And monocyclic compounds

Although steric effects and strain always work against basicity in simple molecules and monocyclic compounds, there are a few compounds in which the steric and strain effects stabilize the HH adduct, increasing the basicity. An example is the 1.8-bis(dimelliylamino)nuphthalene molecule in which steric hindrance of the methyl groups and repulsions of lone pairs on the nitrogen destabilize the free base ... 

Attention in fundamental and applied research on shape-selective catalysis has been largely focused on open-chain and monocyclic compounds. However, we have observed the rapid developments in polymer materials containing multi-ring aromatic units and the need to develop the monomers and other specialty chemicals from polyaromatic hydrocarbons that are rich in coal-derived liquids [Song and Schobert, 1993, 1996]. Scheme 1 shows the structures of some advanced polymer materials containing aromatic ring in the main-chain. 

An interesting study, but of theoretical rather than practical use, linking a nodal notation of the structure with the systematic nomenclature was presented by Navech and Despax. The complex algorithms expect structures to be first coded into so-called SCN code (Structure Code Number). This code number is generated by juxtaposition of the coordination number, the number of free electrons, the number of multiple bonds, and the atomic symbol. The SCN generated for the whole molecule is then processed and the nomenclature is generated. The capabilities of the package are limited to simple acyclic and monocyclic compounds with no heteroatoms and multiple bonds inside chains allowed. 

Nitration and aromatic reactivity C. The nitration of monocyclic compounds... 

If an open-chain organic molecule contains an electron acceptor and an electron donor site, two carbon atoms may be combined intramolecularly. This corresponds to the synthesis of a monocyclic compound. 

A few isothiazoles, 2,1-benzisothiazoles and monocyclic sultams have been prepared by methods involving formation of the 4,5-bond. Thus, condensation of a-cyanooximes (179) with ethyl mercaptoacetate or related compounds gives a compound (180) which cyclizes... 

Tliese derivatives quite generally exist in the oxo or thioxo tautomeric forms. Monocyclic compounds are rare for instance, Lavergne et at reported that compound 58 exists as the thioxo tautomer 58a and not as the more antiaromatic mercapto tautomer 58b on the basis of the similarity of the NMR spectra of 58 with that of 59 (80RTC301). 

This sesquiterpene is a monocyclic compound, first isolated from the essential oil of Bisabol myrrh by Tucholka. It was found in oil of limes, and described by Burgess under the name limene. It occurs in several other essential oils. When separated by fractional distillation from lemon oil, Gildemeister and Mullerfound it to have the following characters —... 

The retrosynthetic operations that we have addressed thus far have not resulted in significant structural simplification. After all, intermediate 6 still possesses a linear fusion of four rings and six contiguous asymmetric carbon atoms. But, nevertheless, intermediate 6 could potentially be derived in one step from intermediate 8, a polyunsaturated monocyclic compound containing only one stereogenic center. Under conditions that would be conducive to a heterolytic cleavage of the C-OH bond in 8, it is conceivable that the resultant tertiary allylic carbonium ion 7 would participate in a... 

In most cases there exists at elevated temperatures a mobile equilibrium with the monocyclic compound 4 dominating in the equilibrium mixture, whereas at room temperature the individual structures 3 and 4, respectively, are stable and can be isolated in pure form. 

Intramolecular versions of the Diels-Alder reaction are well known, and this is a powerful method for the synthesis of mono- and polycyclic compounds.There are many examples and variations. One interesting internal Diels-Alder reaction links the diene and dienophile by a C—O—SiR2—or a C—O—SiR2—O—C linkage. Internal cyclization to give a bicyclic product is followed by cleavage of the O-Si unit to give a monocyclic alcohol. 

The major structural difference between monocyclic and bicyclic compounds should be obvious camphene and camphor exhibit bridged structures. It should be noted, however, that the monocyclic compounds can be further distinguished from each other based on the position of the oxygen atom, located at C-2 in carvone, and at C-3 in pulegone, and in the menthones. Work by others had shown that the... 

Before the advent of the petrochemical industry carbocyclic aromatic compounds, such as naphthalene, phenol, and pyridine, provided the source of many important industrial chemicals including dyestuffs, while the monocyclic compounds continue to play an important role as fuels and starting materials. 

A central focus in modem organic synthesis has been the development of highly efficient catalytic processes for the syntheses of natural and unnatural compounds of medicinal interest or intermediates useful for functional materials. A particularly attractive approach is to apply transition metal catalysed cyclisation reactions for the transformation of simple starting materials into monocyclic, bicyclic and polycyclic scaffolds that can be further elaborated into specific targets. 

Monocyclic compounds with two amino functionalities like 1 were converted to the dinitriles 2 and subsequently reduced to the amines 3. An intramolecular... 

Ring Synthesis from Monocyclic and Acyclic Compounds... 

Various heterocyclic structures, among them 3-substituted-hexahydro-277-pyrimido[l,2- ]pyrimidin-2-ones 190, have been prepared by solid-phase synthesis. The acetates 187 were reacted with diaminoalkanes, the resulting diamines 188 cyclized with BrCN to the monocyclic compounds 189, which were cleaved and cyclized with Et3N to give 190 (Scheme 30) <2005TL5289>. 

In compounds with R=H, at equilibrium the proton completely exchanged to R = D. For 297 (R = Me) and 299 (R = Me) ring closures were slower and the equilibrium shifted more toward the monocyclic compounds (Equations 29 and 30) <20050BC1964>. 

A series of l/f-pyrrolo[2,l-r][l,4]oxazin-l-ones 196 are also the product of an LJgi multicomponent reaction between proline (and also other a-amino acids that gave the corresponding monocyclic compounds) and several isonitriles in the presence of commercially available glycolaldehyde dimer (Equation 3) <20010L4149>. 

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