501419-65-4Relevant academic research and scientific papers
Synthesis of Nonracemic 1,4-Benzoxazines via Ring Opening/Cyclization of Activated Aziridines with 2-Halophenols: Formal Synthesis of Levofloxacin
Mal, Abhijit,Wani, Imtiyaz Ahmad,Goswami, Gaurav,Ghorai, Manas K.
, p. 7907 - 7918 (2018/06/11)
Novel 3,4-dihydro-1,4-benzoxazine derivatives have been synthesized by an efficient and simple method in excellent enantio- and diastereospecificity (ee > 99%, de > 99%). The reaction proceeds via Lewis acid-catalyzed SN2-type ring opening of activated aziridines with 2-halophenols followed by Cu(I)-catalyzed intramolecular C-N cyclization in a stepwise fashion under one-pot conditions to furnish the 3,4-dihydro-1,4-benzoxazine derivatives in excellent yields (up to 95%). The strategy offers a short and efficient synthesis to (S)-3-methyl-1,4-benzoxazine (S)-3v, a late stage intermediate in the synthesis of levofloxacin.
Alumina-supported Cu(II), A versatile and recyclable catalyst for regioselective ring opening of aziridines and epoxides and subsequent cyclization to functionalized 1,4-benzoxazines and 1,4-benzodioxanes
Bhadra, Sukalyan,Adak, Laksmikanta,Samanta, Subhas,Maidul Islam,Mukherjee, Manabendra,Ranu, Brindaban C.
experimental part, p. 8533 - 8541 (2011/03/19)
An easily accessible catalyst, alumina-supported copper(II), efficiently catalyzes the ring opening of aziridines and epoxides followed by cyclization of the corresponding intermediate to produce a variety of functionalized 1,4-benzoxazines and 1,4-benzodioxanes, respectively, in one pot without any ligand in high yields. The ring cleavages of aziridines and epoxides are highly regioselective. The catalyst is inexpensive, non-air-sensitive, environmentally friendly, and recyclable. The function of the catalyst and the reaction pathway are postulated. This protocol is successfully utilized for the formation of three carbon-heteroatom bonds, namely, C-O, C-N, and C-S, in one pot.
