Synthesis of Fluorine-Containing Cyclic α-Amino Acid and α-Amino Phosphonate Derivatives by Alkene Metathesis

The electrophilic imino esters XF2CC(=NPG)CO2Me and imino phosphonates CF3CC(=NPG)P(O)(OR)2 (PG = SO2Ph, Cbz, Boc) were transformed by nucleophilic and then electrophilic additions into fluorine-containing amino esters and amino phosphonates with two pendent alkene chains (XF2C)(CH2=CH(CH2)nC(NPG)(Z)(CH2)mCH=CH2 [Z = CO2Me, P(O)(OR)2]. The ring-closing metathesis was performed on the α-amino ester dienes with Ru=CHPh(Cl)2(PCy3)2 catalyst and afforded five-, six-, and seven-membered cyclic amino esters, whereas the α-aminophosphonate dienes were transformed with RCM catalyst [Ru=C=C=CPh2(Cl)(PCy3)(p-cymene)]OTf to give six- and seven-membered cyclic α-amino-α-(trifluoromethyl)phosphonates.