Synthesis of N-[2-(2-pyridyl)ethyl]-17a-aza-d-homosteroids and their biomimetic copper-mediated ligand hydroxylations with molecular oxygen
摘要:
Starting with the oximes of 3-O-methylestrone and 3-O-methyl-13alpha-estrone we have synthesized 17a-aza steroids as chiral trans- and cis-fused piperidines via a Beckmann rearrangement. These could then be transformed to the corresponding N-[2-(2-pyridyl)ethyl]-17a-aza-steroids. Copper(I) complexes of these bidentate ligands bind and activate molecular oxygen. While the cis-azasteroids are inert towards hydroxylation, in the trans-series hydroxylation occurs beta to the N-atom on the ring (C-16) and in the side chain: The former hydroxylation is completely stereoselective with only the (16R)-epimer being produced while the latter oxidation occurs with low stereoselectivity. The influence of how the copper(I) complexes were prepared on the oxidation behavior is discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.
Synthesis of N-[2-(2-pyridyl)ethyl]-17a-aza-d-homosteroids and their biomimetic copper-mediated ligand hydroxylations with molecular oxygen
摘要:
Starting with the oximes of 3-O-methylestrone and 3-O-methyl-13alpha-estrone we have synthesized 17a-aza steroids as chiral trans- and cis-fused piperidines via a Beckmann rearrangement. These could then be transformed to the corresponding N-[2-(2-pyridyl)ethyl]-17a-aza-steroids. Copper(I) complexes of these bidentate ligands bind and activate molecular oxygen. While the cis-azasteroids are inert towards hydroxylation, in the trans-series hydroxylation occurs beta to the N-atom on the ring (C-16) and in the side chain: The former hydroxylation is completely stereoselective with only the (16R)-epimer being produced while the latter oxidation occurs with low stereoselectivity. The influence of how the copper(I) complexes were prepared on the oxidation behavior is discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.
Starting with the oximes of 3-O-methylestrone and 3-O-methyl-13alpha-estrone we have synthesized 17a-aza steroids as chiral trans- and cis-fused piperidines via a Beckmann rearrangement. These could then be transformed to the corresponding N-[2-(2-pyridyl)ethyl]-17a-aza-steroids. Copper(I) complexes of these bidentate ligands bind and activate molecular oxygen. While the cis-azasteroids are inert towards hydroxylation, in the trans-series hydroxylation occurs beta to the N-atom on the ring (C-16) and in the side chain: The former hydroxylation is completely stereoselective with only the (16R)-epimer being produced while the latter oxidation occurs with low stereoselectivity. The influence of how the copper(I) complexes were prepared on the oxidation behavior is discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.