Preparation of fused carbocyclic ring derivatives of pyridine

A process for preparing compounds of formula I ##STR11## or acid addition salts thereof, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different and represent hydrogen or alkyl of 1-6 carbon atoms, cycloalkyl of 4-6 carbon atoms, aralkyl of 7-12 carbon atoms, or phenyl groups, any of which groups may be substituted by alkyl of 1-6 carbon atoms, alkoxy of 1-6 carbon atoms, or trifluoromethyl;

• or R.sup.1 and R.sup.2 taken together, or R.sup.2 and R.sup.3 taken together, form a 5, 6 or 7 membered carbocyclic ring which may be saturated or unsaturated and when R.sup.1 and R.sup.2 form a ring, the ring has the same number of carbon atoms as the ring carrying X;
• R.sup.4 and R.sup.5 may also represent alkoxy of 1-6 carbon atoms;
• n is 1, 2 or 3;
• and X is CN, CONH.sub.2, or CSNH.sub.2 ;
• which process comprises treating a compound of formula II ##STR12## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and n are as defined in connection with formula I, and M is sodium, potassium, lithium, or MgHal, where Hal is chlorine, bromine or iodine;
• with a silyl compound of formula III, R.sup.a.sub.x Si(NCY).sub.4-x wherein R.sup.a is selected from electron donating substituents consisting of alkoxy of 1-10 carbon atoms, cycloalkoxy of 4-8 carbon atoms, aralkoxy of 7-12 carbon atoms, phenoxy which may be substituted by alkyl of 1-10 carbon atoms, alkoxy of 1-10 carbon atoms, or trifluoromethyl, the group R.sup.b R.sup.c N- wherein R.sup.b and R.sup.c are selected from alkyl of 1-6 carbon atoms, cycloalkyl of 4-6 carbon atoms, phenyl which may be substituted by alkyl of 1-10 carbon atoms, alkoxy of 1-10 carbon atoms, or trifluoromethyl, and aralkyl of 7-12 carbon atoms or R.sup.b and R.sup.c may be joined to form a pyrrolidinyl or piperidinyl ring with the nitrogen atom which may be substituted by alkyl of 1-10 carbon atoms, alkylthio of 1-10 carbon atoms, cycloalkylthio of 4-8 carbon atoms, aralkylthio of 7-12 carbon atoms, phenylthio which may be substituted by alkyl of 1-10 carbon atoms, alkoxy of 1-10 carbon atoms, or trifluoromethyl, and hydrocarbon substituents selected from alkyl of 1-10 carbon atoms, cycloalkyl of 4-8 carbon atoms, aralkyl of 7-12 carbon atoms, or phenyl which may be substituted by alkyl of 1-10 carbon atoms, alkoxy of 1-10 carbon atoms, or trifluoromethyl, at least one group R.sup.a being an electron donating substituent, Y is oxygen or sulphur, x has a value from 1 to 3, then subjecting the product to hydrolysis or alcoholysis, with the proviso that when a compound of formula I in which X is CN is desired the molar ratio of compound R.sup.a.sub.x Si(NCY).sub.4-x to compound II is at least 2:1 and x is 3 and y is S and, if desired, isolating the product as an acid addition salt.