2b with 1 in refluxing xylene under a water separator, conditions that we and others' had found useful for conversion of 2a to 3a, led to no observable reaction. As an alternative means of removing the water formed in the reaction, we refluxed the lactone 2b with 3 equiv of 1 (no other solvent) under a Soxhlet apparatus charged with 4A molecular sieve. This was very successful, leading to nearly complete conversion of 2b to 3b in about 6 days, as ...
![ethyl 4-[(1-hydroxy-2-methylpropan-2-yl)amino]butanoate Structure](https://image.chemsrc.com/caspic/249/61484-28-4.png)