... CN X S Amine S X NH2 12 5 ... We have arranged this large volume of data in terms of the type of heterocyclic, starting with 5- and 6-membered rings in order to increase the number of hetero atoms. ... 42 ClCO2Et S N H O NHPh 43 CO2Et S 44 N N Ph O OH POCl3/ PCl5 S 45 N ...