Alicyclic compound

Alicyclic Compounds.—Ikarugamycin. In a series of papers, the full structure and stereochemistry of Ikarugamycin, an antibiotic from culture broth of 

Streptomyces phaeochromogenes var. ikaruganensis, was determined as (161). Its biosynthesis is considered to involve two hexa-acetate units and L-ornithine, and an intramolecular Diels-Alder reaction of a hypothetical intermediate (160) has been put forward as a suggested route to the trans-anti-cis-decdihydrsL-asym-mdsLcene skeleton [i.e. the a, b, and c rings of (161)]. 

Other common MOCVD compounds are produced from alicyclic hydrocarbons, where the carbon chain forms a ring, such as in 

As the preceding section correctly suggests, aromatic rings a-hound in compounds that show biologic activity. The reasons for this are many the role of the pi electrons in some form of charge transfer complex ranks among the more Important. There ire few monocyclic alicyclic compounds known that are used as medicinal agents. 

An interesting appetite suppressant very distantly related to hexahydroamphetamines is somanta-dine (24). The reported synthesis starts with conversion of 1-adamantanecarboxylic acid (20) via the usual steps to the ester, reduction to the alcohol, transformation to the bromide (21), conversion of the latter to a Grignard reagent with magnesium metal, and transformation to tertiary alcohol 22 by reaction with acetone. Displacement to the fomiamide (23) and hydrolysis to the tertiary amine (24) completes the preparation of somantadine [6]. 

Some alicyclic 1,2-diamine derivatives have recently been shown to have interesting CNS properties. For example, eclanamine (34) is an antidepressant with a rapid onset of action. The reasons for its potency are not as yet clear but pharmacologists note that the drug desensitizes adrenergic alpha-2 receptors and antagonizes the actions of clonidine. The synthesis of eclanamine starts with attack of cyclopentene oxide (30) by dimethylamine (to give 31). This product is converted to the mesylate by reaction with sodium hydride followed by mesyl chloride. Attack of 

A structurally unrelated agent is tazadolene (40). The synthesis of tazadolene begins with P-keto ester 37 and subsequent enamine formation with 3-amino-1-propanol followed by hydrogenolysis to give 38. This phenylhydroxymethyl compound is then dehydrated with hydrochloride acid to form olefin 39. Treatment with bromine and triphenylphosphine effects cycliza-tion to form the azetidine ring of tazadolene [10]. 

The structural relationship of pivopril to the commercially important analogues captopril (51) and enalaprilat (52) is readily apparent. 

Retinoids are needed for cellular differentiation and skin growth. Some retinoids even exert a prophylactic effect on preneoplastic and malignant skin lesions. Fenretlnide (54) is somewhat more selective and less toxic than retinyl acetate (vitamin A acetate) for this purpose. It is synthesized by reaction of all trans-retinoic acid (53), via its acid chloride, with g-aminophe-nol to give ester 54 (13). 

S -Abscisic acid (Dormin) [21293-29-8] M 264.3, m 160-161°, 161-163° (sublimation), [aljs +24,000°, [0)245 -69,000° (c l-50pg/ml in acidified MeOH or EtOH), 3.9. Crystallise the acid from CCVpetroleum 

Acetylcyclohexane (cyclohexyl methylketone) [823-76-7] M 126.2, b 64°/llmm, 76.2-77°/25mm, d4 0.9178, n D 1.4519. Dissolve acetylcyclohexane in Et20, shake it with H2O, dry, evaporate and fractionate it under reduced pressure. [UV Mariella Raube JAm Chem Soc 74 518 1952, enol content Gero J Org Chem 19 1960 1954( The semicarbazone has m 174° and the 2,4-dimtrophenylhydrazone has m 139-140° [Theus  

2-Acetylcyclohexanone [874-23-7] M 140.2, m -11°, b 62-64 /2.5mm, 95-98 /10mm, lll-112°/18mm, d 4 1.08, n D 1.51. Dissolve it in ligroin (b 30-60°), wash it with saturated aqueous NaHC03, dry over Drierite and fractionate in a vacuum. [Perfetti Levine J Am Chem Soc 75 626 1953, Manyik et al. JAm Chem Soc 75 5030 1953, Eistert Reiss Chem Ber 87 108 1954.] It forms a Cu salt which crystallises in green leaflets from EtOH, m 162-163° [UV McEntee Finder J Chem Soc 4419 1957]. 

Purify it by fiactiorration under reduced pressure in vacuo, and if it is almost pirre it can be fractionated at atmospheric pressure, preferably in an inert atmosphere. It forms two 5e/M/c 7r7 azone5oneofwhichismoresolrrblein C6Hg, arrdbothcanbe recrystallised from EtOH the more 

Chapter 4. Purification of Organic Chemicals — Alicyclic Compounds 

FIGURE 9.48 Examples of radical-induced dissociations of distonic ions. 

FIGURE 9.51 Hydrogen atom transfers through five-membered (top) and four-membered (bottom) transition states and consecutive radical-induced fragmentations. 

The two mechanisms following an a cleavage are the eliminations of a propyl radical and an ethyl radical. The first implies a six-membered transition state requiring 

FIGURE 9.52 Hydrogen transfer tbrongb five-membered transition state following a cleavage and consecutive radical-induced fragmentations. 

FIGURE 9.53 Electron ionization mass spectrum of cyclohexanamine and fragmentations of the molecular ion leading to m/z 56 and m/z 70 ions. 

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Chapters V-X deal respectively with Heterocyclic and Alicyclic Compounds Miscellaneous Reactions Organic Reagents in Inorganic and Organic Chemistry Dyestuffs, Indicators and Related Compounds Some Physiologically-Active Compounds and Synthetic Polymers. Many of these preparations are of course intended for advanced students, but a mere perusal of the experimental details of selected preparations by those whose time for experimental work is limited may assist to impress them on the memory. Attention is particularly directed to the chapter... 

For purely alicyclic compounds, the selection process proceeds successively until a decision is reached (a) the maximum number of substituents corresponding to the characteristic group cited earliest in Table 1.7, (b) the maximum number of double and triple bonds considered together, (c) the maximum length of the chain, and (d) the maximum number of double bonds. Additional criteria, if needed for complicated compounds, are given in the lUPAC nomenclature rules. 

Carbocyclic compounds are very usefully divided into (a) saturated (alicyclic) compounds, (b) aromatic compounds and (c) the intermediate partially unsaturated (alicyclic) compounds. Heterocyclic compounds can be subdivided in exactly the same way, and equally usefully. 

In the main, the physical and chemical properties of saturated and partially unsaturated alicyclic compounds closely resemble those of the analogous acyclic compounds formally derived by cleavage of the carbon ring at a point remote from any functionality. Relatively small, but often significant, differences in properties arise from conformational effects, and from strain effects in small rings, and these differences can be striking in properties which are particularly sensitive to molecular shape. 

Of alicyclic compounds, fluorination of cyclopentane and cyclohexane has been sufficiently investigated in the past. Cycloheptane on fluorination with cobalt trifluoride gives a mixture of highly fluorinated and perfluorinated cycloheptanes and methylcyclohexanes [/2] (equation 12). 

O. Wallach (Gottingen) pioneer work in the field of alicyclic compounds. 

Raney nickel desulfurization of the macrocyclic ketones or their reduction products confirmed the structures assigned to these compounds and simultaneously offers new methods for the synthesis of macrocyclic alicyclic compounds. =°... 

The double bond may be present in an acyclic or alicyclic compound, including dienes. The reaction is activated by the presence of... 

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