33694-15-4Relevant academic research and scientific papers
Organocatalytic Asymmetric Annulation between Hydroxymaleimides and Nitrosoarenes: Stereoselective Preparation of Chiral Quaternary N-Hydroxyindolines
Yang, Yu,Ren, Hong-Xia,Chen, Feng,Zhang, Zheng-Bing,Zou, Ying,Chen, Chao,Song, Xiang-Jia,Tian, Fang,Peng, Lin,Wang, Li-Xin
supporting information, p. 2805 - 2808 (2017/06/07)
An unusual and highly effective asymmetric annulation of nitrosoarenes with hydroxymaleimides catalyzed by a chiral bifunctional amine squaramide catalyst has been disclosed. A wide range of highly fused chiral N-hydroxyindolines with two consecutive quaternary stereocenters and multifunctional groups were directly and effectively prepared in excellent yields (up to >99%) with complete regioselective cyclization and excellent stereoselectivities (up to >99:1 dr and >99% ee). The efficiency and potentials of the new reaction and the target chiral entities were well demonstrated by delicate transformations into a series of new chiral indolines.
2-HALOVINYL ARYL SULFONES: NEW COUPLING REAGENTS FOR CARBOXAMIDE FORMATION
Shimagaki, Masayuki,Koshiji, Hiroko,Oishi, Takeshi
, p. 45 - 58 (2007/10/02)
E-2-Chlorovinyl p-nitrophenyl sulfone 6 and 2-bromo-2-trifluoromethylvinyl phenyl sulfone 7a reacted with carboxylic acids in the presence of a molar equiv of Et3N affording the corresponding 2-acyloxyvinyl sulfones 8, 11, 17, 18, 22, 25, 28 and 29.The latter, on treatment with amines, gave amides 9, 13, 19, 23 and 26 and peptides 30 and 32.These reagents 6 and 7a were also used for the formation of N-methylanilides 13d, 13e, 19d, 23 and 26.Particularly, 6 was successfully used for synthesis of a macrocyclic lactam 23 involving a N-methylanilide moiety.The amidation reac tions proceeded under essentially neutral conditions.Therefore, base-sensitive β-hydroxycarboxy-N-methylanilides such as 26, whose structural unit was involved in maytansine 5, could be prepared by the present method.The reagent 6 was also effective for the preparation of peptides such as Val-N-MeVal derivatives (e.g.32), which were difficult to prepare by other methods.
