16751-59-0Relevant articles and documents
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Iffland,Yen
, p. 4180 (1954)
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The dutch resolution variant of the classical resolution of racemates by formation of diastereomeric salts: Family behaviour in nucleation inhibition
Dalmolen, Jan,Tiemersma-Wegman, Theodora D.,Nieuwenhuijzen, Jose W.,Van Der Sluis, Marcel,Van Echten, Erik,Vries, Ton R.,Kaptein, Bernard,Broxterman, Quirinius B.,Kellogg, Richard M.
, p. 5619 - 5624 (2007/10/03)
The resolution of racemates through their diastereomeric salts can be positively affected by the addition of small amounts of suitable nucleation inhibitors. This discovery is a logical extension of "Dutch Resolution", in which equimolar amounts of resolving agents that are members of the same family (i.e., structurally related) are used. We conducted a systematic search for nucleation inhibitors of the resolving agent 1-phenylethylamine. A wide range of amines that bear possible family resemblances to 1-phenylethylamine was investigated. It was found that (R)-1-phenylbutylamine is a good inhibitor of (R)-1-phenylethylamine. Results of turbidity measurements showed that, for the model case of mandelic acid resolution, the chief effect of this inhibitor was to widen the metastable zone for the more soluble diastereomer. This observation is in accordance with previous experience. Further scouting for possible family members revealed a wide variation in the effectiveness of inhibitors, dependent on their structure. By far the most effective inhibitors are bifunctional 1-phenylethylamine and/or 1-phenylbutylamine analogues. The effect of racemic inhibitors was found to approach that of enantiomerically pure inhibitors of the same absolute configuration of the 1-phenylethylamine used for resolution. The most effective inhibitors were tested for the resolution of a structural variety of racemates, and were shown to be broadly applicable.
Stereospecific fragmentation of 3-dimethylaminocyclohexanols upon electron impact ionization
Vais,Mandelbaum
, p. 750 - 754 (2007/10/03)
Stereoisomeric cis- and trans-1-butyl-3-dimethylaminocyclohexanols have been previously reported to exhibit different electron impact (EI) mass spectra. The m/z 100 [C6H14N]+ ion is obtained only from the cis-isomer. The results of a collision-induced dissociation study are inconsistent with the previously proposed protonated dimethylaminocyclobutane structure (ion a) and suggest the N,N-dimethyl-1-butaneimmonium (CH3CH2CH2CH=N+(CH3)2) structure (ion b) for this ion. The mechanistic pathway proposed for this highly stereospecific process involves initial hydrogen migration from the hydroxy group to the radical site at the charged amino group as the stereospecific step, this being possible only for the cis-amino alcohol. The EI mass spectra of the corresponding stereoisomeric methyl ethers exhibit preferential elimination of formaldehyde from the cis-isomer, which is explained by initial hydrogen migration from the methoxy group to the N atom. The unsubstituted cis- and trans-1-methoxy-3-dimethylaminocyclohexanes do not show any stereospecificity in their behavior under EI.