1. L-pipecolinic acid derived lewis base organocatalyst for asymmetric reduction of n-aryl imines by trichlorosilane: effects of the side amide group on catalytic performances.
Zhouyu Wang, Chao Wang, Jian Sun, Li Zhou. Org Biomol Chem. 2013 Feb 7; 11(5): 787-97. DOI: 10.1039/c2ob26772a. PMID: 23223869.
A series of N-formamides derived from pipecolinic acid have been synthesized and tested as Lewis base catalysts for the enantioselective reduction of N-aryl imines by trichlorosilane. Through the investigation of the structure-efficacy relationship between the side amide group and catalytic performance, several highly effective catalysts were discovered. In particular, arylamido-type catalyst 5i and non-arylamido-type catalyst 6c exhibited high reactivity and enantioselectivity, furnishing the reduction of a wide variety of N-aryl imines with high isolated yields (up to 98%) and ee values (up to 96%) under mild conditions. Moreover, these two catalysts complement each other in terms of their tolerances to nonaromatic ketimines and non-methyl ketimines.
2. Xylapeptide a, An antibacterial cyclopentapeptide with an uncommon l-pipecolinic acid moiety from the associated fungus xylaria sp. (gdg-102).
Rui-Yun Yang, Na Zheng, Chang-Lun Shao, Chang-Yun Wang, Wei-Feng Xu, Jun Li, Fei-Hua Yao, Xue-Mei Hou. Sci Rep. 2017 Jul 31; 7(1): 6937. DOI: 10.1038/s41598-017-07331-4. PMID: 28761094.
Two new cyclopentapeptides, xylapeptide A (1) with an uncommon L-pipecolinic acid moiety, and xylapeptide B (2) having a common L-proline residue were identified from an associated fungus Xylaria sp. isolated from the Chinese medicinal plant Sophora tonkinensis. Their planar structures were elucidated by a comprehensive analysis of NMR and MS spectroscopic spectra. The absolute configurations were determined by Marfey's method and single-crystal X-ray diffraction (Cu Kα) analysis. Xylapeptide A (1) is the first example of cyclopentapeptide with L-Pip of terrestrial origin and showed strong antibacterial activity against Bacillus subtilis and B. cereus with MIC value of 12.5 μg/mL.
