A" rapid injection" NMR system is described for use on a 360-MHz superconducting spectrometer. The major advantages of the high-field system over our original system are increased sensitivity, resolution, and rapidity. The technique was used to study the ozonolysis of tetramethylethylene and (briefly) cis-but-2-ene, particularly the decomposition of the corresponding primary ozonides 2 and 4, with half-lives of 0.74 and 0.06 s, ...