Recoverable Phospha-Michael Additions Catalyzed by a 4- N , N -Dimethylaminopyridinium Saccharinate Salt or a Fluorous Long-Chained Pyridine: Two Types of Reusable Base Catalysts. - Tessema, Eskedar; Elakkat, Vijayanath; Chiu, Chiao-Fan; Zheng, Jing-Hung; Chan, Ka Long; Shen, Chia-Rui; Zhang, Peng; Lu, Norman; Puglisi, Alessandra (Molecules, 2021)