Prins reaction



The Prins reaction is an esters are formed.

History

The original reactants employed by Dutch chemist Prins in his 1919 publication were anethole.

In 1937 the reaction was investigated as part of a quest for di-olefins to be used in synthetic rubber.

Reaction mechanism

The concertedness, the charge built-up will be modest.

The three reaction modes open to this oxo-carbenium intermediate are:

  • in blue: capture of the carbocation by water or any suitable nucleophile through 5 to the 1,3-adduct 6.
  • in black: proton abstraction in an ene reaction in scheme 6.
  • in green: capture of the carbocation by additional carbonyl reactant. In this mode the positive charge is dispersed over oxygen and carbon in the resonance structures 8a and 8b. Ring closure leads through intermediate 9 to the styrene to 4-phenyl-m-dioxane [4].
  • in gray: only in specific reactions and when the carbocation is very stable the reaction takes a shortcut to the oxetane 12. The photochemical Paterno-Büchi reaction between alkenes and aldehydes to oxetanes is more straightforward.

Variations

Many variations of the Prins reaction exist because it lends itself easily to cyclization reactions and because it is possible to capture the oxo-carbenium ion with a large array of nucleophiles. The halo-Prins reaction is one such modification with replacement of protic acids and water by room temperature.

The Prins-pinacol reaction is a aldehyde group in the final product as a mixture of cis and trans isomers with modest diastereoselectivity.

References

  1. ^  Condensation of formaldehyde with some unsaturated compounds H. J. Prins, Chemisch Weekblad, 16, 64, 1072, 1510 1919
  2. ^  Chemical Abstracts 13, 3155 1919
  3. ^  The Olefin-Aldehyde Condensation. The Prins Reaction. E. Arundale, L. A. Mikeska Chem. Rev.; 1952; 51(3); 505-555. Link
  4. ^  4-Phenyl-m-dioxane R. L. Shriner and Philip R. Ruby Organic Syntheses, Coll. Vol. 4, p.786 (1963); Vol. 33, p.72 (1953). Article
  5. ^  Syn- and Anti-Selective Prins Cyclizations of ,-Unsaturated Ketones to 1,3-Halohydrins with Lewis Acids R. Brandon Miles, Chad E. Davis, and Robert M. Coates J. Org. Chem.; 2006; 71(4) pp 1493 - 1501; Abstract
  6. ^  Scope and Facial Selectivity of the Prins-Pinacol Synthesis of Attached Rings J. Org. Chem.; 2006; 71(4) pp 1581 - 1587; Abstract
 
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