Table 4.

Global Deprotection to the Target α-(2′Z-Fluoro)vinyl-AA’s^a

entry	Rb	AA	yield
a	Me	Ala	89%d
b		Phe	85%d
c		m-Tyr	88%d
d		DOPA	93%d
e		Lys	63%e
f		Asp	52%e

^aProcedure: The fully protected stannylvinyl amino acid (9) was suspended in 6 N HCl and refluxed for 12–30 h.

^bR groups are given as they are found in the educts 9. Under the reaction conditions, the side chain of aspartate is de-esterified, that of lysine is debenzoylated, and those of m-Tyr and DOPA are desilylated. Geometry is assigned as Z as J_1,2(H–F) = 43–46 Hz, as opposed to ≈17 Hz for E, see ref 10].

^dThese fluorovinyl AA’s were isolated as their hydrochloride salts.

^eFurther purified by Dowex 50 cation exchange chromatography.