Synthesis, structure, and stereochemistry of the bora derivatives of 1-[(2-hydroxy-1-naphthyl)methyl]proline

Novel chiral bora derivatives of 1-[(2-hydroxy-1-naphthyl)-methyl]proline have been synthesized in over 98% diastereoselectivity. Their structures and stereochemistry were elucidated by means of 2D NMR spectra as well as quantum-mechanical calculation.

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3,4,5,5a-Tetrahydro-8-phenyl-1H,6H-naphtho[1,2-h]pyrrolo[2,1-e][1,3,6,2]dioxazaboronin-6-oneC22H20O3NB[α]D25=-61.0 (c 1.72, CHCl3)

3,4,5,6-Tetrahydro-8-(3-chlorophenyl)-1H,6H-naphtho[1,2-h]pyrrolo[2,1-e][1,3,6,2]dioxazaboronin-6-oneC22H19O3NBCl[α]D25=-25.0 (c 0.35, CH2Cl2)

3,4,5,6-Tetrahydro-8-(3,5-dibromophenyl)-1H,6H-naphtho[1,2-h]pyrrolo[2,1-e][1,3,6,2]dioxazaboronin-6-oneC22H18O3NBBr2[α]D25=-49.7 (c 0.63, CH2Cl2)

3,4,5,6-Tetrahydro-8-hydroxy-1H,6H-naphtho[1,2-h]pyrrolo[2,1-e][1,3,6,2]dioxazaboronin-6-oneC16H16O4NB[α]D25=-126.7 (0.32, DMSO)

3,4,5,6-Tetrahydro-8-methoxy-1H,6H-naphtho[1,2-h]pyrrolo[2,1-e][1,3,6,2]dioxazaboronin-6-oneC17H18O4NB[α]D25=-168.4 (c 1.66, CHCl3)