Silyl-alkyn-en-ylamine derivatives

A compound of the formula I:

• wherein R.sub.1 represents a group of formula IIa, IIb, IIc or IId:
• ##STR9## R.sub.2 represents hydrogen or lower alkyl or, R.sub.1 and R.sub.2 together with the carbon atom to which they are attached represent a group of formula IIe, ##STR10## R.sub.3 and R.sub.4 represent independently hydrogen or lower alkyl or, when R.sub.1 represents a group of formula IIa, IIb, IIc or IId, can also represent together a straight-chain C.sub.3 -C.sub.5 alkylene bridge,
• R.sub.8, R.sub.9 and R.sub.10 represent independently lower alkyl or lower alkenyl, and
• m is 0, 1 or 2,
• R.sub.5 and R.sub.6 represent independently hydrogen, halogen, lower alkyl, lower alkoxy or trifluoromethyl,
• X represents oxygen, sulphur, --O--CH.sub.2 --, --S--CH.sub.2 --, --CH.sub.2 -- or --N(R.sub.7)--, wherein R.sub.7 represents hydrogen or lower alkyl,
• p is 1, 2 or 3 and
• s is 3, 4 or 5,
• or an acid addition salt thereof.