3.4- Dimethoxyphenyl- oxazoline

Organoaluminum reagents have been used in the copper-catalyzed conjugate addition to enones with some success. Iwata and co-workers (182) demonstrated that dimethoxyphenyl oxazoline (247) provides modest selectivities in the copper-catalyzed conjugate addition of trimethylaluminum to 3,4,4-trimethylcyclohexadi-enone to provide the adduct in 68% ee, Eq. 145. The use of TBSOTf is crucial to attain high conversion and selectivity in this process. Woodward and co-workers (183) subsequently reported that a Cu(I) complex of thiocarbamate 248 provides modest facial discrimination in the addition of trimethylaluminum to a linear enone to afford 245b in 51% ee, Eq. 146. The authors note that this catalyst system decomposes under the reaction conditions at ambient temperature. 

A. 2-(2,3-Dimethoxyphenyl)-4,4-dimethyl-2-oxazoline. To a 100-mL. round-bottomed flask, fitted with a magnetic stirring bar and a reflux condenser and placed in an ice-water bath, is added 24.5 g (0.206 mol) of thionyl chloride (Note 1). To this is added 12.2 g (0.067 mol) of 2,3-dimethoxybenzoic acid (Note 2). The resulting mixture is stirred at 0°C for 1 hr and then at room temperature for 24 hr. Excess thionyl chloride is removed by rotary evaporation (HOOD ) and the residue is distilled using a Kugelrohr apparatus at 105°C (0.05 mm) to give 12.7-13.1 g of 2,3-dimethoxybenzoyl chloride, which crystallizes on cooling (Note 3). 

Dimethoxyphenyl)-4,4-dimethyl-2-oxazoline Oxazole, 2-(2,3-dimethoxyphenyl)-4,5-dihydro-4,4-dimethyl- (9) (57598-32-0)... 

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