1,2,3-Pentane triol

Returning to another example in Gottlieb s follow-on paper, his Figure 9 is reproduced here as Figure 15. Note that two acceptable names are presented l,6,8-trioxa[6.23]octane and [4.12]pentane-l,4,5-triol. This allowable ambiguity follows the traditional approach of IUPAC in accepting alternate names, rather than maintaining a uniform set of priorities. In the proposed nomenclature, there is exactly one name that is the canonical name ... 

Figure 5.2.11. Cellulose pyrolysate obtained at 59(P C and separated on a methyl silicone with 5% phenyl silicone type column. 1 acetic anhydride, 2 pentanal, 3 2-hydroxybutanedialdehyde, 4 1,4-dioxadiene, 5 tetrahydro-2-furanmethanol, 6 2-(hydroxymethyl)-furan, 7 3-methyl-2-hexanone, 8 2-methoxy-2,3-dihydrofuran, 9 2(5H)-furanone, 10 1-acetyloxypropan-2-one, 11 hydroxycyclopentenone, 12 5-methylfurfural, 13 2,3-dihydro-5-methylfuran-2-one, 14 1-cyclopentylethanone, 15 2-hydroxy-3-methyl-2-cyclopenten-1-one, 16 3,5-dimethylcyclopentan-1,2-dione, 17 unknown, 18 3-ethyl-2,4(3H,5H)-furandione, 19 6-methyl-1,4-dioxaspiro[2,4]heptan-5-one, 20 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one, 21 1,4 3,6-dianhydro-a-D-glucopyranose, 22 5-(hydroxymethyl)-furfural, 23 4-cyclopenten-1,2,3-triol, 24 5-ethyl-3-hydroxy-4-methyl-tetrahydrofuran-2-one, 25 levoglucosan, 26 1,6-anhydro-p-D-glucofuranose.

Let s work through how you might think about the stereochemistry of a simple example, the linear triol 2,3,4-trihydroxypentane or pentane-2,3,4-triol. 

The differences in reactivities in poly(vinyl alcohol)s between isotactic meso) and syndiotactic (trans acetals [26-28] is another example. In extending this to model compounds, reactions of stereo isomers of pentane-2,4-diol and heptane-1,4,6-triol with formaldehyde take place much faster for the meso than for the dl-diol portions [26-28]. Even more important are the steric effects imposed by restricted rotations. For instance, quatemizations of chloromethylated polyether sulfmies exhibit decreasing rates at high degrees of substitution. This can be attributed to restricted rotations of the polymeric chains, because this phenomenon is not observed with more flexible chloromethylated polystyrene under identical conditions [23, 24]. 

A soln. of /er/-butyl benzyloxyacetate in pentane (or ether) treated with dibutyl-borinyl triflate at —78° in the presence of ethyldiisopropylamine, and 3-phenyl-propanal added - product. Y 76% (> 99% 5yn-isomer). The method is compatible with various carboxyl protective groups and is especially useful for substrates which are sensitive to /-PrjNLi. F.e. and with (C5H,)2BOTf, also reduction to the corresponding 1,2,3-triols, s. Y. Sugano, S. Naruto, Chem. Pharm. Bull. 37, 840-2 (1989) a-organothio-analogs s. ibid. 36, 4619-21 (1988). 

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