Improved asymmetric synthesis of dopamine D1 full agonist, dihydrexidine, employing chiral ligand-controlled asymmetric conjugate addition of aryllithium to a nitroalkene
摘要:
Asymmetric conjugate addition of 2-trityloxymethylpheyllithium to a nitroalkene was mediated by a chiral ligand to give the key intermediate for dopamine D1 full agonist dihydrexidine 1. The shortcut of both Curtius rearrangement and Pictet-Spengler type cyclization, which were the drawback of the previously reported synthesis involving asymmetric conjugate addition of phenyllithium to an enoate, was realized by the newly developed asymmetric reaction. Short and efficient synthetic way gave optically pure dihydrexidine in 45% overall yield via eight steps. Improved synthesis of the best chiral ligand 13 was realized under the Buchwald conditions. (C) 2004 Elsevier Ltd. All rights reserved.
PROCESS FOR PREPARATION OF ERIBULIN AND INTERMEDIATES THEREOF
申请人:DR. REDDY'S LABORATORIES LIMITED
公开号:US20190276470A1
公开(公告)日:2019-09-12
The present application relate to process for preparation of tetrahydrofuran compound of formula II, 4-Methylene tetrahydrofuran compound of formula V and tetrahydropyran compound of formula IX which are useful as intermediates for the preparation of halichondrin B analogues such as Eribulin or its pharmaceutically acceptable salts.
Enantioselective reaction of benzaldehyde 4-anisidineimine 1 with methyllithium in toluene was mediated by a series of chiral aminoethers 3-11 to give the corresponding amine 2 in good to moderate ee. The chiral tridentate aminoethers 7-11 are superior to the bidentate ligands 3-6, Lithium bromide affects significantly the enantioselectivity in the catalytic reaction, but not in the stoichiometric reaction.
Optical Resolution of 2-Amino-1,2-diphenylethanol by Preferential Crystallization and Its Utilization in Fractional Crystallization and Enantioselective Reduction of Prochiral Ketones
3-endo-benzamido-5-norbornene-2-endo-carboxylic acid. Chiralhydrides prepared fromlithiumaluminiumhydride and optically active threo- or erythro-2-amino-1,2-diphenylethanol derivatives were applied to the enantioface differentiating reduction of prochiral ketones to give the corresponding optically active alcohols in 26–72% optical purities.
Improved asymmetric synthesis of dopamine D1 full agonist, dihydrexidine, employing chiral ligand-controlled asymmetric conjugate addition of aryllithium to a nitroalkene
Asymmetric conjugate addition of 2-trityloxymethylpheyllithium to a nitroalkene was mediated by a chiral ligand to give the key intermediate for dopamine D1 full agonist dihydrexidine 1. The shortcut of both Curtius rearrangement and Pictet-Spengler type cyclization, which were the drawback of the previously reported synthesis involving asymmetric conjugate addition of phenyllithium to an enoate, was realized by the newly developed asymmetric reaction. Short and efficient synthetic way gave optically pure dihydrexidine in 45% overall yield via eight steps. Improved synthesis of the best chiral ligand 13 was realized under the Buchwald conditions. (C) 2004 Elsevier Ltd. All rights reserved.