Ethylene linkage

The bromine adds on at the ethylenic linkage to form thedibromo compound (I), which easily loses hydrogen bromide to give the mono-bromo keto ester (II) ... 

The number of ethylenic linkages In a given compound can be established with accuracy by quantitative titration with perbenzoic acid. A solution of the substance ajid excess of perbenzoic acid in chloroform is allowed to stand for several hours at a low temperature and the amount of unreacted perbenzoic acid in solution is determined a blank experiment is run simultaneously. 

By changing the substituents on the ethylenic linkage and exchanging phenyl rings for heteroaromatic rings, photochromic systems that are thermally reversible are transformed into systems that are thermally irreversible but photochemically reversible. The transition between the ben2othiophene-derivative... 

On heating arecoline with ammonia in alcohol, addition occurs at the ethylenic linkage followed by amination at the ester group the products formed are A -methyl-4-aminopiperidinc-3-carboxyamide, m.p. 180° ... 

Lobinine. CigHajOaN. R=Me Ri=CH3.CH2 Ethylenic linkage from C3 to C4. ZsoLobinine. 

These observations suggest a similarity in structure to sparteine, and Orekhov has proposed for aphylline a formula identical with Clemo s formula for oxysparteine (p. 138 (VIII) with the change of CHj at position 10 into CO), aphyllidine having in addition an ethylenic linkage at C — C. ... 

To dehydrolaudanosoline chloride Robinson and Sugasawa, and independently Schopf and Thierfelder ascribe formula (VI), which makes it 2 3 11 12-tetrahydroxy-8-methyldibenzotetrahydropyrrocolinium chloride. The primary tetracetyl-derivative, m.p. 148°, is represented by (VII R = acetyl) and the second acetyl derivative, m.p. 215°, by (VII R = acetyl) with an ethylenic linkage between carbon atoms 15 and 16. Similarly, the initial tetramethoxy-derivative is to be represented by (VI) with the four hydroxyl groups replaced by methoxyl groups the primary product formed on heating, by loss of methyl chloride, will be represented by (VII R = OMe), and the second product, m.p. 201-3°, of the reaction will be represented by (VII R = OMe), with an ethylenic linkage between and C e-... 

Though the Knorr-Horlein formula was generally accepted until 1923, difficulties were frequently encountered in explaining reactions of the morphine alkaloids by it, and in some cases led to suggestions for its modification. Knorr and Horlein adopted an ethylenic linkage at C to because (1) positions C and must, for the reasons given above, be... 

Small and Browning agree with Schbpf and Winterhalder that thebainone methyl enolate (formed by 1 6 addition in which the oxygen bridge is ruptured and ethylenic linkages produced at C —C and C —C ) may be the primary intermediate in tWs reaction since it is hydrogenated... 

On catalytic hydrogenation a-methylmorphimethine yields first a dihydro-derivative oil, B. HCl, m.p. 133°, identical with Freund s de-iV-methyldihydrocodeine, in which the ethylenic linkage at C —C is saturated and finally the tetrahydro-a-methylmorphimethine (II), described above. 

The and -methylmorphimethines (formula, p. 251) are catalytically hydrogenated to hexahydro-derivatives by saturation of the two ethylenic linkages and opening of the oxide ring. The one from the e-form has m.p. 155° and that given by the -form, m.p. 174-5° (Speyer and Koulen ). 

The relationship of psychotrinc and 0-methylpsychotrine to the two pairs of stereoisomerides a) cephaeline -j- tsocephaeline, and (b) emetine + isoemetine respectively, implies that in each of these reductions one ethylenic linkage is saturated and produces one new centre of asymmetry. This ethylenic linkage is assumed to he at to C , so that on this basis the components of each of the stereoisomeric pairs a) and (b) just referred to must he epimeric pairs about C. ... 

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