Phosphorus oxychloride and DMF

By DMF and phosphorus oxychloride, dithieno[3,2-6 2, 3 -d]-thiophene (6) was converted into the 2-formyl derivative in 93% yield. The production of 2,6-diformyldithieno[3,2-6 2, 3 -[Pg.193]

When DMF and phosphorus oxychloride are reacted together in the Vilsmeier reaction, the A,A-dimethylamino(chloro)methyleniminium cation is generated, and this reacts with indole at 5 °C to give 3-(A,A-dimethylaminomethylene)indolenine (see Section 6.1.2). When hydrolysed by treatment with dilute sodium hydroxide, this gives an excellent yield of 3-formylindole (Scheme 7.5). 

Russian workers (74KGS58) carried out Vilsmeier reactions on 4,5-disubstituted 2-acylthienylamines and cyclized the resulting 3-formyl compounds with substances containing active methylene groups (Scheme 60). A versatile new synthesis of thieno[2,3-6]pyridines is also based on the Vilsmeier formylation of 2-acetamidothiophenes. Whereas with equimolar amounts of DMF and phosphorus oxychloride 3-formyl derivatives are obtained,... 

The formylating agent, also known as the Vilsmeyer-Haack Reagent, is formed in situ from DMF and phosphorus oxychlorid ... 

A kinetic study of the Vilsmeier-Haak formylation of thiophene derivatives in dichloroethane solution has been recently reported.156 Reactions of thiophene and 2-methylthiophene follow third-order kinetics, first-order in substrate, dimethylformamide (DMF), and phosphorus oxychloride. These results are in agreement with a mechanism involving a rapid preequilibrium step leading to an... 

The Vilsmeier-Haack formylation, using DMF and phosphorus oxychloride has been applied to l,6,6aA4-trithiapentalenes (71AHC(l3)161,p. 194.72BSF4181), l-oxa-6,6aA4-... 

---