Catalysis and Chemodivergence in the Interrupted, Formal Homo-Nazarov Cyclization Using Allylsilanes
作者:Raynold Shenje、Corey W. Williams、Katherine M. Francois、Stefan France
DOI:10.1021/ol503305r
日期:2014.12.19
A chemodivergent, Lewis acid catalyzed allylsilane interrupted formal homo-Nazarov cyclization is disclosed. With catalytic amounts of SnCl4 and in the presence of allyltrimethylsilane, a formal HosomiSakurai-type allylation of the oxyallyl cation intermediate is observed. A variety of functionalized donoracceptor cyclopropanes and allylsilanes were shown to be amenable to the reaction transformation and the allyl products were formed in up to 92% yield. Under dilute reaction conditions with stoichiometric SnCl4 and at reduced temperatures, an unusual formal [3 + 2]-cycloaddition between the allylsilane and the oxyallyl cation occurred to give hexahydrobenzofuran products in up to 69% yield.
Indium-Catalyzed Homo-Nazarov Cyclizations of Alkenyl Cyclopropyl Ketones
作者:Dadasaheb V. Patil、Lien H. Phun、Stefan France
DOI:10.1021/ol102497w
日期:2010.12.17
Herein, an efficient Lewis acid catalyzed protocol for the homo-Nazarov cyclizations of alkenyl cyclopropylketones is reported. Alkenes bearing β-hydrogens (or silyl groups) provide 1.5:1 mixtures of methylene cyclohexenols and cyclohexenones. When no β-hydrogens (or silyl groups) are present, only cyclohexenones are observed. Products are rapidly formed in good to high yields (up to 93%) under mild