The generality of the reaction was investigated with α,βunsaturated aldehydes and benzaldehydes bearing different substituents (Scheme 2). Under our optimized reaction conditions, the reaction works well with both electron donating groups (compounds 11-13, 16) and electron withdrawing groups (compounds 14, 15, and 17) with both para-and ortosubstitution on the aromatic ring giving good yields. A gramscale synthesis of 3 was also viable and could be obtained without using any chromatography. An aldehyde bearing an anthracene-moiety was converted to compound 18 in 87% yield. Moreover, a non-aromatic α,β-unsaturated aldehyde was viable, generating 19 in 70% yield. It was also noted that α,βunsaturated aldehydes with electron donating groups on the aromatic ring required a more electron-rich catalyst 4 to furnish the products. The benzaldehydes, being less activated than their α,β-unsaturated counterpart, required slightly higher loadings of catalyst 4. Good yields were obtained with benzaldehydes containing electron donating groups (20, 21, 23, and 24) whereas electron withdrawing groups was only able to give compound 22 in acceptable yields (43%). The low yields were attributed to the formation of the benzoic acids via direct oxygenative oxidation of the Breslow intermediate with O2. Next, the oxazolidinone-part was investigated (Scheme 3).