Additions to non-activated alkenes: Recent advances

Non-activated olefins represent one of the most explored platform in organic synthesis affording new and useful compounds with several biological applications, among others. The typical reactivity of these compounds is the addition-type reactions. A plethora of transformations and studies were reported in the literature by many research groups. The focus of this review is to organize and describe the most recent synthetic transformations of non-activated alkenes in organic synthesis. Therefore, it is divided into five sections corresponding to each type of the products obtained: synthesis of fluoro-, chloro- and bromo-compounds; synthesis of alkyl/vinyl/aryl/heteroaryl compounds; synthesis of phospho/sulfur/silyl/cyano-compounds; synthesis of amine/amide/oxygenated compounds and synthesis of other functionalized compounds.     

Cascades to substituted indoles

This paper describes the synthesis of dithioindoles from the free-radical cyclizations of arylisonitriles having pendant alkynes. Also described is the synthesis of substituted indoles and spiro-fused indoles from the coupling of dithioindoles with active hydrogen-containing compounds.     

A new and convenient approach to heterotetracyclic benzoxazocines through addition of 1,3-dicarbonyl compounds to quinolinium salts

The synthesis of a series of benzoxazocines has been achieved in good yields by tandem C-alkylation and intramolecular O-alkylation of 1,3-dicarbonyl compounds with quinolinium salts. This is a novel example of the synthesis of eight-membered rings via a tandem process, which provides a method for the synthesis of medium-ring heterocycles.     

A chemoenzymatic approach to (+)-pilocarpine

A short synthesis for the alkaloid (+)-pilocarpine has been developed. Key step of this synthesis is a chemoenzymatic resolution utilizing the lipase AP.     

Facile Entry to 4‐ and 5‐Hydroxybenzofuran and to Their Amino Derivatives

An innovative one‐step procedure for the synthesis of 4‐hydroxybenzofuran and an improved synthesis of 5‐hydroxybenzofuran is reported. Such compounds were also transformed into their amino derivatives via Smiles rearrangement with good to high overall yields.     

Application of thermal analysis to mineral synthesis

Differential thermal analysis (DTA) and thermogravimetry (TG) are applied to various fields of mineral science. The present work illustrates the importance of the application of thermal analysis to mineral synthesis, to the determination of the mechanism and optimum temperature of synthesis and the thermal behaviour of minerals and starting materials. Selected examples of applications in this field are given. These include DTA studies of the synthesis of topaz, cryptohalite, wulfenite, perovskite, scheelite and the refractory materials, baddeleyite and corundum. Thermal analysis is proved to be an important and valuable tool in mineral synthesis.     

An expedient enyne metathesis approach to dysidiolide

A short and efficient enyne metathesis route is reported for the construction of a key intermediate required in the synthesis of dysidiolide thus completing its formal synthesis.     

An efficient approach to new dihydroxyquinolizidines

Using d-glyceraldehyde acetonide as a starting material, a four-step synthesis of enantiomerically pure 3,4-dihydroxyquinolizidines is described. The key steps of the synthesis consist of a Mitsunobu ring-closing reaction and the subsequent reduction of a pyridinium ring.     

Metal-chelating capacities attached to fullerenes

This review describes the synthesis, properties and application of fullerenes covalently attached to metal-chelating groups. The application of these structures in artificial photosynthetic systems and their reaction on external stimuli, such as light or electrons is described. Furthermore, the use of fullerene organometallic building blocks in macromolecular synthesis and catalysis has been highlighted.     

Transition-metal-free access to 7-azaindoles

A novel method for transition-metal-free synthesis of 7-azaindoles is developed through a one-pot synthesis involving amination of pyridine N-oxides and intramolecular enamine formation. Remarkable features of the method include simple operation, mild reaction conditions, wide substrate scope, and easily accessible starting materials.     

甲烷三重整制合成气

甲烷三重整是利用CO₂-H₂O-O₂ 同时重整甲烷的过程。该工艺既可以生产H₂/CO 为1.5 —2.0的合成气,又可以缓解甚至消除催化剂的积炭,适合于更廉价地生产用于合成甲醇、二甲醚以及清洁燃料等下游产品的合成气。本文重点评述了近年来国内外甲烷三重整制合成气在热力学、催化剂、反应器、动力学等方面的研究进展,指出甲烷三重整反应在电厂烟气、煤层气、天然气综合利用方面具备良好前景,但要通过该过程实现廉价合成气的生产,仍需研制高活性、抗积炭性能强的催化剂,并对反应器进行改进,以及进行反应机理和反应动力学的深入研究。     

硅基催化结构合成的策略

Two approaches to synthesize silicon-based catalytic structures that aim at capturing the properties and functionalities of natural enzymes are described in this brief review:unit-by-unit synthesis of macromolecular units and templating/imprinting synthesis of nanocages. The unit-by-unit approach mimics the peptide synthesis method,offers atomic control of the structure,but is inefficient in synthesizing large structures such as nanocages. The templating/imprinting method is more suitable for nanocages at the sacrifice of atomic control,and the nanocages obtained are shown to possess properties exhibited by enzyme cavities.     

An approach to the synthesis of pseudomonic acids

The synthesis of the cis-fused γ-lactone 2,7-dioxabicyclo-[4,3,0]non-4-en-8-one (3) by two routes is reported. Its stereoselective conversion to a key intermediate for pseudomonic acid synthesis is described.     

A comprehensive approach to the synthesis of sulfate esters

A comprehensive approach to the synthesis of sulfate esters was developed. This approach permits the direct and high-yielding synthesis of protected sulfate monoesters. Subsequent deblocking to reveal sulfate monoesters is accomplished in near-quantitative yield. The exceptionally stable neopentyl protecting group and the labile isobutyl protecting group were utilized in the synthesis of aromatic and aliphatic sulfate monoesters. Strategies for tuning protecting group reactivity were also explored and developed.     

A biomimetic type expedient approach to the tricyclic core of xyloketals. Application to a short, stereocontrolled synthesis of alboatrin and a remarkable epi to natural isomerisation

An expedient synthesis of the linear tetrahydrofurano benzopyran ring system of xyloketals is described involving an ortho ester Claisen rearrangement and an intramolecular cationic cyclisation. This strategy was applied for a short, stereocontrolled and high yield synthesis of the phytotoxic metabolite alboatrin.     

A New Approach to the Synthesis of Cortical Steroids

A new bondset for cortical steroid synthesis is developed from the dual concepts of convergent assembly and multiple construction. A short synthesis on this bondset is presented in which the final bond construction by electrocyclization took an unwanted course. Stereocontrol is discussed separately.     

Diastereoselective phenol para-alkylation: access to a cross-conjugated cyclohexadienone en route to resiniferatoxin

We document a route for the synthesis of a densely functionalized spiro-fused 2,5-cyclohexadienone as an intermediate for the synthesis of resineferatoxin. The strategy is based on an unprecedented diastereoselective, intramolecular phenol para-alkylation to a cross-conjugated cyclohexadienone. In the course of these synthetic studies we developed rapid access to a chiral nitrile possessing a quaternary stereocenter and disclose an unusual acetal rearrangement from a dioxane, which favors the corresponding dioxepane.     

Technological aspects of fructose conversion to high-purity 5-hydroxymethylfurfural,a versatile platform chemical

Two improved methods for the synthesis of 5-hydroxymethylfurfural by acid-catalyzed dehydration of fructose have been developed. The first one is the synthesis in ionic liquids with continuous removal of water under reduced pressure, and the second is the synthesis in the two-phase system consisting of aqueous NaHSO₄ and methyl isobutyl ketone under atmospheric pressure. Both methods ensure isolation of crystalline 5-hydroxymethylfurfural with high purity and multiple recycling of the catalytic system. The synthesis in ionic liquid is convenient on a laboratory scale. Despite relatively low yield, the two-phase synthesis is preferred for industrial scale-up due to simple isolation and purification procedures combined with efficient regeneration of extractant and the catalytic system.     

Strategy-Level Separations in Organic Synthesis: From Planning to Practice

A dirty word in synthesis: separation! The normally unavoidable separation at the end of each reaction finds no friends among synthetic chemists and is often regarded as a technical procedure. However, the need to quickly and cheaply produce pure products is driving the development of new separation and purification techniques. Astonishingly, the modern concepts and techniques for coupling synthesis and separation are rooted in workup procedures that are as old as the art of synthesis itself.     

Efficient metathesis route to the B-ring of eleutherobin and other medium-sized cyclic ethers

A short and efficient RCM route is reported for the synthesis of the B-ring of eleutherobin and other medium-sized cyclic ethers from readily available 1,2,5,6-diisopropylidene-d-glucose. This strategy is successfully extended to the synthesis of a few bicyclic ethers, which may find applications in the synthesis of novel bicyclic nucleosides.