Isocyanates 3,4-dihydro-4-hydroxy

Ring closures with isocyanates 3,4-Dihydro-4-hydroxy-2H-l,3-benzoxazin-2-ones from o-hydroxyaldehydes and isocyanates... 

Treatment of 172 with aromatic or heteroaromatic isocyanates yielded the expected 4-carbamoyl derivatives 173 claimed to have anti-inflammatory activity.130 4-Carbamoyl-3,4-dihydro-3-hydroxy-2-methyl-2/f-thieno [3,4-e]-and [2,3-e]-l,2-thiazine l,l-dioxides(174and 175) were prepared analogously... 

The 2-oxosulfonamides (e.g., (233)) are versatile reagents and with carbonyl compounds can serve as synthons for a variety of heterocyclic systems including 3,4-dihydro-2//-l,2,4-thiadiazine 1,1-dioxides (234), as exemplified in Scheme 40 <85LA579>. Reaction of the oxosulfonamide with methyl isocyanate produces the 2//-l,2,4-thiadiazin-3(4. -one 1,1-dioxide (235), whereas with phenyl isothiocyanate the 5-hydroxy-5,6-dihydro-2//-l,2,4-thiadiazin-3(4//)-thione 1,1-dioxide (236) is obtained. 

In einer allgemein anwendbaren Synthese konnen t/ireo-a-Amino-jS-hydroxy-carbonsau-ren iiber analoge 4,5-Dihydro-l,3-oxazole aus a-Isocyan-acetamid durch stereoselektive trarcy-Addition von aliphatischen, aromatischenund heteroaromatischen Aldehyden unter... 

Butyl-2,3-dihydro[l,2,4]thiadiazolo[4,5-a]benzimidazol-3-one (111 R = Bu") undergoes exchange of the isocyanate moiety (see Section 8.05.10). With DMAD 2,3-dimethoxycarbonyl-thiazolo[3,2-a]benzimidazole (137) is obtained. The reaction with 4-(l-cyclohexen-l-yl)morpholine gives 10a-hydroxy-6a,7,8,9,10,10a-hexahydrobenzimidazo[2,l-ft][l,3]benzothiazole (138) (Scheme... 

A soln. of methyl isocyanate in toluene followed by triethylamine added to a soln. of 5-nitrosalicylaldehyde in chloroform, the flask stoppered, and allowed to stand 20 hrs. at room temp. 3,4-dihydro-4-hydroxy-3-methyl-6-nitro-2H-l,3-benzoxazin-2-one. Y 80%. F. e. s. R. E. Strube and F. A. Mackellar, R. 83, 1191 (1964) l,3-benzoxazine-2,4-diones s. R. F. Rekker and W. T. Nauta, R. 83, 1039. 

Chloro ulfonyl isocyanate and isoprene in ether give 5-hydroxy-3-methyl-2-pentenoic acid lactone (4-methyl-5,6-dihydro-2-pyrone, XII-98) and 5-amino-3-methyl-3-pentenoic acid lactam (4-methyl-3,6-dihydro-2-pyridone, XII-99) by hydrolysis of intermediate N-sulfochlorides that were not isolated ... 

---