The nonselective synthesis of bisonium chlorofumarates
and mixed onium chlorofumarates 5-7 (Scheme 1) commenced
by reacting in parallel enantiopure (R)-(-)-5¢-
methoxylaudanosine4 (1) and (S)-(+)-cryptostyline III5 (2b)
with 3-chloro-1-propanol and sodium iodide in refluxing
2-butanone.6 This provided trans/cis mixtures (trans/cis refers
to the relationship of the 1-benzyl or 1-phenyl substituent
and the 3-hydroxy-1-propyl chain at N-2) of the corresponding
quaternary ammonium iodides in 3:1 ratios, as indicated
by 1H NMR spectroscopy and HPLC analysis. Ion exchange
followed by preparative HPLC (12% methanol/dichloromethane/
0.25 mL of methanesulfonic acid/L) provided
(1R)-trans-1-benzyl headgroup 3a (95% trans) in 35%
yield. The (1S)-trans/cis-1-phenyl mixture 4ab was used in
the next step without further purification.