The present invention relates to a group of unique diazabicyclo alkane derivatives having interesting neurokinin-NK1 receptor antagonistic activity represented by the general formula (1) wherein: R1 represents phenyl, 2-indolyl, 3-indolyl, 3-indazolyl or benzo[b]thiophen-3-yl, which groups may be substituted with halogen or alkyl (1–3C), R2 and R3 independently represent halogen, H, OCH3, CH3 and CF3, R4, R5 and R6 independently represent H, OH, O-alkyl(1–4C), CH2OH, NH2, dialkyl(1–3C)N, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl or morpholin-4-yl substituted with one or two methyl or methoxymethyl groups, morpholin-4-ylamino, morpholin-4-ylmethyl, imidazol-1-yl, thiomorpholin-4-yl, 1,1-dioxothiomorpholin-4-yl or 3-oxa-8-azabicyclo[3.2.1]oct-8-yl; R4 and R5 together may represent a keto, a 1,3-dioxan-2-yl or a 1,3-dioxolan-2-yl group, X represents either O or S, n has the value of 1, 2 or 3, a is the asymmetrical carbon atom 8a, 9a or 10a when n equals 1, 2 or 3 respectively The invention also relates to a method for the preparation of the novel compounds, and to pharmaceutical compositions containing at least one of these compounds as an active ingredient