Dextrorotatory compound

X-ray analysis of an optically active oxaziridine substituted at nitrogen with the 1-phenylethyl group of known configuration led to the absolute configuration (+)-(2R,3R)-2-(5-l-phenylethyl)-3-(p-bromophenyl)oxaziridine of the dextrorotatory compound as expected, C-aryl and A-alkyl groups were trans to each other (79MI50800). 

Falk and Schlogl 42> as late as 1968 established the absolute configuration of compound 13a as (+) —(S)-4-carboxy[2.2]paracyclophane. They did this by kinetic resolution of the racemic carboxylic anhydride with ( —)-a-phenylethylamine this kinetically controlled amidation afforded the dextrorotatory compound (13) in 3.8% optical yield 42C The similar topology of the carboxyl-group environment in 13 and in a-substituted metallocene carboxylic acids (14), configurations con-... 

Interestingly, both enantiomers of 5 -methoxypropacin (24) are known and these were isolated from two different plant sources the dextrorotatory compound was... 

Whether a sample is dextrorotatory (abbreviated "(+) ) or levorotatory (abbreviated (-)") is determined experimentally by a polarimeter. Except for the molecule glyceraldehyde, there is no direct, universal correlation between direction of optical rotation ((-i-) and (-)) and designation of configuration (R and 5). In other words, one dextrorotatory compound might have R configuration while a different dextrorotatory compound might have S configuration. 

Table 26.5 shows some experimental data for the active isomers of the fluoro analogs of the tricyclic neuroleptic clotepin as compared to the corresponding racemate. In this example, it appears clearly that the neuroleptic activity is concentrated in the dextrorotatory compound (+)2 whereas the toxicity resides in the (-)3 antipode. 

In reporting either observed or specific rotation, it is common to indicate a dextrorotatory compound with a plus sign in parentheses, (-f), and a levorotatory compound with a minus sign in parentheses, (—). For any pair of enantiomers, one enantiomer is dextrorotatory and the other is levorotatory. For each member, the value of the specific rotation is exactly the same, but the sign is opposite. Following are the specific rotations of the enantiomers of 2-butanol at 25 °C, observed with the D line of sodium ... 

The experimental difficulty with silica gels of this type is that in aqueous suspension they continue to undergo rearrangement of structure, with loss of specific surface area. Also, unless the gel is carefully analyzed for the organic compound present during its formation, there remains some doubt as to whether the agent is completely extracted prior to the test for selectivity. However, in this case it would seem to be relatively certain that the optical activity of the eluate was not due to any organic residue left in the gel, since the eluate exhibited levorotatory activity, whereas the dextrorotatory compound was initially used in the preparation of the gel. 

This compound was first isolated from milk concentrates in two forms differing very significantly in their optical rotation. The dextrorotatory compound was found to be. a highly active growth factor for Saccharomyces cerevisiae (as active as biotin) whereas the levorotatory isomer showed hardly any activity ". The oxidation of biotin with one mole of hydrogen peroxide also yielded both forms which were separated by crystallization and were called [Pg.83]

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