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By R.H.F Manske, H.L. Holmes

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Extra info for Alkaloids: Chemistry and Pharmacology, Volume 14

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TOMKO AND z. VOTICK+ 36 hydroxyl, and mono- and dimethylamino groups; it was similar to that of cyclobuxine-D (146). Signals due to two tertiary C-methyl groups and one secondary C-methyl group were seen in the PMR spectrum. The proper assignment of the methyl- and dimethylamino groups to the steroidal skeleton was based on the mass spectral fragmentation. To confirm the assumed structure 145 cyclobuxine-B was methylated and compared with cyclobuxine-A (147). The spectra of both preparations were found to be superimposable, thus proving the postulated structural formula and stereochemistry of this base.

Alkaline hydrolysis of 88 yielded the diol89. Through partial oxidation with one equivalent of chromium trioxide, the N-acetyldiol (89)gave the ketone 90. Treatment of this ketone with ethanedithiol-hydrochloric acid, followed by desulfurization of the resulting thioketal 91 with Raney nickel, yielded 92. CH3C0 I) " RO 88 89 90 91 92 R CH&O H H H H R1 CH,CO, a-H OH, a-H 0 SC,H,S H, H 86 21 1. STEROID ALKALOIDS Saponification of the amide 92 furnished the amine 93 which was chlorinated to 94 with N-chlorosuccinimide.

The acid hydrolysis of cycloposine produced D-glucose and veratramine (33),the latter being identified by TLC and by I R spectroscopy. The expected cyclopamine was not obtained since it readily aromatized in ring D in acid conditions t o veratramine. Veratramine could not be the original aglycone of cycloposiiie by reason of the molecular weight, lack of aromatic character, the presence of an ether bridge, and mass spectrometric fragmentation. These results were interpreted as proving the structure of cycloposine t o be 3/3-D-glucosyl-11-deoxojervine (3/3-D-glucosylcyclopamine).

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