Hydroxyl reaction with elemental carbon

In an Interesting extension of the application of the mechanism Involved In the reaction of the 1,5-anhydrorlbltol with calcium chloride, the effect of aqueous calcium chloride on the solubility of neo-lnosltol was Investigated, Neo-lnosltol has two axial hydroxyl groups on opposite carbons In the ring and four equatorial hydroxyl groups between them, and thus has a center of Inversion as an element of Its symmetry. It Is the least soluble of the Inositols, to the extent that It Is not possible to record a Raman spectrum of a solution of neo-lnosltol In water. It was reasoned that If the calcium chloride solution could result In conversion of the neo-lnosltol from the more stable form to the alternate form where two ends of the molecule would have axlal-equatorlal-axlal conformations, the solubility of the Inositol might be enhanced. Such an experiment was carried out, and It was observed that the concentration of neo-lnosltol which entered into solution in the aqueous calcium chloride was Indeed sufficient to permit acquisition of a Raman spectrum. The main bands In the spectrum of the solution did not coincide with those observed In the spectrum of the solid, and thus the Indication Is that the neo-lnosltol in solution is predominately In the alternate conformation and complexed to calcium cations. 

These experiments demonstrate that the C-19 carbon atom detaches itself as formaldehyde from the 19-oxo compound leaving a double bond at C-1 (Fig. 1, pathway a). There could, however, be two other ways in which formaldehyde arises in the eourse of aromatization (1) It is conceivable that formaldehyde is removed from the 19-hydroxy compound (Fig. 1, pathway b) the resulting 19-nor steroid could aromatize after hydroxylation at C-1 or C-2 and subsequent loss of the elements of water. This route, however, does not appear to be followed in placental microsomes, since after incubation in this stem, the relative yield of estradiol-17/8 from 19-nortestosteronc is only one-fifth of that from testosterone (Ryan, 1959a). If 19-nortestosterone is actually an intermediate in this reaction, this compound should give at least the same yield of estradiol-17j8 as that observed with testosterone. (2) The second possibility which does not involve the 19-oxo compound requires the introduction of a double bond into the 19-hydroxy compound (Fig. 1, pathway c). As has been shown by Khrenstein and Otto (1959), the A -19-hydroxy compound aromatizes... 

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