The yield was 0.15 g.n.sub.D.sup.20 1.6342In accordance with the same method as in the above examples, the compounds of the formula (I) are shown in the following tables.In the tables, -- for R.sup.3 and R.sup.4 means n is 0 and in such case, the corresponding ring-structure is 5-membered heterocyclic ring.The case where X is a sulfur atom and the formula (I) represents the following formula: --