Abstract: The present invention provides aza-bicyclo[2.2.1]heptane compounds which are useful for modulating a muscarinic receptor.

Abstract: 2,3-Dioxo-1,2,3,4-tetrahydro-quinoxalinyl derivatives of formula (I), ##STR1## wherein one of the radicals R.sub.1, and R.sub.2 is a group R.sub.5 and the other is a group of formula --CH(R.sub.6)--alk--R.sub.7 (Ia), --alk--CH(R.sub.6 -R.sub.7 (Ib), --alk--N(R.sub.8)--X--R.sub.7 (Ic), --alk--N.sup.+ (R.sub.8)(R.sup.9)--X--R.sub.7 A.sup.- (Id), --alk--O--X--R.sub.7 (Ie) or --alk--S--X--R.sub.7 (If), R.sub.3, R.sub.4 and R.sub.5 are each independently of the others hydrogen, lower alkyl, halogen, trifluoromethyl, cyano or nitro, R.sub.6 is unsubstituted or lower alkylated and/or lower alkanoylated amino, R.sub.