Regioselectivity Switch Achieved in the Palladium Catalyzed α-Arylation of Enones by Employing the Modified Kuwajima–Urabe Conditions
摘要:
A new regioselective approach to the synthesis of alpha-aryl enones is reported. This represents an important application of the Kuwajima-Urabe protocol toward the synthesis of this simple albeit complex functional array. Several a-aryl enones were synthesized by the palladium catalyzed arylation of triethylsilylenol ethers of enones with high regioselectivity and broad scope, utilizing sterically encumbered electron-rich phosphine ligands to drive the reaction.
Cyclic α-Alkoxyphosphonium Salts from (2-(Diphenylphosphino)phenyl)methanol and Aldehydes and Their Application in Synthesis of Vinyl Ethers and Ketones via Wittig Olefination
作者:Wenhua Huang、Hong-Ying Rong、Jie Xu
DOI:10.1021/acs.joc.5b01031
日期:2015.7.2
synthesized from (2-(diphenylphosphino)phenyl)methanol and aldehydes in 36–89% yields. These phosphonium salts are bench-stable solids and undergo Wittig olefination with aldehydes under basic conditions (K2CO3 or t-BuOK) to form benzylic vinyl ethers, which are readily hydrolyzed to 1,2-disubstituted ethanones under acidic conditions. The formation mechanism of these phosphonium salts via hemiacetal
环状α-烷氧基phosph盐是由(2-(二苯基膦基)苯基)甲醇和醛合成的,产率为36-89%。这些phospho盐是稳定的固体,并在碱性条件下(K 2 CO 3或叔丁基)与醛进行Wittig烯化反应,形成苄基乙烯基醚,该苄基乙烯基醚在酸性条件下容易水解为1,2-二取代的乙酮。还提出了这些phospho盐通过半缩醛的形成机理。
Kleucker, Chemische Berichte, 1922, vol. 55, p. 1648