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).

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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

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

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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.

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).  

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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Citalopram/Escitalopram Oxalate, Isolation & Synthesis of Novel Impurities, Emcure paper

Citalopram

Citalopram  brand names: Celexa, Cipramil) is an antidepressantdrug of the selective serotonin reuptake inhibitor (SSRI) class. It has U.S. Food and Drug Administration (FDA) approval to treat major depression, and is prescribed off-label for a number of anxiety conditions.

Escitalopram (trade names Nexito, Anxiset-E (India), Lexapro,Cipralex, Seroplex, Lexamil, Lexam, Entact, Losita(Bangladesh) Reposil (Chile)), is an antidepressant of theselective serotonin reuptake inhibitor (SSRI) class. It is approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults and children over 12 years of age with major depressive disorder and generalized anxiety disorder. Escitalopram is the (S)-stereoisomer (enantiomer) of the earlier Lundbeck drugcitalopram

Citalopram/Escitalopram Oxalate: Isolation & Synthesis of Novel Impurities

READ AT

http://pubs.acs.org/doi/abs/10.1021/op300039c

Emcure Pharmaceuticals Ltd, R & D Centre, Pimpri, Pune -411018, India

During process optimization of Escitalopram oxalate novel impurities, 6 and 7 were observed, which were isolated and characterized, and the proposed structure was confirmed by chemical synthesis. Investigation of the cause of impurities formation improved the yield and purity of the drug product during the bulk API synthesis

SPECTROSCOPIC DATA IS AVAILABLE IN SUPPORTING INFORMATION FILE IN THE PAPER