251538-67-7Relevant articles and documents
The effect of substituents on the chiral solvating properties of (S)-1,6-dialkylpiperazine-2,5-diones
Malavasic, Crt,Stanovnik, Branko,Wagger, Jernej,Svete, Jurij
, p. 1364 - 1371 (2011)
The effect of substituents on the chiral solvating properties of 13 different (S)-1,6-dialkylpiperazine-2,5-diones (S)-1a-m and five (3S,6S)-1,3,6-trialkyl analogues (S,S)-1n-r was studied by NMR in CDCl 3 with methyl (RS)-N-benzoylleucinate (R
Regiodivergent Enantioselective γ-Additions of Oxazolones to 2,3-Butadienoates Catalyzed by Phosphines: Synthesis of α,α-Disubstituted α-Amino Acids and N,O-Acetal Derivatives
Wang, Tianli,Yu, Zhaoyuan,Hoon, Ding Long,Phee, Claire Yan,Lan, Yu,Lu, Yixin
, p. 265 - 271 (2016/01/25)
Phosphine-catalyzed regiodivergent enantioselective C-2- and C-4-selective γ-additions of oxazolones to 2,3-butadienoates have been developed. The C-4-selective γ-addition of oxazolones occurred in a highly enantioselective manner when 2-aryl-4-alkyloxazol-5-(4H)-ones were employed as pronucleophiles. With the employment of 2-alkyl-4-aryloxazol-5-(4H)-ones as the donor, C-2-selective γ-addition of oxazolones took place in a highly enantioselective manner. The C-4-selective adducts provided rapid access to optically enriched α,α-disubstituted α-amino acid derivatives, and the C-2-selective products led to facile synthesis of chiral N,O-acetals and γ-lactols. Theoretical studies via DFT calculations suggested that the origin of the observed regioselectivity was due to the distortion energy that resulted from the interaction between the nucleophilic oxazolide and the electrophilic phosphonium intermediate.
