Poisoning, quinoline

The synthesis shown above can be modified for preparation of 4-alkylbutenolides (8) by reduction of the acetylenic acid with quinoline-poisoned catalyst (equation II). The optically active bulenolides have been used for a synthesis of optically pure enantiomers of threo- and Aro-4-methy 1-3-heptanols.2... 

In contrast to Lindlar catalyst we have found that the hydrogenation of an alkyne over ethylenediamine-poisoned "P-2" nickel boride or quinoline-poisoned palladium-on-barium sulfate always gives a minor amount of the saturated hydrocarbon in addition to the olefin. The ratio of saturated hydrocarbon to olefin (about 0.01) also is nearly constant throughout the hydrogenation until the alkyne is consumed, and then it increases. Further reaction of the alkene on the catalyst surface before desorption would explain these results. 

Rosenmund reduction , i.e. catalytic hydrogenation, of acid chlorides with poisoned Pd-BaS04 (in the presence of sulfur and quinoline poison) afforded aldehyde. 

Effect of Addition of Sulfur-Refluxed Quinoline Poison added Percentage yield of benzaldehyde... 

ACRIDINE Dibenio [ b,e) Pyridine, 10-Azaanthraccne. Benzo(b)-Quinoline Poison. Ill NL NX NL ... 

A benzene solution of the cyclic dimer 61 when refluxed with a saturated solution of t-BuOK in BuOH gave a red solution of the bisdehydro[20]annulene 63 [62]. The cyclic trimer 62 was rearranged similarly to tridehydro[30]annulene 64. Both species show characteristic UV-vis spectra [62]. The bisdehydro[20]annulene was partially hydrogenated in benzene solution over a Lindlar catalyst (quinoline-poisoned palladium calcium carbonate catalyst). This procedure led to the [20]an-nulene 65. Similarly, the reduction of tridehydro[30]annulene 64 with Lindlar catalyst yielded the [30]annulene 66 [62]. 

Terminal acetylenes are often used as precursors to the E- and Z-olefins. A typical synthesis is that reported by Schwarz and Waters (187) (Scheme 80). The alkali metal salt of the acetylene is coupled with an appropriate alkyl halide to give the acetylenic tetrahydropyranyl ether (444). Sodium in liquid ammonia reduction of the ether stereo-specifically affords.pure -olefins, which can be hydrolyzed to an alcohol and then acetylated. For Z-isomers, the protecting group must first be removed and the alcohol acetylated. Reduction over quinoline-poisoned... 

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