Addition to carbon-sulfur double

A number of reactions of organomagnesium compounds, giving rise to new organomagnesium compounds, are covered in other chapters. They include addition to carbon-carbon multiple bonds (see Chapter 4), addition to isonitriles (see Section 5.4), addition to carbon monoxide (see Section 6.5), thiophilic addition to carbon-sulfur double bonds (see Chapter 7) and addition to carbenes (see Section 9.1). 

Dipolar addition to carbon-sulfur double bonds O... 

A third tin-based method of free-radical production also utilizes tin radical addition to a carbon-sulfur double bond as a key reaction. In this case a thio-noester (usually a thiono carbonate) is the reactant. As in the previous method, addition of tin to the sulfur atom is followed by fragmentation to a carbon-centered radical. 

Thioaldehyde S-oxides behave as dienophiles with 1,3-dienes [241]. Cycloaddition involves the carbon-sulfur double bond of the heterocumulene to furnish dihydro-2H-thiapyran S-oxides (Table 6, entry 1). The cis trans product ratio was found to depend upon the initial diene/sulfine ratio. A large excess of diene selectively provided the cis cycloadducts, as a result of a stereospecific reaction of the (Z) sulfine. With a produced proportion of diene, mixtures of cis trans isomers are obtained, with a preference for the cis compound. The Italian authors have demonstrated that the slower reaction allows a (Z) to (E) isomerisation of the sulfines prior to addition. 

This methodology of chemo- and regioselective cycloaddition for the synthesis of stable anionic zirconocene complexes can be extended to other phosphorus metallocenes. As an example, addition of phenylisothiocyanate to 5 led to the expected complex 30. However, the same reaction performed with 5 and carbon disulfide afforded unique dimeric species 31 arising from successive (or concomitant) cycloaddition reactions on the two carbon sulfur double bonds of CS2 (Scheme 8). 

Dioxene and 3,4-dihydro-2//-pyran have been reported to afford (2 + 2)-cycloadducts (20) via addition to the carbon-sulfur double bond of hexafluorothioacetone at —78°.47 Although no conclusive evidence has been given, the 2-oxa-8-thiabicyclo[4.2.0]octane structure (20b) was preferred to others on the basis of mass spectrometric data.47... 

IV Addition of a tin-methoxide linkage to the carbon-sulfur double bond in ... 

Diphenylthiirene 1-oxide reacts with hydroxylamine to give the oxime of benzyl phenyl ketone (79JA390). The reaction probably occurs by addition to the carbon-carbon double bond followed by loss of sulfur monoxide (Scheme 80). Dimethylamine adds to the double bond of 2,3-diphenylthiirene 1,1-dioxide with loss of sulfur dioxide (Scheme 81) (75JOC3189). Azide ion gives seven products, one of which involves cleavage of the carbon-carbon bond of an intermediate cycloadduct (Scheme 81) (80JOC2604). 

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