塑料是一种多功能材料,可为各个行业提供轻质、耐用且经济实惠的解决方案。然而,它们的不可降解特性在其使用寿命结束时带来了挑战。本研究提出了一种创新的羰基萃取方法,利用废弃的聚(双酚 A 碳酸酯)(PC)作为反应前体来合成活性呋喃,作为光开关 Stenhouse 加合物的前体。这种创新的化学策略不仅产生了N,N'-功能化巴比妥酸盐,而且还为传统合成方法提供了一种环保且经济高效的替代方案。本文提出的方法不仅通过在绿色条件下将废弃聚碳酸酯重新用作羰基等价物来促进可持续性,而且还产生了可重复使用的双酚A(BPA)。此外,衍生的活化呋喃通过在胺化聚合物表面形成有色的供体-受体斯滕豪斯加合物(DASA)来展示其功能。这项工作展示了从线性塑料经济向循环经济的转变,凸显了塑料废物作为创造具有改进性能的材料的资源的潜力。
AbstractThe classical Lossen rearrangement converts activated hydroxamic acids to isocyanates that form numerous products upon their reaction with nucleophiles. We report a simple and highly efficient method of using Heck reaction conditions to initiate Lossen rearrangements of hydroxamic acids. In addition, Lossen rearrangements occur in the presence of palladium(II) acetate or triethylamine, components of the Heck reaction, alone. A potential mechanism is provided to explain this reactivity and these results show that Heck reactions and Lossen rearrangements occur under the same conditions and may provide new methods for facile initiation of Lossen rearrangements.magnified image
Iron-catalyzed urea synthesis: dehydrogenative coupling of methanol and amines
作者:Elizabeth M. Lane、Nilay Hazari、Wesley H. Bernskoetter
DOI:10.1039/c8sc00775f
日期:——
byproduct. Mechanistic studies indicate a stepwise pathway beginning with methanol dehydrogenation to give formaldehyde, which is trapped by amine to afford a formamide. The formamide is then dehydrogenated to produce a transient isocyanate, which reacts with another equivalent of amine to form a urea. These mechanisticinsights enabled the development of an iron-catalyzed method for the synthesis of unsymmetric
取代脲有许多应用,但它们的合成通常需要使用剧毒的起始材料。在此,我们描述了第一种通过甲醇与伯胺脱氢偶联选择性合成对称脲的贱金属催化剂。使用钳形负载铁催化剂,生成了一系列尿素,分离产率高达 80%(相当于催化转化率高达 160),且 H 2为唯一副产物。机理研究表明,从甲醇脱氢开始逐步生成甲醛,甲醛被胺捕获,生成甲酰胺。然后甲酰胺脱氢产生暂时的异氰酸酯,其与另一当量的胺反应形成脲。这些机理见解使得铁催化方法得以开发,用于从酰胺和胺合成不对称脲。
Ir-Catalyzed C–H Amidation Using Carbamoyl Azides for the Syntheses of Unsymmetrical Ureas
作者:Kwangho Yoo、Jooyeon Lee、Myung Hwan Park、Youngjo Kim、Hyun Jin Kim、Min Kim
DOI:10.1021/acs.joc.0c00659
日期:2020.5.1
An iridium-catalyzed C-H amidation for the syntheses of unsymmetrical urea was developed using carbamoyl azides (R(R')N-C(O)-N3) as the nitrogen source. A combination of iridium and silver gave an active catalyst for C-N bond formation. A variety of urea derivatives were synthesized using carbamoyl azides with only dinitrogen byproducts. Finally, the use of the transientdirectinggroupstrategy with
observed in situ, which resulted in the formation of CO and dimethylamine. The scope of this new mode of bond activation is extended to the synthesis of urea derivatives from amines using DMF as a carbon monoxide (CO) surrogate. This catalytic protocol allows the synthesis of simple and functionalized urea derivatives with liberation of hydrogen, devoid of any stoichiometric activating reagents, and avoids
Compositions and Methods for Controlling Nematodes
申请人:Slomczynska Urszula
公开号:US20100210849A1
公开(公告)日:2010-08-19
Compositions and processes for controlling nematodes are described herein, e.g., nematodes that infest plants or animals. The compounds include oxazoles, oxadiazoles and thiadiazoles.
A convenient synthesis of symmetrical N,N′-dialkylureas by the reactions of 4-chloro-5H-1,2,3-dithiazol-5-one with alkylamines
作者:Yong-Goo Chang、Hyi-Seung Lee、Kyongtae Kim
DOI:10.1016/s0040-4039(01)01761-0
日期:2001.11
Treatment of 4-chloro-5H-1,2,3-dithiazol-5-one with primary and secondary alkylamines (>2 equiv.) in CH2Cl2 at rt afforded symmetrical N,N′-disubstituted ureas in moderate to good yields. Similarly, the reactions with amino acid ester hydrochlorides in the presence of Et3N (>3 equiv.) under the same conditions gave symmetrical ureas.
在室温下,在CH 2 Cl 2中用伯和仲烷基胺(> 2当量)处理4-氯-5 H -1,2,3-二噻唑-5-酮,得到对称的N,N'-二取代脲良品率高。类似地,在相同条件下,在Et 3 N(> 3当量)存在下,与氨基酸盐酸盐的反应生成对称的脲。