Xxvii

Bingham R C, M J S Dewar and D H Lo 1975c. Ground States of Molecules. XXVII. MNDO/S. 

GENERAL INDEXES TO VOLUMES I-XXVII OF MAIN SERIES AND FIRST SUPPLEMENT AND ALSO TO SECOND SUPPLEMENT ... 

M. E. WiUiams, in K. Y. Marcaccio, ed.. Gale Directory of Databases, Gale Research Institute, Detroit, 1993, pp. xvii—xxvii. 

The importance of tropinone as a possible starting-point for the production of the therapeutically valuable alkaloids atropine, hyoscyamine, cocaine, tropacocaine and the artificial tropeines (p. 73) led Robinson to consider the possibility of preparing this substance by a simple method. Starting with the idea that the formula for tropinone (XXX) may be regarded as made up of the formulae of the residues of succindialdehyde (XXVII), methylamine (XXV III) and acetone (XXIX), he found that a mixture of these substances in water, when allowed to stand for thirty minutes produced tropinone, which could be detected by means of its characteristic dipiperonylidene derivative (bright yellow needles, m.p. 214°). 

Constitution. Comparison of the empirical formula of the three alkaloids, and the fact that jatrorrhizine and columbamine each stands to palmatine in the relation of a monohydric phenol to its methyl ether, makes it clear that the only difference between jatrorrhizine and columbamine must be in the position of the free hydroxyl group. The method by which this point was settled is described in dealing with the two tetrahydro-derivatives of these alkaloids (p. 291). The constitution of palmatine (XXV R = R = Me) is dealt with under tetrahydropalmatine, but it is still necessary to describe the complete synthesis of this alkaloid via oxypalmatine (XXVII) and tetrahydropalmatine. 

This loeation of the double bond in the neo-bases in juxtaposition to N(6) was at first eonsidered to favour formula (XXV) rather than (XXVII) for stryehnine. In (XXVII) a double bond eould be inserted at C —C , C —C or C —C, and the possibilities of eaeh position were discussed in detail. In the meantime Chakravarti and Robinson found that brucine and strychnine can be converted easily into neobrucine and ncostrycbnine... 

N—C(CHO) This is taken to imply that the unsaturation in the wco-bases lies between C and C (XXVII), i.e., in the change from strychnine to neostrychnine (XXVIII) the ethylenic linkage moves one step nearer Nfi). 

Analogues of vomicidine are produced by the electrolytic reduction of proximate derivatives of vomicine, still containing the lactam group, e.g., isoVomicine, C22H24O4N2 isovomicidine, C22H2SO3N2, m.p. 290° (dec.) (Part XXVII). 

Intramolecular addition of the amide group to the triple bond in pyrazoles is more difficult, and results in closure of the 5-lactam rather than the y-lactam ring. The reaction time of the 4-phenylethynylpyrazole-3-carboxylic acid amide under the same conditions is extended to 42 h (Scheme 129) (Table XXVII). The cyclization of l-methyl-4-phenylethynyl-l//-pyrazole-3-carboxylic acid amide, in which the acetylene substituent is located in the 7r-electron-rich position of the heterocycle, is the only one complete after 107 h (Scheme 130) (90IZV2089). 

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