Corey-Seebach synthesis

In an extension of the procedure, thiols react with gem-dihaloalkanes (Table 4.4) to produce thioacetals [ 10,20-23] and the reaction can be employed in the Corey-Seebach synthesis of aldehydes and ketones (see ref. 24 and references cited therein), gem-Dichlorocyclopiopanes having an electron-withdrawing group at the 2-position react with thiols to produce the thioacetals [25]. In the corresponding reaction of the thiols with biomochloromethane exclusive nucleophilic substitution of the bromo group by the thiolate anion occurs to yield the chloromethyl thioethers [13, 14] (Table 4.5). 

E. J. Corey and D. Seebach, Synthesis of 1, n-dicarbonyl derivatives using carbanions from... 

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

The following experimental procedures illustrate the use of these Teagents 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). 

The use in organic synthesis of carbanions stabilized by one or more adjacent thioether groups is now a well-established technique [272-275]. A landmark in this development was the work of Corey and Seebach on 1,3-dithianes [276]. They pointed out the use of the anions of 1,3-dithianes as... 

Dithioacetals are important synthons in organic synthesis as acyl-masked reactants. The synthesis carried out by Corey and Seebach [69] is a two-step procedure alkylation with a reactive iodo electrophile followed by monomethyla-tion of disulfide [Eq. (36)]. 

As an example, the methyl group in thioanisole can be metalated using n-butyllithium to produce phenylthiomethyllithium by contrast, anisole under the same conditions is metalated at an ortho position. This reaction has been of little practical use in synthesis since the maximum yield of the lithium intermediate is only about 35%. However, Corey and Seebach (23) recently developed an excellent procedure for generating phenylthiomethyllithium in essentially quantitative yield by reaction between equimolar amounts of thioanisole, n-butyllithium, and DABCO in tetrahydrofuran at 0°C. 

Dithiane metallate alkylation was introduced by Corey and Seebach in 1965 and has served well as a method for forging carbon-carbon bonds at a masked carbonyl group by nucleophilic displacement. The method, an example of an umpolung process, has found extensive use for advanced fragment assembly in target-directed synthesis. Contributions from the Smith research group at the University of Pennsylvania, in particular, have served to demonstrate the power of this... 

Although 1,3-dithianes have been known for some time, their importance for organic synthesis has only been recognized since 1965. Corey and Seebach found that 1,3-dithiane and 2-monosubstituted... 

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... 

The importance of 1,3-difhianes for organic synthesis has been recognized since 1965 (Corey and Seebach). On treatment with n-butyllithium in THF at —40°C,... 

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