Tributylstannyl dienes

Destannylative reactions. l-Trimethylstannyl-2,4-pentadiene reacts with aldehydes and ketones in a -y-selective manner, whereas conjugated dienes are generated from 3-(tributylstannyl)propenyl pyrans. ... 

Coupling on a polymeric support can of course readily be applied to library building by combinatorial techniques. Several groups have reported work of this type thus Havranek and Dvofak [69] have carried out repeated coupling of 3-substituted 3-(tributylstannyl)allyl alcohols with substrates linked to a TentaGel S OH resin to obtain a 21 x 21 library of skipped dienes and a 21 x 21 x 21 library of skipped trienes. 

The lithium[2-tri- -butylstannyl-Z-l-alkenyl]-l-borates, prepared by copper catalyzed addition of Bu3SnB-(OCH3)-9-BBNLb to 1-alkynes (vide supra), are selectively coupled via organopalladium or organocuprate with allylbromide, exclusively at the vinyl boron bond. The process results into the exclusive or predominant formation of 5-tributylstannyl-l,4-(fi)-dienes (Chart 24.8) [38]. 

Bis(9-borabicyclo[3.3.1]nonyl)acetylene is rapidly prepared [39] in situ, utilizing neat bis(tributylstannyl)acetylene and 2 equiv of 9-bromo-9-BBN at -78 °C. The reagent is an effective dienophile and undergoes reactions with simple acyclic dienes at 110 °C. The 1,4-cyclohexadienes are obtained in good yields after debromination of the Diels-Alder adducts with acetic acid (Chart 30.6) [39]. 

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