Adamantane derivatives and process for producing them

An adamantane derivative shown by the following formula (1):

• wherein X1 represents a hydroxyl group which may be protected by a protective group, X2 represents nitro group, an amino group or N-substituted amino group which may be protected by a protective group, a hydroxyl group which may be protected by a protective group, a carboxyl group which may be protected by a protective group, a hydroxymethyl group which may be protected by a protective group, or isocyanato group;
• (i) when X2 is nitro group, X3 and X4 are the same or different from each other and each represents a hydrogen atom, an alkyl group, a nitro group, a hydroxyl group which may be protected by a protective group, an amino group or N-substituted amino group which may be protected by a protective group, a carboxyl group which may be protected by a protective group, a hydroxymethyl group which may be protected by a protective group, or an isocyanato group, excluding the case where X3 and X4 are both hydrogen atoms when X1 is hydroxyl group and excluding 1,3,5-trinitro-7-adamantanol;
• (ii) when X2 is an amino group or N-substituted amino group which may be protected by a protective group, X3 and X4 are the same or different from each other and each represents a hydrogen atom, an alkyl group, an amino group or N-substituted amino group which may be protected by a protective group, a hydroxyl group which may be protected by a protective group, a carboxyl group which may be protected by a protective group, a hydroxymethyl group which may be protected by a protective group, or an isocyanato group, excluding the case where X3 and X4 are both hydrogen atoms or alkyl groups when X1 is hydroxyl group;
• (iii) when X2 is a hydroxyl group which may be protected by a protective group, X3 and X4 are the same or different from each other and each represents a hydrogen atom, an alkyl group, a hydroxyl group which may be protected by a protective group, a carboxyl group which may be protected by a protective group, a hydroxymethyl group which may be protected by a protective group, or an isocyanato group, excluding the case where X3 and X4 are both hydrogen atoms or alkyl groups when X1 is hydroxyl group or a saturated aliphatic acyloxy group and X2 is hydroxyl group or a saturated aliphatic acyloxy group and the case where X3 and X4 are a combination of hydrogen atom and a carboxyl group which may be protected by a protective group when X1 and X2 are both hydroxyl groups and excluding the case where each of X1, X2, X3, and X4 are all a hydroxyl group, or all a hydroxyl group protected by an acetyl group;
• (iv) when X2 is a carboxyl group which may be protected by a protective group, X3 and X4 are the same or different from each other and each represents a hydrogen atom, an alkyl group, a carboxyl group which may be protected by a protective group, a hydroxymethyl group which may be protected by a protective group, or an isocyanato group, excluding the case where X3 and X4 are both hydrogen atoms or alkyl groups or a combination of a hydrogen atom and an alkyl group when X1 is a hydroxyl group or a saturated aliphatic acyloxy group;
• (v) when X2 is a hydroxymethyl group which may be protected by a protective group, X3 and X4 are the same or different from each other and each represents a hydrogen atom, an alkyl group, a hydroxymethyl group which may be protected by a protective group, or an isocyanato group, excluding the case where, X3 and X4 are both hydrogen atoms when X1 is hydroxyl group;
• and
• (vi) when X2 is isocyanato group, X3 and X4 are the same or different from each other and each represents a hydrogen atom, an alkyl group or an isocyanato group, excluding the case where, X3 and X4 are both hydrogen atoms when X1 is hydroxyl group;
• or a salt thereof.