Part A: We report the first efforts toward regiospecifically and stereospecifically or stereoselectively C9 and C10 deuterio labelled dihydrosterculic acids. The acids were prepared from (SS,SS)-1,1-bis(p-tolylsulfinyl)methane in a sequence involving an asymmetric Corey–Chaykovsky cyclopropanation and two sulfoxide-lithium exchange reactions. By using a d-1-aldehyde we obtained 9-d-dihydrosterculic acid, with a remote mass label at C18, in a 14% yield and 98% D incorporation (at C9) over 7 linear steps. We also prepared a d-10 alkene, which was readily converted to d-10 dihydrosterculic acid. The deuterium label was installed via a stereospecific lithium-sulfoxide exchange and subsequent quenching with MeOD. Transformation to the d-10 dihydrosterculic acid was completed in analogy to the d-9 congener. Part B: A method for the preparation of gram quantities of N-methyl-d3-N-nitroso-p-toluene sulfonamide (Diazald-d3) and N-methyl-13C-N-nitroso-p-toluene sulfonamide (Diazald-13C) and their conversion to labelled diazomethanes is presented. This method uses robust and straightforward chemistry, and employs readily commercially available and inexpensive methanol as a methyl label source.