Shapiro Reaction Mechanism, Examples, and Applications

Table of Contents

Shapiro reaction mechanism, examples, and applications in organic chemistry have been discussed here:

Shapiro reaction

Robert H. Shapiro discovered this reaction in 1967. Shapiro reaction is such an organic reaction that leads to the formation of alkene when tosyl hydrazone of an aldehyde or ketone is treated with a strong base. It uses bases such as alkyl lithium & Grignard reagents and affords less-substituted alkenes. Two equivalents of an organolithium compound are used in this process.

The Shapiro reaction is a variant of the Bamford−Stevens reaction. Basically, the reaction is an elimination reaction accompanied by a hydrogen shift.

Shapiro reaction examples

Some of the examples of Shapiro reactions are

Shapiro reaction examples, Shapiro reactions

Shapiro reaction mechanism

Two equivalents of RLi are required, and the hydrogen in the product results from the water rather than the adjacent carbon are the two major pieces of evidence of this reaction.

The mechanism of Shapiro reaction takes place as

Shapiro reaction mechanism, Shapiro reaction, Shapiro reaction examples
Figure source: By <a href=”//commons.wikimedia.org/wiki/User:Dissolution” title=”User:Dissolution”>Dissolution</a> – <span class=”int-own-work” lang=”en”>Own work</span>, CC BY-SA 3.0, Link

In another way, the mechanism can be also carried out in the following way also:

Shapiro reaction mechanism, Shapiro reaction, Shapiro reaction examples

Application of Shapiro reaction

Some of the major applications of Shapiro reactions are discussed below:

  • used to generate olefins
  • The Shapiro reaction was used in the Nicolaou Taxol total synthesis.

Shapiro reaction Video

FAQs/MCQs

What is Shapiro reaction?

Treatment of tosylhydrazone of an aldehyde or ketone is treated with strong base that leads to the formation of alkene called as Shapiro reaction.

How to distinguish between Shapiro reaction and Bamford steven reaction?

The Bamford-Stevens reaction is a version of the Shapiro reaction. Bases such as alkyl lithium and Grignard reagents are used in the Bamford-stevens reaction, whereas bases such as Na, NaOMe, LiH, NaH, NaNH2, and others are used in the latter. As a result, the Shapiro reaction produces less-substituted olefins (kinetic products), whereas the Bamford-Stevens process produces more-substituted olefins (the thermodynamic products).

References

  • March, J., Advanced Organic Chemistry, Wiley Eastern Limited, 1986.
  • Skyes, P., A Guide Book to Mechanism in Organic Chemistry, Second edition, Orient Longman Ltd., 1988.
  • Shapiro, R. H.; Duncan, J. H.; Clopton, J. C. J. Am. Chem. Soc. 1967, 89, 471–472.
  • Shapiro, R. H.; Heath, M. J. J. Am. Chem. Soc. 1967, 89, 5734–5735.

Shapiro Reaction Mechanism, Examples and Applications

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