Pomeranz–Fritsch reaction

In today's world, interest in Pomeranz–Fritsch reaction has been constantly increasing. Whether due to its relevance today or its impact on history, Pomeranz–Fritsch reaction has captured the attention of a wide audience. Over the years, debates, research and studies have been generated that have delved into its meaning and significance. Both in the academic and popular spheres, Pomeranz–Fritsch reaction has aroused genuine interest and has generated all kinds of reflections and discussions. In this article, we will delve into the world of Pomeranz–Fritsch reaction and explore its many facets, with the goal of better understanding its importance and relevance in today's society.

Pomeranz–Fritsch reaction
Named after Cäsar Pomeranz
Paul Fritsch
Reaction type Ring forming reaction

The Pomeranz–Fritsch reaction, also named Pomeranz–Fritsch cyclization, is a named reaction in organic chemistry. It is named after Paul Fritsch (1859–1913) and Cäsar Pomeranz (1860–1926).[1][2] In general it is a synthesis of isoquinoline.[2][3][4]

General reaction scheme

The reaction below shows the acid-promoted synthesis of isoquinoline from benzaldehyde and a 2,2-dialkoxyethylamine.[5]

Pomeranz-Fritsch-Reaktion-Übersichtsreaktion
Pomeranz-Fritsch-Reaktion-Übersichtsreaktion

Various alkyl groups, e.g. methyl and ethyl groups, can be used as substituent R.

In the archetypical reaction sulfuric acid was used as proton donor, but Lewis acids such as trifluoroacetic anhydride and lanthanide triflates have been used occasionally.[1][2][4] Later, a wide range of diverse isoquinolines were successfully prepared.[4]

Reaction mechanism

A possible mechanism is depicted below:[5]

proposed mechanism Pomeranz-Fritsch reaction
proposed mechanism Pomeranz-Fritsch reaction

First the benzalaminoacetal 1 is built by the condensation of benzaldehyde and a 2,2-dialkoxyethylamine. After the condensation a hydrogen-atom is added to one of the alkoxy groups. Subsequently, an alcohol is removed. Next, the compound 2 is built. After that a second hydrogen-atom is added to the compound. In the last step a second alcohol is removed and the bicyclic system becomes aromatic.

Applications

The Pomeranz–Fritsch reaction has general application in the preparation of isoquinoline derivatives.
Isoquinolines find many applications, including:[3][4]

  • vasodilators, a well-known example, papaverine, shown below.

Papaverine

See also

References

  1. ^ a b Pomeranz, C. (December 1893). "Uber eine neue Isochinolinsynthese". Monatshefte für Chemie. 14 (1): 116–119. doi:10.1007/BF01517862. S2CID 95923801.
  2. ^ a b c Fritsch, Paul (January 1893). "Synthesen in der Isocumarin- und Isochinolinreihe". Berichte der Deutschen Chemischen Gesellschaft. 26 (1): 419–422. doi:10.1002/cber.18930260191.
  3. ^ a b Wang, Zerong (2009). Comprehensive organic name reactions and reagents. Hoboken, N.J.: John Wiley. pp. 2256–2259. ISBN 978-0-471-70450-8.
  4. ^ a b c d Kürti, László; Czakó, Barbara (2007). Strategic applications of named reactions in organic synthesis : background and detailed mechanisms ; 250 named reactions (Pbk. ed., . ed.). Amsterdam : Elsevier Academic Press. pp. 358–359. ISBN 978-0-12-429785-2.
  5. ^ a b Li, Jie Jack (2006). Name reactions : a collection of detailed reaction mechanisms ; (3., expanded ed.). Berlin : Springer. pp. 472–474. ISBN 978-3-540-30030-4.