Sequence rule bonds

Scheme 2.8. Stereoisomeric Alkenes and Related Molecules with the Double-Bond Geometry Named According to the Sequence Rule...

Cahn-Ingold-Prelog sequence rules (Sections 6.5, 9.5) A series of rules for assigning relative priorities to substituent groups on a double-bond carbon atom or on a chirality center. 

Conformations about an sp2-sp2 bond may be similarly designated. It is known that in these cases the stable conformation involves the eclipsing of a double bond by a single bond (25). Therefore, the following symbols are given if A>B>C and X>Y in the Sequence Rule (Scheme 2). 

According to the Sequence Rule, the 1,2 and 1,6 bonds of equatorial cy-clohexanol are both to be described as ap. Although this correctly expresses the achiral disposition of the two fiducial groups, the OH at C(l) and the CH2 at C(2) or C(6), it fails completely in distinguishing between the two bonds (31a... 

Those atoms in sphere N which are of equal rank with respect to those in the preceding sphere (N-l) to which they are bonded are ranked by means of the sequence rules, and these are applied exhaustively in turn first the entire graph is analyzed by Sequence Rule 1 if no decision is reached, Sequence Rule 2 is applied, and so forth. 

An order of precedence is established for the two atoms or groups attached to each end of the double bond according to the sequence rules of Section 19-6. When these rules are applied to l-fluoro-l-chloro-2-bromo-2-iodoethene, the priority sequence is ... 

Sequence Rules for Geometric Isomers and Chiral Compounds. Although cis and trans designations have been used for many years, this approach becomes useless in complex systems. To eliminate confusion when each carbon of a double bond or a chiral center is... 

The conversion of L-glycerol 3-phosphate to a phosphatidic acid does not affect any of the bonds to the stereogenic center, nor does it alter the sequence rule ranking of the substituents. 

The following points should be made here a) In the sequence rules, isotopic differences are to be considered only after all other material differences are exhausted, thus s > OP > OC > lsO= but, 8(>s >, 60=e. b) Resonating P=0 double bonds and negative charges (and sometimes... 

Priorities are assigned to groups by a series of rules known as the Cahn-Ingold-Prelog sequence rules, named after the three chemists who developed them. These rules use the atomic numbers of the atoms attached to the carbons of the double bond. 

Double and triple bonds are split by the sequence rule into two and three single bonds, respectively. The duplicated or triplicated atoms are considered carrying no substituents and are drawn in brackets. Diagrams XII give a few examples. Aromatic... 

A molecular structure such as the one shown in diagram XLII is achiral (presence of a plane of symmetry), but when a b and c = d it can exist in two diastereoisomeric forms. When the two largest or remarkable substituents are on the same side of the double bond, the isomer is cis, and it is designated trans in the other case. Ambiguities have been encountered, and it is recommended to designate as (Z) the isomer with the two sequence rule-preferred substituents on the same side of the double bond (usually the cis-form), and as (E) the other isomer (usually the Wwts-form) (XLIII a>H,c>H) ([53], and refs, therein). 

Klyne and Prelog [72] have proposed a very useful nomenclature for the description of steric relationships across single bonds. In the system A-X-Y-B, the torsion angle about X-Y is defined as exemplified in LXVII, A and B being selected according to criteria derived from the sequence rule (for details, see [72]). The nomenclature of Klyne and Prelog is given in Table 6. 

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