Sulfonate esters reaction with Grignard reagents

The formation of halogenation products from Grignard reagents and sulfonic acid anhydrides is the result of an oxidative reaction pathway . This side-reaction can be reduced by using sulfonic acid esters, however, in these cases alkylations as well as twofold sulfonylations (cf. corresponding results with sulfonyl fluorides ) are competing (equations 64 and 65). 

Li2CuCl4 in THF-NMP efficiently catalyzes the reaction of alkenyl Grignard reagents with primary alkyl bromides. Functional groups (ketone, ester, nitrile, sulfonate) are tolerated in this reaction (Scheme 34).91... 

Nicolaou et al. used the same sulfonate ester system to prove the compatibility of sulfonate esters with carbon-carbon bond-forming reactions [305]. Functionalization and a simultaneous cleavage procedure have been applied successfully by the use of Grignard reagents 585, the Nagata reagent 583 and stannane as well as lithium organic compounds (579, 581). All compounds namely a-allyl ketone 580, epoxide 582, a-cyano ketone 584 and carbinol 586 could be isolated in 65-85% yield (Scheme 85). 

Another feasible combination for iron-catalyzed cross-coupling reactions is those of functionalized arylcopper reagents as nucleophiles with alkenyl sulfonates as electrophiles. Tris(acetylacetonato)iron (10 mol%) functions as a precatalyst in this system that tolerates ester or cyano groups. The required arylcopper reagents can be prepared from the corresponding Grignard reagents by treatment with copper(I) cyanide di(lithium chloride) (Scheme 4—217). ... 

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