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Quinuclidines
Quinuclidine is an organic compound with the formula . It is a bicyclic amine that can be viewed as a tied back version of triethylamine. It is a colorless solid. It is used as a reagent (base) and catalyst. It can be prepared by reduction of quinuclidone. Structure and chemical properties Regarding its structure, quinuclidine is unusual in that the methylene hydrogen atoms are eclipsed within each of the three ethylene linkages. Furthermore, the cyclohexane rings, of which there are three, adopt the boat conformations, not the usual chair conformations. Quinuclidine is a relatively strong organic base with p''K''a of the conjugate acid of 11.3. The basicity of other quinuclidines have been evaluated: 3-hydroxy- quinuclidine (9.9), 3-acetoxyquinuclidine (9.3), 3-chloroquinuclidine (8.9), DABCO (8.7), and 3-quinuclidone (7.2). It forms adducts with a variety of Lewis acids. Because of its compact structure, quinuclidine binds to trimethylborane more tightly than does t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quinuclidone
Quinuclidones are a class of bicyclic organic compounds with chemical formula C7H11NO with two structural isomers for the base skeleton 3-quinuclidone and 2-quinuclidone. 3-Quinuclidone (1-azabicyclo .2.2ctan-3-one) is an uneventful molecule that can be synthesized as the hydrochloric acid salt by a Dieckman condensation: The other isomer, 2-quinuclidone, appears equally uneventful, but in fact it has defied synthesis until 2006. The reason is that this molecule is very unstable because its amide group has the amine lone pair and the carbonyl group not properly aligned, as may be expected for an amide, as a result of steric strain. This behaviour is predicted by Bredt's Rule, and formal amide group resembles in fact an amine, as evidenced by the ease of salt formation. The organic synthesis of the tetrafluoroborate salt of 2-quinuclidone is a six-step affair starting from norcamphor the final step being an azide - ketone Schmidt reaction (38% yield): This compound rapi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Quinuclidone
3-Quinuclidinone is a bicyclic organic compounds with chemical formula . Its basicity is indicated by the pKa of the conjugate acid, which is 7.2. In contrast quinuclidine is about 100x more basic. Synthesis and reactions Its hydrochloride salt can be synthesized by a Dieckman condensation: It is a precursor to quinuclidine. Organic reduction of 3-quinuclidone gives the compound quinuclidine, structurally related to DABCO, which has one additional bridgehead nitrogen atom. References {{DEFAULTSORT:Quinuclidone, 3- Quinuclidines Cyclic ketones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
