Hetero-Diels-Alder reaction

from Wikipedia, the free encyclopedia

The hetero-Diels-Alder reaction is a name reaction in organic chemistry , named after Otto Diels and Kurt Alder . It is one of the [4 + 2] cycloadditions . In the known Diels-Alder reaction , a 1,3-diene reacts with a dienophile (e.g. an alkene ) via a six-membered transition state to form a cyclohexene derivative. The hetero-Diels-Alder reaction differs from the Diels-Alder reaction in that a ketone , an aldehyde , an imine or a thioketone is used as the dienophile instead of the alkene . In the hetero-Diels-Alder reaction, reaction with the diene creates a six-membered heterocycle with a carbon-carbon double bond.

mechanism

The mechanism of the hetero-Diels-Alder reaction is shown here with an aldehyde as the “dienophile” and with an α, β-unsaturated carbonyl compound as the “diene”. The dienophile reacts with the diene via a six-membered transition state to form a monounsaturated six-membered ring with two oxygen atoms in the ring:

Mechanism of the hetero-Diels-Alder reaction

Aza-Diels-Alder reactions are also known in which a nitrogen atom is located in the dienophile. The enantioselective aza-Diels-Alder reaction of the imine from 4-methoxyaniline and formaldehyde with cyclohexenone is catalyzed by ( S ) -proline and leads to an aza- norbornene derivative.

Examples

For example, the following reactions serve as a dienophile an aldehyde , an imine , and sulfur dioxide (from top to bottom). These all react with different 1,3- dienes :

Mechanism of the hetero-Diels-Alder reaction

Web links

Individual evidence

  1. ↑ Sulan Yao, Steen Saaby, Rita G. Hazell, Karl Anker Jørgensen: Catalytic Enantioselective Aza Diels-Alder Reactions of imine-An Approach to Optically Active α-Amino Acids Nonproteinogenic. In: Chemistry - A European Journal. 6, No. 13, 2000, pp. 2435-2448, doi : 10.1002 / 1521-3765 (20000703) 6:13 <2435 :: AID-CHEM2435> 3.0.CO; 2-Z .
  2. ↑ B. König, J. Martens , K. Praefcke , A. Schönberg , H. Schwarz , R. Zeisberg: Organic sulfur compounds, VIII. Formation of thiophenes by pyrolysis of dihydrothiopyrans, reactions of the Diels-Alder adducts from thiofluorenone and 1, 3-butadiene in the heat and under electron impact. In: Chemical Reports. 107, No. 9, 1974, pp. 2931-2937, DOI: 10.1002 / cber.19741070916 .
  3. ↑ L. Kürti, B. Czakó: Strategic Applications Of Named Reactions In Organic Synthesis . Elsevier Academic Press, 2005, pp. 204 .
  4. ↑ Henrik Sundén, Ismail Ibrahem, Lars Eriksson, Armando Córdova: Direct Catalytic Enantioselective Aza Diels-Alder Reactions. In: Angewandte Chemie International Edition. 44, No. 31, 2005, pp. 4877-4880, DOI: 10.1002 / anie.200500811 .