Mechanism of the reaction of trialkyl phosphites with α-halogenoacetophenones in alcoholic solvents
作者:Imre Petneházy、György Keglevich、László Tőke、Harry R. Hudson
DOI:10.1039/p29880000127
日期:——
suggested betaine as a common intermediate in alcoholic solution. Further reaction then involvesrearrangement to give the vinyloxyphosphonium species (and hence the Perkow product) or protonation followed by dealkylation to give the α-hydroxyphosphonate. Evidence for the possible formation of dehalogenated ketone via solvolysis of the α-hydroxyphosphonium intermediate is also presented.
The reactions of phenacyl benzoates, X–C6H4COCH2OCOC6H4–Y (1a–i), with trialkylphosphites (2a–c) giving dialkyl 1-arylvinyl phosphates (3a–d) in high yields were studied kinetically using the GLC technique. The overall reactions are second order, and exhibit a moderate solvent effect and catalysis upon the addition of certain organic acids. The activation energy, Ea=16.5 kcal/mol, and entropy, ΔS\eweq=−38
Catalyst-Free Difunctionalization of Activated Alkenes in Water: Efficient Synthesis of β-Keto Sulfides and Sulfones
作者:Huamin Wang、Guangyu Wang、Qingquan Lu、Chien-Wei Chiang、Pan Peng、Jiufu Zhou、Aiwen Lei
DOI:10.1002/chem.201603041
日期:2016.10.4
Difunctionalization of activated alkenes, a powerful strategy in chemical synthesis, has been accomplished for direct synthesis of a series of β‐keto sulfides and β‐keto sulfones. The transformation, mediated by O2, proceeds smoothly in water and without any catalyst. Prominent advantages of this method include mild reaction conditions, purification simplicity, and gram‐scale synthesis, underlining
π-Lewis basic palladium (0) catalysis, delivering benzofuran-fused eight-membered heterocycles in high efficiency, regio- and enantioselectivities. Highly diastereoselective derivatizations of the resultant eight-membered cyclic alkenes provide a facile access to diverse fused polycyclic compounds in excellent efficiency.
Electrophilic Trifluoromethylthiolation of Allylsilanes with Trifluoromethanesulfanamide
作者:Jianbo Liu、Lingling Chu、Feng-Ling Qing
DOI:10.1021/ol400032g
日期:2013.2.15
A CH3COCl-promoted allylic trifluoromethylthiolation of allylsilanes with trifluoromethanesulfanamide has been described. The method allows for an efficient synthesis of a wide range of allylic trifluoromethylthiolated compounds under mild conditions.