Cycloalkanes condensed

Reduction of cycloalkane-condensed 2-phenyl-5,6-dihydro-4//-l,3-benzoxazines 144 with lithium aluminium hydride (LAH) afforded A -benzyl-substituted 2-(aminomethyl)cycloalkanols 145 in a reductive ring opening via the ring-chain tautomeric tetrahydro-l,3-oxazine intermediates. Catalytic reduction of 1,3-oxazines 144 under mild conditions in the presence of palladium-on-carbon catalyst similarly resulted in formation of the A -benzyl-1,3-amino alcohols 145. When the catalytic reduction was performed at elevated temperature at hydrogen pressure of 7.1 MPa, the N-unsubstituted 2-(aminomethyl)cycloalkanols 146 were formed in good yields (Scheme 22) <1998SC2303>. 

Epsztajn. J.. Hahn, W. E., and Tosik, B, K., Cycloalkanes condensed with heterocyclic rings. XIV. Synthesis of 6-methyl-2,3-cy-cloalkanopyridines, Rocz, Chem., 44, 431, 1970 Chem. Ahstr., 72, 132478, 1970. 

In the Diels-Alder reaction with inverse electron demand, the overlap of the LUMO of the 1-oxa-l,3-butadiene with the HOMO of the dienophile is dominant. Since the electron-withdrawing group at the oxabutadiene at the 3-position lowers its LUMO dramatically, the cycloaddition as well as the condensation usually take place at room or slightly elevated temperature. There is actually no restriction for the aldehydes. Thus, aromatic, heteroaromatic, saturated aliphatic and unsaturated aliphatic aldehydes may be used. For example, a-oxocarbocylic esters or 1,2-dike-tones for instance have been employed as ketones. Furthermore, 1,3-dicarbonyl compounds cyclic and acyclic substances such as Meldmm s acid, barbituric acid and derivates, coumarins, any type of cycloalkane-1,3-dione, (1-ketoesters, and 1,3-diones as well as their phosphorus, nitrogen and sulfur analogues, can also be ap-... 

The acyloin condensation was used in an ingenious manner to prepare the first reported catenane (see p. 91).727 The catenane (39) was prepared by a statistical synthesis (p. 91) in the following manner An acyloin condensation was performed on the diethyl ester of the C34 dicarboxylic acid (tetratriacontandioic acid) to give the cyclic acyloin 37. This was reduced by a Clemmensen reduction with DCI in D20 instead of HC1 in H20, thus producing a C34 cycloalkane containing deuterium (38) 728... 

Naphthenic acids are based on saturated single or inulticyclic condensed ring structures, The low molecular weight naphthenic acids contain alkylated cyclopentane carboxylic acids, with smaller amounts of cyclohexane derivatives occurring, The carboxyl group is usually attached to a side chain rather than directly attached to the cycloalkane, The simplest naphthenic... 

The molecular weight of the polyaromatic fraction as calculated by NMR is well below that determined by VPO. As pointed out earlier the NMR analysis of this fraction can only be semiquantitative because tetra-and higher aromatic systems will be calculated as mono- and diaromatics and all the calculations will be affected accordingly. In our separation scheme all of the polar non-hydrocarbons are concentrated in the resin fractions. Only ethers and thioethers are included in the oil and are eventually concentrated in the di- -f- triaromatics and polyaromatics, as the data in Table III show. Also only half of the saturates are condensed cycloalkanes, mainly of two and three rings. These observations are indirect evidence that no significant amounts of large condensed systems are present and that at least part of the polyaromatic fraction consists of noncondensed mono-, di-, and triaromatic units. 

The mass spectrometric analyses of the saturate fractions are reported in Table VI. These fractions appear to be composed mostly of alkanes and noncondensed cycloalkanes with smaller amounts of condensed cycloalkanes, mainly two- and three-ring systems. However, because of the presence of olefins in these fractions the analyses are only semiquantitative. In fact, an olefin should make a contribution to the cycloalkane group type which has the same molecular weight. That is, a monoolefin will contribute to the cycloalkanes, a diolefin or a cyclic olein will contribute to the bicycloalkanes, etc. However, to determine the extent of these contributions more analytical work is necessary. 

Only the Big Horn coal liquids have more condensed cycloalkanes than noncondensed cycloalkanes. The tar sands have an equal distribution of the two types of saturates, and the remaining fuels have a higher concentration of noncondensed cycloalkanes. The effect of the olefins on the mass analysis of the saturates from the shale oils must, however, be kept in mind in making this comparison. 

Even condensed structures are awkward for cyclic molecules, and a streamlined way of drawing structures is often used in which cycloalkanes are represented by polygons. A triangle represents cyclopropane, a square represents cyclobutane, and so on. Carbon and hydrogen atoms aren t shown explicitly in these structures. A carbon atom is simply understood to be at every junction of lines, and the proper number of hydrogen atoms needed to give each carbon four bonds is supplied mentally. Methylcyclohexane, for instance, looks like this ... 

The third class of organic donor molecules are a-donors, viz., alkanes and cycloalkanes. These substrates have inherently high ionization and oxidation potentials. Therefore, their radical cations are not readily available by photoinduced electron transfer, but typically require radiolysis and electron impact in the condensed phases or the gas phase, respectively. Thus, radical cations of simple alkanes (methane [206], ethane [207]) or unstrained cycloalkanes (cyclopentane, cyclohexane) [208] were identified and characterized following radiolysis in frozen matrices. In contrast, strained ring compounds have significantly lower oxidation potentials so that the radical cations of appropriate derivatives can be generated by photoinduced electron transfer. 

The syntheses of spirocycloalkane-condensed-hydrotetrazines 43 and 44 have been described starting from l,2,4,5-tetraazaspiro-cycloalkane-3-thiones 42 <02IJC(B)400>. 

CH2 cycloalkanes 7 C cycloalkane substituted 8 C trans-condensed cycles 9 C02... 

Define or identify each of the following terms (a) organic chemistry, (b) total bond order, (c) condensed formula, (d) structural formula, (e) fine formula, (/) hydrocarbon, (g) alkane, (h) aUcene, (/) alkyne, j) aromatic hydrocarbon, (k) saturated, (1) delocalized double bond, (m) isomerism, (n) cycloalkane, (o) radical, (p) functional group, (q) alcohol, (r) ether, (s) aldehyde, (f) ketone, (u) carbonyl group, and (v) ester. 

Applicability Particularly accurate for the following families alkanes, alkenes, aromatic alcohols, cycloalkanes, epoxides, aliphatic acids, condensed rings. 

Acyloin condensation (2, 435-436). Japanese chemists3 have extended Bloomfield s procedure for ring enlargement of cycloalkane-1,2-dicarboxylie esters. Thus the esters (1) were treated with sodium in xylene at 110-120° in the presence of trimethylchlorosilane and the reaction mixture refluxed to ensure ring opening of the cyclobutenes (2) to 1,3-dienes (3). Acidic hydrolysis gave 1,2-diketones (4) in 71 -74% yields. These can be reduced to acyloins (5) by alkaline hydrolysis with triethyl phosphite (74-79%). 

Aromatic hydrocarbon, p. 940 Carboxylic acid, p. 958 Condensation reaction, p. 957 Cycloalkane, p. 947... 

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