The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Synthesis of new cationic BINAP-ruthenium(II) complexes and their use in asymmetric hydrogenation [BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl]》. Authors are Mashima, Kazushi; Kusano, Kohhei; Ohta, Tetsuo; Noyori, Ryoji; Takaya, Hidemasa.The article about the compound:(S)-Methyl 3-hydroxybutanoatecas:53562-86-0,SMILESS:C[C@H](O)CC(OC)=O).Quality Control of (S)-Methyl 3-hydroxybutanoate. Through the article, more information about this compound (cas:53562-86-0) is conveyed.
Reaction of [RuX2(arene)]2 with (S)-BINAP gives cationic BINAP-ruthenium complexes I (X = Cl, Br, iodo; Z = Cl, Br, iodo, BF4, BPh4; arene = C6H6, p-MeC6H4CHMe2) which are efficient catalyst precursors for enantioselective hydrogenation of various prochiral alkenic and ketonic substrates; a crystal structure of I (X = Cl, Z = BF4) was obtained.
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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics