterogeneously-catalyzed Strecker reaction under the mild conditions. This material was evidenced to be a dual-centered solid acid with a large density of Brönsted acid (borate hydroxyl groups, B-OH) and Lewis acid sites (Cr3+), and therefore showed much