Trans- Decal ins

An investigation of the isotopic composition of the Decal ins, which were formed as minor products in the donor solvent experiments, showed that cis-Decalin was formed preferentially. Its formation and its increased protiurn incorporation may have resulted from increased contact with the coal surface. Trans-Decal in contained less protiurn than the Tetralin, which suggests that most of the trans-Decalin was formed with deuterium from the Tetralin-di2 and deuterium gas. 

Ozone oxidation of the trans-decal in di of benzylidene 133 has been carried out (71). Under kinetically controlled conditions, it produces the axial benzoate 134 in preference to the more stable equatorial benzoate 135. Similar results were obtained with an analogous case derived from cholestane-2e,3e-diol. These results are essentially identical to those obtained by King and Allbutt (60, 62) in their study on the hydrolysis of dioxolane orthoesters and dioxolenium salts (cf. p. 82), and can therefore be explained in the same manner. These results further confirm that the oxidation of acetals by ozone produces an intermediate which behaves like the hemiorthoester tetrahedral intermediate which is formed in the hydrolysis of orthoesters. 

Figure 6 Dependence of the product distribution on conversion for H-Beta zeolites (filled), TT-Y-12 (open), Pt/IT-Beta zeolites (half-filled), and Pt/fl-Y-1 2 (open with dash). A) Trans-decal in ( , U, H, B), cis-decalin ( , O, , 0), Isomers (A, A, A, A), B) ROP ( , t>, t>, t>), CP ( , O, ), HP (, ...

If the energy of trans-decal in is equated to zero kcal mof what is the energy of ris-decalin. 

The light-scattering data of Nose and Chu on a PS sample of = 190kD in trans-decal in at 20.0 C) seem to fit fairly well to the curve of Fig. 7, if one fits the first data point (c = 0.21 g/dl) to the theoretical curve at = 0.91 to fix the concentration scale of the figure. However, another publication in literature, using a mixture of randomly substituted p-iodostyrene and a PS sample of M = 110 kD in trans-decalin at T9 = 21.2 C, showed by SAXS that the polymer coil dimension remained constant independent of concentration up to a volume fraction of 0.4 within the experimental error of 5%. More experimental studies are certainly needed before a reliable conclusion could be drawn, especially when results obtained by independent methods are avail-... 

Irie and co-workers (37) have recently observed that the double Michael reaction of dimethyl acetone dicarboxylate on dienone 104 gave the cis decal-in product 106. This result indicates that intermediate 105 underwent a stereoelectronically controlled internal Michael addition to give 106. Without stereoelectronic control in the Michael reaction, there is no apparent reason to prevent the formation of the trans isomer 107. However, if this factor is taken into consideration, examination of molecular models indicates that it seems impossible to obtain isomer 107. 

Notice that wc have confidently assigned the configuration of these compounds without ever being able to see the yellow proton at the ring junction. Since nitrogen can invert rapidly, we know that this decal in-like structure will adopt the more stable trans arrangement at the ring junction. 

The first precise evaluation of the anomeric effect was realized by Descotes and co-workers in 1968 (22). These authors have studied the acid catalyzed isomerization of the cis and trans bicyclic acetals and 6 and found that, at equilibrium, the mixture contains 575S ci and 43% trans at 80°C. The cis isomer is therefore more stable than the trans by 0.17 kcal/mol. The cis isomer has one (stabilizing) anomeric effect whereas the trans isomer 6 has none. Steric interactions in cis acetal were estimated tobel.65 kcal/mol (one gauche form of ji-butane, 0.85 kcal/mol and an OR group axial to cyclohexane, 0.8 kcal/mol). By subtracting an entropy factor (0.42 kcal/ mol at 80 C) caused by the fact that the cis acetal exists as a mixture of two conformations (cis decal in system), they arrived at a value of 1.4 kcal/mol for the anomeric effect. 

The chemical (Gif system) and the electrochemical conversion (Gif-Orsay system) have been compared in the oxidation of six saturated hydrocarbons (cyclohexane, 3-ethylpentane, methylcyclopentane, cis- and traus-decalin and adamantane). The results obtained for pyridine, acetone and pyridine-acetone were similar for both systems. Total or partial replacement of pyridine for acetone affects the selectivity for the secondary position and lowers the ratio ketone secondary alcohol. The formation of the same ratio of cis- and traws-decal-9-ol from either cis- or trans-deca in indicates that tertiary alcohols result from a mechanism essentially radical in nature. The C /C ratio between 6.5 and 32.7 rules out a radical mechanism for the formation of ketones and secondary alcohols. Ratios of 0.14 and 0.4 were reported for radical-type oxidations of adamantane and cis-decalin. Partial replacement of pyridine by methanol, ethanol or f-propanol results in diminished yields and a lower selectivity. Acetone gives comparable yields however, the C /C ratio drops to 0.2-10.7. 

Wylde and Cerveau have examined the n.m.r. spectra of the four 3-dimethylamino-trans-decal-2-ols (345)—(348) and the derived quaternary ammonium iodides (350)—(353) with a view to uncovering conformational distortion. For (345) and (346) the C-2 methine proton has = 7 Hz and 20—22 Hz, respectively these values are unexceptional although in the case of... 

The thallium trinitrate-mediated ring contraction of frani-decal-2-ones has opened up a new route to the hydrindane system, and fluorinative ring contraction of cyclic alkenes to afford difluorocycloalkanes has been induced by iodotoluene difluoride and EtsN-HF. A possible mechanism is shown in Scheme 78. The double bond of the cyclohexene ring is attacked by iodotoluene difluoride activated by HF from the axial direction, followed by the addition of a fluoride ion from the trans direction. Reductive elimination of iodotoluene from the resulting adduct, ring contraction and the addition of the fluoride ion to the carbocation stabilized by fluorine then take place to give the ring-contracted difluorinated product. 

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