176035-15-7Relevant articles and documents
Chemical and Genetic Studies on the Formation of Pyrrolones During the Biosynthesis of Cytochalasans
Zhang, Haili,Hantke, Verena,Bruhnke, Pia,Skellam, Elizabeth J.,Cox, Russell J.
supporting information, p. 3106 - 3113 (2021/01/20)
A key step during the biosynthesis of cytochalasans is a proposed Knoevenagel condensation to form the pyrrolone core, enabling the subsequent 4+2 cycloaddition reaction that results in the characteristic octahydroisoindolone motif of all cytochalasans. In this work, we investigate the role of the highly conserved α,β-hydrolase enzymes PyiE and ORFZ during the biosynthesis of pyrichalasin H and the ACE1 metabolite, respectively, using gene knockout and complementation techniques. Using synthetic aldehyde models we demonstrate that the Knoevenagel condensation proceeds spontaneously but results in the 1,3-dihydro-2H-pyrrol-2-one tautomer, rather than the required 1,5-dihydro-2H-pyrrol-2-one tautomer. Taken together our results suggest that the α,β-hydrolase enzymes are essential for first ring cyclisation, but the precise nature of the intermediates remains to be determined.
Synthesis of Water-Soluble Chiral DOTA Lanthanide Complexes with Predominantly Twisted Square Antiprism Isomers and Circularly Polarized Luminescence
Dai, Lixiong,Zhang, Junhui,Chen, Yuqing,Mackenzie, Lewis E.,Pal, Robert,Law, Ga-Lai
supporting information, p. 12506 - 12510 (2019/10/02)
One-step cyclization of a tetraazamacrocycle 5 with 70% yield in a 25-g scale was performed. Its chiral DOTA derivatives, L4, has ?93% of TSAP coordination isomer in its Eu(III) and Yb(III) complexes in aqueous solution. [GdL4]5- exhibits a high relaxivity, making it a promising and efficient MRI contrast agent. High luminescence dissymmetry factor (glum) values of 0.285 (ΔJ = 1) for [TbL3]- and 0.241 (ΔJ = 1) for [TbL4]5- in buffer solutions were recorded.
Chiral ethylene-bridged flavinium salts: the stereoselectivity of flavin-10a-hydroperoxide formation and the effect of substitution on the photochemical properties
?urek, Ji?í,Svobodová, Eva,?turala, Ji?í,Dvo?áková, Hana,Svoboda, Ji?í,Cibulka, Radek
, p. 1780 - 1791 (2017/11/17)
A series of chiral non-racemic N1,N10-ethylene bridged flavinium salts 4 was prepared using enantiomerically pure 2-substituted 2-aminoethanols (R = isopropyl, phenyl, benzyl, 4-methoxybenzyl, 4-benzyloxybenzyl) derived from amino acids as the sole source of chirality. The flavinium salts were shown to form 10a-hydroperoxy- and 10a-methoxy-adducts with moderate to high diastereoselectivity depending on the ethylene bridge substituent originating from the starting amino acid. High diastereoselectivities (dr values from 80:20 to >95:5) were observed for flavinium salts bearing benzyl substituents attached to the ethylene bridge. The benzyl group preferred the face-to-face (syn) orientation relative to the flavinium unit; thereby effectively preventing nucleophilic attack from one side. This conformation was found to be the most stable according to the DFT calculations. Consequently, the presence of benzyl groups causes intermolecular fluorescence quenching resulting in a significant decrease in the fluorescence quantum yield from 11% for 4a bearing an isopropyl substituent to 0.3% for 4c containing a benzyl group and to a value lower than 0.1% for the benzyloxybenzyl derivative 4e.
