Table 1. XPS Results for the Optimization of the Alkylation/Charge–Neutralization Reaction on 2, via Either the Sodium Salt (a–d) or the Protected Acid (e–h) of the Indicated Alkyl halides (See Figure S3).

reactant		conversiona (%)
a	sodium iodoacetate	87
b	sodium bromoacetate	54
c	sodium bromoethane sulfonate	74
d	sodium bromopropane sulfonate	70
e	tert-butyl iodoacetate + deprotection	85
f	tert-butyl bromoacetate + deprotection	93
g	methyl iodoacetate + deprotection	79
h	methyl bromoacetate + deprotection	77

^aBased on conversion to quaternary amine as measured by XPS N 1s narrow scans.