321566-90-9Relevant academic research and scientific papers
Diastereoselective ritter-like reaction on cyclic trifluoromethylated N,O-acetals derived from L-tartaric acid
Jamaa, Abdelkhalek Ben,Grellepois, Fabienne
, p. 10360 - 10375 (2018/05/31)
Despite the presence of the highly electron-withdrawing fluorinated substituent, cyclic α-trifluoromethylated N-acyliminium ions were successfully generated from fluorinated O-acetyl-N,O-acetal L-tartaric acid derivatives. The addition of nitriles on these intermediates occurred with high to excellent syn diastereoselectivity and led, in most cases, to oxazolines and amides as single diastereomers. The diastereoselectivity of the addition and the nature of the reaction product depend on the substituents on the hydroxyl groups of the tartaric acid scaffold. This methodology gave access to enantiopure, highly functionalized 5-(trifluoromethyl)pyrrolidin-2-one derivatives, bearing the fluorinated substituent on a tetrasubstituted carbon.
Asymmetric synthesis of gem-difluoromethylenated dihydroxypyrrolizidines and indolizidines
Thaharn, Watcharaporn,Bootwicha, Teerawut,Soorukram, Darunee,Kuhakarn, Chutima,Prabpai, Samran,Kongsaeree, Palangpon,Tuchinda, Patoomratana,Reutrakul, Vichai,Pohmakotr, Manat
, p. 8465 - 8479,15 (2020/09/15)
An asymmetric synthesis of gem-difluoromethylenated dihydroxypyrrolizidines and indolizidines is described. The fluoride-catalyzed nucleophilic addition of PhSCF2SiMe3 (1) to chiral imides was achieved in satisfactory yields to provide mixtures of syn- and anti-isomers 6-9 with moderate to good diastereoselectivities. Reductive cleavage of the phenylsulfanyl group followed by intramolecular radical cyclization of the syn-isomers 6-9 occurred under refluxing conditions to afford the corresponding gem-difluoromethylenated 1-azabicyclic compounds 10-13 in moderate yields as a separable mixture of cis- and trans-isomers. The cis-isomers of compounds 10 and 12 and trans-13 were readily transformed to gem-difluoromethylenated dihydroxypyrrolizidines 20 and 27 and indolizidine 28, respectively, by reductive cleavage of the hydroxyl group and organometallic addition followed by hydrogenolysis.
A study on the racemization step in the synthesis of pyrrolidinols via cyclic α-hydroxyimides
Zheng, Jin-Li,Liu, Hui,Zhang, Yu-Feng,Zhao, Wei,Tong, Jin-Shuan,Ruan, Yuan-Ping,Huang, Pei-Qiang
scheme or table, p. 257 - 263 (2011/05/12)
Analytical HPLC methods for the determination of the enantiomeric excess of N-protected malimides 1 as well as the corresponding pyrrolidinol 5 and tartarimides 2 and 3 have been established. On this basis, a study to reveal the racemization step in the synthesis of pyrrolidinols from α-hydroxyacids, via chiral cyclic α-hydroxyimides, has been undertaken. It was confirmed that the known, one-step method for the synthesis of the N-protected chiral cyclic imides from α-hydroxydiacids proceeded with little racemization, and partial racemization has been proven to occur during the reduction of the resultant imide 1a with LAH to yield the corresponding pyrrolidinol 5. Conditions have been defined in order to avoid racemization in the LAH reduction step.
A versatile approach to pyrrolidine azasugars and homoazasugars based on a highly diastereoselective reductive benzyloxymethylation of protected tartarimide
Zhou, Xiang,Liu, Wen-Jun,Ye, Jian-Liang,Huang, Pei-Qiang
, p. 6346 - 6357 (2008/02/05)
A highly diastereoselective synthesis of enantio-enriched all trans-3,4-dibenzyloxyl-5-benzyloxymethyl-2-pyrrolidinone 13a was developed based on SmI2-mediated benzyloxymethylation of O,O′-dibenzyltartarimide. The versatility of 13a and its antipode as the key building blocks for the asymmetric synthesis of pyrrolidine azasugars and homoazasugars has been demonstrated by elaborating them into naturally occurring DAB 1 (1), LAB 1 (2), N-hydroxyethyl-DAB 1 (4), 6-deoxy-DMDP 7, and 5-epi-radicamine B 36 as well as the reductive ring-opening product 35.
