Specialized Heterocycles

New catalytic reactions of oxa- and azabicycloalkenes, including oxa- and azabenzonorbornadienes 07ACR971. 

Polar acetalization and transacetalization in the gas phase to form cyclic acetals (the Eberlin reaction) 06CRV188. 

Anionic tethered N-heterocyclic carbene chemistry 07CSR1732. 

Aryl and 1 -dioxoindanyl derivatives of azoles and azines 07KGS1603. 

Coordination chemistry and catalytic applications of functionalized N-heterocyclic carbene ligands 07COC1491. 

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C. Specialized Heterocycles 1. Nitrogen Heterocycles (Except Alkaloids)... 

Disidea Herbacca, obtained the /3-ketoester H2N—CH(iPr)—CO— CH2—COOEt from L-valine. The ester was cyclized to 5-isopropyl-tetramic acid in toluene in the presence of potassium 2-methyl-2-butoxide (84HCA1783). In other cases esters of 4-amino-3-oxobutanoic acid, subsequently cyclized in the presence of base, were synthesized using special heterocycles, such as /3-lactams (91TL3115), imidazoles (91IZV437) or pyrones (89TL3217). (See Fig. 30.)... 

We will discuss aromatic heterocycles in the following order ground-state properties (Sect. 3), reactivity (Sect. 4), spectroscopy (Sect. 5), special heterocycles (Sect. 6), and supramolecular and macrocycles (Sect. 7). 

Methyl isocyanate and all isocyanic acid esters are an interesting and highly reactive class of organic compounds, since the isocyanate group (-NC0) reacts readily with a wide variety of compounds as well as with itself to form dimers, trimers, ureas, and carbodi-imides. Methyl isocyanate (MIC) is an intermediate in the preparation of carbamate pesticides and conceivably could be applied to the production of special heterocyclic polymers and derivatives. 

Bis(phosphinoylmethyl)ainines (58) are useful precursors of bidentate P-ligands (59) obtained after double deoxy-genabon by silanes, e.g., trichlorosilane that could be used for the synthesis of ring platinum complexes (60) by reaction with dichlorodibenzonitrile platinum (Scheme 22) [75-78]. Ring Pt complexes are special heterocycles that may be regarded potential catalysts in homogeneous catalysis. 

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