Cir-Decalins

The reagent has been used by Magnus in studies directed towards a synthesis of bachrachotoxin (71). A cir-decalin was oxidized selectively at the 7-position without the acetal or triple bond moieties present being affected (equation 37). The reagent has also found use in an approach to forskolin ° cyclohexadienone (72) was prepared by exclusive oxidation at the 7-position of (73 equation 38). 

C. Taillefumier and Y. Chapleur, An entry to enantiomerically pure cir-decalinic structures from carbohydrates, J. Chem. Soc. Chem. Commun. p. 937 (1995). 

Fig. 4.12 State diagrams of colloid-polymer mixtures for q = 0.57 (/ ) and = 1.0 (right) as in Fig. 4.3 but now compared to theoretical GFVT predictions (curves) of Fleer and Tuinier [39]. Experimental data PMMA spheres plus polystyrene polymers in cir-decalin [16, 17]...

Tri-O-acetyl-D-glucal has been used for the synthesis of a number of functionalized cir-decalins, via pyranone 79. Intramolecular Diels-Alder reaction of 79 gives the tricylic intermediate 80. Lithium aluminium hydride reduction affords a 1 1.7 mixture of alcohols which are separated and elaborated to 81 and 82 (Scheme 15). Ferrier rearrangement converts these to cir-decalins 83 the structures of which were proven by single crystal X-ray analysis. ... 

Therefore, nine steps or synthetic operations are necessary in the conessine synthesis for isomerising the cir-B/C decalin system to trans-hIC, a transformation that in the cortisone synthesis is accomplished without any extra step, since it takes place spontaneously in the oxidation step, which, in turn, is necessary to introduce the second angular methyl group and build up ring D of cortisone in a stereoselective manner. Better correlation amongst different synthetic operations would be difficult to find in more recent synthesis of similar complexity and magnitude than that of Sarett. 

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