Method of preparing amine stereoisomers

A compound of formula

• wherein A1 is (R7)R7′N+ Q− in which Q− is an anion and each of R7 and R7′ independently represents substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl, or two substituents R7 together with the nitrogen atom to which they are attached and, optionally R8, form an unsubstituted or substituted heterocyclic group, or one R7 substituent together with the nitrogen atom to which it is attached and the carbon atom to which the nitrogen atom is attached form an unsubstituted or substituted heterocyclic group;
• A2 is O, S or NR7c in which R7c is substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl;
• and each of R8, R9, R10 and R11 is independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl, or R8 and R11 together form a substituted or unsubstituted alkylene or heteroalkylene chain, or a salt thereof.