Novel alcohols of the formula ##STR1## wherein R.sup.a is azido or phthalimido, R.sup.4 is alkyl, cycloalkyl, cycloalkylalkyl, aryl or aralkyl, R.sup.7 and R.sup.8 together are a trimethylene or tetramethylene group which is optionally substituted by hydroxy, alkoxycarbonylamino or acylamino or in which one --CH.sub.2 -- group is replaced by --NH--, --N(alkoxycarbonyl)--, --N(acyl)-- or --S-- or which carries a fused cycloalkane, aromatic or heteroaromatic ring, and R.sup.9 is alkoxycarbonyl, monoalkylcarbamoyl, monoaralkylcarbamoyl, monoarylcarbamoyl or a group of the formula ##STR2## in which R.sup.10 and R.sup.11 each is alkyl, are described along with a process for their manufacture. These alcohols are useful as intermediates, for example in the manufacture of amino acid derivatives having antiviral activity.