The incorporation of progestrone-7alpha-(3)H and pregnenolone-7alpha-(3)H into digitoxigenin, gitoxigenin, and digoxigenin in isolated, surviving leaves of Digitalis lanata was demonstrated. In addition, the conversion of pregnenolone to progesterone in the same system was proved. The results tend to indicate that progesterone is as good a precursor of cardenolides as pregnenolone It is suggested that the biosynthesis of cardenolides might proceed through the intermediacy of progesterone.

n-Butyraldehyde and D-glucose condensed to give 4,6-O-butylidene-~glucose , which on reduction yielded 4, B-O-butylidene-~-glucitol ( 1,3-0butylidene-L-gulitol) . Periodate oxidation of either the glucose or glucitol acetal gave 2,4-O-butylidene-~-erythrose, and thence on reduction 1,3-0butylidene-L-erythritol.THIS Paper describes the synthesis and proof of structure of 4,6-0-butylidene-~-glucitol (I) (1,3-0-butylidene-~-gulitol), an acetal which, as expected, was not obtained as an endproduct by direct butylidenation of D-glucitol.n-Butyraldehyde and D-glucose condense in the presence of a trace of concentrated sulphuric acid to yield the expected 4,6-0-butylidene-~-glucose (24-38%).This acetal appears to be dimorphic, one form melting at 150" and the other at 168"; but in chemical reactions or physical properties (infrared spectra in a Nujol mull, paper chromatography and specific rotation) other than melting point the two forms are identical. Both the dimorphs would be expected to have the same conformation as 4,6-0-benzylidene-~-glucose ,2 and from the high initial positive rotation which exhibits a downward directed mutarotation, we would infer that the solid dimorphs are both a-glucoses. The a-configuration was also tentatively assigned to them for their infrared spectra 3 in Nujol mulls. The acetal was characterised through its crystalline 9-nitrophenylhydrazone, the formation of which indicates that C-1 is not involved in the acetal linkage.The acetal consumed 2 mol. of periodate in a slightly acid solution, and liberated 2 mol. of formic acid but no formaldehyde. The major periodate oxidation product was solid 2,4-0-butylidene-~-erythrose. Evidence that the erythrose acetal was not monomeric was (a) that a Nujol mull of the compound showed no carbonyl absorption in the infrared, (b) that the acetal mutarotated in solution, and (c) that a cryoscopic determination of the molecular weight using dry benzene as solvent showed that the acetal was a dimer at infinite dilution. The material became increasingly associated with increase in concentration.Using dry acetic acid as solvent again showed that the solute was associated. Schaffer found that 2,4-0-ethylidene-~erythrose in formaniide has a molecular weight corresponding to 2-16 monomer units (no concentration of solute was stated), and he proposed that two monomer units link together through a 1,3-dioxan ring. A similar structure could exist for the butylidene acetal, for which structure (11) could presumably be a favoured conformation, since the large substituents on all three rings are equatorial.The association was rapidly reversed on dilution.

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The stereochemistry of the 2-aminobicyclononan-9-ones and their reduction products is discussed, and fragmentation reactions of 9-hydroxybicyclononan-2-ylammonium salts are described. New observations are reported on the preparation of 5-carboxycyclo-octene.

The role of deoxycorticosterone in the biosynthesis of digitoxigenin was investigated by the simultaneous administration of deoxy[1,2-(3)H(2)]corticosterone and [4-(14)C]progesterone to a Digitalis lanata plant. The biosynthetically formed [(3)H,(14)C]digitoxigenin and deoxy[(3)H,(14)C]corticosterone were isolated and the distribution of the two isotopes in these products was determined. The transformation of progesterone into deoxycorticosterone in vivo was established. The biosynthetic route from progesterone via deoxycorticosterone to cardenolides was found to be of little significance.