Spiro nonane-1,6-diols, chiral

A chiral diphosphite based on binaphthol, coordinated with rhodium (I) forming a nine-member ed ring, led to an efficient hydroformylation of vinylarenes, although moderate ees were obtained (up to 46%) at mild pressure and temperature reaction conditions.364 Chiral diphosphites and phosphinite-phosphites derived from spiro[4.4]nonane-l,6-diol were synthesized. Using these catalysts in the asymmetric hydroformylation of styrene, high regioselectivity (97%) and... 

Nieman and Keay198 reported the use of c/.v,c/s-spiro 4,4]nonanc-1, 6-diol as a new chiral auxiliary to be used in asymmetric Diels-Alder reactions. Their best results in a series of reactions between chiral acrylates and cyclopentadiene were obtained when the pivalate ester of ds,ds-spiro[4,4]nonane-l,6-diol was used as the chiral auxiliary. When 318 was treated with cyclopentadiene, the expected endo adduct 319 was obtained with more than 97% de (equation 88). 

The absolute configuration of (-)-spiro[4.4]nonane-l,6-dione was determined by application of Horeau s method of optical rotations.[45] In support of the assignment, and with greater certainty, the Exciton Chirality Rule was applied to the bis-p-dimethylamino-benzoate of the cis,trans-diol obtained following reduction of the diketone. The cis,trans-diol is readily distinguished by NMR from the C2-symmetry cis,cis and rrans,rrans-diols. Since the cis,trans-diol dibenzoate from the (-)-dione exhibits a (-) exciton chirality CD, it follows that the absolute configuration of the dione is that shown in Figure 37. The absolute stereochemistry is easily determined by CD. 

Figure 37. (a) Formation of the ds,trans-diol of (-)-spiro[4.4]nonane-l,6-dione. (b) Observed CD of the bis-p-dimethylaminobenzoate of the cis,trans-diol. (c) Exciton chirality. 

Figure 1 Spiro[4,4]nonane- 1,6-diol and related chiral auxiliaries...

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