Carbocyclic derivatives

Casas R., Chen Z., Diaz M., Hanafi N., Ibarzo J., Jimenez J. M., Ortuno R. M. Some Versatile and Useful Strategies for the Asymmetric Synthesis of Chiral Polyfunctional Carbocyclic Derivatives An. Quim. 1995 91 42-49... 

Three different fused systems have been reported in the literature thieno[3, 2 4,5]thieno[2,3-c]pyridine (f/r-thiophenes), thieno[2, 3 4,5]thieno[2,3-c]pyridine (tram- thiophenes) and thicno[3,2-g]thicno [3,2-d pyridine derivatives. So far, the parent thienothienopyridines have only been prepared via the corresponding pyrylium salts (see below) all others are benzo or extended carbocyclic derivatives, for example, thienothienoquinolines. 

The compounds obtained by the replacement of ring sulfur by carbon, as in the case of penicillins, show somewhat improved antibiotic properties. A free radical— based route has been described for the conversion of fermentation derived cephalosporins to their carbocyclic derivatives. The first step in this sequence consists of the condensation of the cephalosporin sulfone (36-1) with formaldehyde and dimethyla-mine the initial product from the Mannich-like reaction consists of the exomethylene derivative at the position adjacent to the activating sulfone. The product is treated in situ with phenylselenol to give the Michael adduct (36-2). This fragments with an extmsion of sulfur dioxide when heated with the free radical initiator AIBN in the presence of tributyltin hydride the reaction can be envisaged as leading to the... 

The conformational properties of such eight-membered ring molecules have been reviewed fairly recently (74MI51900). Cyclooctane is the archetypical molecule in this class, and the heterocyclic analogs, such as the azocanes, oxocanes and thiocanes, as well as carbocyclic derivatives, such as cyclooctanone, all have closely related conformational features and a brief overview of their conformations will now be given. 

Volume 2 Five-membered Rings with One Heteroatom and Fused Carbocyclic Derivatives... 

The bridging carbonate has an unusual T-T 1 T 2-rnode of coordination to U atoms with a fluxional structure, whereas the squarate species has a p-q2 ]2 structure (Figure 4.14). This is the first example of the formation of a carbocycle derived purely from a C02 carbon source. 

Simple tertiary enaminones derived from acetylacetone and benzoylacetone react with acryloyl chloride to yield carbocyclic derivatives. The reaction proceeds via an initial Michael addition of the enaminone / -carbon to the enone107 (equation 76). Analogous behavior of cyclic enaminones leads, according to ring size, to tetrahydroindole, quinoline and benzazepine derivatives108 (equation 77). 

The next four procedures describe the regioselective preparation of bicyclic ring systems, specifically, condensed five-membered carbocyclic derivatives. A large... 

Prompted by the success achieved with simple carbocyclic compounds (e.g., 35), which are potent inhibitors of influenza neuraminidase, several other Neu5Ac2en mimetics of this kind were studied. The isomeric carbocyclic derivatives 37 and 38 are selective for influenza A sialidase, but only 38 showed signihcant inhibition (IC50 = 2 X 10 M) [87]. Other carbocyclic neuraminidase inhibitors include the guanidino substituted cyclohexene 39 [88] and amine derivatives [89] such as 40, which was found to be an inhibitor of influenza B neuraminidase comparable with oseltamivir 35, but was not as potent against influenza A virus [89a]. 

Previously, carbocyclic nucleosides have been studied in some detail, but these analogues were often poor substrates for enzymes. This may be a reason for why there have been so few reports on carbocyclic derivatives in oligonucleotides. The carbocyclic L-nucleoside derivatives (61, 62) which are fixed in the anti-glycosyl conformation, have been prepared to examine factors determining the helicity of dsDNA. The anti-conformer was prepared to determine whether... 

The same trend in the electronic effects is observed experimentally for the urazole-bridged 4,5-diazacyclopentane-l,3-diyl triplet diradicals 7 (Table 5), which were chosen to probe for the effect of heteroatom substitution on the D parameter. Substitution of a phenyl by a methyl group in 7d also results in an increased D value in 7g, but is less effective (18%) as seen in the carbocyclic derivatives. These results are in line with the earlier reported [17] D values of iV-phenylurazole-bridged cyclopentene-1,3-diyl triplet diradicals 7a-c (cf. Table 1). As for the carbocyclic diradicals, the electronic substituent effects are reproduced in the diradicals 7e and f not only qualitatively but quantitatively (Table 5). For example, the spin-accepting p-CN substituent in the triplet diradical 7e reduces while the spin-donating... 

T. V. RajanBabu, Functionalized Carbocyclic Derivatives from Carbohydrates Free Radical and Organometallic Methods, in Preparative Carbohydrate Chemistry (Ed. S. Hanessian), Marcel Dekker, 1997, Chap 25. 

Other Carbocyclic Derivatives. The only (C3R3)M compounds yet prepared are those containing (C3Ph3) combined with nickel.17 They are obtained by the reactions... 

From Other Carbocyclic Derivatives as Substrates Indenes as Substrates... 

Reviews have appeared on the synthesis of inositols, carba sugars, conduritols and amino conduritols utilizing the non-carbohydrate sources of benzene cis-diols, quinic acid and Vogel s naked sugar methodology. Other reviews on the preparation of cyclophellitol and ep/-cyclophellitol from glycals and the use of D-glyceraldehyde as a chiral precursor in Diels-Alder and 1,3-dipolar cycloaddition approaches to carbocyclic derivatives have also been reported. 

Herein, we review nonexhaustively our contribution to the field of transition-metal-mediated heterocyclic synthesis. This chemistry is based mainly on using cyclopalladated complexes and their reactions with disubstituted alkynes that in many cases, lead to heterocyclic products by the selective intramolecular formation of carbon-carbon and carbon-heteroatom (C-N, C-O and C-S) bonds. In some instances these reactions also lead to interesting carbocyclic derivatives. Emphasis is placed on the transformations of the alkynes. When they are allowed to react with the metallated ligands, they lead in several instances to heterocyclic or carbocyclic final products. We present in particular some of the more recent results emanating from our laboratory and comment briefly on some similarities of this chemistry to other, selected and related transition-metal-mediated reactions, thus demonstrating that this field of research remains in vogue in many different research groups. 

As with their monoinserted counterparts, rj -butadienyl-bound complexes are often very stable, and activation methods are usually needed to employ them for synthesis. Moreover, we do not always observe heterocyclization processes and quite often carbocyclic derivatives, re-... 

Singh and co-workers applied their methodology for the synthesis of embellished spiro-fused bicyclo[2.2.2]octane systems to the synthesis of seven-membered ring carbocyclic derivatives. Treatment of diene 299 with 10 mol % of 3 in dichloromethane gave the corresponding spirocyclic carbocycle 300 in 86% yield. 

Russel DK, Press JB (1996) Five-membered rings with one heteroatom and fused carbocyclic derivatives. In Katritzky AR, Rees CW, Scriven EFV (eds) Comprehensive heterocyclic chemistry II, vol 2. Oxford, Pergamon, p 680... 

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