Stereogenic atoms center

The P-atom in sarin (9.84), soman (9.85), and tabun (9.87) is a stereogen-ic center, allowing for stereoselective enzymatic hydrolysis [162], This aspect has been extensively investigated for soman, which exists as four stereoisomers by virtue of the presence of a second stereogenic center (C-atom). These stereoisomers are usually designated as C(+)P(-), C(-)P(+), C(+)P(+), and C(-)P(-), where C(+/-) refers to the 1,2,2-trimethylpropyl moiety and P(+/ ) to the P-atom. Such a nomenclature may be convenient but has no implication for the absolute configuration. The C(+)P( ) and Cf-)P(-) epimers are the more active toward acetylcholinesterase and, hence, the more toxic ones. In contrast, the C(+)P(+) and C(-)P(+) epimers are preferentially hydrolyzed... 

Asymmetric Atom (Center) - This is an outdated term that usually should be replaced by stereogenic center (unit). 

The term stereocenter (stereogenic atom) is not consistently defined. The original (Mislow) definition is given here. Some sources simply define it as a synonym for an asymmetric carbon (chiral carbon) or for a chirality center. 

The thermal rearrangement of allylic xanthates to allylic dithiocarbonates is a well-known reaction which results in the creation of a new stereogenic carbon center when the starting xanthate contains an unsymmetrically substituted C-C double bond. Moreover, in the case of chiral xanthates this rearrangement is accompanied by the transfer of chirality from the stereogenic carbon atom in the substrate to the newly created stcrcogcnic center in the product. 

A chirality center (or chiral center ) is one type of stereogenic center or, simply, stereocenter. A stereogenic atom is defined as one bonded to several groups of such nature that interchange of any two groups produces a stereoisomer. See E. L. Eliel and S. H. Wilen, Stereochemistry of Organic Compounds, Wiley-Interscience New York, 1994, p. 53. 

Section 7.16 Atoms other than carbon can be stereogenic centers. Examples include those based on tetracoordinate silicon and tricoordinate sulfur as the stereogenic atom. In principle, tricoordinate nitrogen can be a stereogenic center in compounds of the type N(x, y, z), where x, y, and z are different, but inversion of the nitrogen pyramid is so fast that racemization occurs virtually instantly at room temperature. 

For (-) castoramine (56) Rule 6 allows a priority determination that assigns the stereogenic nitrogen center as (R). Just as a nitrogen atom can be stereogenic, a phosphorus atom in a phosphine such as 53 can be considered chiral since the rate of inversion is negligible at temperatures up to = 130°C, as noted in Table 1.4. The lone pair electrons have the lowest priority by Rule 6 and the absolute configuration is (R). 

Stereogenic center (Section 5.4) When the exchange of two groups bonded to the same atom produces stereoisomers, the atom is said to be a stereogenic atom, or stereogenic center. 

Although stereogenic sulfur centers had been used as the source of chiral auxiliaries and hgands [190-195], organocatalysts incorporating chirality solely through the sulfur atom had been almost overlooked in the hterature before the development of... 

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