1088705-88-7Relevant academic research and scientific papers
Asymmetric aza-Henry reaction with α-substituted nitroacetates catalyzed by a bifunctional thiourea-guanidine catalyst
Han, Bo,Huang, Wei,Xu, Zhen Rui,Dong, Xiao Ping
experimental part, p. 923 - 926 (2012/01/11)
The asymmetric aza-Henry reaction of α-substituted nitroacetates and N-Boc imines was achieved with a new-type thiourea-guanidine bifunctional organocatalyst. The novel transformations exhibited high diastereoselectivities, and the adducts bearing adjacent quaternary and tertiary chiral centers were generally obtained in moderate to good enantioselectivities (up to 88% ee).
Discovery of bifunctional thiourea/secondary-amine organocatalysts for the highly stereoselective nitro-Mannich reaction of α-substituted nitroacetates
Han, Bo,Liu, Qing-Ping,Li, Rui,Tian, Xu,Xiong, Xiao-Feng,Deng, Jin-Gen,Chen, Ying-Chun
supporting information; experimental part, p. 8094 - 8097 (2009/09/28)
The readily accessible bifunctional thiourea/secondary-amine organocatalysts for the highly stereoselective Nitro-Mannich reaction of simple esters of α-substituted nitroacids and N-Boc imines were reported. The enantioselectivity of the isomer is found to increase and the N-H group plays a crucial role in the catalytic transition state other than acting as Bronsted base. Good enantioselectivity could be obtained catalyzed by urea-secondary amine and the enantiomeric excess (ee) value is found to decrease in the absence of 4A molecular sieves. In case of methyl 2-nitropropanoiate, excellent diastereo- and enantioselectivities are observed for aryl imines nearing diverse electron-withdrawing or donating substitutions. The nitro-Mannich products resulting from α-phenyl nitroacetate and N-Boc benzaldimine, are found to be labile at ambient temperature due to its crowded structure.
