Interaction of Methyl N-(3-oxoalkyl)carbamates, S-methyl -Carbamates, and -Dithiocarbamates with Sodium Borohydride. Synthesis of Tetrahydro-1,3-oxazin-2-ones and -thiones

The interaction of N-(3-oxoalkyl)carbamates, -thiocarbamates, and -dithiocarbamates with sodium borohydride has been studied. It was shown that reaction proceeds diastereoselectively, and reductive cyclization with the formation of tetrahydro-1,3-oxazin-2-ones and -thiones may occur. The tend to cyclization of the N-(3-hydroxyalkyl)carbamates, -thiocarbamates, and -dithiocarbamates formed as intermediates depends on the number of substituents in the alkyl chain.