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Sunday, 2 September 2012

NEW BRONZE AGE, Cu Catalysis

Angew. Chem. Int. Ed. 201251, No. 28, 6993-6997


Copper-Mediated and Copper-Catalyzed Cross-Coupling of Indoles and 1,3-Azoles: Double C-H Activation

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.

Ruthenium-Catalyzed Carbonylation of ortho C-H Bonds in Arylacetamides: C-H Bond Activation Utilizing a Bidentate-Chelation System

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
Thumbnail image of graphical abstract


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).

Monday, 27 August 2012

FROM OPEN ACESS CHEMISTRY-Download ChemDraw Ultra 12.0 for free

Download ChemDraw Ultra 12.0 for free

 

 

 http://www.openaccesschemistry.com/2012/05/download-chemdraw-ultra-120-for-free.html

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enjoy the blog and download

 

 

Monday, 6 August 2012

New carbon-carbon bond in an organic reaction with the original functional groups completely disappearing




http://www.nature.com/nchem/journal/v2/n4/full/nchem.576.html
Mundal et al form a New carbon-carbon bond in an organic reaction with the original functional groups completelely dissapearing, boc protected allyl hydrazone, takes part in an triflimide catalysed sigmatropic reaction with subsequent loss of isobutylene, nitrogen gas and carbondioxide

Monday, 30 July 2012

Stereochemistry of [n,m] Sigmatropic Rearrangements




Stereochemistry of [n,m] Sigmatropic Rearrangements

Basically, [n,m] sigmatropic rearrangements can proceed through a chair or boat  transition state. Only the chair transition state has been observed experimentally though both are suprafacial and are allowed in 4n+2 electron systems.


Chair and boat transition states in [n,m] sigmatropic rearrangements
Fig.1Chair



Fig.2Boat



Examples for sigmatropic rearrangements with a chair transition state

 Fig.3Cope rearrangement

 



Fig.4[3,3] Sigmatropic

               
                        6 Electrons
                   
                        Hückel aromatic
                   
                        Supra-supra


 view animation, 2D Animation of the Cope rearrangement

try copy paste of link below, do not miss out on a beautiful animation


http://www.chemgapedia.de/vsengine/supplement/Vlu/vsc/en/ch/2/vlu/pericyclische_reaktionen/pericyclisch_sigmatrop.vlu/Page/vsc/en/ch/2/oc/reaktionen/formale_systematik/pericyclische_reaktionen/sigmatrop/stereochemie_n_m.vscml/Fragment/0d47d3304bb08cfd9c68c1c3590965d2-19.html


Large substituents similar to their behavior in chair conformations of cyclohexane rings prefer an equatorial configuration in the transition state of [3,3] sigmatropic reactions. Heating S,S-3,4-dimethyl-1,5-hexadiene to approximately 200°C  yields in 90% a product derived from a chair transition state with equatorial methyl groups.  The product arising from a diaxial conformation is formed in only 10% yield. Obviously, the reaction does not proceed through the boat transition state.

Sunday, 29 July 2012

Enantiomeric Ibuprofen via Environmentally Benign Selective Crystallization

 Ibuprofen was developed by the Boots Group, a pharmacy chain in the United Kingdom, in the 1950’s-1960s. It was discovered by Stewart Adams (along with John Nicholson, Andrew RM Dunlop, Jeffrey Bruce Wilson & Colin Burrows). The Boots group originally licensed Ibuprofen to two large drug companies. The first was Whitehall Laboratories (who sold the product as Advil) and the second was Upjohn who used Bristol-Meyers to market their product “Nuprin”. Boots held the patent until 1985 along with the rights to market it until 1986. Afterwards new products entered the market creating multiple new “generic” brands.





Selective crystallization of ibuprofen/lysinate from 1 mol of (R,S)-(racemic) ibuprofen and ≤0.5 mol of (S)-lysine in aqueous ethanol affords either (S)-(+)-ibuprofen/(S)-lysinate or (R)-ibuprofen/(S)-lysinate (in preponderance) depending on the crystallization conditions. The previously unreported temperature selective diastereo-recognition (TSD) provides simple and efficient means to prepare either enantiomer of ibuprofen from (R,S)-ibuprofen utilizing the same commercially available inexpensive resolving agent, (S)-lysine. The unwanted enantiomeric ibuprofen could be recovered from the mother liquor and racemized by a simple, relatively waste-free thermal process. This racemization method when utilized in conjunction with the selective crystallization technology provides a simple, efficient, and eco-friendly means to prepare (S)-(+)-ibuprofen lysinate in an overall essentially quantitative yield. This technology also incorporates the fundamental principle of atom economy (via direct production of the preferred pharmaceutical salt of (S)-lysine). Abstract Image 

Temperature Selective Diastereo-Recognition (TSD):  Enantiomeric Ibuprofen via Environmentally Benign Selective Crystallization

 see also
http://onlinelibrary.wiley.com/doi/10.1002/aic.11087/abstract;jsessionid=D60C69E3DB7266BE103A2875A7FEA6C5.d02t03?deniedAccessCustomisedMessage=&userIsAuthenticated=false
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read more at
 http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322006000300003
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