Urea → ethyl (2E)-2H-1,4-benzothiazin-3(4H)-ylideneethanoate

HRID 491344Notes

Reaction equation

HRID 491344 reaction equation
[N+:1]([C:4]1[CH:12]=[CH:11][C:7]2[N:8]=[CH:9][S:10][C:6]=2[CH:5]=1)([O-:3])=[O:2].C(Cl)Cl.S1(C[CH2:21][CH2:20][CH2:19]1)(=O)=O.NC(N)=[O:25].[O:27]1CCO[CH2:29][CH2:28]1>CC#N.C1C=CC=CC=1.C1COCC1.C1COCC1.ClC1C=CC=CC=1.C1(C)C=CC=CC=1.C1C=CC=CC=1.CN(C=O)C>[NH2:8][C:7]1[CH:11]=[CH:12][C:4]([N+:1]([O-:3])=[O:2])=[CH:5][C:6]=1[SH:10].[S:10]1[C:6]2[CH:5]=[CH:4][CH:12]=[CH:11][C:7]=2[NH:8]/[C:21](=[CH:20]/[C:19]([O:27][CH2:28][CH3:29])=[O:25])/[CH2:9]1

Participants

14

Reactant 5

HCID 1176UreaHCID 6344DichloromethaneHCID 312751,4-DioxaneHCID 31347SulfolaneHCID 762566-Nitrobenzothiazole

Product 2

HCID 5303657ethyl (2E)-2H-1,4-benzothiazin-3(4H)-ylideneethanoateHCID 109866912-Amino-5-nitrobenzenethiol

Reagents, catalysts & solvents 7

HCID 241BenzeneSolventHCID 1140TolueneSolventHCID 6228DimethylformamideSolventHCID 6342AcetonitrileSolventHCID 7964ChlorobenzeneSolventHCID 8028TetrahydrofuranSolventHCID 22633675Benzene tetrahydrofuranSolvent

Procedure

(7-Nitro-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,4]thiazin-3-yl)-acetic acid ethyl ester (12b) was prepared by alkylation and cyclization of 2-amino-5-nitro-thiophenol (11) and ethyl 3-chloroacetoacetate (17) to afford ethyl [4H-benzo[1,4]thiazin-(3E)-ylidene]-acetate (12a). The thiophenol 11 was prepared by unraveling 6-nitro-benzothiazole (10; CAS Reg. No. 2942-06-5). The alkylation of thiols and amines is optionally carried out in a solvent or mixture of solvents such as DCM, DMF, PhH, toluene, chlorobenzene, THF, PhH/THF, dioxane, MeCN or sulfolane with an alkylating agent such as an alkyl 3-chloroacetoacetate, optionally in the presence of a tertiary amine organic base or in the presence of an inorganic base, conveniently at temperatures between 0 and 150° C., preferably at temperatures between 0 and 100° C. Cyclization of the intermediate aminoketone occurs spontaneously under the reaction condition to afford 12a. Oxidation of the sulfide to the corresponding sulfone (12a→12b) and hydrolysis of the ethyl ester (12b→13) were carried out using standard protocols to afford 13.

Sources & evidence

ORD record
ord-92f59a423358417897063df09da493a3
Source dataset
uspto-grants-2009_05
Patent number
US07531534B2

Reaction notes

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