Self-reproduction of chirality on α-aminophosphonates: asymmetric synthesis of α-alkylated diethyl pyrrolidin-2-yl-phosphonate
摘要:
A simple method for the asymmetric synthesis of alpha-substituted diethyl pyrrolidin-2-yl-phosphonate is described. The chiral oxazolopyrrolidine phosphonate was alkylated diastereospecifically with an alkyl halide. The key intermediate is an alpha-phosphonate-stabilized carbanion that can be alkylated without loss of optical activity and a single enantiomer of product was formed exclusively in 10-80% yield. The configurational assignment of the products relied on H-1-H-1 NOESY analysis of the alkylated oxazolopyrrolidine phosphonates. This represents an unprecedented case of self-regeneration of stereocenters (SRS) of cyclic aminophosphonates. The enantiomerically pure alpha-aminophosphonate dietlhyl-(2S)-(2-methylpyrrolidin-2-yl)-phosphonate, a surrogate of 2-methyl proline, was obtained upon hydrogenolysis of the chiral auxiliary in 83% yield. (C) 2004 Elsevier Ltd. All rights reserved.
Self-reproduction of chirality on α-aminophosphonates: asymmetric synthesis of α-alkylated diethyl pyrrolidin-2-yl-phosphonate
摘要:
A simple method for the asymmetric synthesis of alpha-substituted diethyl pyrrolidin-2-yl-phosphonate is described. The chiral oxazolopyrrolidine phosphonate was alkylated diastereospecifically with an alkyl halide. The key intermediate is an alpha-phosphonate-stabilized carbanion that can be alkylated without loss of optical activity and a single enantiomer of product was formed exclusively in 10-80% yield. The configurational assignment of the products relied on H-1-H-1 NOESY analysis of the alkylated oxazolopyrrolidine phosphonates. This represents an unprecedented case of self-regeneration of stereocenters (SRS) of cyclic aminophosphonates. The enantiomerically pure alpha-aminophosphonate dietlhyl-(2S)-(2-methylpyrrolidin-2-yl)-phosphonate, a surrogate of 2-methyl proline, was obtained upon hydrogenolysis of the chiral auxiliary in 83% yield. (C) 2004 Elsevier Ltd. All rights reserved.
Aminophosphonates as organocatalysts in the direct asymmetric aldol reaction: towards syn selectivity in the presence of Lewis bases
作者:Peter Dinér、Mohamed Amedjkouh
DOI:10.1039/b605091c
日期:——
and their performance was evaluated as organocatalysts in the direct asymmetric aldol reaction. High enantioselectivities (up to 99% ee) were achieved for a range of substituted cyclohexanones and benzaldehydes. Several organic bases, such as DBU, DBN, and TMG, were used together with the alpha-aminophosphonates in the aldol reactions and were found to favor syn-selectivity.
Pyrrolidine Analogues of Lobelane: Relationship of Affinity for the Dihydrotetrabenazine Binding Site with Function of the Vesicular Monoamine Transporter 2 (VMAT2)
作者:Ashish P. Vartak、Justin R. Nickell、Jaturaporn Chagkutip、Linda P. Dwoskin、Peter A. Crooks
DOI:10.1021/jm900770h
日期:2009.12.10
Ring size reduction of the central piperidine ring of lobelane yielded pyrrolidine analogues that showed marked inconsistencies in their ability to bind to the dihydrotetrabenazine (DTBZ) binding site on the vesicular mono-amine transporter-2 (VMAT2) and their ability to inhibit VMAT2 function. The structure-activity relationships indicate that structural modification within the pyrrolidine series resulted in analogues that interact with two different sites, i.e., the DTBZ binding site and all alternative site on VMAT2 to inhibit transporter function.
Self-reproduction of chirality on α-aminophosphonates: asymmetric synthesis of α-alkylated diethyl pyrrolidin-2-yl-phosphonate
作者:Mohamed Amedjkouh、Kristina Westerlund
DOI:10.1016/j.tetlet.2004.04.009
日期:2004.6
A simple method for the asymmetric synthesis of alpha-substituted diethyl pyrrolidin-2-yl-phosphonate is described. The chiral oxazolopyrrolidine phosphonate was alkylated diastereospecifically with an alkyl halide. The key intermediate is an alpha-phosphonate-stabilized carbanion that can be alkylated without loss of optical activity and a single enantiomer of product was formed exclusively in 10-80% yield. The configurational assignment of the products relied on H-1-H-1 NOESY analysis of the alkylated oxazolopyrrolidine phosphonates. This represents an unprecedented case of self-regeneration of stereocenters (SRS) of cyclic aminophosphonates. The enantiomerically pure alpha-aminophosphonate dietlhyl-(2S)-(2-methylpyrrolidin-2-yl)-phosphonate, a surrogate of 2-methyl proline, was obtained upon hydrogenolysis of the chiral auxiliary in 83% yield. (C) 2004 Elsevier Ltd. All rights reserved.