We were intrigued by the finding that boron and aluminum catalysts gave opposite enantiomers of 13, each from the same enantiomer of the ligand (Scheme 3). The first thought was that this could be somehow related to the nature of the aldehyde 2a. To test this, a number of other aldehydes were examined (Table ). The reaction of benzaldehyde 18 with diazoacetamide 1a gave the epoxide 24a in 84% yield and 99% ee with the aluminum VAPOL catalyst and in 89% yield and 81% ee with the aluminum VANOL catalyst Table ). Again, this is the opposite enantiomer of 24a that was seen with the (R)-VANOL ligand and the boron catalyst which gave a 98% yield of 24a in 97% ee. As with aldehyde 2a, the VAPOL ligand in the aluminum catalyst gives higher asymmetric induction in epoxide 24a than the VANOL ligand (99% vs 81%, entries 3 and 4). Four of the six aryl aldehydes in Table are converted to the corresponding epoxide in 99% ee with 5 mol% of the aluminum VAPOL catalyst. The exceptions are 4-nitrobenzaldehyde 23 for which the induction in the epoxide 29a can be boosted from 62% to 93% ee with 10 mol% catalyst. The other was 4methoxybenzaldehyde which was a very sluggish substrate giving the epoxide 27a in 11% yield at 50% conversion along with a 10% yield of the corresponding b-ketoamide. It is to be noted that the reaction of benzaldehyde is much faster with the boron catalyst than with the aluminum catalyst (Table and). The reaction of diazoacetamide 1c and benzaldehyde with the 5 mol% of the boron catalyst is complete in 2 h at -40 °C giving 86% yield of 24c, whereas the reaction with 10 mol% of the aluminum catalyst gives a 19% yield at -40 °C after 12 h.