Intramolecular silicon-assisted cross-coupling reactions: general synthesis of medium-sized rings containing a 1,3-cis-cis diene unit.
The combination of ring-closing metathesis and Pd-catalyzed, silicon-assisted intramolecular cross-coupling has been developed to provide an effective and powerful method for construction of medium-sized rings with an internal 1,3-cis-cis diene unit. Allylic alcohols bearing a Z-iodoalkenyl tether can be silylated with chlorodimethylvinylsilane and subjected to Mo-catalyzed ring-closing metathesis to form unsaturated siloxanes. Activation of the siloxane with tetrabutylammonium fluoride in the presence of [allylPdCl](2) leads to high yielding ring-closing reactions to form 9-, 10-, 11- and 12-membered rings. Extension to the synthesis of 9-membered ring unsaturated ethers has also been accomplished. Noteworthy features of this process include: (1) a highly stereospecific intramolecular coupling process, (2) flexible positioning of the hydroxy group, and (3) potential extension to other medium-sized carbocycles and heterocycles.
Denmark
Scott E
SE
Roger Adams Laboratory, Department of Chemistry, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Yang
Shyh-Ming
SM
D000475:Alkenes / Q000138:chemical synthesis*; D006844:Hydrocarbons, Cyclic / Q000138:chemical synthesis*; D009942:Organometallic Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*; D013237:Stereoisomerism
D000475:Alkenes; D006844:Hydrocarbons, Cyclic; D009942:Organometallic Compounds; D010165:Palladium; D012825:Silicon