Method and catalyst for synthesising aziridine

A method of synthesising aziridine (III) or a salt thereof, said method comprising contacting imine (I) or a salt, with a diazo compound (II) or a salt thereof, in a solvent comprising a mixture of halocarbons, in the presence of a catalyst:

• wherein R1, R2 and R3 are each independently a hydrogen atom, a halogen atom or a substituted or unsubstituted, straight-chain, branched or cyclic alkyl, alkenyl, alkynyl, acyl, aryl, arylalkyl, arylalkenyl, arylalkynyl, alkylaryl, alkenylaryl or alkynylaryl group which optionally includes one or more heteroatoms in its carbon skeleton, and wherein any two or more of R1, R2 and R3 together with the atom or atoms to which they are attached may form a cyclic hydrocarbyl group which may optionally be substituted and which may optionally include one or more heteroatoms N, O or S in its carbon skeleton;
• wherein R4 and R5 are each independently a hydrogen atom, a halogen atom or a substituted or unsubstituted, straight-chain, branched or cyclic alkyl, alkenyl, alkynyl, acyl, aryl, arylalkyl, arylalkenyl, arylalkynyl, alkylaryl, alkenylaryl or alkynylaryl group which optionally includes one or more heteroatoms in its carbon skeleton, and wherein R4 and R5 together with the atom or atoms to which they are attached may form a cyclic hydrocarbyl group which may optionally be substituted and which may optionally include one or more heteroatoms N, O or S in its carbon skeleton;
• wherein the catalyst is a compound of formula (IV) or a salt thereof:
• wherein:
• X is O;
• R6 is —SO2—Re;
• Re is a substituted or unsubstituted, straight-chain, branched or cyclic alkyl, alkenyl, aryl, arylalkyl, arylalkenyl, alkylaryl, or alkenylaryl group which optionally includes one or more heteroatoms in its carbon skeleton;
• R7 and R8 together form a chiral bidentate ligand of formula (VIb), (VIb′) or (VIb″):
• wherein Y6 and Y7 are each independently selected from a substituted or unsubstituted aryl or alkylaryl group which optionally includes one or more heteroatoms in its carbon skeleton;
• and
• wherein optionally the imine (I), and/or the diazo compound (II) are isotopically labelled such that the resultant aziridine (III) is also isotopically labelled.