Synthesis and transformation of sphingosine analogue pinane-based 2-amino-1,3-diols

Abstract

A library of pinane-based 2-amino-1,3-diols, analogues of biologically active sphingosine, was synthesised in a stereoselective manner. Isopinocarveol prepared from (–)-α-pinene was converted to condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray technics. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from commercially available (1R)-(–)-myrtenol. Reduction or alkaline hydrolysis of oxazolidines followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.