Tosylmethyl isocyanide

Description

Tosylmethyl isocyanide is a versatile synthon in organic chemistry, widely used as a reagent for the preparation of biologically active pyrroles and imidazoles. Tosylmethyl isocyanide undergoes a base-promoted 1,3-dipolar cycloaddition reaction with immobilised imines under microwave irradiation to give 1,5-disubstituted imidazoles.

Chemical properties

Pale yellow to light brown crystalline powder

The Uses of Tosylmethyl isocyanide

Tosylmethyl Isocyanide is used as a synthetic reagent in the preparation of variety or biologically active heterocycles such as pyrroles and imidazoles. Tosylmethyl Isocyanide is reported to inhibit [ Fe]-hydrogenase with very high affinity.

Preparation

N-(p-Tolylsulfonylmethyl)formamide 1609:

A 3-L, three-necked, round-bottomed flask, equipped with a mechanical stirrer, a condenser, and a thermometer, was charged with sodium p-toluenesulfinate 1606 (267 g, 1.5 mol). After the addition of water (750 mL), a 34–37% solution of formaldehyde 1607 (350 mL, 378 g, ca. 4.4 mol), formamide 1608 (600 mL, 680 g, 15 mol), and formic acid (200 mL, 244 g, 5.3 mol), the stirred reaction mixture was heated at 90 C°. The sodium p-toluenesulfinate dissolved during the heating, and the clear solution was kept at 90–95 C° for 2 h. It was then cooled in an ice/salt bath with continued stirring and further cooled overnight in a freezer at 20 C°. The white solid produced was collected by suction filtration. It was washed thoroughly in a beaker by stirring with three 250 mL portions of iced water. The product was dried under reduced pressure over phosphorus pentoxide at 70 C° to provide 134–150 g (42–47%) of crude N-(p-tolylsulfonylmethyl)formamide 1609; mp 106–110 C°. This product was sufficiently pure to be used directly in the following reaction.

Definition

Tosylmethyl isocyanide is a chemical compound of cyanide that Versatile synthon in organic chemistry, especially in the synthesis of heterocyclic Compounds.

What are the applications of Application

Tosylmethyl isocyanide was used:
(1) in the synthesis of triplet drugs with the 1,3,5-trioxazatriquinane skeleton;
(2) as reagent in the preparation of biologically active pyrroles and imidazoles;
(3) as the isonitrile component in a diastereoselective Passerini reaction employing sugar-derived aldehydes.

Purification Methods

Use an efficient fume cupboard. Purify TOSMIC by dissolving (50g) in CH2Cl2 (150mL) and passing it through a column (40x3cm) containing neutral alumina (100g) in CH2Cl2 and eluting with CH2Cl2. A nearly colourless solution (700mL) is collected, evaporated in vacuo and the residue (42-47g) of TOSMIC (m 113-114o dec) is recrystallised once from MeOH (m 116-117o dec). [Hoogenboom et al. Org Synth 57 102 1977, Lensen Tetrahedron Lett 2367 1972.] It also crystallises from EtOH (charcoal) [Saito & Itano, J Chem Soc, Perkin Trans 1 1 1986].

Hazard

Tosylmethyl isocyanide is toxic to humans and may cause irritation on contact; it is toxic by ingestion, inhalation and skin absorption. Short-term exposure to high concentrations of cyanide can damage the brain and heart and can even lead to coma, convulsions, apnoea, cardiac arrest and death. Prolonged inhalation of cyanide can cause breathing difficulties, chest pain, vomiting, blood changes, headaches and goiter. Skin contact with cyanide salts can cause irritation and ulcers.

Toxicity

Cyanide is an inhibitor of cytochrome c oxidase in the fourth complex of the electron transport chain (found in the membrane of the mitochondria of eukaryotic cells). It complexes with the ferric iron atom in this enzyme. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted and the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Cyanide is also known produce some of its toxic effects by binding to catalase, glutathione peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, succinic dehydrogenase, and Cu/Zn superoxide dismutase. Cyanide binds to the ferric ion of methemoglobin to form inactive cyanmethemoglobin.