Luisa Maria Rossi

New esters of R-(+)-usnic acid

Abstract By reacting R -(+)-usnic acid ( 1 ) with propionic anhydride and chloroacetyl chloride and pyridine the corresponding diesters at the 8-OH and 9-OH groups ( 2b and c , respectively) were obtained. On reaction of compound 1 with aroyl chlorides and pyridine, the esterification occurred on OH-3 and on the enol form of the acetyl group at C-2 yielding the diesters 3a,c . A tetrabenzoate ( 4a ) and a diacetate-dibenzoate ( 4b ) of compound 1 were also produced.

v-Triazolines. Part I. Synthesis and properties of 5-amino-4-(α-aminoethyl)-1-aryl-4,5-dihydro-v-triazoles

5-Amino-4-(α-aminoethyl)-1-aryl-v-triazolines have been obtained by treating but-1-ene-1,3-diamines with aryl azides. Mixtures of two diastereoisomeric triazolines were always formed. The diastereoisomers were separated in some cases and, on the basis of their n.m.r. spectra, configurations were assigned to the members of each diastereoisomeric pair. These triazolines were rapidly attacked by strong alkali, yielding the corresponding triazoles. The members of a pair of diastereoisomeric triazolines suffer deamination at different rates.

v-Triazolines. Part 7. 3-Arylaminothiophens from hexahydrothiopyrano[3,4-d]-v-triazoles

By treating tetrahydrothiopyran-4-one with secondary amines and aryl azides. 1-aryl-7a-amino-1,3a,4,6,7,7a-hexahydrothiopyrano[3,4-d]-v-triazoles (2) were obtained. On heating with acids, compounds (2) afforded mixtures of the corresponding 3-arylamino-2-methylthiophen (3) and 1-aryl-1,4,6,7-tetrahydrothiopyrano[3,4-d]-v-triazole (4). The triazoles (4) were also obtained on heating compounds (2) with sodium hydroxide in methanol. 3,6-Dihydro-4-morpholino-2H-thiopyran (6) was treated with 4-nitrophenylsulphonyl azide yielding 4-morpholino-3-(4-nitrophenylsulphonylamino)-3,6-dihydro-2H-thiopyran (7). Reaction mechanisms are discussed.

v-Triazolines. Part II. Synthesis and reactions of 5-amino-4-aminomethyl-1-aryl-v-triazolines

5-Amino-4-aminomethyl-1-aryl-v-triazolines are synthesized by treating aryl azides with acrylaldehyde and secondary amines. The triazolines readily react with strong bases yielding the corresponding triazoles. Acids act differently, depending on the kind of the amine residues. When these are strongly basic (aliphatic) the triazoline ring is cleaved with nitrogen evolution. Among the degradation products propane-1,2-dione is identified. When the amine residues are less basic (aromatic) the ring is not cleaved and both the corresponding 1-aryl-v-triazoles and 4-aminomethyl-1-aryl-v-triazoles are obtained. The mechanisms of these reactions are discussed.