Cij-Decalin

The opening of the epoxide in the cij-decalin 24 by acetic acid leads exclusively to the hydroxyacetate 25 (through a kinetically controlled rrani-diaxial opening) rather than to the wanted diastereomer 26 (c/ the stereochemistry of the "southern" part of reserpine). To obtain the correct diastereomer the epoxy-lactone 22 is first formed (Scheme 8.6). Thus the conformation of the cij-decalin system, and therefore that of the substituents, is reversed. The kinetic tran -diaxial opening of the epoxide occurs in a regio- and stereoselective manner to afford compound 28 in which the substituents have the correct position and configuration (a-OH, P-OAc),... 

Only acyclic addition compounds are obtained from monosubstituted 1,6-hepta-dienes. Use of bromine leads only to addition products. lodocylization is also observed when transannular interactions are possible 1,5-cyclodecadiene -> 1,4-diodo-cij-decalin. ... 

The fluorescence of liquid alkanes is supposed to originate entirely from the relaxed 5 1 state. Walter and Lipsky [154], by measuring the fluorescence yields of alkane solutions irradiated with 165 nm photons or Kr beta particles ( niax = 0-67 MeV) relative to benzene fluorescence, determined the following yields 2.3-dimethylbutane G(Si) < 1.3, cyclohexane 1.4-1.7, methylcyclohexane 1.9-2.2, dodecane 3.3-3.9, hexadecane 3.3-3.9, cij-decalin 3.4, and bicyclohexyl 3.5. After reinvestigating the intrinsic quantum yield of cyclohexane fluorescence, Choi et al. published G(Si) = 1.45 for this alkane in Ref. 155. For tra 5-decalin a G(Si) value of 2.8-3.1 has been accepted [65,128,132]. The uncertainties in the values reflect the uncertainties in the intrinsic fluorescence quantum yields. 

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