Sorry!
Since the last word in my query should be "autocomplete" or at least it should propose the best fitting results, I need to use the wildcard "%".
As Mr. Ford says I can't use the multi-chars escaping method ({}), so I need to escape every special char with the backslash "\".
But I found some problems with the escaping of { and }. The official documentation says:
" To include the close brace character in an escaped query expression, use }}."
But if you run the following statements:
INSERT INTO inv_dev VALUES (10, '{}lawnmower');
-- throws an exception
SELECT * FROM inv_dev i
WHERE CONTAINS(i.name,
'<query>
<textquery grammar="context">
<progression>
<seq>{}}law%</seq>
</progression>
</textquery>
<score datatype="FLOAT" algorithm="DEFAULT"/>
<order>
<orderkey> Score DESC </orderkey>
</order>
</query>', 1) > 0;
-- <seq>{}}law%</seq> or <seq>\{}}law%</seq> or <seq>%}}law%</seq> DOESN'T WORK NEITHER
As I already said the example you sent to me works, because it just removes all the non alphnum chars.