Synthesis of Phosphaguanidines by Hydrophosphination of Carbodiimides with Phosphine Boranes
摘要:
The direct addition of anionic secondary phosphine boranes to carbodiimides yields both chiral and achiral phosphaguanidine boranes, under ambient temperature conditions. An analogous preparation of menthol-derived phosphinite boranes is also described. These products can be deborinated to give the corresponding phosphines, and subsequently oxidized to give phosphine oxides. The robustness of this method was further demonstrated in the synthesis of structurally novel cyclic phosphaguanidines.
O-羧酸酐 (OCA) 的开环聚合可为聚酯提供多种官能团,而传统上这些官能团很难通过内酯聚合获得。典型的开环催化剂不可避免地会发生大多数 OCA 单体的外消旋化,这阻碍了高度等规结晶聚合物的合成。在这里,我们描述了一种有效的双功能单分子有机催化,用于无差向异构化的 OCA 选择性开环聚合。同一分子中两个活化基团的紧密相邻会产生放大的协同效应,从而允许使用温和的碱,从而使聚合的差向异构化最小化。由双功能单分子有机催化剂介导的 manOCA 单体(来自扁桃酸的 OCA)的开环聚合产生高度全同立构的聚(扁桃酸)(PMA),其分子量受控(高达 19.8 kg mol-1)。PMA 的两种对映异构体的混合在该区域产生了结晶立体复合物的第一个例子,它在 150 °C 左右显示出不同的 Tm 值。值得注意的是,双功能催化剂具有防潮、可回收和易于使用的特点,允许可持续和可扩展地合成有规立构功能聚酯。
Cerium ammonium nitrate-catalyzed aerobic oxidative coupling of dithiocarbamates: facile synthesis of thioureas and bis(aminothiocarbonyl)disulfides
作者:Tian-Tian Li、Xiang-Hai Song、Mei-Shuang Wang、Ning Ma
DOI:10.1039/c4ra04628e
日期:——
Diverse disubstituted and trisubstituted thioureas were synthesized by the condensation of dithiocarbamate TEA (or DABCO) salts and amines using cerium ammonium nitrate (CAN) as a catalyst in high yields at room temperature. It is a one-pot method and it is unnecessary to isolate isothiocyanates. This reaction probably took place through nucleophilic addition of amines to isothiocyanates, which were generated by oxidative coupling of dithiocarbamates and the following decomposition of bis(aminothiocarbonyl)disulfides. When secondary amines and CS2 served as the reactants, bis(aminothiocarbonyl)disulfides were obtained via tandem nucleophilic addition/oxidative coupling reactions in moderate to excellent yields. In all the coupling reactions, the oxidant was air and CAN possibly acted as an SET catalyst.
Synthetic Studies toward Aryl-(4-aryl-4<i>H</i>-[1,2,4]triazole-3-yl)-amine from 1,3-Diarylthiourea as Urea Mimetics
作者:Amarnath Natarajan、Yuhong Guo、Haribabu Arthanari、Gerhard Wagner、Jose A. Halperin、Michael Chorev
DOI:10.1021/jo0508189
日期:2005.8.1
4]triazole-3-yl-amines as urea mimetics from the corresponding 1,3-disubstituted thioureas has been studied, and the scope and limitations of this reaction are presented. The reaction proceeds through the formation of a carbodiimide, followed by a sequential addition−dehydration with acyl hydrazides. 1,3-Branched dialkylthioureas result in the formation of the corresponding ureas. The electronic and steric
BIODEGRADABLE ORGANIC RADICAL-FUNCTIONALIZED POLYCARBONATES FOR MEDICAL APPLICATIONS
申请人:International Business Machines Corporation
公开号:US20160220705A1
公开(公告)日:2016-08-04
Paramagnetic, amphiphilic, biocompatible polymers were prepared comprising a carbonate repeat unit bearing a paramagnetic organic radical, more specifically a nitroxyl radical. The radical polymers can be produced in one step from a precursor polymer bearing an active ester side chain by treating the precursor polymer with a radical-bearing nucleophile. The precursor polymer can be prepared by organocatalyzed catalyzed ring opening polymerization (ROP) of a cyclic carbonate monomer bearing an active ester side chain. The radical polymers can be non-toxic and partially biodegradable. The radical polymers have utility as contrast enhancing agents in a medical imaging application and/or as therapeutic agents for treating a medical condition. The radical polymers can also serve as carriers for therapeutic agents (e.g., drugs) and/or medical image enhancing agents (e.g., NIRF dyes).
CYCLIC CARBONYL COMPOUNDS WITH PENDANT CARBONATE GROUPS, PREPARATIONS THEREOF, AND POLYMERS THEREFROM
申请人:Fujiwara Masaki
公开号:US20110269917A1
公开(公告)日:2011-11-03
A one pot method of preparing cyclic carbonyl compounds comprising an active pendant pentafluorophenyl carbonate group is disclosed. The cyclic carbonyl compounds can be polymerized by ring opening methods to form ROP polymers comprising repeat units comprising a side chain pentafluorophenyl carbonate group. Using a suitable nucleophile, the pendant pentafluorophenyl carbonate group can be selectively transformed into a variety of other functional groups before or after the ring opening polymerization.
Antimicrobial cationic polymers having one or two cationic polycarbonate chains were prepared by organocatalyzed ring opening polymerization. One antimicrobial cationic polymer has a polymer chain consisting essentially of cationic carbonate repeat units linked to one or two end groups. The end groups can comprise a covalently bound form of biologically active compound such as cholesterol. Other antimicrobial cationic polymers have a random copolycarbonate chain comprising a minor mole fraction of hydrophobic repeat units bearing a covalently bound form of a vitamin E and/or vitamin D2. The cationic polymers exhibit high activity and selectivity against Gram-negative and Gram-positive microbes and fungi.