Efficient, scalable and economical preparation of tris(deuterium)‐ and 13 C‐labelled N ‐methyl‐ N ‐nitroso‐ p ‐toluenesulfonamide (Diazald®) and their conversion to labelled diazomethane

A method for the preparation of multi‐gramme quantities of N ‐methyl‐ d 3 ‐ N ‐nitroso‐ p ‐toluenesulfonamide (Diazald‐ d 3 ) and N ‐methyl‐ 13 C‐N ‐nitroso‐ p ‐toluenesulfonamide (Diazald‐ 13 C ) and their conversion to diazomethane‐ d 2 and diazomethane‐ 13 C , respectively, is presented. This approach uses robust and reliable chemistry, and critically, employs readily commercially available and inexpensive methanol as the label source. Several reactions of labelled diazomethane are also reported, including alkene cyclopropanation, phenol methylation and α‐diazoketone formation, as well as deuterium scrambling in the preparation of diazomethane‐ d 2 and subsequent methyl esterification of benzoic acid.