Street et al., J. Med. Chem. 35, 293-305 (1992) disclose the cortical muscarinic activity of a group of quinuclidinyl and 1-azanorbonyl pyrazine derivatives.
DE 3839385 discloses some alkyl, alkenyl or alkinyl ether derivatives of quinuclidine as muscarinic receptor agonist s.
E.P. 0,458,214 discloses variously substituted ethers of 1-azabicyclic alkanes as muscarinic agonists.
U.S. Pat. No. 5,082,843 discloses a series of N-heteroaryl ethers of azabicyclic alkanes as 5-HT.sub.3 antagonists.
Ward et al., J. Med. Chem. 35,4011 (1992) disclose a series of 3-(3-substituted-pyrazinyl)-1,2,5,6-tetrahydro-1-methylpyridines having high affinity for the central muscarinic receptors.