Removal, recovery, and recycling of triarylphosphonium-supported tin reagents for various organic transformations.

Phosphonium-supported tin reagents and catalysts were prepared and were shown to be effective in Stille couplings, radical dehalogenations, radical cyclizations, and carbonyl allylations. Not only could the tin residues be removed from the crude reaction mixture through a phase separation process but also they could be recovered and recycled.

Highly efficient two-step synthesis of C-sp3-centered geminal diiodides.

[reaction: see text] Trisubstituted gem-diiodoalkenes of functionalized chains are efficiently reduced to the corresponding terminal geminal diiodides in high yields upon treatment with the diazene precursor, diethyl 4-(hydrazinosulfonyl)-benzyl phosphonate.

PtCl2-Catalyzed transannular cycloisomerization of 1,5-enynes: a new efficient regio- and stereocontrolled access to tricyclic derivatives.

[reaction: see text] Transannular PtCl(2)-catalyzed cycloisomerizations open a new route to cyclopropanic tricyclic systems. Ketones A or C were efficiently prepared from the same cycloundec-5-en-1-yne precursor B, depending on the substituent at the propargylic position (either benzoate or methoxy).