A general method of preparation of N-diformylmethylazoles and cycloimonium diformyl methylides

Abstract

Formylation of easily accessible heteroarylacetic acids (R-CH2COOH, R = imidazole, pyrazole, tetrazole, pyridine) afforded in high yields the corresponding trimethinium salts R-C(=CH-N(CH3)2)CH=N(CH3)2)n+ nX- which on alkaline hydrolysis were converted into N-diformylmethylazoles R-C(CHO)=CH-OH. Their quaternization gave cycloimonium diformyl methylides.

A Novel Synthesis of New 1,8‐Naphthyridine Derivatives Using the Reaction of Vinamidinium Salts With 2,6‐Diaminopyridine

“…The most used method of preparation, exemplified in Table , starts from a 2‐substituted vinamidinium salt which is converted into a 1,8‐naphthyridine by means of reaction with 2,6‐diaminopyridine. 2‐Substituted vinamidinium salts were synthesized by means of Vilsmeier‐Arnold formylation . In this study, several conditions were tested at first, including diverse solvents, temperatures, and catalysts in order to find the best reaction conditions for the synthesis of 2a , 2b , 2c , 2d , 2e , 2f , 2g .…”

“…2‐(1‐(Dimethylamino)‐3‐(dimethylimino)prop‐1‐en‐2‐yl)isoquinolinium as 2‐substituted vinamidinium salt was prepared according to procedures described by means of Vilsmeier‐Arnold formylation . To a vigorously stirring solution of 2‐substituted vinamidinium salt (1.0 mmol, 0.454 g) and AcOH (1 mL) in CH 3 CN (7.0 mL), was added dropwise a solution of 2,6‐diaminopyridine (1.0 mmol, 0.109 g) in CH 3 CN (3.0 mmol) under reflux.…”

“…It has been proved that the Vilsmeier‐Haack reagent is a multipurpose reagent which is capable of performing many synthetic transformations . It is applied in formylation , cyclohaloaddition , cyclization and ring annulations . We have synthesized the novel 1,8‐naphthyridine derivatives using the reaction of 2‐substituted vinamidinium salts with 2,6‐diaminopyridine.…”

Synthesis of New Metal-Free 1,4,8,11-Tetraaza[14]annulene Derivatives Using 2-Heteroaryl-substituted Trimethinium Salts

“…All new 6,13‐disubstituted 1,4,8,11‐tetraaza[14]annulene derivatives were synthesized using a two‐step procedure as shown in Schemes : (1) synthesis of 2‐heteroaryl‐substituted trimethinium salts (A, B, and C) by Vilsmeier–Arnold formylation of corresponding N ‐heteroaryl acetic acid salts and (2) synthesis of 1 , 2 , 3 , 4 , 5 (Scheme ), 6 , 7 , 8 , 9 , 10 (Scheme ), and 11 , 12 , 13 , 14 (Scheme ) from salts A, B, or C with the 1,2‐diamines a , b , c , d , or e respectively.…”

Synthesis of Some Bromomethyl‐ and (4‐Bromomethyl)phenyl‐Derivatives of 1,4,8,11 Tetraaza[14] annulene and Their Corresponding Sulfanylmethylene‐Derivatives Using 3‐Substituted Trimethinium Salts

“…The vinamidinium salts A and B were prepared by the standard Vilsmeier–Haack–Arnold formylation reaction of 3‐bromopropanoic acid and [4‐(bromomethyl)phenyl]acetic acid. A mixture of N, N ‐dimethylformamide (0.2 mmol, 1.8 mL) and phosphorus oxytrichloride (0.09 mmol, 8.3 mL) was stirred for 5 min at 0°C.…”