Synthesis and Structure of 2,3-Tetra-Methylene-5,6-Trimethylene-4-Pyrone

The title compound was synthesized by the reaction of adipyl chloride with cyclohexanone piperidine enamine and its structure was finally confirmed by the single - crystal determination in addition to conventional IR, (HNMR)-H-1 and elemental analysis.

苎麻三倍体新品种Tri-1和Tri-2选育报告

以湘苎3号为材料,利用秋水仙素诱导二倍体苎麻为四倍体,再从四倍体群体中择优与二倍体杂交,育成三倍体苎麻新品种Tri-1和Tri-2。区试Tri-1原麻产量为2 930.4 kg/hm2,比对照增产17.4%,Tri-2原麻产量为2 397.6 kg/hm2,比对照减产约4%;Tri-2的纤维支数达2 130公支,远高于对照品种湘苎3号;Tri-1、Tri-2抗炭疽病、立枯病、花叶病等,Tri-1的抗风性明显强于对照湘苎3号。

The [4+2] Cycloaddition of 2-Pyrone in Total Synthesis

Diels-Alder reaction is one of the most important reactions in organic synthesis and has witnessed great achievements in total syntheses of complex natural products.In this review,we will focus on the [4+2] cycloaddition that utilizes 2-pyrone as the diene component.Major advances of its applications in the total syntheses of natural products in the past fifty years will be discussed here.

N-heterocyclic carbene-catalyzed atroposelective synthesis of axially chiral 5-aryl 2-pyrones from enals

Axially chiral molecules have been widely used in inorganic,material and medicinal chemistry.Compared with well-established N-heterocyclic carbene(NHC)-catalyzed asymmetric construction of centrally chiral molecules,NHC-catalyzed atroposelective synthesis of axially chiral molecules remains largely underdeveloped.Notably,alkynyl acyl azolium intermediates were commonly used in constructing a heteroaryl ring to furnish axially enantioenriched heteroaryl-aryls.The inherent character of the intermediates often led to react with sterically hindered substrates difficultly.Herein,we have successfully disclosed the atroposelective synthesis of axially chiral heteroaryl-aryls from sterically hindered enols through the use of chiral NHCs as catalysts for highly enantioselective Coates-Claisen rearrangements via catalytically generatedα,β-unsaturated acyl azoliums.This approach will enable the concise synthesis of valuable tetra-ortho-substituted 2-pyrones in one step with good yield and chirality control.

Transition-metal-free [3+3] annulation reaction of sulfoxonium ylides with cyclopropenones for the synthesis of 2-pyrones

An efficient and practical synthetic approach was developed for the tandem synthesis of trisubstituted 2-pyrone derivatives from sulfoxonium ylides and cyclopropenones.This[3+3]annulation reaction was carried out under transition-metal-free conditions.A broad range of functional groups were tolerant under mild conditions,and a variety of 2-pyrones were obtained in moderate to good yields.

Transesterification catalyzed by samarium tri-2-propoxide

A facile method for transesterification was reported. Under catalysis by samarium tri-2-propoxide the yields of transesterification are good to excellent, and this reaction has surprising selectivity and mildness due to the neutral condition during the reaction.

An Enantioselective Approach to Heteroatom-Containing Bicyclic Derivatives via Inverse-Electron-Demand Diels-Alder Reactions

Chiral heteroatom-containing bicyclic scaffolds are important pharmacophores and prevalent in bioactive natural products and drug molecules.Herein,we report a unified approach for the divergent synthesis of chiral heteroatom-containing bicyclic derivatives by lanthanide(lil)-catalyzed asymmetric inverse-electron-demand Diels-Alder reactions of 2-pyrones.These reactions occur with vari-ous readily available dihydropyrroles and dihydrofurans as dienophiles,providing a step-economical synthetic platform for densely functionalized ciss-hydroindoles and cis-hydrobenzofurans with excellent yields and enantioselectivities.The synthetic utility of this approach is demonstrated by the concise synthesis of(-)-α-lycorane and(-)-lycorine alkaloids.

Tribological behavior of ammonium-based protic ionic liquid as lubricant additive

In this study, the tribological behavior of an ammonium-based protic ionic liquid(PIL) as an additive in a base mineral oil(MO) is investigated on a steel–steel contact at room temperature and 100℃. Tri-[bis(2-hydroxyethylammonium)] citrate(DCi) was synthesized in a simple and low-cost way, and the ionic structure of DCi was confirmed by proton nuclear magnetic resonance(^(1)H NMR). The stability measurement of 1 wt% DCi to a MO was investigated, and the lubricating ability and anti-wear properties of DCi as an additive in MO were also examined using a custom-designed reciprocating ball-on-flat tribometer. Optical microscope and profilometry were used to obtain the worn morphology of the steel disks. Scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS) were carried out to investigate the wear mechanism and to analyze the surface interactions between the rubbing components. When 1 wt% DCi is added into the base MO, frictional performance is improved at both temperatures studied with a friction reduction of 29.0% and 35.5%, respectively. Moreover, the addition of 1 wt% DCi to MO reduced the wear volume 59.4% compared to the use of MO. An oxygen-richened tribolayer is confirmed by EDS on the disk surface when DCi was used as additive under 100℃.