No abstract

Non-activated iodides (MeI, EtI, iPrI) provide moderate to good levels of conversion (55−100%) of 1,4-oxazin-2-one (1) into monoalkylated 3-alkyl-1,4-oxazin-2-ones 5, with satisfactory diastereoselectivities (89:11 to 92:8) and reasonably low amounts of dialkylation (0 to 36%). Alkylation of 3-methyl-1,4-oxazin-2-one (5a) occurs with high levels of conversion (82 to 100%), total diastereoselectivity, and only a small amount of O-alkylation, thus providing a three-step During work on the synthesis of unnatural amino acids [1] we prepared and determined the absolute configuration of the chiral 1,4-oxazin-2-one 1, [2] which was easier to obtain than the similar literature compounds 2 [3] and 3. [4] Moreover, the corresponding chiral hydroxy ketone 4, which could be recovered and reused, was easy to handle.Here we present alkylations of oxazinones 1 and 5, as well as a study of the diastereoselective synthesis of type-5 [a]