[Synthesis of tert-butylcyclopentane-fused 1,3-oxazines and 1,3-thiazines].

Chlorosulphonyl isocyanate (CSI) addition to 4-tert-butylcyclopentene furnished the azetidinone (3) in a stereospecific reaction. Azetidinone 3 was transformed by ring opening esterification and lithium aluminium hydride (LAH) reduction to the 2-hydroxy-methyl-4-tert-butyl-1-cyclopentylamine (6). The N-methyl-aminoalcohol (8) was prepared from amino esters (5) with ethyl chloroformate and subsequent LAH reduction. By different ring-closure methods, a number of tert-butyl-cyclopentante-fused 1,3-oxazines and 1,3-thiazines were synthesized. A comparative study of the prepared compounds was performed by IR, 1H- and 13C-NMR, DEPT and DNOE measurements.