Efficient and stereoselective synthesis of threo-β-hydroxy-l-glutamic acid via a tandem (Z)-olefination-conjugate addition
摘要:
threo-beta-Hydroxy-L-glutamic acid I is an attractive target as a biologically active compound and as a chiral synthon. The required beta-hydroxyl group in 1 was efficiently and stereoselectively introduced via an intramolecular conjugate addition of the N-hydroxymethyl group of gamma-amino-alpha,beta-unsaturated (Z)-ester 4. While the corresponding (E)-ester 3 gave a lower selectivity of ca. 5:1 in the intramolecular conjugate addition, a selectivity of up to 70:1 was shown with (Z)-ester 4. The tandem (Z)-olefination-conjugate addition could be achieved by simply changing the reaction conditions to give a selectivity of >20:1. Thus, the target compound I was obtained as its hydrochloride salt in 70% overall yield over four steps from lactol 2. (C) 2009 Elsevier Ltd. All rights reserved.
Efficient and stereoselective synthesis of threo-β-hydroxy-l-glutamic acid via a tandem (Z)-olefination-conjugate addition
摘要:
threo-beta-Hydroxy-L-glutamic acid I is an attractive target as a biologically active compound and as a chiral synthon. The required beta-hydroxyl group in 1 was efficiently and stereoselectively introduced via an intramolecular conjugate addition of the N-hydroxymethyl group of gamma-amino-alpha,beta-unsaturated (Z)-ester 4. While the corresponding (E)-ester 3 gave a lower selectivity of ca. 5:1 in the intramolecular conjugate addition, a selectivity of up to 70:1 was shown with (Z)-ester 4. The tandem (Z)-olefination-conjugate addition could be achieved by simply changing the reaction conditions to give a selectivity of >20:1. Thus, the target compound I was obtained as its hydrochloride salt in 70% overall yield over four steps from lactol 2. (C) 2009 Elsevier Ltd. All rights reserved.
Efficient and stereoselective synthesis of threo-β-hydroxy-l-glutamic acid via a tandem (Z)-olefination-conjugate addition
作者:Hyeonjeong Kim、Dongwon Yoo、Seah Kwon、Young Gyu Kim
DOI:10.1016/j.tetasy.2009.11.023
日期:2009.12
threo-beta-Hydroxy-L-glutamic acid I is an attractive target as a biologically active compound and as a chiral synthon. The required beta-hydroxyl group in 1 was efficiently and stereoselectively introduced via an intramolecular conjugate addition of the N-hydroxymethyl group of gamma-amino-alpha,beta-unsaturated (Z)-ester 4. While the corresponding (E)-ester 3 gave a lower selectivity of ca. 5:1 in the intramolecular conjugate addition, a selectivity of up to 70:1 was shown with (Z)-ester 4. The tandem (Z)-olefination-conjugate addition could be achieved by simply changing the reaction conditions to give a selectivity of >20:1. Thus, the target compound I was obtained as its hydrochloride salt in 70% overall yield over four steps from lactol 2. (C) 2009 Elsevier Ltd. All rights reserved.