Dehydrating reagent

Tnfluoroacetic anhydride is an efficient dehydrating reagent [46, 47] In the presence of pyndine, it smoothly dehydrates amides and aldoximes to the correspond ing nitriles [46] and adducts of CH-acids and 1,2,3-indantnone [47] (equation 20)... 

Burgess dehydrating reagent is efficient at generating oiefins from secondary and tertiary aicohois where the first-order thermoiytic Ei (during the eiimination, the two groups ieave at about the same time and bond to each other concurrentiy) mechanism prevaiis. 

Dehydrates secondary and tertiary alcohols to give olefins, but forms ethers with primary alcohols. Cf. Burgess dehydrating reagent. 

Martin, J. C. Arhart, R. J. J. Am. Chem. Soc. 1971, 93, 2339, 2341. J. C. Martin was a professor at the University of Illinois at Urbana, where he discovered the Martin s snl-furane dehydrating reagent. Martin also developed the Dess-Martin periodinane oxidation (page 195) with his student Daniele Dess. 

Nitriles are most commonly prepared via the conversion of carboxylic acids to primary amides, followed by dehydration with boiling acetic anhydride, or other commonly employed dehydration reagents, e.g. SOCI2 or POCI3. This is a useful synthesis for amide, because it is not limited by steric hindrance. Alkyl nitriles can be prepared by the action of metal cyanides on alkyl halides (see Section 5.5.2). 

Look, G. C. Murphy, M. M. Campbell, D. A. Gallop, M. A. Trimethylor-thoformate A Mild and Effective Dehydrating Reagent for Solution and Solid-Phase Imine Formation, Tetrahedron Lett. 1995, 36, 2937. 

The synthesis of hexakis(cyclohexylsilsesquioxane) in 10% yield by the treatment of cyclohexyltrichlorosilane with water was first reported in 1965108. The X-ray structure of hexakis(cyclohexylsilsesquioxane) was determined by Molloy and coworkers in 1994109. The hexasilsesquioxanes (80) substituted by /-butyl or 1,1,2-trimethylpropyl groups are prepared by condensation of the corresponding silanetriol (78) or tetrahydroxysiloxane (79) using dicyclohexylcarbodiimide (DCC) as a dehydrating reagent in DMSO or DMF (Scheme 20)no. 

Conversion of amides into nitriles may be effected by treating them with a variety of dehydrating reagents. Among those that have been employed are phosphorus pentoxide, phosphorus pentachloride,170 ethyl polyphosphate,171... 

The only method for the synthesis of dioxetanones reported within the last decade relies on the cyclization of a-hydroperoxy acids. This method furnished the desired dioxetanones in reasonable yields and relies on removal of water by the use of a dehydrating reagent such as dicyclohexylcarbodiimide (DCC). For example, spiro-adamantyl dioxetanone was prepared in 55% yield utilizing this method (Equation 7) <1997JOC1623>. The reader is directed to CHEC-II(1996) <1996CHEC-II(1B)1041> for examples prior to 1996. 

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