Regiocontrolled Construction of Functionalized Spiro[4.4]Nonanones Through Mercury(II) Salt-Assisted and Acid-Induced Spiroannulation Reactions
摘要:
The mercuric(II)-assisted spiroannulation reactions of the enol silyl ethers derived from alpha-(4-pentynyl)-cyclopentanones 8a and 11 gave functionalized spiro[4.4]nonanones, exo-3 and exo-4, respectively, in moderate yields. On the other hand, the treatment of 8a and 8b with methanesulfonic acid provided endo-3 in high yield.
is presented. The procedure requires the easily available terminal alkynes as starting materials as well as commercially and readily available reagents such as diethylthiophosphite. The experimental procedure consists of a one‐pot process without any slow addition of one of the reagents.
method for cyclization of alkynes is described. The reaction cascade involves the intermolecular addition of a phenylthiyl radical to a terminal triple bond generating an alkenylradical, followed by a 1,5-hydrogen atom transfer and a 5-exo-trig radicalcyclization. This very efficient tin-free procedure allows one to prepare highly functionalized cyclopentane derivatives as well as fused bicyclic and
Construction of Methylenecycloheptane Frameworks through 7<i>-Exo-Dig</i> Cyclization of Acetylenic Silyl Enol Ethers Catalyzed by Triethynylphosphine−Gold Complex
作者:Hideto Ito、Hirohisa Ohmiya、Masaya Sawamura
DOI:10.1021/ol101860j
日期:2010.10.1
A cationic gold(I) complex bearing a semihollow-shaped triethynylphosphine ligand efficiently catalyzed the 7-exo-dig cyclization of silylenolethers with an ω-alkynic substituent. The reaction gave various methylenecycloheptane derivatives with an exo- or endocyclic carbonyl group. The protocol was applicable not only to cyclic substrates that form bicyclic frameworks but also to acyclic ones with
The mercuric(II)-assisted spiroannulation reactions of the enol silyl ethers derived from alpha-(4-pentynyl)-cyclopentanones 8a and 11 gave functionalized spiro[4.4]nonanones, exo-3 and exo-4, respectively, in moderate yields. On the other hand, the treatment of 8a and 8b with methanesulfonic acid provided endo-3 in high yield.