Progress in Microwave-Aided Chemical Synthesis

Progress in Microwave-Aided Chemical Synthesis

Hani Mutlak A. Hassan ^{A B}, Steve Harakeh ^A, Kaltoom A. Sakkaf ^A and Iuliana Denetiu <sup>A

A</sup> King Fahd Medical Research Centre, King Abdulaziz University, PO Box 80216, Jeddah 21589, Kingdom of Saudi Arabia. ^B Corresponding author. Email: hmahassan@kau.edu.sa

Australian Journal of Chemistry - http://dx.doi.org/10.1071/CH12366
Submitted: 5 August 2012  Accepted: 16 September 2012   Published online: 29 October 2012

 LINK IS
 http://www.publish.csiro.au/paper/CH12366.htm



The continuing use of microwave (µwave) energy in chemical synthesis has been impressive over the past decade, with many reports incorporating µwave-based reactions. Two of the major benefits of using µwave heating are the remarkable decrease in reaction times and often high yield of products in comparison with classical heating, an ideal technology for synthetic chemists. Herein, we highlight some exciting examples of its recent utility in organic, medicinal, and natural product synthetic endeavours.

Enabling integrated biorefineries through high-yield conversion of fractionated pentosans into furfural

Enabling integrated biorefineries through high-yield conversion of fractionated pentosans into furfural

Anurag Mandalika and Troy Runge

Green Chem., 2012, Advance Article
DOI: 10.1039/C2GC35759C, Paper 
 http://pubs.rsc.org/en/content/articlelanding/2012/gc/c2gc35759c



 Batch reactive distillation of biomass hydrolysates was employed to produce furfural in high yield using an entirely aqueous acid-catalyzed process. 

 Dilute aqueous solutions of furfural were produced in high yield from biomass hydrolysates using an acid-catalyzed batch reactive distillation process that separated the vapor phase from the aqueous reactant medium. Hot water hydrolysates from hybrid poplar, miscanthus, switchgrass and corn stover were dehydrated using sulfuric acid. The vapor fraction from the reactor was condensed to produce furfural in excess of 85% of the theoretical yield based on total pentose. Using xylose as the model compound, and temperature and acid concentration as the variables, the process conditions were optimized by the construction of a three-level statistical model. Hot water hydrolysis of biomass provided with a cellulose-rich solid fraction which has potential for conversion into pulp or cellulosic ethanol, while the liquid fraction, rich in hemicellulose sugars, was converted into furfural. Fractionating the biomass allows for exploration of the concept of the integrated biorefinery where the hemicellulose sugars are not underutilized or encountered as potential inhibitors during microbial conversions of the solid stream, but are converted into furfural, a valuable chemical precursor. The availability of the cellulose fraction for further conversion into pulp or ethanol gives the current process a major advantage over the conventional batch process used in industry, where theoretical yields do not exceed 45–50% with the conspicuous absence of a usable cellulose stream.

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Preparation of Pentafluorinated Phenyl-Monohydro[60]fullerenes

 https://www.thieme-connect.de/ejournals/abstract/10.1055/s-0032-1316578
 Wenli Shang et al
 Pentafluorinated phenyl-monohydro[60]fullerenes [C₆₀(Ar_f)₅H] are synthesized in good yields via reaction of the corresponding fluorinated phenyl copper reagent, itself prepared in situ from the fluorinated phenyl Grignard reagent (Ar_fMgBr) and copper(I) bromide-dimethyl sulfide complex, with [60]fullerene (C₆₀) in 1,2-dichlorobenzene under a nitrogen atmosphere.

NO METAL IN C-H BOND FORMATION

ChemCatChem 2011, 3, No. 05, 827-829

Recently, several research groups have reported that the C-H bond arylation of aromatic compounds with haloarenes can be promoted by potassium or sodium tert-butoxide, without the addition of any exogenous transition metal species. 

These serendipitous discoveries are highlighted and summarized.

Shuichi Yanagisawa, Kenichiro Itami
tert-Butoxide-Mediated C-H Bond Arylation of Aromatic Compounds with Haloarenes

NEW BRONZE AGE, Cu Catalysis

Angew. Chem. Int. Ed. 2012, 51, No. 28, 6993-6997




The described copper-mediated cross-coupling with double C-H activation can provide a convergent access to indole-containing biheteroaryls that are of high interest in pharmaceutical and medicinal chemistry. In this strategy an easily attachable and detachable 2-pyrimidyl directing group is used. Moreover, a variant that is catalytic in copper is achieved by using atmospheric oxygen as an ideal co-oxidant (see scheme).
Mayuko Nishino,et al
Copper-Mediated and Copper-Catalyzed Cross-Coupling of Indoles and 1,3-Azoles: Double C-H Activation

Direct carbonylation of C-H bonds

Direct carbonylation of C-H bonds

Kaname Shibata, ET AL
Ruthenium-Catalyzed Carbonylation of ortho C-H Bonds in Arylacetamides: C-H Bond Activation Utilizing a Bidentate-Chelation System

ChemCatChem, Aug 28, 2012, DOI: 10.1002/cctc.201200352
DOI: 10.1002/cctc.201200352
Direct carbonylation of C-H bonds in arylacetamides was achieved using a bidentate-chelation system. The use of 2-pyridynylmethyl amino moiety is essential for the reaction to proceed. For achieving an efficient reaction, the presence of both ethylene (for a hydrogen acceptor) and H₂O (probably for an efficient generation of catalytic active species) are required.

SYNTHESIS OF INDOLES

http://onlinelibrary.wiley.com/doi/10.1002/anie.201203657/abstract

Synthesis of Indoles 

Synthesis of Indoles through Highly Efficient Cascade Reactions of Sulfur Ylides and N-(ortho-Chloromethyl)aryl Amides 

Qing-Qing Yang, ET AL

DOI: 10.1002/anie.201203657

A simple procedure carried out under mild conditions allows the direct and efficient synthesis of structurally diverse indoles. This approach involves a cascade reaction of sulfur ylides and N-(ortho-chloromethyl)aryl amides (see scheme).