Process Chemistry Related to the Experimental Rice Herbicide 2,2-Dimethyl-1-(4-methylthio-5-pyrimidinyl)indane

Two concise syntheses of the experimental rice herbicide 2,2-dimethyl-1-(4-methylthio-5-pyrimidinyl)indane are reported. The initial synthesis relies on a low-temperature addition of 5-lithio-4-methylthiopyrimidine to 2,2-dimethyl-1-indanone to construct the pyrimidinylindane system. Process improvements to this route are described and resulted in the preparation of 90 kg of the title compound on pilot plant scale. Economics dictated the need to identify a new synthetic route which utilized inexpensive raw materials. Detailed herein is the initial discovery of a new route which features a novel combination of dissolving metal reduction/formylation/cyclization to construct the requisite pyrimidine ring. Process improvements to this chemistry have allowed us to deliver an appropriately substituted pyrimidinylindane in a minimal number of synthetic operations.