What is the principle of Shapiro reaction?

The Shapiro reaction or tosylhydrazone decomposition is an organic reaction in which a ketone or aldehyde is converted to an alkene through an intermediate hydrazone in the presence of 2 equivalents of organolithium reagent.

What is the structure of hydrazone?

Hydrazones are a class of organic compounds with the structure R. 1R. 2C=NNH. 2. They are related to ketones and aldehydes by the replacement of the oxygen with the NNH.

Which base is used in Shapiro reaction?

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.

Which base is used in Bamford Stevens 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.

What is Corey winter reaction?

Mechanism. The reaction mechanism involves the formation of a cyclic thiocarbonate from the diol and thiophosgene. The second step involves treatment with trimethyl phosphite, which attacks the sulfur atom, producing S=P(OMe)3 (driven by the formation of a strong P=S double bond) and leaving a carbene.

What is hydrazone formation?

The hydrazone anion has a resonance structure that places a double bond between the nitrogens and a negative charge on carbon. The hydrazone anion is then protonated to form a neutral intermediate. A second weakly acidic N-H bond is deprotonated which causes the formation of N2 gas and a carbanion.

Which one is a hydrazone?

Hydrazones are compounds containing the group >CNN<, and they are typically generated by the elimination of a water molecule between a hydrazine and a carbonyl compound (aldehyde or ketone).

What is the difference between Shapiro and Bamford Stevens reaction?

* Both the Bamford-Stevens reaction and the Shapiro reaction afford alkenes from tosyl hydrazones. * In case of Bamford-Stevens reaction, the more substituted alkene is formed as the thermodynamic product. * Whereas in Shapiro reaction, the less substituted alkene is formed as the kinetic product.

What is olefinic bond?

olefin, also called alkene, compound made up of hydrogen and carbon that contains one or more pairs of carbon atoms linked by a double bond. Olefins are examples of unsaturated hydrocarbons (compounds that contain only hydrogen and carbon and at least one double or triple bond).

How do you convert diol to an alkene?

Conversion of 1,2-diols to alkenes. The cyclic thiocarbonate is available from reaction of the diol with thiophosgene or thiocarbonyldiimidazole, and reacts with added trimethylphosphite via a syn-elimination to the alkene.