The utility of the dehalogenation–deetherification sequence for the proof of structure of methoxyhalocyclohexanols and methoxyhalocyclopentanols. Synthesis of the cis- and trans-2- and -3-methoxy-cyclohexanols and -cyclopentanols

1967 ◽  
Vol 45 (21) ◽  
pp. 2605-2611 ◽  
Author(s):  
R. A. B. Bannard ◽  
A. A. Casselman ◽  
E. J. Langstaff ◽  
R. Y. Moir
Keyword(s):  
Raney Nickel ◽  
Hydrobromic Acid ◽  
Cis And Trans

An unequivocal proof of structure for the methoxychlorocyclopentanols (I′c–IV′c) was obtained by deetherification with 68% hydrobromic acid at 65–70°, followed by hydrogenolysis with Raney nickel and hydrogen, to the 1,2- and 1,3-cyclopentanediols, in the same manner as the methoxybromocyclohexanols (I–IV) were converted into the 1,2- and 1,3-cyclohexanediols. Hydrogenolysis of the methoxybromocyclohexanols and the methoxychlorocyclopentanols provided stereospeciflc syntheses for the cis- and trans-2- and -3-methoxycy-clohexanols and -cyclopentanols in 80–97% yields. Deetherification of the latter compounds with 68% hydrobromic acid gave the corresponding 1,2- and 1,3-cyclohexanediols and 1,2-cyclopentanediols in 70–90% yields, but only 5–7% yields of the 1,3-cyclopentanediols. For the proof of structure of methoxyhalocyclanols, deetherification should therefore precede, rather than follow, dehalogenation.

SYNTHESES IN THE TERPENE SERIES: VIII. SYNTHESIS OF THE CIS- AND TRANS-ISOMERS OF 7,7,10-TRIMETHYLDECAL-1-ONE. A CONVENIENT MODIFICATION OF THE BROWN HYDRATION REACTION

1959 ◽  
Vol 37 (11) ◽  
pp. 1870-1880 ◽  
Author(s):  
Franz Sondheimer ◽  
Saul Wolfe
Keyword(s):  
Trans Isomer ◽  
Raney Nickel ◽  
Equilibrium Mixture ◽  
Hydration Reaction ◽  
Trans Isomers ◽  
Perbenzoic Acid ◽  
Cis And Trans Isomers ◽  
Cis And Trans

7,7,10-Trimethyl-Δ1(9)-octal-2-one (VII) was converted to the cycloethylenedithioketal (VIII), which on Raney nickel reduction yielded 7,7,10-trimethyl-Δ1(9)-octalin (IX). Oxidation with perbenzoic acid led to the corresponding oxide (X), which could be rearranged in low yield to an equilibrium mixture of 7,7,10-trimethyldecal-1-one consisting essentially of the trans-isomer (XI).A convenient modification of the Brown hydration reaction is described, whereby the necessity of generating diborane or of using diglyme is avoided. 7,7,10-Trimethyl-Δ1(9)-octalin (IX) on Brown hydration using this modification stereospecifically furnished 7,7,10β-tri-methyl-cis-decal-1β-ol (XII), which was oxidized to 7,7,10-trimethyl-cis-decal-1-one (XIII). Isomerization resulted in the above-described equilibrium mixture containing at least 90% of the trans-isomer (XI). Similarly, the previously described 10-methyl-Δ1(9)-octalin (XVI) yielded a mixture of the cis- and trans-isomers of 10-methyldecal-1-one (XIX). Syntheses of 2-methylene-7,7,10-trimethyl-Δ1(9)-octalin (XIV) and of 7,7,10-trimethyl-cis-decal-2,3-dione 3-dithiotrimethylene ketal (XXII) are also described.

Synthetical applications of activated metal catalysts. XXII. The desulphurization of 2,5-Diphenyl-1,4-dithiin

1964 ◽  
Vol 17 (3) ◽  
pp. 353 ◽  
Author(s):  
GM Badger ◽  
P Cheuychit ◽  
WHF Sasse
Keyword(s):  
Raney Nickel ◽  
Hydrogen Content ◽  
Metal Catalysts ◽  
Hydrocarbon Fraction ◽  
Sulphur Atom ◽  
Cis And Trans

The desulphurization of 2,5-diphenyl-1,4-dithiin (II) with a hydrogen-poor Raney nickel (W-7J Raney nickel) has been shown to give 2,4-diphenylthiophen together with three hydrocarbons, viz. cis- and trans-1,3-diphenylbuta-1,3-diene, and 1,3-diphenylcyclobut-1-ene. In another experiment with a Raney nickel having a higher hydrogen content, the hydrocarbon fraction was found to be 1,3-diphenylbut-2- ene. It has been concluded that chemisorption via one sulphur atom leads to 2,4-diphenylthiophen, but that chemisorption via both sulphur atoms leads to the intermediate diradicals (VI) which subsequently react further to give the observed hydrocarbon products.

Trypanocidal Structure-Activity Relationshipfor Cis- and Trans-methylpluviatolide

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
R Silva ◽  
J Saraiva ◽  
S Albuquerque ◽  
C Curti ◽  
PM Donate ◽  
...  
Keyword(s):  
Structure Activity ◽  
Cis And Trans
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