Bamford-Stevens-Shapiro Olefination

The base catalyzed decomposition of arylsulfonylhydrazones of aldehydes and ketones to provide alkenes is called the Bamford-Stevens reaction. When an organolithium compound is used as the base, the reaction is termed the Shapiro reaction. The most synthetically useful protocol involves treatment of the substrate with at least two equivalents of an organolithium compound (usually MeLi or BuLi) in ether, hexane, or tetramethylenediamine. The in s/ft formed alkenyllithium is then protonated to give the alkene. The above procedure provides good yields of alkenes without side reactions and where there is a choice, the less highly substituted alkene is predominantly formed. Under these reaction conditions tosylhydrazones of a,(3-unsaturated ketones give rise to conjugated dienes. It is also possible to trap the alkenyllithium with electrophiles other than a proton. 

The first enantioselective total synthesis of (-)-myltaylenol was achieved in the laboratory of E. Winterfeldt. The authors used an intramolecular Diels-Alder cycloaddition and the Shapiro reaction as key transformations to construct the unusual carbon framework of this sesquiterpenoid alcohol natural product, which contains three consecutive quaternary carbon atoms. 

In the laboratory of K. Mori the task of determining the absolute configuration of the phytocassane group of phytoalexins was undertaken. To this end, the naturally occurring (-)-phytocassane D was synthesized from (R)-Wieland-Miescher ketone. During the synthesis, a tricyclic ketone intermediate was subjected to the Shapiro olefination reaction to give the desired cyclic alkene in good yield. 

A novel class of chiral indenes (verbindenes) was prepared from enantiopure verbenone by K.C. Rupert and coworkers who utilized the Shapiro reaction and the Nazarov cyciization as the key transformations. The bicyclic ketone substrate was treated with triisopropylbenzenesulfonyl hydrazide to prepare the trisyl hydrazone that was then exposed to n-BuLi. The resulting vinyllithium intermediate was reacted with various aromatic aldehydes to afford the corresponding allylic alcohols. 

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Related reactions Bamford-Stevens-Shapiro olefination ... 

The Bamford-Stevens reaction and the Shapiro reaction share a similar mechanistic pathway. The former uses a base such as Na, NaOMe, LiH, NaH, NaNHa, heat, etc., whereas the latter employs bases such as alkyllithiums and Grignard reagents. As a result, the Bamford-Stevens reaction furnishes more-substituted olefins as the thermodynamic products, while the Shapiro reaction generally affords less-substituted olefins as the kinetic products. 

The reduction of a carbonyl group to an olefin has been accomplished by the Shapiro modification5 of the Bamford-Stevens reaction and by the hydride reduction of the corresponding enol ether,6 enol acetate,7 or en-amine.8 The nickel reduction of the thioketal has also been used successfully.9... 

BAMFORD - STEVENS CAGLIOTI. SHAPIRO delination Conversion ol ketones to olefins via tosyl hydrazones with NaOR, LAH, LDA or BuLi... 

The Bamford-Stevens synthesis is related to the Shapiro reaction (Shapiro and Heath, 1967 reviews Shapiro, 1976 Adlington and Barrett, 1983), in which a 4-toluenesulfonyl hydrazone of an aldehyde or a ketone is treated with at least two equivalents of a very strong base, usually, methyllithium (see Organic Syntheses examples of Chamberlin et al., 1983, and Shapiro et al., 1988). The Shapiro reaction leads to an olefin by a hydrogen shift. The mechanism has been proposed by Casanova and Waegell (1975) as given in (2-34). This mechanism involves a diazenide anion 2.81 as intermediate. 

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