2,3-dihydro-4H-1-benzothiopyran-4-one oxime synthesis

Yield:15857-68-8 87%

Reaction Conditions:

with pyridine;hydroxylamine hydrochloride at 20; for 3 h;

Steps:

4.1.3. General produce for the preparation of 2,3,4,5-tetrahydro-1Hbenzo[b]azepine by reductive ring expansion

General procedure: Hydroxylamine hydrochloride (2 equiv) was added to a stirredsolution of 3,4-dihydronaphthalen-1(2H)-one in pyridine (1 equiv).After the mixture was stirred for 3 h at room temperature, pyridinewas removed under reduced pressure. Then the products wereisolated following recrystallizations from aqueous ethanol. Moreover, the mixture could be extracted by EtOAc and purified bycolumn chromatography (PE/EA 5/1) to yield corresponding 3,4-dihydronaphthalen-1(2H)-one oxime.DIBALH (1Min n-hexane, 6 equiv)was added to a stirred solutionof 3,4-dihydronaphthalen-1(2H)-one oxime inCH2Cl2 drop by drop at0 C. Then the mixture was transferred to room temperature andstirred for another 2 h. The reaction was quenched carefully byaddition of NaF (12 equiv) and water at 0 C. The aluminum saltprecipitated out as colloid. Then the mixture was stirred at roomtemperature for another 2 h, and aluminumsaltwas filtered as sandlikesolid. The filtrate was dried over Na2SO4 and concentrated invacuo. The crude product was purified by column chromatography(Al2O3, PE/EA 5:1) to give 2,3,4,5-tetrahydro-1H-benzo[b]azepine.Then the designed compounds were obtained as methodsabove.

References:

Guo, Zheng;Zhang, Zixue;Zhang, Yi;Wang, Guan;Huang, Ziyi;Zhang, Qinwei;Li, Jianqi [European Journal of Medicinal Chemistry,2021,vol. 218,art. no. 113383]