Poly(ethylene glycol) (PEG) as an efficient and recyclable reaction medium for the synthesis of dibenz[b,f]-1,4-oxazepine

Reinvestigation of alternative method for the preparation of dibenz[b,f][1,4]oxazepine

“…Our last tentative in the preparation of 7 was based on the usage of 2-fluorobenzaldehyde (a fluoro derivative of 1) in conjunction with polyethylene glycol as was outlined recently [24]. 2-fluorobenzaldehyde is more expensive that 1 (7 fold) but the procedure offered soft conditions to obtain high-yield pure product.…”

“…2-fluorobenzaldehyde is more expensive that 1 (7 fold) but the procedure offered soft conditions to obtain high-yield pure product. Simultaneous mixing of 2-fluorobenzaldehyde, 2-aminophenol (2), K 2 CO 3 and PEG(300) (as was reported [24]) has not conducted us to the considered results. It seems that simultaneous addition of K 2 CO 3 with other reactants causes formation of potassium salt of 2 which alter imine formation and its subsequent cyclization to 7.…”

“…There are different methods for the preparation of 7 [12][13][14][15][16][17][18][19][20][21][22][23][24]. Two pathways starting from different raw materials can be considered for the preparation of this compound (Schemes 1 and 2).…”

“…The last report on the synthesis of 7 was consisted in the reaction of 2-fluorobenzaldehyde (fluoro derivative of 1) with 2-aminophenol using K 2 CO 3 in polyethylene glycol (PEG-400) at 100 C, affording 89% of 7 after 8 h [24].…”

One-pot, clean and energy efficient synthesis of dibenzo[b,f][1,4]oxazepine derivatives promoted by ultrasound

“…In 2008, Jorapur and coworkers reported the synthesis of dibenzo [b,f] [1,4] oxazepine in good yield using high molecular weight poly ethylene glycol, but it suffers from poor substituent tolerance [16]. Recently, hydrogenation and nucleophilic addition to imine dibenzo[b,f] [1,4]oxazepines by using of catalysts such as iridium complex or proline were also reported [17,18].…”