A convergent method for the stereoselective synthesis of trisubstituted alkenes
摘要:
A method for the stereoselective, convergent synthesis of trisubstituted alkenes has been developed. The procedure features the synthesis of allylic alcohols 9 by coupling an aldehyde with a vinyl organometallic reagent. Treatment of 9 with carbon disulfide and methyl iodide gave the intermediate allylic xanthates 10 that underwent facile [3,3]-sigmatropic rearrangement to give the dithiocarbonates 11 and 12, radical reduction of which gave the (E)-alkenes 13 as the major products.
Nickel-Catalyzed Regio- and Stereoselective Reductive Coupling between Methylenecyclopropanes, Aldehydes, and Triethylborane with Retention of the Cyclopropane Ring
Running rings: The first regio‐ and stereoselective reductive coupling between methylenecyclopropanes, aldehydes, and triethylborane with retention of the cyclopropanering was achieved using a nickel–phosphine catalyst (see scheme). The reductive coupling reaction constructed a stereo‐defined cyclopropanering with formation of a quaternary stereogenic carbon center.