STEREOCHEMICAL STUDIES 136. SATURATED HETEROCYCLES 141. SYNTHESIS AND CONFORMATIONAL STUDY OF STEREOISOMERIC 2,2-DISUBSTITUTED-5,6-TRI- AND -5,6-TETRAMETHYLENE-TETRAHYDRO-1,3-OXAZIN-4-ONES

Article abstract of DOI:10.1016/S0040-4020(01)86898-8

Diastereomers of 2,2-disubstituted-5,6-tri- and 5,6-tetramethylenetetrahydro-1,3-oxazin-ones (5a,b-12a,b) were synthesized from cis-2-hydroxycyclopentane and -cyclohexanecarboxamides (3,4) by condensing them with 2-butanone, 3-methyl-2-butanone, 3,3-dimetyl-2-butanone or acetophenone.The stereoselectivity of the ring closure depends on the steric requirements of the C-2 geminal substituents, although the predominant conformation (O-in) remains the same in both sets of heterocycles.