Hydrochloric Acid → 4-hydroxy-2H-naphtho[2,1-e]-1,2thiazine-3-carboxylic acid methyl ester-1,1-dioxide

HRID 1730532Notes

Reaction equation

[Na].[CH3:2][O:3][C:4](=[O:22])[CH2:5][N:6]1[C:10](=[O:11])[C:9]2[CH:12]=[CH:13][C:14]3[C:19]([C:8]=2[S:7]1(=[O:21])=[O:20])=[CH:18][CH:17]=[CH:16][CH:15]=3.C(O)(C)(C)C.Cl>CO>[CH3:2][O:3][C:4]([C:5]1[NH:6][S:7](=[O:21])(=[O:20])[C:8]2[C:19]3[C:14](=[CH:15][CH:16]=[CH:17][CH:18]=3)[CH:13]=[CH:12][C:9]=2[C:10]=1[OH:11])=[O:22]

Participants

Conditions

Temperature: 60 °C

Procedure

0.90 mol of methanol-free sodium methylate was prepared by dissolving 20.7 gm (0.90 gm-atom) of sodium in 350 ml of absolute methanol, subsequently distilling off the alcohol, and repeated azeotropic distillation with xylene. After addition of 9.15 gm (0.30 mol) of 3-oxo-naphth[2,1-d]isothiazoline-2-acetic acid methyl ester-1,1-dioxide, 250 ml of anhydrous tert.butanol were added. The reaction mixture was slowly heated to 60° C, kept at 60°-65° C for 11/4 hours, and subsequently refluxed for 1 hour. The mixture was allowed to cool, was then decomposed with ice and adjusted to a pH-value of 3-4 with concentrated hydrochloric acid. The solid product which formed was suction-filtered off, washed with water and dried, yielding 72.0 gm (78% of theroy) of 4-hydroxy-2H-naphtho[2,1-e]-1,2-thiazine-3-carboxylic acid methyl ester-1,1 -dioxide, m.p. 218°-220° C (after recrystallizing twice from ethylene chloride).

Workup

distillationsubsequently distilling off the alcohol
distillationdistillation with xylene
additionwere added
customkept at 60°-65° C for 11
custom4 hours
temperaturesubsequently refluxed for 1 hour
temperatureto cool
customThe solid product which formed
filtrationwas suction-filtered off
washwashed with water
customdried

Sources & evidence

ORD record: ord-bd1707ec503a4ac183f0dca0f7bb8e82
Source dataset: uspto-grants-1976_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US03992535

Reaction notes

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