212560-70-8Relevant articles and documents
A novel Barton decarboxylation produces a 1,4-phenyl radical rearrangement domino reaction
Manchado, Alejandro,García, Mercedes,Salgado, Mateo M.,Díez, David,Garrido, Narciso M.
, p. 5240 - 5247 (2018)
A novel 1,4-Phenyl radical rearrangement (1,4-PhRR) is described in a typical Barton decarboxylation procedure. While carrying out this reaction in presence of a N,N-disubstituted β-amino acid derivative, the decarboxyphenyl rearranged derivative is obtained, as well as in presence of β-N,N-acylamide. On the other hand, secondary amines give the β-lactam derivative without rearrangement, as well as N-Fmoc derivatives give the normal decarboxylation reaction. In regards of amines which are far away from the carboxylic group, such as δ-amino acid derivatives, the reaction occur through a typical Barton decarboxylation without rearrangement. The diversity of the reaction proves synthetic usefulness paving the way to interesting biologically active compounds.
Direct Synthesis of Chiral NH Lactams via Ru-Catalyzed Asymmetric Reductive Amination/Cyclization Cascade of Keto Acids/Esters
Shi, Yongjie,Tan, Xuefeng,Gao, Shuang,Zhang, Yao,Wang, Jingxin,Zhang, Xumu,Yin, Qin
supporting information, p. 2707 - 2713 (2020/03/30)
Lactams with a stereogenic center adjacent to the N atom have existed in many medicinal agents and bioactive alkaloids. Herein we report a broadly applicable synthesis of enantioenriched NH lactams through a one-pot asymmetric reductive amination/cyclization sequence of easily available keto acids/esters. Such cascade processes alleviate the demand for protecting group manipulations as well as intermediate purification. This strategy is capable of constructing enantioenriched lactams and benzo-lactams of a five-, six-, or seven-membered ring in generally high yield and with excellent enantioselectivities (up to 97% ee). Scalable and concise syntheses of key drug intermediates have further displayed the importance of this methodology.
Conversion of γ- and δ-Keto Esters into Optically Active Lactams. Transaminases in Cascade Processes
Mourelle-Insua, ángela,Zampieri, Luiz Arthur,Lavandera, Iván,Gotor-Fernández, Vicente
supporting information, p. 686 - 695 (2018/02/21)
A one-pot two-step enzymatic strategy has been designed for the production of optically active γ- and δ-lactams in aqueous medium under mild conditions. The approach is based on the biotransamination of ethyl or methyl keto esters bearing different alkyl or aryl substitution patterns at α-position to the ketone functionality. In this manner, the keto esters were transformed into the corresponding amino esters with excellent conversions, which underwent spontaneous cyclisation in the reaction medium without addition of external reagents. Depending on the transaminase selectivity, both lactam enantiomers can be obtained, so initial enzyme screenings were performed using commercially available and made in house enzymes. Reaction conditions were optimised focusing on the substrate concentration, temperature and ratio of amine donor vs acceptor. Thus, ten γ- and δ-lactams were obtained in good to high isolated yields (70–90%) and excellent selectivities (94–99%) after one or two days at 30 or 45 °C. (Figure presented.).
