Asymmetric aldol reactions using catalytic d(+)-proline: a new, economic and practical approach to a commonly employed C1–C6 keto-acid synthon of the epothilones
摘要:
A new approach to ketoacid 4, a common C1-C6 fragment used in the total synthesis of epothilones was initiated by direct aldol reaction of acetone with a pivaldehyde-like substance 5, catalyzed with D-proline, leading to a 2,6-diketoalcohol with better than 99% ee. Further intramolecular closure of the diketone 8 followed by oxidation of the silyl protected hydroxycyclohexenone 14 led to the desired product 4. None of the steps have been optimized, yet the overall yield for the four-step process is 31%. The use of commercially available D-proline to construct the chiral center of 4 under very mild reaction conditions provided an economical and practical method for its construction. (C) 2004 Elsevier Ltd. All rights reserved.
Asymmetric aldol reactions using catalytic d(+)-proline: a new, economic and practical approach to a commonly employed C1–C6 keto-acid synthon of the epothilones
摘要:
A new approach to ketoacid 4, a common C1-C6 fragment used in the total synthesis of epothilones was initiated by direct aldol reaction of acetone with a pivaldehyde-like substance 5, catalyzed with D-proline, leading to a 2,6-diketoalcohol with better than 99% ee. Further intramolecular closure of the diketone 8 followed by oxidation of the silyl protected hydroxycyclohexenone 14 led to the desired product 4. None of the steps have been optimized, yet the overall yield for the four-step process is 31%. The use of commercially available D-proline to construct the chiral center of 4 under very mild reaction conditions provided an economical and practical method for its construction. (C) 2004 Elsevier Ltd. All rights reserved.
[EN] SYNTHESIS OF THE C1-C6 KETO-ACID SYNTHON OF THE EPOTHILONES<br/>[FR] SYNTHESE DU SYNTHON CETO-ACIDE EN C1-C6 DES EPOTHILONES
申请人:UNIV MISSISSIPPI
公开号:WO2005054429A2
公开(公告)日:2005-06-16
The present invention relates to alternative methods for producing keto-acid synthons, which are useful for the synthesis of epothilones and analogs and derivatives thereof. A general method according to the present invention broadly comprises performing aldol condensation of a first aldehyde of a general formula: (I) with a carbonyl compound in the form of a ketone or a second aldehyde having a generalized formula: (II) thereby to form a first compound having a generalized formula : (III) and thereafter converting the first compound to a protected keto-`acid synthon of generalized formula: (IV) The present invention is also directed to chemical compounds useful in the synthesis of epothilones and analogs and derivatives thereof and to methods for forming each of these chemical compounds.
Asymmetric aldol reactions using catalytic d(+)-proline: a new, economic and practical approach to a commonly employed C1–C6 keto-acid synthon of the epothilones
作者:Yansong Zheng、Mitchell A Avery
DOI:10.1016/j.tet.2003.12.048
日期:2004.2
A new approach to ketoacid 4, a common C1-C6 fragment used in the total synthesis of epothilones was initiated by direct aldol reaction of acetone with a pivaldehyde-like substance 5, catalyzed with D-proline, leading to a 2,6-diketoalcohol with better than 99% ee. Further intramolecular closure of the diketone 8 followed by oxidation of the silyl protected hydroxycyclohexenone 14 led to the desired product 4. None of the steps have been optimized, yet the overall yield for the four-step process is 31%. The use of commercially available D-proline to construct the chiral center of 4 under very mild reaction conditions provided an economical and practical method for its construction. (C) 2004 Elsevier Ltd. All rights reserved.