A mild access to chiral syn 1,2-diaryl glycols by stereoselective ring opening of ortho substituted trans 2,3-diaryl-oxiranes using Amberlyst 15 in H2O/THF system
摘要:
Amberlyst 15 was an efficient and green catalyst for the reaction of 2,3-diaryloxiranes with H2O in organic co-solvent to prepare glycols in high yield. Ortho substituted trans 2,3-diaryloxiranes afforded the corresponding syn glycols stereo- and enantiospecifically. Stereoselectivity appeared related to the coordination ability of the substituents, irrespective of their electronic properties. Indeed o-OCH3 and o-OBn substituted syn glycols were obtained in high stereochemical ratios (6/1 and 10/1, respectively), and o-OTIPS and o-NO2 substituted ones were obtained as exclusive products, with the same ee of the parent epoxides. (C) 2015 Elsevier Ltd. All rights reserved.
Abstract Seven flavonoids and seven stilbenes were isolated from the heartwood of Pinus armandii Fr. var. mastersiana Hay. Among them, trans -3,5-dimethoxystilbene oxide is a new compound and 3-acetyloxy-5,7-dihydroxyflavanone is the first report of its occurrence in nature. Comparison of the flavonoid and stilbene components in P. armandii , P. morrisonicola Hay. and P. parviflora Sieb. et Zucc. supports
摘要 从华山松心材中分离得到七种黄酮类化合物和七种芪。变种 主干草。其中,反式-3,5-二甲氧基二苯乙烯氧化物是一种新化合物,3-乙酰氧基-5,7-二羟基黄烷酮是其在自然界中的首次报道。P. armandii , P. morrisonicola Hay 中类黄酮和芪成分的比较。和 P. parviflora Sieb。等祖克。支持三个物种的化学分类。