substitution, acid catalyst, and temperature. This is particularly useful in the case of the bicyclo[5.4.0]undecanes, which are not readily available.14 Supplementary Material Available: Spectral and other analytical data for 2, 6-10, and 12-16 and crystallographic experimental details, ortep drawings, and tables of positional and thermal parameters and significant distances and angles for 9 and 10 (20 pages). Ordering information is given on any current masthead page.(14) For previous syntheses of the bicyclo[5.4.0]undecane skeleton via intramolecular Diels-Alder reactions, see:

The development of a manufacturing process for the initial commercial production of pyroxsulam sulfonamide herbicide is described. The process encompasses seven reaction steps, and includes a new route to 4-(trifluoromethyl)pyridines, a scaleable method of lithiating a pyridine intermediate, and a sulfiliminecatalyzed formation of a sulfonamide.

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Two concise syntheses of the experimental rice herbicide 2,2dimethyl-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.

Fifteen tetraenes, comprised primarily of methylated analogs of (3E,8E)-1,3,8,10-undecatetraene, were synthesized and treated with acid to study the influence of alkyl substitution on the intramolecular ionic Diels-Alder reaction. Depending on methyl substitution patterns of these tetraenes, bicyclo[4.3.0] nonyl, bicyclo[4.4.0]decyl, and bicyclo[5.4.0]undecyl ring systems were produced. For two tetraenes, the ring preference between two different Diels-Alder-derived ring skeletons could be controlled using different temperatures and acid catalysts. Mechanistically, a stepwise process was postulated for at least some of these Diels-Alder reactions. The irreversible and stereoselective formation of the same Diels-Alder product from two noninterconverting tetraenes, which differed only by the cis-trans relationship of a terminal methyl group, was best explained by a stepwise process. A stepwise process was best demonstrated when intermediate triene products isolated from a reaction mixture irreversibly cyclized to Diels-Alder products when resubmitted to the reaction conditions. Although several of the tetraenes failed to give significant amounts of Diels-Alder products, certain alkyl substitution patterns were identified which generally led to high yields of cyclized products.