Synthesis of enantiomeric spirooxazolines and spirooxazolidines by the regioselective ring closure of (-)-α-pinene-based aminodiols

Abstract

Starting from (1R,2S,3S,5R)-2-benzylaminomethyl-6,6-dimethylbicyclo[3.1.1] heptane-2,3-diol (4) and (1R,2S,3S,5R)-2-aminomethyl-6,6-dimethylbicyclo[3.1.1] heptane-2,3-diol (5), spirooxazolines and spirooxazolidines were prepared. In the reactions of 4 and 5 with alkyl or aryl isothiocyanate, the ring closure proceeded regioselectively and resulted only in spiro derivatives of 2-aryl- and alkyliminooxazolidines 12-17. The primary aminodiol 5 was transformed with ethyl 4-chlorobenzimidate to a spiro-2-(4-chlorophenyl)oxazoline 18 in a highly regioselective ring closure. The reaction of 5 with formaldehyde resulted in tetracyclic compound 19. ©ARKAT USA, Inc.