Designing the Macrocyclic Dimension in Main Group Chemistry

Outside the confines and well-established domain of organic chemistry, the systematic building of large macromolecular arrangements based on non-carbon elements represents a significant and exciting challenge. Our aim in the past two decades has been to develop robust synthetic methods to construct new types of main group architectures in a methodical way, principles of design that parallel those used in the organic arena. This concept article addresses the fundamental thermodynamic and kinetic problems involved in the design and synthesis of main group macrocycles and looks to future developments of macromolecules in this area, as well as new applications in coordination chemistry.ERC. Grant Number: 291280 EU. Grant Number: RYC-2015-1903

Sesquiterpenoids lactones: benefits to plants and people

Sesquiterpenoids, and specifically sesquiterpene lactones from Asteraceae, may play a highly significant role in human health, both as part of a balanced diet and as pharmaceutical agents, due to their potential for the treatment of cardiovascular disease and cancer. This review highlights the role of sesquiterpene lactones endogenously in the plants that produce them, and explores mechanisms by which they interact in animal and human consumers of these plants. Several mechanisms are proposed for the reduction of inflammation and tumorigenesis at potentially achievable levels in humans. Plants can be classified by their specific array of produced sesquiterpene lactones, showing high levels of translational control. Studies of folk medicines implicate sesquiterpene lactones as the active ingredient in many treatments for other ailments such as diarrhea, burns, influenza, and neurodegradation. In addition to the anti-inflammatory response, sesquiterpene lactones have been found to sensitize tumor cells to conventional drug treatments. This review explores the varied ecological roles of sesquiterpenes in the plant producer, depending upon the plant and the compound. These include allelopathy with other plants, insects, and microbes, thereby causing behavioural or developmental modification to these secondary organisms to the benefit of the sesquiterpenoid producer. Some sesquiterpenoid lactones are antimicrobial, disrupting the cell wall of fungi and invasive bacteria, whereas others protect the plant from environmental stresses that would otherwise cause oxidative damage. Many of the compounds are effective due to their bitter flavor, which has obvious implications for human consumers. The implications of sesquiterpenoid lactone qualitiesfor future crop production are discussed

A Modular Approach to Inorganic Phosphazane Macrocycles

Inorganic macrocycles, based on non-carbon backbones, present exciting synthetic challenges in the systematic assembly of inorganic molecules, as well as new avenues in host-guest and supramolecular chemistry. Here we demonstrate a new high-yielding modular approach to a broad range of trimeric and hexameric S- and Se-bridged inorganic macrocycles based on cyclophosphazane frameworks, using the building blocks [S=(H)P(μ-NR)]2 . The method involves the in situ generation of the key intermediate [E....._ (S....._ )P(μ-NR)]22- (E=S, Se) dianion, which can be reacted with electrophilic [ClP(μ-NR)]2 to give PIII /PV hexameric rings or reacted with I2 to give trimeric PV variants. Important issues which are highlighted in this work are the competitive bridging ability of S versus Se in these systems and the synthesis of the first air-stable and chiral inorganic macrocycles.We thank the EU (ERC‐advanced grant for D.S.W., studentship for C.G.M.B., Intra European Fellowship Framework 7 for R.G.‐R.), the EPSRC (studentship for P.D.M.) for support, and the University of Heidelberg for travel grants

Synthesis and structure of the li-13 cage [{[o - p(mu-(nbu)-bu-t)](2)li-2}(3)(licl)(6)li(cl/(obu)-bu-n)(0.5)(thf)(7)], containing a [o - p(mu-(nbu)-bu-t)](2)(2-) dianion

The hydrolysis of [ClP(-NtBu)]2 with H2O-Et3N in thf, followed by in situ lithiation with nBuLi gives the Li13 cage [{[OP(-NtBu)]2Li2}3(LiCl)6Li(Cl/OnBu)0.5(thf)7], containing a [OP(-NtBu)]22- dianion that is isoelectronic with ligands of the type [(RN)P(-NR)]22-. (Abstract edited from: http://www.rsc.org/Publishing/Journals/CC/article.asp?doi=b800051d