Ali-cyclic compounds

Aromatic hydrocarbon a hydrocarbon characterized by the presence of an aromatic ring or condensed aromatic rings benzene and substituted benzene, naphthalene and substituted naphthalene, phenan-threne and substituted phenan-threne, as well as the higher condensed ring systems compounds that are distinct from those of aliphatic compounds (q.v.) or ali-cyclic compounds (q.v.). 

Saturated and partially saturated ali cyclic compounds having six-membered rings are readily converted to the corresponding aromatic compounds by several dehydrogenation procedures. The more nearly saturated compounds are the most difficult to dehydrogenate. Alicyclic rings con-... 

A. ALI-CYCLIC COMPOUNDS OR CARBO-CYCLIC COMPOUNDS NOT DERIVED FROM BENZENE. 

Another group of ali-cyclic compounds should be mentioned briefly, viz., those which contain unsaturated groups, i.e., carbon atoms linked by double or triple bonds. Just as 1-3-di-brom propane yields cyclo propane or tri-methylene so 1-3-di-brom propene yields a cyclic compound in which a double bond is present. 

All of these ali-cyclic compounds containing double or triple bonds are unsaturated compounds distinctly different from the saturated ali-cyclic compounds. 

While, however, penta-methylene is the most stable ali-cyclic compound of the poly-methylene group it is hexa-methylene which is of special interest and importance. This importance is due to the fact that it is the connecting link between the ali-cyclic compounds (carbo-cyclic compounds not derived from benzene, i.e. the poly methylenes) and benzene itself. Thus it becomes the connecting link between the aliphatic open-chain compounds and the very large and important division including benzene and its derivatives. 

Such a formula as this agrees with the facts we have thus far given in regard to benzene, viz., that it is not an unsaturated open chain compound, nor is it an ali-cyclic compound like cyclo-hexane. It is, however, directly related to the latter. 

In recognition of his services to organic chemistry and the chemical industry by his pioneer work in the field of ali-cyclic compounds. ... 

Perkin alicyclic synthesis. Synthesis of ali-cyclic compounds from a, IGKW-dihaloalkanes and compounds containing active methylene groups in the presence of sodium ethoxide. 

NITROSO COMPOUNDS AlIphat i c and Ali cyclic Aromatic N i trosamines... 

Food, flavors consist of numerous compounds, none of which alone is characteristic of specific food. Classes of compounds which emcompass food flavors are - hydrocarbons (aliphatic, ali-cyclic, aromatic) carbonyls (aldehydes, ketones) carboxylic acids, esters, imides, anhydrides alcohols, phenols, ethers alkylamines, alkylimines aliphatic sulfur compounds (thiols, mono-, di- and tri-sulfides) nitrogen heterocyclics (pyrroles, pyrazines, pyridines) sulfur heterocylics (thiophenes, thiazoles, trithiolane, thialidine) and oxygen-heterocyclics (lactone, pyrone, furan). Discussion will be limited to striking developments in heterocyclics. 

Part II Carbo-cyclic compounds including not only carbon ring compounds derived from benezene iso-cyclic, but also carbon ring compounds not derived from benzene, ali-cyclic in addition to these the hetero-cyclic compounds as a group. 

Ali-cyclic Compotmds.—Cyclo propane and its homologues, therefore, are saturated carho-cyclic compounds. They are similar to aliphatic compounds in certain respects, and are not like benzene compounds. We indicate this by the name ali-cyclic as suggested by Bamberger, to distinguish them from the carho-cyclic compounds related to benzene which are termed iso-cyclic. 

Referring again to the saturated ali-cyclic, or poly-methylene, compounds and comparing them with the isomeric olefine compounds, we find some exceedingly interesting facts. In connection with the idea... 

Except for four-membered rings, these factors are favourable to ring formation so that we can use the norraai disconnections and ali the normal guidelines to choose one disconnection rather than another. We have already analysed the formation of many cyclic compounds in this way (e.g, in Chapters 17, 20, 21, 27, and 28), but we shall now take each ring size in turn and discuss its synthesis systematically, starting with C-X disconnections in this chapter, and progressing to C-C disconnections in Chapters 30-37. 

Carotenoids a large class of yellow and red pigments, which are highly unsaturated aliphatic and ali-cyclic hydrocarbons and their oxidation products. C. are biosynthesized from isoprene units (CsHj) and therefore have the methyl branches typical of isopre-noid compounds. Most C. have 40 C atoms and are thus tetraterpenes (consisting of 8 isoprene units). A few C. contain 45 and 50 C atoms, particularly in nonphotosynthetic bacteria. C. with fewer than 40 C atoms are called nor-, seco- or apocarotenoids. 

As part of an extensive study of the 1,3-dipolar cycloadditions of cyclic nitrones, Ali et al. (392-397) found that the reaction of the 1,4-oxazine 349 with various dipolarophiles afforded the expected isoxazolidinyloxazine adducts (Scheme 1.78) (398). In line with earlier results (399,400), oxidation of styrene-derived adduct 350 with m-CPBA facilitated N—O cleavage and further oxidation as above to afford a mixture of three compounds, an inseparable mixture of ketonitrone 351 and bicyclic hydroxylamine 352, along with aldonitrone 353 with a solvent-dependent ratio (401). These workers have prepared the analogous nitrones based on the 1,3-oxazine ring by oxidative cleavage of isoxazolidines to afford the hydroxylamine followed by a second oxidation with benzoquinone or Hg(ll) oxide (402-404). These dipoles, along with a more recently reported pyrazine nitrone (405), were aU used in successful cycloaddition reactions with alkenes. Elsewhere, the synthesis and cycloaddition reactions of related pyrazine-3-one nitrone 354 (406,407) or a benzoxazine-3-one dipolarophile 355 (408) have been reported. These workers have also reported the use of isoxazoles with an exocychc alkene in the preparation of spiro[isoxazolidine-5,4 -isoxazolines] (409). 

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