CIP selection rules

The addition of lithium dimethyl-, dibutyl-, diphenyl- or 1-butenylcuprate to 2d produced (JiS) 94% ee, ifiS) 95% ee, (jiR) 96% ec, and ifiR) 90% ee, respectively. In this case the difference between S and R results from the CIP selection rules and not to the steric course of the reactions. The conformation of the chiral auxiliary in 1 d is such that one IV-methyl group is axially, the other equatorially, arranged on the bicyclic structure. The reagents attack the double bond from the side opposite to the equatorial iV-methyl group. Other chiral auxiliaries such as a-c14 were less effective15. 

This inversion of configuration is only due to the CIP selection rules and does not correspond to the steric course of the reaction. 

Determining the relative priority a to d) is accomplished by a series of rules, the so-called Cahn-Ingold-Prelog (or CIP) selection rules.1644,15... 

If all the substituents at X or Y are different, the group most preferred according to the CIP sequence rules is selected (examples la, b). 

Selection of the most perfect and reliable electrolyte-anode adjoining method based on CIP techniques was performed as follows. Anode and electrolyte layers in various conditions (press-powder, green compact, partially sintered compact, or sintered ceramics) were jointly isostatically pressed at pressure values from 0.05 to 0.8 GPa. Since the electrolyte layer should be much thinner than the anode one, such joint isostatical pressing, as a rule, had a nature of adpressing the electrolyte powder onto a pre-formed anode compact. The two-layered plate produced by such a way was sintered at 1500°C. Thereafter a cathode layer was build up in a similar manner. Alternatively the cathode layer was applied by molding a slip prepared from a mixture of the powder and alcohol. A green cathode layer on the plate was sintered at 1200°C. 

Deboronation of (S ,absolute configuration merely agrees with the priority order in the CIP rules. This oxide was then stereo-selectively reduced and reboronated with a procedure known to provide inverted products (see Chapter 1, Section 1.3.1). Although the desired eom-pound was obtained in optically pure form, the yield was disappointingly low (24%). 

---