Cyclic compounds heterocyclic

Not all cyclic compounds are hydrocarbons Many substances include an atom other than carbon called a heteroatom (Section 1 7) as part of a ring A ring that contains at least one heteroatom is called a heterocycle, and a substance based on a heterocyclic ring is... 

Cyclic compounds that contain at least one atom other than carbon within their ring are called heterocyclic compounds, and those that possess aromatic stability are called het erocyclic aromatic compounds Some representative heterocyclic aromatic compounds are pyridine pyrrole furan and thiophene The structures and the lUPAC numbering system used m naming their derivatives are shown In their stability and chemical behav lor all these compounds resemble benzene more than they resemble alkenes... 

HETCOR (Section 13 19) A 2D NMR technique that correlates the H chemical shift of a proton to the chemical shift of the carbon to which it is attached HETCOR stands for heteronuclear chemical shift correlation Heteroatom (Section 1 7) An atom in an organic molecule that IS neither carbon nor hydrogen Heterocyclic compound (Section 3 15) Cyclic compound in which one or more of the atoms in the nng are elements other than carbon Heterocyclic compounds may or may not be aromatic... 

Whereas oxaziridine and diaziridine were partial subjects of comprehensive theoretical studies on cyclic compounds (73MI50800), diazirine and some of its simple derivatives were the special target of quantum chemical investigations. Since diazirine, the lowest molecular weight heterocycle, has only five atoms and is of high symmetry, there was a chance for ab initio calculations, which followed some semiempirical studies. 

Part 2 (Volumes 2 and 3) deals with mono- and poly-cyclic compounds with one or more six-membered heterocyclic ring, with nitrogen, oxygen and sulfur as the heteroatoms. Volume 2 contains the six-membered rings with one nitrogen atom (Part 2A) and Volume... 

Heterocyclic compound (Section 3.15) Cyclic compound in which one or more of the atoms in the ring are elements other than carbon. Heterocyclic compounds may or may not be aromatic. 

A heterocycle is a cyclic compound that contains atoms of two or more elements in its ring, usually carbon along with nitrogen, oxygen, or sulfur. Heterocyclic amines are particularly common, and many have important biological properties. Pyridoxal phosphate, a coenzyme sildenafil (Viagra),... 

Topics in Heterocyclic Chemistry presents critical accounts of heterocyclic compounds (cyclic compounds containing at least one heteroatom other than carbon in the ring) ranging from three members to supramolecules. More than half of the more than 10000 compounds hsted in Chemical Abstracts are hete-rocychc compounds. The branch of chemistry deahng with these heterocyclic compounds is called heterocyclic chemistry, which is the largest branch of chemistry and as such the chemical hterature appearing every year as research papers and review articles is vast and can not be covered in a single volume. 

Further exploitation of the molecular shape feature has led more recently to the design of another series of clathrate hosts by substituting on the allene rigid backbone bulky groups 22>, Representative compounds of this new host family are 20 and 21. The allene 20 (R = t-butyl) shows an interesting clathration behaviour upon crystallization from various environments, including alicyclic and aromatic compounds, heterocycles, cyclic ketones and eyclohexaneamine 26>. 

I should like to attempt to explain why a starting material that may apparently afford a propellane and/or a dispiran sometimes gives one or another, apparently not a mixture of both. There does not appear to be a denominator common for all the cases to be discussed but perhaps discussion of cases pertaining both to carbo-cyclic and heterocyclic compounds may cast some light on the problem there need not be a unique reason for the behavior in the two series. 

Different strategies all including nucleophilic addition to acceptor-substituted allenes have been used for the synthesis of cyclic compounds, mostly heterocycles. Thus, it is obvious to release a nucleophile already existing within the allenic compound in a protected form. For example, treatment of silyl ethers 197 with tetrabu-tylammonium fluoride (TBAF) leads to the intermediates 198, which yield the dihy-drofurans 199 by nucleophilic addition (Scheme 7.32) [251]. 

The cyclizahon of amino alcohols should be an attractive method for the synthesis of N-heterocyclic compounds, mainly because they can be obtained in a single step and without the generation of wasteful byproducts. Carbon-nitrogen bond formation catalyzed by Cp lr complexes has been extended to the synthesis of N-hetero-cyclic compounds by the cyclization of amino alcohols. 

Cyclic compounds in which one or more of the ring atoms is not carbon are termed heterocycles the noncarbon atoms are referred to as heteroatoms. We shall limit our discussions to compounds in which the heteroatoms are nitrogen, oxygen, or sulfur. For the purposes of studying and understanding their properties, heterocycles are conveniently grouped into two classes, i.e. non-aromatic and aromatic. 

Later Grubbs discovered ruthenium carbene complex and used it for a metathesis reaction to synthesize cyclic compounds 5a-d [Eqs. (6.4) and (6.5)]. In 1995, Grubbs found that ruthenium benzylidene carbene complex Ic," which is now commercially available, has the same reactivity as that of lb. Many researchers have therefore used this complex for olefin metathesis, and this reaction has been useful for the synthesis of carbo- and heterocyclic compounds and fused bicyclic compounds [Eq. [6.6)] °... 

As mentioned previously (see p. 237), the 1,2,3-benzotriazinones function as masked diazonium compounds, and the so-called Pologenowe dyes developed in Poland are operated on this principle and have been in use there since 1959. There are three major advantages associated with the use of 1,2,3-benzotriazinones as azo-dye equivalents (1) The equilibrium that theoretically exists between the heterocyclic system and the diazonium compound normally lies completely to the side of the cyclic compound. Opening of the heterocyclic ring can be easily accomplished thermally, and hence dye formation can be induced by heat treatment processes. (2) Many 1,2,3-benzotriazinones are reasonably water soluble and the sodium salts even more so consequently, complete permeation of fabric fibres by the dye precursors immediately prior to generation of the dye can be ensured. (3) The colors produced are fast, and some of them can be made highly water insoluble. ... 

Heptachlor under Unsaturated Alkyl Halides Heptanes under Alkanes and Cyclic Alkanes Heterocyclic Nitrogen Compounds Heterocyclic Oxygen Compounds Heterocyclic Sulfur Compounds... 

Cyclic compounds that have one or more of atoms other than carbon, e.g. N, O or S (hetero-atoms), in their rings are called heterocyclic compounds or heterocycles, e.g. pyridine, tetrahydrofuran, thiophene and so on. 

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