Hydroxyl group stereoselective transformation

As illustrated, the transformation is stereoselective, displaying a significant preference for formation of the product wherein the ring junction hydrogen and hydroxyl group on the vicinal carbon are cis to one another. Furthermore, in those instances where there are substituents on the tether (e.g., 182a, b), cycliza-... 

There are a number of ways to substitute hydroxylic groups with Cl. The simplest is the reaction with HCl in the presence of an acid catalyst, for example ZnCl2. Reaction with tionyl chloride, SOCI2 is more convenient, as it often allows stereoselective transformation and provides the opportunity to obtain both enantiomers of the product with either the same or the opposite configuration (Fig. 15) ... 

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