Corey-Seebach reagent

COREY-SEEBACH Dithiane Reagents Dithianes as acyl anion equivalents useful for synthesis of carbonyl compounds. 

We owe to Corey and Seebach [302] an efficient procedure for the generation of phenylthiomethyllithium (PhSCH2Li), opening the way for practical applications. They found that this reagent was produced in about a 97% yield through reaction of equimolar amounts of n-butyllithium, DABCO and thioanisole in THF at 0°C for 45 min. 

The action of buQ Uithium on thioanisole in THF generates (phenylthio)methyllithium in a low yield of 35%. - Corey and Seebach found that reaction of equimolar amounts of bu Uithium, DABCO and thioanisole in THF at 0 "C produces (phenylthio)methyllithium in ca. 97% yield. Dimethyl sulfide can be metalated with a butyllithium-TMEDA complex at room temperature (equation 1). Treatment of chloromethyl p-tolyl sulfide with magnesium produces the corresponding Grignard reagent a reaction temperature between 10 and 20 C is crucial for its efficient generation (equation 2). ... 

Corey, E. J., Seebach, D. Carbanions of 1,3-dithianes. Reagents for C-C bond formation by nucieophiiic dispiacement and carbonyi addition. Angew. Chem., Int. Ed. Engl. 1965,4, 1075-1077. 

The following experimental procedures illustrate the use of these reagents for the synthesis of the monosulfoxide (2) and monosulfone (3) derived from the useful 1,3-dithiane (1) of Corey and Seebach (they can and have been used in a similar fashion). 

Review. Seebach and Corey have published a general paper on the preparation and metalation of 1,3-dithianes and examples of the reaction of 2-lithio-l,3-dithianes with electrophilic reagents (alkyl halides, carbonyl compounds, acids, and oxides). The value of these sulfur-stabilized anionic reagents is that they are equivalent to acyl anions (a), in which the normal polarity of the carbonyl group is reversed (reversible umpolung). 

Corey and Seebach have reported the use of 2-lithio-l,3-dithianes as useful reagents in organic synthesis. The method involves the use of... 

Yus, M. Najera, C. Foubelo, F. The Role of 1,3-Dithianes in Natural Product Synthesis Tetrahedron 2003, 59, 6147-6212. Groebel, B. T. Seebach, D. Umpolung of the Reactivity of Carbonyl Compounds Through Sulfur-Containing Reagents Synthesis 1977, 357-402. Seebach, D. Corey, E. J. Generation and Synthetic Applications of 2-Lithio-l,3-dithianes /. Or f. Chem. 1975, 40, 231-237. 

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