Trans-9-Methyldecalin

An increment system has been derived for methyldecalins [230] and methylated perhy-drophenanthrenes [231] by regressional analysis, because these compounds are steroid models and the increments, in fact, have proved to be of help in carbon-13 shift assignments of steroids (Section 5.2). Eq. (4.2) permits prediction of <5C using the increments A, of structural elements in position l to the carbon atom k to be considered (Table 4.9). These increments clearly indicate the configurational influence of the y substituent, decreasing for example from eclipsed via gauche to trans interactions (I , > Vq > Vt and... 

Propellane upon hydrogenolysis with Pt/AcOH gives almost equal amounts of the CIS- and trans-angular methyldecalins. ... 

Conformational relationships for the three cis-trans pairs of dimethyl-cyclohexanes were examined by Beckett et al. (34). Here the situation becomes more involved than for methylcyclohexane because some of the isomers are dl pairs, each of which can exist as a pair of chair conformations. However, the conformational analysis of this system merits attention because it will provide a nearly complete basis for the conformational analysis of the deoalins, methyldecalins, and dimethyl-decalins in the following sections. 

The relative volatility of tran -onti-2-methyldecalin shifts toward that of trana-ayn-2-methyldecalin at higher temperatures. The actual difference in boiling points at atmospheric pressure may be negligible (see text). 

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