Yang Da-cheng
2003
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Journal
Chinese Journal of Medicinal Chemistry
Abstract
Aim To study on the synthetic methodology of benzyl O-benzyl-L-serinate hydrochloride.Methods The key intermediate of benzyl O-benzyl-N-t-butyloxycarbonyl-L-serinate[Boc-Ser(Bzl)-OBzl,Ⅲ]was synthesized by the reaction of O-benzyl-N-t-butyloxycarbonyl-L-serine[Boc-Ser(Bzl)-OH,]which was prepared from L-Ser(Bzl)and Boc 2O/NaOH with Bzl-Br/Et 3N(THF/11℃ or EtOAc/reflux),PhCH 2OH/DCC and PhCH 2OH/CDI.The deprotecting Boc group from Boc-Ser(Bzl)-OBzl,the target molecule HCl·Ser(Bzl)-OBzl were obtained using saturated HCl/EtOAc or HCl/EtOH,respectively.Results Boc-Ser(Bzl)-OH was prepared from L-Ser(Bzl)and Boc 2O in 1 mol/L NaOH in the yield of 83.7%.Boc-Ser(Bzl)-OBzl was obtained by the reaction of Boc-Ser(Bzl)-OH with PhCH 2Br under the reaction condition of Et 3N/THF(11℃/11 h) or Et 3N/EtOAc(reflux/5 h) in the yield of 51.1% and 81.3%,respectively.Ⅲ can also be synthesized using Boc-Ser(Bzl)-OH and PhCH 2OH as reactants via the activating reagent of CDI or DCC/HOBt in the yield of 76.1% and 65%~90%,respectively.The removal Boc group from Boc-Ser(Bzl)-OBzl using saturated HCl/EtOAc or HCl/EtOH,the target molecule HCl·Ser(Bzl)-OBzl were acquired in the yield of 60%~84%.Conclusion As the starting material,L-Ser(Bzl)-OH reacted with Boc 2O to produceⅡ.Interacting with Bzl-Br/Et 3N(THF/11℃ or EtOAc/reflux),PhCH 2OH/DCC and PhCH 2OH/CDI,Ⅱ was turned into Ⅲ with the yield between the middle and high yields smoothly.Among all of them,Bzl-Br/Et 3N/EtOAc/reflux is most facile and fastest,the yield over 81%.The experimental result demonstrates that HCl/EtOAc is better than HCl/EtOH and the yield is between 60% and 84%.The structures of these compounds were confirmed by 1H-NMR and/or 13C-NMR.