Department of Chemistry, University of California, Berkeley, California 94720, USA.
J Am Chem Soc. 2012 Feb 8;134(5):2742-9. doi: 10.1021/ja210388g. Epub 2012 Jan 31.
The discovery of complementary methods for enantioselective transition metal-catalyzed cyclization with silyloxyenynes has been accomplished using chiral phosphine ligands. Under palladium catalysis, 1,6-silyloxyenynes bearing a terminal alkyne led to the desired five-membered ring with high enantioselectivities (up to 91% ee). As for reactions under cationic gold catalysis, 1,6- and 1,5-silyloxyenynes bearing an internal alkyne furnished the chiral cyclopentane derivatives with excellent enantiomeric excess (up to 94% ee). Modification of the substrate by incorporating an α,β-unsaturation led to the discovery of a tandem cyclization. Remarkably, using silyloxy-1,3-dien-7-ynes under gold catalysis conditions provided the bicyclic derivatives with excellent diastereo- and enantioselectivities (up to >20:1 dr and 99% ee).
使用手性膦配体，实现了对硅氧基炔丙基与手性膦配体的对映选择性过渡金属催化环化反应的互补方法的发现。在钯催化下，带有末端炔烃的 1,6-硅氧基炔丙基可得到具有高对映选择性（高达 91%ee）的五元环。对于阳离子金催化下的反应，带有内部炔烃的 1,6-和 1,5-硅氧基炔丙基以优异的对映体过量（高达 94%ee）得到手性环戊烷衍生物。通过在底物中进行 α,β-不饱和改性，发现了串联环化反应。值得注意的是，在金催化条件下使用硅氧基-1,3-二烯-7-炔，可以得到具有优异的非对映和对映选择性（高达 >20:1dr 和 99%ee）的双环衍生物。
