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).

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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

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.