SYNTHESIS AND CONFORMATIONAL BEHAVIOR OF 2-PHENYLPERHYDROPYRROLO[1,2-D][1,3,4]OXADIAZINE AND 2-PHENYLPERHYDROPYRIDO[1,2-D][1,3,4]OXADIAZINE- NEW HETEROCYCLIC RING-SYSTEMS

Hydrazino alcohols, 1-amino-2-hydroxymethylpyrrolidine (1) and 1-amino -2-hydroxymethylpiperidine (2), were synthesized and subsequently ring closured with ethyl benzimidate to the title compounds (7) and (8), w hich have new ring systems. Variable-temperature H-1 nmr measurements, supported by X-ray analysis, indicated that pyrrolo[1,2-d][1,3,4]oxad iazine (7) exists exclusively in a cis-fused conformation (in CDCl3 at room temperature), whereas pyrido[1,2-d][1,3,4]oxadiazine (8) adopts a irans-fused conformation.