A series of N-2-furoyl and N(2)pyrimidinyl beta-carbolines was discovered to possess potent inhibitors activity against PDE5. During the synthesis we developed a tandem resin quenching protocol. which allowed us to synthesize large number of target compounds in a rapid fashion. Representative Compounds exhibit superior selectivity to sildenafil versus other isozymes of PDEs. and demonstrated in vivo efficacy in increasing introcavernosal pressure in dogs. (C) 2003 Elsevier Science Ltd. All rights reserved.