469904-27-6Relevant articles and documents
Transition-state effects in acid-catalyzed aryl epoxide hydrolyses
Sampson, Kyere,Paik, Augustine,Duvall, Bridget,Whalen, Dale L.
, p. 5204 - 5211 (2004)
The hydronium ion-catalyzed hydrolyses of 5-methoxyindene 1,2-oxide and of 6-methoxy-1,2,3,4-tetrohydronaphthalene-1,2-epoxide were each found to yield 75-80% of cis diol and only 20-25% of trans diol as hydrolysis products. The relative stabilities of the cis and trans diols in each system were determined by treating either cis or trans diols with perchloric acid in water solutions and following the approach to an equilibrium cis/trans mixture as a function of time. These studies establish that the trans diol in each system is more stable than the corresponding cis diol. Thus, acid-catalyzed hydrolysis of each epoxide, which proceeds via a carbocation intermediate, yields the less stable cis diol as the major product. Transition-state effects, presumably of a hydrogen-bonding nature, selectively stabilize the transition state for attack of water on the intermediate 2-hydroxy-1-indanyl carbocation leading to the less stable cis diol in this system. Transition-state effects must also be responsible for formation of the less stable cis diol as the major product in the acid-catalyzed hydrolysis of 5-methoxy-1,2,3,4-tetrahydronaphthalene 1,2-epoxide. However, in this system steric effects at the transition state may be more important than hydrogen bonding in determining the cis/trans diol product ratio. The synthesis of 5-methoxyindene 1,2-oxide and a study of its rate of reaction as a function of pH in water and dioxane-water solutions are reported. Both an acid-catalyzed reaction leading to only diol products and a pH-independent reaction yielding 71% of 5-methoxy-2-indanone and 29% of diols are observed; the half-life of its pH-independent reaction in water is only 2.4 s.
Piperazine compounds
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Page/Page column 9, (2008/06/13)
A compound selected from those of formula (I): wherein: R1, R2, R3 and R4, which may be the same or different, each represent an atom or group selected from hydrogen, halogen, alkyl, alkoxy, phenyl and cyano, X represents a bond, an oxygen atom or a group selected from —(CH2)m—, —OCH2— and —NR5—, wherein m represents 1 or 2, and R5 is as defined in the description, Y represents an oxygen atom or a group selected from NR7 and CHR8, wherein R7 and R8 are as defined in the description, Z represents a nitrogen atom or a CH group, n represents 1 or 2, Ak represents an alkylene chain, Ar represents an aryl or heteroaryl group, its optical isomers, and addition salts thereof with a pharmaceutically acceptable acid. Medical products containing the same which are useful in the treatment of conditions requiring a serotonin reuptake inhibitor and/or NK1 antagonist.
