The laccase-catalyzed domino reaction between catechols and 6-substituted 1,2,3,4-tetrahydro-4-oxo-2-thioxo-5-pyrimidinecarbonitriles using aerial O2 as the oxidant delivers new pyrimidobenzothiazole derivatives. The complete structure elucidation of the ring-proton deficient heterocyclic products and the unambiguous determination of the regioselectivity of the reactions have been achieved by extended NMR spectroscopic methods including HSQMBC, super long-range HMBC, and (15)N measurements.