Cis-1,2-Cyclopentanediol

Problem 13.4 The ir spectra of trans- and cis-1,2-cyclopentanediol show a broad band in the region 3450-3570 cm-1. On dilution with CC14, this band of the cis isomer remains unchanged, but the band of the trans isomer shifts to a higher frequency and becomes sharper. Account for this difference in behavior. ... 

Triphenylbismuth(V) diacetate acts as O-phenylating agent of alcohols. The reaction of cis-1,2-cyclopentanediol catalyzed by a Cu(II) acetate-chiral pyridinyloxazoline combined system gives the mono-phenylation product in up to 50% ee (Scheme 127) (307). 

The mirror image of cis-1,2-cyclopentanediol is identical to and superimposable upon the cis compound itself. By examining the structure a bit more closely, we find that the compound is actually a meso compound. 

The infrared spectrum of cis-1,2-cyclopentanediol has an 0-H stretching band at a lower frequency than for a free -OH group, and this band does not disappear even at high dilution, trans-1,2-Cyclopentanediol shows no such band. Can you suggest a possible explanation ... 

It is known that the absorption band of a group may be shifted by various structural features conjugation, electron withdrawal by a neighboring substituent, angle strain or van der Waals strain, and hydrogen bonding. The structure of cis-1,2-cyclopentanediol (below) reveals an interesting fact. 

Figure 23 Morrison s proposed complexes of the cis-1,2-cyclopentanediol ester of 8-quinolineboronic acid with solvent water and phenol molecules bridging the nitrogen and boron centres. Blue bonds are used to represent dative bonding.

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